Construction method for tunnel partition grading excavation and collaborative support

Abstract

The application discloses a tunnel partition grading excavation and collaborative support construction method, belongs to the technical field of tunnel construction, solves the problems of poor matching of excavation and support timing, inaccurate surrounding rock deformation control, lack of system closed-loop management and control, and easy instability of surrounding rock and uneven stress of support structure, and its technical scheme is that: first, according to the geological survey data, the surrounding rock grade and the construction section are divided to form a construction basic unit, a five-dimensional corresponding database is established by presetting parameters, then the surrounding rock deformation is excavated and monitored in real time according to the preset mode, the deformation rate and the support intervention time threshold are compared, the conventional collaborative support or support reinforcement mechanism is executed respectively, the single cycle construction is completed, the section is switched for repeated operation, and the whole tunnel excavation-monitoring-support-reinforcement closed-loop construction is realized. The application is mainly used for the partition grading excavation and collaborative support construction of various tunnels, can improve the construction safety and support reliability, and guarantees the tunnel construction quality.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology. More specifically, this invention relates to a construction method for zoned and graded excavation and coordinated support of tunnels. Background Technology

[0002] In the field of tunnel engineering construction, zoned and graded excavation and coordinated support are key construction methods to ensure construction safety and control the deformation of surrounding rock. At present, there are still many technical problems that need to be solved when carrying out zoned and graded excavation and coordinated support construction in tunnels, which affect the stability and rationality of construction.

[0003] In existing construction methods, the classification of tunnel surrounding rock and the division of construction sections lack a systematic corresponding design. Instead, a rough zoning is based solely on geological survey results, failing to establish standardized construction units. This results in a lack of unified reference for the selection of excavation and support technologies, easily leading to mismatches between technologies and actual geological conditions. Furthermore, a systematic parameter database for different surrounding rock grades and construction zones is not established before construction. The setting of parameters such as excavation methods, support structure forms, and support intervention times relies heavily on construction experience, lacking precise pre-set standards and exhibiting poor coordination between parameters, making it difficult to form standardized construction guidance. During the excavation phase, the monitoring of surrounding rock deformation after a single cycle of excavation is relatively singular, and the monitoring data is not linked to the timing of support intervention. Support operations are carried out only at fixed time points, failing to adjust support strategies according to the actual deformation rate of the surrounding rock, easily leading to poor matching between excavation and support sequences. When the deformation rate of the surrounding rock exceeds expectations, the existing support and reinforcement methods lack clear implementation standards, and the adjustment of reinforcement parameters also relies on experience. There is no unified basis for optimizing parameters such as steel arch spacing and grouting pressure, making it difficult to form a targeted reinforcement and synergistic support structure. This makes it impossible to effectively control the further deformation of the surrounding rock and easily leads to problems such as arch crown settlement and sidewall convergence.

[0004] Furthermore, during construction, no advance detection or process adjustments were made for local geological variations within the same surrounding rock section. Faced with sudden geological conditions such as fractured zones and localized water-rich points, the original excavation and support parameters were still used, which easily led to increased construction disturbance. The excavation intervals for parallel construction in multiple sections were not quantitatively defined, resulting in overlapping excavation disturbances from adjacent work faces and the formation of stress concentration areas. Simultaneously, the impact of environmental parameters such as groundwater pressure and surrounding rock temperature on the support effect was not considered during construction. Grouting pressure and grouting material ratios were not dynamically adjusted according to environmental parameters, easily leading to problems such as poor water-blocking effect and abnormal solidification speed of grouting materials, affecting the stability of the support structure. In the detailed aspects of support construction, loose rocks and dust on the excavation face were not thoroughly cleaned, resulting in poor adhesion between the initial shotcrete and the surrounding rock interface, which easily led to interface delamination. Furthermore, the lack of specialized methods for testing interface density resulted in the support structure and surrounding rock failing to deform in tandem, reducing the support effectiveness. Additionally, the connection between support structures in adjacent construction cycles lacked standardized methods; the overlap of steel arches and anchor bolts had no clear length requirements, and the overlap locations were not reinforced, easily creating weak points in the support structure and causing discontinuity in stress distribution between successive cycles, posing a potential risk of sudden stress changes. These problems made it difficult to achieve closed-loop construction of zoned and graded excavation and coordinated support in the tunnel, hindering the improvement of tunnel construction quality and safety.

[0005] In summary, existing technologies suffer from the following systemic defects: Discretized decision-making: Rock grading, zoning, support design, and monitoring feedback are relatively independent processes, relying on manual experience and lacking a unified data center and linkage rules; Lagging control: Support timing is based on fixed timeframes, and adjustments are made based on the "result" of deformation rather than its "rate trend," failing to achieve proactive control; Coarse-grained parameters: Faced with geological variations or abnormal deformation, reinforcement measures lack quantitative standards, relying on "trial and error based on experience." Therefore, a tunnel construction method capable of achieving full-process, digital, and adaptive closed-loop management is urgently needed. Summary of the Invention

[0006] This invention provides a construction method for segmented and graded excavation and coordinated support of tunnels. It solves the technical problems in existing segmented and graded excavation and coordinated support construction methods, such as poor matching of excavation and support sequence, inaccurate control of surrounding rock deformation, and lack of systematic closed-loop management, which easily leads to surrounding rock instability and uneven stress on the support structure. This method is mainly applicable to segmented and graded excavation and coordinated support construction of various types of tunnels, improving construction safety and support reliability, and ensuring tunnel construction quality.

[0007] To achieve these objectives and other advantages according to the present invention, a construction method for segmented and graded excavation and coordinated support of tunnels is provided, comprising the following steps:

[0008] S1. Based on the geological survey data of the tunnel project, the surrounding rock grade of the tunnel is classified along the axial direction in advance, and the construction sections are divided in combination with the cross-sectional structure, forming a construction basic unit that is classified longitudinally according to the surrounding rock grade and divided laterally according to the cross-sectional structure.

[0009] S2. For each construction foundation unit, pre-set the excavation method, support structure form, support intervention time threshold and hourly deformation rate warning threshold corresponding to the surrounding rock grade, and establish a five-dimensional corresponding database of zone-grade-process-sequence-parameter. The database contains the excavation advance, initial shotcrete thickness, steel arch frame model and spacing, support intervention time threshold, hourly arch crown settlement rate warning threshold and hourly perimeter convergence rate warning threshold corresponding to different surrounding rock grades and construction zones, and is stored in a solidified data table format.

[0010] S3: Perform zoned and graded excavation on the current construction section according to the preset excavation method. After completing a single cycle of excavation, immediately monitor the arch subsidence and surrounding convergence of the surrounding rock within 10 m behind the working face in real time.

[0011] S4: Compare the hourly deformation rate of the surrounding rock obtained from real-time monitoring with the hourly deformation rate warning threshold, and determine whether the current excavation completion time has reached the corresponding support intervention time threshold.

[0012] S5: If the hourly deformation rate of the surrounding rock does not exceed the hourly deformation rate warning threshold, wait until the excavation completion time reaches the support intervention time threshold, and then perform conventional collaborative support according to the preset support strength and structural form; if the hourly deformation rate of the surrounding rock exceeds the hourly deformation rate warning threshold, proceed to step S6 and do not execute this step again.

[0013] S6: Immediately activate the support reinforcement mechanism; when the hourly deformation rate of the surrounding rock exceeds 1.2 times the hourly deformation rate warning threshold, on the basis of conventional collaborative support, increase the spacing of the steel arch frame, add locking anchor rods and increase the grouting pressure to form a reinforced collaborative support structure;

[0014] S7: After completing the current cycle of excavation and reinforced support, switch to the next construction section and repeat steps S3 to S6 to achieve closed-loop construction of full tunnel excavation-monitoring-support-reinforcement section by section.

[0015] Preferably, in S1, the surrounding rock grade of the tunnel along the axial direction is classified, and the construction sections are divided in combination with the cross-sectional structure. Specifically, the tunnel is divided into multiple continuous construction sections along the longitudinal direction. Each construction section is divided into Class III, Class IV, and Class V surrounding rock sections according to the geological survey results. Each construction section is further divided into upper bench area, lower bench area, and core soil area along the cross section, forming a construction basic unit with longitudinal classification and transverse partitioning.

[0016] Preferably, the database corresponding to the five dimensions of partitioning, level, process, time series, and parameters specifically includes:

[0017] For different rock grades and construction zones, the following parameters are preset: excavation advance, initial shotcrete thickness, steel arch frame type and spacing (applicable to Class IV and V rock grades; Class III rock grade is preset as needed, and reference is made when steel arch frames are required due to poor rock integrity), support intervention time threshold, hourly arch crown settlement rate warning threshold, and hourly perimeter convergence rate warning threshold, and these are stored in a data table format. At the same time, a daily deformation rate threshold is preset as a macro-control indicator of the long-term stability trend of the rock, which is not involved in the real-time determination of the timing of single-cycle support.

[0018] Preferably, in S3, the real-time monitoring is non-contact real-time monitoring, specifically including:

[0019] Laser point cloud or total station is used to continuously collect data on the surrounding rock of the working face, calculate the crown settlement rate and the surrounding convergence rate in real time, and upload the monitoring data to the construction control terminal in real time.

[0020] Preferably, in S5, the support intervention time threshold is set differently according to the surrounding rock grade: for Grade V surrounding rock sections, initial shotcrete should be completed within 30 minutes after a single cycle of excavation, and steel arch frame should be erected within 1 hour; for Grade IV surrounding rock sections, initial shotcrete should be completed within 45 minutes after a single cycle of excavation, and steel arch frame should be erected within 2 hours; for Grade III surrounding rock sections, initial shotcrete should be completed within 1 hour after a single cycle of excavation; when a Grade III surrounding rock section requires steel arch frame erection due to poor surrounding rock integrity, the steel arch frame should be erected within 2 hours after excavation.

[0021] Preferably, in S6, the support reinforcement mechanism specifically includes:

[0022] When the hourly deformation rate of the surrounding rock exceeds 1.2 times the hourly deformation rate warning threshold, the spacing between the steel arch frames should be reduced by 30% to 50%, and anchor bolts should be added at the arch feet of the steel arch frames. At the same time, the grouting pressure should be increased to 1.2 to 1.5 times the conventional grouting pressure.

[0023] Preferably, after step S2 and before step S3, the method further includes steps for adaptive adjustment of geological variations and control of disturbance during multi-segment excavation. Specifically, within the construction foundation unit formed in S1, ground-penetrating radar is used to conduct real-time advance detection of the surrounding rock section to identify local fracture zones and local water-rich geological variation areas; an adaptive adjustment library for geological variations and construction technology is established. When a geological variation area is detected, the final excavation method and support parameters are corrected and determined in real time based on the five-dimensional correspondence database of zoning, level, technology, time sequence, and parameters and the adaptive adjustment library; when a local water-rich geological variation area is detected in a soft rock section, water-blocking grouting is used in conjunction with short advances. Excavation is carried out in zones and stages, with grouting pressure increased to 1.3 to 1.6 times the conventional grouting pressure. When localized fracture zones with geological variations are detected in hard rock sections, controlled blasting is adopted and advanced pipe roofs are added, with the pipe roof spacing set to 60% to 80% of the conventional pipe roof spacing. Excavation interval thresholds are set for parallel construction of multiple sections. The excavation interval after the upper and lower layers of support at tunnel intersections is no less than 5 days, and the excavation interval after the support of ordinary parallel sections is no less than 3 days, in order to suppress stress concentration caused by the superposition of excavation disturbances. The adaptive adjustment library is linked with the construction control terminal data, and when geological variation zones are detected, process adjustment commands are automatically output to provide adaptive process parameters for the subsequent S3 excavation steps.

[0024] Preferably, the process of implementing adaptive adjustment for geological variations and multi-section excavation disturbance control also includes dynamic monitoring of environmental parameters and process linkage adjustment, as follows: While using ground-penetrating radar to conduct real-time advance detection of the surrounding rock section, environmental monitoring points are simultaneously deployed within the construction foundation unit. Water pressure sensors and temperature sensors are used to continuously monitor groundwater pressure and surrounding rock temperature in real time, and the monitoring data is synchronously uploaded to the construction control terminal. Groundwater pressure warning thresholds and surrounding rock temperature warning thresholds are preset. The groundwater pressure warning threshold is set to 1.2 times the initial water pressure value predicted in the geological survey report for the corresponding section, and the surrounding rock temperature warning threshold is set to 5℃~35℃. When the groundwater pressure is detected to exceed the warning threshold, the construction control terminal automatically links to the adaptive adjustment library, increasing the grouting pressure of the corresponding section by 10%~20% based on the current set value, while extending the grouting holding time to 30 min~40 min. To enhance the water-blocking effect, when the surrounding rock temperature exceeds the warning threshold, the construction control terminal automatically outputs an instruction to adjust the grouting material ratio, adjusting the accelerator dosage in the grouting material to 1.1 to 1.2 times the conventional dosage, ensuring the grouting material's setting speed and support strength. Environmental parameter monitoring data, geological variation detection data, and surrounding rock deformation monitoring data are synchronously stored in the construction control terminal, forming a three-dimensional data linkage analysis system of "environment-geology-deformation," providing data support for the preset process parameters of subsequent construction sections, and avoiding support failure and surrounding rock instability caused by dynamic environmental changes.

[0025] Preferably, after the completion of the S3 single-cycle excavation and monitoring and before the support step, a pretreatment step for the surrounding rock interface is included. Specifically, this involves cleaning the rock face and surrounding rock surfaces with pumice and high-pressure air washing to remove loose rock fragments and dust; before the initial shotcrete, an interface adhesive is sprayed onto the surrounding rock interface to form a bonding reinforcement layer; and the density between the initial shotcrete and the surrounding rock is detected in real time using a radar interface detection device. When a void area is detected, the void area is filled with additional initial shotcrete or pressure grouting to ensure that the initial shotcrete and the surrounding rock are tightly bonded and deform in tandem.

[0026] Preferably, when switching to the next construction section in S7 and repeating steps S3 to S6, a continuous connection step for the support structure between cycles is also included. Specifically, the steel arch frame and anchor rod of the current cycle are connected to the steel arch frame and anchor rod of the next cycle by lap joint, with an overlap length of not less than 50cm. A reinforcing steel plate is added at the overlap position, and the overlap area is thickened with shotcrete to form a locally reinforced section. At the same time, the monitoring data of the settlement rate of the surrounding rock arch, the surrounding convergence rate, and the total deformation of the previous and subsequent cycles are linked and compared. When the difference in deformation rate between adjacent cycles is ≥50%, it is determined to be a stress mutation, and reinforcement measures are taken in time to ensure that the support structure of adjacent construction sections is continuously stressed and without stress mutation.

[0027] The present invention has at least the following beneficial effects: 1. Addressing the technical problems in tunnel zoning and graded excavation and collaborative support construction, such as the lack of systematic correspondence between surrounding rock grading and construction zoning, the absence of standardized preset construction parameters, the determination of excavation and support sequence based solely on fixed times, the lack of a clear mechanism for reinforcement of excessive deformation, and the absence of a closed-loop construction system, the tunnel zoning and graded excavation and collaborative support construction method of the present invention forms corresponding construction basic units by dividing the surrounding rock grade and construction sections, establishes a five-dimensional parameter database, combines the hourly deformation rate of the surrounding rock and the support intervention time as dual thresholds to determine the support strategy, and provides supporting conventional support and support reinforcement mechanisms to achieve closed-loop construction of the entire tunnel excavation-monitoring-support-reinforcement, accurately matches the excavation and support sequence, effectively controls surrounding rock deformation, makes the selection of construction parameters more standardized, and the support decision more scientific, thus constructing a complete construction management and control system. 2. Addressing the technical problems of single-dimensional classification of tunnel surrounding rock and division of construction sections, lack of refined design, and poor operability, which cannot adapt to the construction needs of different cross-sections and surrounding rock grades, the construction method of tunnel zoning and grading excavation and collaborative support of this invention divides the tunnel longitudinally into construction sections of grades III, IV, and V according to the surrounding rock grade, and laterally into upper bench, lower bench, and core soil areas according to the cross-sectional structure, forming a construction basic unit of longitudinal grading and transverse zoning. This makes the zoning more practical, accurately adapts to different construction conditions, and provides a clear and unified unit reference for the selection of subsequent excavation and support processes. 3. Addressing the technical problems of vague and undefined quantitative standards in the five-dimensional database parameters for tunnel construction, the lack of differentiated preset parameters based on surrounding rock grade and construction zone, and the non-standardized storage format, which prevent the provision of accurate parameter guidance for construction, the present invention's tunnel zoned and graded excavation and collaborative support construction method clarifies that the database includes core quantitative indicators such as excavation advance, initial shotcrete thickness, and steel arch frame parameters. It also pre-sets parameters for different surrounding rock grades and construction zones and stores them in a data table format, making the database parameters more specific and accurate. This allows for direct quantitative reference for each stage of construction, improving the scientific and standardized selection of construction parameters. 4. Addressing the technical problems of unclear monitoring methods, single monitoring dimensions, and delayed data calculation and transmission in tunnel surrounding rock deformation monitoring, which fail to provide timely and reliable data support for support decisions, the construction method of tunnel zoning and hierarchical excavation and collaborative support in this invention adopts non-contact real-time monitoring using laser point cloud or total station, continuously collects data and calculates the crown settlement and perimeter convergence rate in real time, and simultaneously uploads the monitoring data to the construction control terminal. This standardizes the data collection, calculation, and transmission process, achieves accurate and real-time monitoring of surrounding rock deformation, and provides timely and effective data support for support decisions.5. Regarding the technical problem that the tunnel support intervention time threshold is not set according to the different levels of surrounding rock, and the use of a uniform time standard leads to a mismatch between the support and the deformation patterns of the surrounding rock, resulting in premature or delayed support, the tunnel zoning and grading excavation and collaborative support construction method of this invention sets gradient support intervention time thresholds for Class V, IV, and III surrounding rock sections. This shortens the support time for unstable surrounding rock and appropriately delays it for stable surrounding rock, precisely adapting to the deformation patterns of different surrounding rock levels. This achieves differentiated control of the support intervention timing, improves the matching degree between support and surrounding rock deformation, and avoids affecting the support effect due to improper support timing. 6. Addressing the technical problems of insufficient triggering conditions, lack of quantitative standards for adjusting reinforcement parameters, reliance on experience, and poor reinforcement effects in tunnel support reinforcement mechanisms after excessive deformation of surrounding rock, this invention's tunnel zoning and grading excavation and collaborative support construction method sets the hourly deformation rate of surrounding rock exceeding the warning threshold by 1.2 times as the reinforcement triggering condition. It also quantitatively specifies a 30%–50% reduction in steel arch spacing, an increase in grouting pressure to 1.2–1.5 times the conventional level, and the addition of anchor bolts. This provides a clear implementation basis for the support reinforcement mechanism, achieving standardization and precision in reinforcement operations. It can rapidly strengthen the collaborative support structure, effectively control excessive deformation of the surrounding rock, and prevent the expansion of surrounding rock instability problems. 7. Addressing the technical problems of tunnel construction lacking consideration for local geological variations, advanced detection, and adaptive process adjustment methods, and the absence of excavation interval limits for parallel multi-section construction, which easily leads to stress concentration due to geological abrupt changes and superimposed disturbances, the present invention's tunnel zonal and graded excavation and collaborative support construction method uses ground-penetrating radar to identify geological variation areas before excavation, establishes an adaptive process adjustment library and corrects construction parameters, and sets quantitative excavation interval thresholds for multi-section construction. This achieves adaptive matching between construction technology and geological conditions, effectively suppresses stress concentration caused by superimposed excavation disturbances, reduces safety risks in complex geology and multi-section construction, and improves construction stability. 8. Addressing the technical problem that environmental parameters such as groundwater pressure and surrounding rock temperature are not monitored during tunnel construction, and there is no linkage adjustment mechanism between environmental parameters and construction technology, making it easy for environmental changes to affect grouting and support effects, the tunnel zoning and graded excavation and collaborative support construction method of this invention monitors environmental parameters in real time by deploying sensors and preset early warning thresholds. It establishes a linkage adjustment mechanism between environmental parameters and grouting pressure and material ratio, forming a three-dimensional data linkage analysis system of "environment-geology-deformation." This effectively avoids the adverse effects of environmental parameter changes on support effects, strengthens water blocking and support effects, prevents support failure caused by dynamic environmental changes, and provides more comprehensive data support for subsequent process parameter presets.9. Addressing the technical problem of poor adhesion between the initial shotcrete and the surrounding rock interface, leading to voids and hindering coordinated deformation between the support structure and the surrounding rock, the present invention's tunnel zoning and grading excavation and coordinated support construction method significantly improves the adhesion between the initial shotcrete and the surrounding rock by cleaning loose rocks from the excavation surface, high-pressure air washing, spraying an interface adhesive, using radar to detect interface density, and filling voided areas. This ensures a tight fit and coordinated deformation between the support structure and the surrounding rock, eliminates the hidden danger of weak support caused by interface voids, and improves the overall stability and reliability of the support structure. 10. Addressing the technical problems of lacking standardized methods for connecting support structures between adjacent tunnel construction cycles, lacking clear requirements for the overlapping of steel arches and anchor bolts, and lacking reinforcement at the overlapping positions, which easily leads to weak support surfaces and discontinuous stress, the tunnel zoning and grading excavation and collaborative support construction method of this invention clarifies the overlapping method and minimum overlapping length of steel arches and anchor bolts, adds reinforcing steel plates and thickens shotcrete at the overlapping positions, and compares deformation data from previous and subsequent cycles to strengthen the structural strength at the overlapping positions. This achieves continuous stress distribution in the support structures of previous and subsequent cycles, avoids sudden stress changes, and allows the entire tunnel support structure to form a complete whole, improving the continuity and stability of the support system.

[0028] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0029] Figure 1 This is a flowchart illustrating the overall process flow of the tunnel zoning and grading excavation and collaborative support construction method of the present invention. Detailed Implementation

[0030] The present invention will now be described in further detail so that those skilled in the art can implement it based on the description.

[0031] It should be noted that, unless otherwise specified, the experimental methods described in the following implementation plan are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified.

[0032] Construction base unit: refers to a basic construction management block divided along the tunnel axis, possessing a single surrounding rock grade (III, IV, V) and clearly defined cross-sectional temporal zoning (upper bench zone, lower bench zone, core soil zone). Conventional collaborative support: refers to standardized support operations implemented based on preset parameters from a five-dimensional database when the surrounding rock deformation is normal. Support reinforcement mechanism: refers to a reinforced support procedure that is immediately activated according to preset quantitative rules (such as densifying steel arch frames, adding anchor bolts, and increasing grouting pressure) when the hourly deformation rate of the surrounding rock exceeds the hourly deformation rate warning threshold. Construction control terminal: refers to a hardware and software system integrating data reception, storage, analysis, display, and command push functions; it is the information hub for the closed-loop construction of this invention.

[0033] This invention provides a construction method for zoned and graded excavation and coordinated support of tunnels, which includes the following steps:

[0034] S1. Based on the geological survey data of the tunnel project, the surrounding rock grade of the tunnel is classified along the axial direction in advance, and the construction sections are divided in combination with the cross-sectional structure, forming a construction basic unit that is classified longitudinally according to the surrounding rock grade and divided laterally according to the cross-sectional structure.

[0035] S2. For each construction foundation unit, pre-set the excavation method, support structure form, support intervention time threshold and hourly deformation rate warning threshold corresponding to the surrounding rock grade, and establish a five-dimensional corresponding database of zone-grade-process-sequence-parameter.

[0036] S3: The current construction section will be excavated in zones and stages according to the preset excavation method, adopting the excavation sequence of "upper bench area → lower bench area → core soil area". After the upper bench area is excavated and the initial support is completed, the lower bench area will be excavated. The core soil area will be excavated using a reserved bench type, vertically divided into 2 to 3 benches, each bench height of 1.5 m to 2.0 m. The excavation follows the principle of "step-by-step demolition and protection as demolition progresses": (1) After demolishing the first step of soil, the exposed arch and sidewall should be sealed with initial shotcrete immediately (within minutes), with the thickness according to the initial shotcrete thickness of the corresponding surrounding rock grade; (2) If the surrounding rock grade requires the installation of steel arch frames (for Class IV and V surrounding rock, or Class III surrounding rock, additional installations may be required), steel arch frames should be erected on the first step and anchor bolts should be welded. The spacing and model of the steel arch frames should be implemented according to the preset parameters in the database; (3) After the first step of support is completed and the inspection is qualified, the second step can be demolished. The above support process is repeated until all the core soil is excavated and the support is completed. This method can minimize the time without support on the exposed surface of the core soil and suppress stress release and convergence deformation during the core soil demolition process. After the single-cycle excavation is completed, the arch settlement and surrounding convergence deformation of the surrounding rock within 10 m behind the working face should be monitored in real time.

[0037] S4: Compare the hourly deformation rate of the surrounding rock obtained from real-time monitoring with the hourly deformation rate warning threshold, and determine whether the current excavation completion time has reached the corresponding support intervention time threshold; the hourly deformation rate warning threshold is the first priority, and the excavation time threshold is the second priority.

[0038] S5: If the hourly deformation rate of the surrounding rock does not exceed the hourly deformation rate warning threshold, wait until the excavation completion time reaches the support intervention time threshold, and then perform conventional collaborative support according to the preset support strength and structural form; if the hourly deformation rate of the surrounding rock exceeds the hourly deformation rate warning threshold, proceed to step S6 and do not execute this step again.

[0039] S6: Immediately activate the support reinforcement mechanism; when the hourly deformation rate of the surrounding rock exceeds 1.2 times the hourly deformation rate warning threshold, on the basis of conventional collaborative support, increase the spacing of the steel arch frame, add locking anchor rods and increase the grouting pressure to form a reinforced collaborative support structure;

[0040] S7: After completing the current cycle of excavation and reinforced support, switch to the next construction section and repeat steps S3 to S6 to achieve closed-loop construction of full tunnel excavation-monitoring-support-reinforcement section by section.

[0041] This implementation method focuses on the zoned and graded excavation and coordinated support construction of tunnels, applicable to various tunnel projects such as highways, railways, and water conservancy projects. Before implementation, a geological survey of the tunnel is conducted, using methods such as borehole sampling and geological mapping to obtain geological data on the lithology, rock mass integrity, and groundwater distribution along the tunnel route. This data serves as the basis for subsequent construction. Based on the obtained geological survey data, the surrounding rock grade is classified along the tunnel axis, following current tunnel engineering surrounding rock classification standards. Simultaneously, considering the tunnel's cross-sectional structure, construction sections are divided, corresponding to the surrounding rock grade and construction sections. This forms multi-level zoning and multi-level surrounding rock grade matching construction basic units. The longitudinal length of each construction basic unit is set at 20 m to ensure precise unit division and operational feasibility. For each completed construction foundation unit, pre-set excavation methods, support structure types, support intervention time thresholds, and hourly deformation rate warning thresholds corresponding to the surrounding rock grade. The excavation method is selected based on the stability of the surrounding rock, including full-section, stepped, or ring-shaped core soil methods. The support structure uses a combined support form of steel arch frame and shotcrete. Based on this, a five-dimensional database corresponding to zoning, grade, process, time sequence, and parameters is established to provide standardized parameter references for subsequent construction. After completing the preliminary parameter setting and database establishment, the current construction section is excavated in zones and grades according to the pre-set excavation methods. During excavation, the excavation advance is strictly controlled, with a single-cycle excavation advance set at 1.5 m to avoid surrounding rock instability caused by excessive excavation. After completing the single-cycle excavation operation, real-time deformation monitoring of the tunnel face and surrounding rock is immediately carried out, including arch settlement and peripheral convergence. The monitoring range covers the surrounding rock area 10 m behind the tunnel face, ensuring that the monitoring data comprehensively reflects the deformation state of the surrounding rock. The hourly deformation rate of the surrounding rock, obtained through real-time monitoring, is compared with a preset hourly deformation rate warning threshold. Simultaneously, it is determined whether the time elapsed since excavation completion has reached the corresponding preset support intervention time threshold. These two judgments are performed concurrently to ensure the accuracy of support timing determination. When the excavation completion time reaches the corresponding support intervention time threshold, and the hourly deformation rate of the surrounding rock is within the hourly deformation rate warning threshold, conventional coordinated support is implemented according to the preset support strength and structural form. The shotcrete thickness is set at 10 cm, and I16 type steel arch frames are used with a spacing of 1.2 m. This method achieves precise timing matching between excavation and support, enabling timely support and constraint of the surrounding rock.

[0042] When monitoring detects that the hourly deformation rate of the surrounding rock exceeds the hourly deformation rate warning threshold, the support intervention time threshold is no longer waited for, and the process immediately switches to support reinforcement. Specifically, when the hourly deformation rate of the surrounding rock exceeds 1.2 times the hourly deformation rate warning threshold, the spacing of the steel arch frames is increased on the basis of conventional collaborative support, reducing the spacing of the steel arch frames from 1.2 m to 0.72 m (a reduction of 40%). At the same time, locking anchor bolts are added at the arch feet of the steel arch frames. Φ22 mortar anchor bolts are selected, with a length of 4.5 m, and the grouting pressure is increased from the conventional 1.0 MPa to 1.4 MPa (1.4 times the conventional pressure). Through multiple reinforcement methods, a reinforced collaborative support structure is formed to quickly suppress excessive deformation of the surrounding rock. After completing the single-cycle excavation and reinforced support operation of the current construction foundation unit, the construction quality of the support structure is promptly inspected. Once it is confirmed that there are no quality problems, the process is switched to the next construction section. The excavation, monitoring, judgment, and support processes described above are repeated to advance the tunnel construction process section by section. Ultimately, a closed-loop construction of the entire tunnel excavation-monitoring-support-reinforcement is achieved, ensuring the overall construction quality and safety of the tunnel.

[0043] In existing technologies for tunnel zoning and graded excavation and collaborative support construction, the surrounding rock is classified and divided into sections based solely on construction experience. Standardized construction units are not established, construction parameters lack systematic presets, and there is no unified database to guide construction. After excavation, support operations are carried out only according to fixed time nodes without adjusting the support strategy according to the actual deformation rate of the surrounding rock. The timing of support is poorly matched, and when the deformation of the surrounding rock exceeds the standard, there is a lack of clear implementation standards for reinforcement methods. Parameter adjustments are arbitrary, making it difficult to form effective reinforced support. Furthermore, a complete closed-loop construction system has not been established, and the connection between various links during construction is poor, which easily leads to problems such as surrounding rock instability and uneven stress on the support structure.

[0044] This implementation method divides the construction into basic units and establishes a standardized five-dimensional parameter database, providing clear parameter references for each stage of construction and changing the existing experience-based construction mode. Simultaneously, it combines the hourly deformation rate of the surrounding rock and the support intervention time as dual indicators to determine the timing of support, enabling dynamic adjustment of the support strategy and solving the problem of poor timing matching in existing technologies. For situations where surrounding rock deformation exceeds the standard, it sets clear support reinforcement mechanisms and measures, quantifies reinforcement parameters, and makes reinforcement operations more targeted and effective. Furthermore, by repeating construction section by section, it forms a closed-loop construction system for the entire tunnel, ensuring close connection between excavation, monitoring, support, and reinforcement, forming a complete construction management system. This effectively controls surrounding rock deformation, improves the stability and safety of tunnel construction, and significantly enhances the standardization and scientific level of tunnel zoning and graded excavation and collaborative support construction compared to existing technologies.

[0045] In another technical solution, in S1, the surrounding rock grade of the tunnel is classified along the axial direction, and the construction sections are divided in combination with the cross-sectional structure. Specifically, the tunnel is divided into multiple continuous construction sections along the longitudinal direction. Each construction section is divided into Class III, Class IV, and Class V surrounding rock sections according to the geological survey results. Each construction section is further divided into upper bench area, lower bench area, and core soil area along the cross section, forming a construction basic unit with longitudinal classification and transverse partitioning.

[0046] This implementation method focuses on the refined division of tunnel surrounding rock grades and construction sections. It is applicable to the zoning and graded excavation and coordinated support construction of tunnels with different cross-sectional structures and different combinations of surrounding rock grades. Before implementation, it is necessary to complete the engineering geological survey of the entire tunnel axis to obtain detailed geological data such as the lithology, rock mass integrity, and joint development of the surrounding rock along the route. At the same time, it is necessary to clarify the basic construction parameters such as the cross-sectional structural dimensions of the tunnel and the designed excavation outline, which serve as the core basis for grading and zoning. When classifying the surrounding rock grade along the tunnel axis, based on the current tunnel engineering surrounding rock classification specifications and combined with the geological data obtained from the survey, the entire longitudinal area of ​​the tunnel is divided into multiple continuous construction sections. The longitudinal length of a single construction section is set at 20 m. Then, the surrounding rock grade of each construction section is determined, and it is accurately divided into Grade III, Grade IV, and Grade V surrounding rock sections. Grade III refers to hard rock surrounding rock with slight or weak weathering, developed fissures due to geological structure, partial opening and mud filling, and a rubble-like mosaic structure, which has good stability. Grade IV refers to surrounding rock with many fractures and weak structural surfaces, and a rubble-like mosaic or crushed structure, which has medium stability. Grade V refers to loose soil layers, fracture zones, or rock masses with a loose structure, which are soft rock or fractured surrounding rock with poor stability. During the classification process, the continuity of surrounding rock sections of the same grade is ensured. If local geological variations are encountered, the sections are locally refined and adjusted. After completing the longitudinal surrounding rock grade and construction section division, and considering the tunnel's cross-sectional structure, each 20-m long construction section is further divided into construction zones along the cross-section, uniformly designated as the upper bench zone, lower bench zone, and core soil zone. The core soil zone refers to the temporary supporting soil reserved to balance the stability of the tunnel face in the ring excavation method. Its longitudinal length is typically greater than 3 m, and its cross-sectional area is determined based on the surrounding rock conditions and stability calculations (generally large, for example, greater than 50% of the total excavation cross-sectional area). In this embodiment, based on geological conditions and construction safety calculations, the core soil zone is retained in the middle of the cross-section, and its cross-sectional area is set at 30% of the total tunnel excavation cross-sectional area to ensure the stability of the tunnel face during excavation. The excavation height of the upper bench zone is set at 5 m, and the excavation height of the lower bench zone is set at 4 m.

[0047] Through the aforementioned dual division in both the longitudinal and transverse directions, the tunnel construction area is divided into construction foundation units that are longitudinally graded according to the surrounding rock level and transversely divided according to the cross-sectional structure. Each unit clearly defines the corresponding surrounding rock level and cross-sectional zoning, and the boundaries between units are clear. A 1-meter transition section is reserved at the junction of adjacent longitudinal units to avoid overlapping construction disturbances at the boundaries of the zoning and grading. At the same time, all the completed construction foundation units are uniformly numbered, and the corresponding geological data and cross-sectional parameters are recorded in conjunction with the numbering, providing clear and specific unit references for the selection of subsequent excavation and support technologies and parameter settings.

[0048] Existing technologies for classifying tunnel surrounding rock grades and construction sections simply rely on geological survey results to classify the overall longitudinal surrounding rock without setting standardized construction section lengths. The classification results are coarse and lack clear section boundaries. Furthermore, they fail to incorporate targeted zoning designs based on the tunnel cross-sectional structure. The entire tunnel cross-section uses a uniform excavation and support method, which cannot adapt to the construction needs of different areas of the cross-section. This results in a lack of systematic and practical division of construction basic units. Consequently, the selection of subsequent excavation and support technologies lacks clear unit basis, which can easily lead to mismatches between the technology and the geological and structural conditions of the actual construction area, thereby affecting construction stability and support effectiveness.

[0049] This implementation method, by setting standardized longitudinal construction section lengths, precisely divides the surrounding rock into three levels: Level III, Level IV, and Level V, making the longitudinal surrounding rock classification more standardized. Simultaneously, combined with the tunnel cross-sectional structure, it uniformly divides the tunnel into upper bench area, lower bench area, and core soil area, setting specific dimensional parameters to achieve refined transverse zoning. The resulting longitudinally graded and transversely zoned construction base units make tunnel construction zoning and grading more practical. Each unit has a clear surrounding rock grade and cross-sectional zoning attributes, providing a clear and unified reference for selecting appropriate excavation methods and setting precise support parameters for different units. This effectively solves the problems of existing technologies having a single zoning and grading dimension and poor practicality, allowing the selection of excavation and support processes to accurately match the geological and structural conditions of different construction areas, improving the targeting and rationality of tunnel zoning and grading excavation and coordinated support construction.

[0050] In another technical solution, the five-dimensional database corresponding to partitioning, level, process, timing, and parameters specifically includes:

[0051] For different surrounding rock grades and different construction zones, excavation advance parameters, initial shotcrete thickness, steel arch frame type and spacing, support intervention time threshold, hourly arch crown settlement rate warning threshold, and hourly peripheral convergence rate warning threshold are preset and stored in the form of data tables. At the same time, a daily deformation rate threshold is preset as a macro-control indicator of the long-term stability trend of the surrounding rock, which is not involved in the real-time determination of the timing of single-cycle support.

[0052] This implementation method focuses on the specific operations of building a parameter database for zoned and graded excavation and collaborative support in tunnels. It is applicable to various tunnel projects where the surrounding rock grade and construction section division have been completed. Before implementation, it is necessary to clarify the surrounding rock grade and construction zone attributes corresponding to all basic construction units, and to sort out the types of excavation, support, and monitoring parameters required for each unit construction, providing a foundation for database construction. When building the five-dimensional corresponding database of zone-grade-process-time-parameter, differentiated parameter presets are made according to different surrounding rock grades and different construction zones. All parameters are set with specific values ​​based on the actual construction needs and surrounding rock stability characteristics, and are stored in the form of data tables. The data tables are classified and archived according to surrounding rock grade and construction zone for easy retrieval and reference during construction. For excavation advance parameters, in Class III surrounding rock sections, the upper bench area is set to 2 m, the lower bench area to 2.5 m, and the core soil area has a reserved width of 3 m; in Class IV surrounding rock sections, the upper bench area is set to 1.5 m, the lower bench area to 2 m, and the core soil area has a reserved width of 3.5 m; in Class V surrounding rock sections, both the upper and lower bench areas are set to 1 m, and the core soil area has a reserved width of 4 m. For initial shotcrete thickness parameters, Class III surrounding rock is uniformly set to 8 cm across all zones, Class IV surrounding rock to 10 cm across all zones, and Class V surrounding rock to 12 cm across all zones. The steel arch frame model and spacing are preset differently according to the surrounding rock grade and installation conditions: Class V surrounding rock: I18 type steel arch frames are selected, with a spacing set at 0.8 m; in the core soil area, steel arch frames are installed at 1 m intervals after each bench is removed, and anchor bolts are installed. Class IV surrounding rock: I16 type steel arch frames are selected, with a spacing of 1.2 m. After each step in the core soil area is removed, the installation of lightweight steel arch frames and shotcrete sealing should be completed simultaneously within 2 hours to ensure that the support closely follows the excavation face and controls deformation. Class III surrounding rock: Shotcrete support is the main method, and steel arch frames are not set by default. When the surrounding rock integrity is good and the stability meets the self-stabilization requirements, steel arch frames are not required, and only shotcrete support is used. When advanced geological exploration reveals that the surrounding rock integrity coefficient Kv < 0.5, there are local fracture zones, or real-time surrounding rock deformation monitoring shows an abnormally high deformation rate (such as reaching 80% or more of the warning threshold), steel arch frames should be added as needed. In this case, refer to the database preset parameters: I14 type steel arch frames are selected, with a spacing of 1.5 m. The installation of steel arch frames should be completed within 2 hours after the completion of a single cycle of excavation. No dedicated steel arch frames are set in the core soil area.

[0053] For the support intervention time threshold, the standardized time values ​​corresponding to different surrounding rock grades are directly adopted (2 hours are used when steel arches are required for Class III surrounding rock). The five-dimensional corresponding database is layered and preset with two types of surrounding rock deformation control indicators: (1) Hourly deformation rate warning threshold: used for real-time determination of the support timing after single-cycle excavation. This threshold is set according to the rheological characteristics of the surrounding rock and the initial support bearing rate requirements, and is the only basis for the comparison of "surrounding rock deformation rate" in steps S4 to S6. The specific values ​​are: Class III surrounding rock: arch settlement ≤ 0.1 mm / h, peripheral convergence ≤ 0.15 mm / h; Class IV surrounding rock: arch settlement ≤ 0.2 mm / h, peripheral convergence ≤ 0.25 mm / h; Class V surrounding rock: arch settlement ≤ 0.3 mm / h, peripheral convergence ≤ 0.35 mm / h. (2) Daily deformation rate and cumulative deformation threshold: used for long-term stability assessment of surrounding rock and decision-making on the timing of secondary lining construction. This threshold reflects the convergence trend of the surrounding rock under initial support and does not participate in the real-time support decision-making during cyclic tunneling. Specific values ​​are as follows: Class III surrounding rock: crown settlement ≤ 2 mm / d, peripheral convergence ≤ 3 mm / d; Class IV surrounding rock: crown settlement ≤ 4 mm / d, peripheral convergence ≤ 5 mm / d; Class V surrounding rock: crown settlement ≤ 6 mm / d, peripheral convergence ≤ 7 mm / d.

[0054] Two sets of indicators are stored in parallel in the construction control terminal with separate functions. The system automatically matches the corresponding threshold according to the calling scenario. Simultaneously, preset benchmark values ​​for conventional grouting pressure are established for each surrounding rock grade, serving as the pressure base for subsequent adjustments to various processes: 0.8–1.0 MPa for Grade III surrounding rock, 1.0–1.2 MPa for Grade IV, and 1.2–1.5 MPa for Grade V. All subsequent adjustments to grouting pressure multiples are based on the benchmark values ​​for the corresponding surrounding rock grade. After the database is built, dedicated personnel maintain and update the parameters. If minor changes in geological conditions occur during construction, the parameters of the corresponding units are promptly fine-tuned and updated synchronously to the data table, ensuring that the parameters in the database always match the actual construction needs. Before carrying out excavation and support operations for each construction foundation unit, construction personnel retrieve the corresponding parameters from the database and strictly execute construction operations according to the preset values.

[0055] Current technologies in tunnel construction lack a systematic five-dimensional parameter database. They rely solely on construction experience to roughly set parameters for excavation, support, and other aspects. There are no differentiated parameter standards for different surrounding rock grades and construction zones. The preset ranges of various construction parameters are vague and not stored in a standardized manner. Parameter retrieval during construction lacks clear basis, which can easily lead to the use of the same construction parameters in different construction zones with the same surrounding rock grade. This results in a mismatch between construction parameters and actual geological and construction conditions, affecting excavation efficiency and support effectiveness, and failing to provide standardized parameter guidance for construction.

[0056] This implementation method, by setting refined and differentiated parameters according to the surrounding rock grade and construction zone, assigns specific and reasonable values ​​to each construction stage, making the parameters in the database more targeted and practical. Simultaneously, the parameters are stored in a fixed and categorized manner in the form of data tables, achieving standardized management of construction parameters. Construction personnel can quickly retrieve the construction parameters for the corresponding unit, effectively avoiding the blind selection of parameters. The database provides clear, quantifiable parameter references for all construction stages of tunnel zoning and graded excavation and collaborative support, enabling precise parameter guidance for construction. This significantly improves the scientific and standardized nature of construction parameter selection, solving the problems of vague parameter presets and lack of standardized database guidance in existing technologies. It ensures that construction operations of different surrounding rock grades and different construction zones can be matched with appropriate parameter standards, further guaranteeing the construction quality of excavation and support.

[0057] In another technical solution, S3, real-time monitoring is non-contact real-time monitoring, which specifically includes: using laser point cloud or total station to continuously collect data on the surrounding rock of the working face, calculating the crown settlement rate and the surrounding convergence rate in real time, and uploading the monitoring data to the construction control terminal in real time.

[0058] This implementation method focuses on non-contact real-time monitoring of surrounding rock deformation after sectional and graded excavation of tunnels. It is applicable to the monitoring of deformation at the tunnel face and surrounding rock in various tunnel construction projects. Before implementation, the monitoring equipment must be debugged and deployed. Monitoring benchmarks should be set up at fixed locations in the tunnel construction area in advance to ensure their stability. Simultaneously, the monitoring equipment and the construction control terminal must be connected and debugged to ensure real-time and stable data transmission. The construction control terminal integrates data management, threshold comparison, and instruction recommendation functions. All process adjustment or reinforcement instructions automatically generated by the terminal are pushed to on-site technicians for final confirmation before execution. The system can also be switched to a manual-led mode, making decisions based on preset parameters in the database and monitoring data, ensuring applicability and reliability under different construction conditions and technical levels.

[0059] After completing the single-cycle excavation of the tunnel, a non-contact real-time monitoring process was immediately initiated. A total station was selected as the core monitoring equipment to conduct multi-dimensional deformation monitoring of the tunnel face and surrounding rock, including crown settlement and perimeter convergence. The monitoring range covered the tunnel face and the surrounding rock area up to 10 m behind it. Monitoring points were evenly distributed within this range, with three monitoring points at the crown and four monitoring points on each of the two sidewalls of the surrounding rock. All monitoring points were associated with a monitoring reference point. During the monitoring process, the total station continuously acquired spatial position data of each monitoring point at a frequency of once per minute. By calculating the changes in spatial position of the monitoring points within adjacent acquisition cycles in real time, the crown settlement rate and perimeter convergence rate were calculated. The calculation process was completed synchronously at the construction control terminal, eliminating the need for manual secondary calculations. All monitoring data and calculated deformation rate data will be uploaded to the construction control terminal in real time. The terminal will automatically record and display the data in real time. Construction personnel can view the dynamic data of surrounding rock deformation at any time through the terminal. If data transmission is interrupted or abnormal, the terminal will immediately issue an alert to ensure the continuity of monitoring.

[0060] If a total station is unsuitable for use at the construction site due to space limitations or other factors, a laser point cloud device can be used instead for monitoring. This device performs a 3D scan of the tunnel face and surrounding rock to acquire complete point cloud data of the rock surface. The scan cycle is set to once every five minutes. By comparing point cloud data from different cycles, the device calculates the crown settlement and surrounding convergence deformation data and deformation rate of the surrounding rock. All data is uploaded to the construction control terminal in real time, achieving the same monitoring and data transmission effect as a total station. The entire monitoring process is non-contact, eliminating the need for drilling or other contact operations on the surrounding rock, thus avoiding secondary disturbance. Continuous data acquisition and real-time calculation and transmission allow construction personnel to grasp the deformation status of the surrounding rock immediately, providing timely and accurate data support for subsequent support timing determination and support strategy adjustments.

[0061] Current technologies for monitoring surrounding rock deformation after tunnel excavation lack a standardized monitoring method. Most rely on contact monitoring, requiring the installation of contact measuring points on the surrounding rock, which can easily cause secondary disturbance. Furthermore, data collection is often done manually at set intervals, resulting in low frequency and inability to achieve continuous monitoring. The collected deformation data also requires manual calculation, which is inefficient and exhibits significant time lag. Simultaneously, existing technologies lack standardized methods for transmitting and managing monitoring data. Data is mostly recorded and organized manually, failing to be uploaded to a unified construction control terminal in real time. This prevents construction personnel from promptly grasping the dynamics of surrounding rock deformation, hindering the rapid and effective support of subsequent support decisions and increasing the risk of errors in determining the timing of support due to data delays.

[0062] This implementation method explicitly adopts a non-contact monitoring approach, using total stations or laser point cloud equipment for monitoring. This avoids secondary disturbance to the surrounding rock and establishes a fixed continuous acquisition frequency, enabling continuous collection of surrounding rock deformation data. Real-time calculation and data uploading are completed through the construction control terminal, eliminating the need for manual calculation and recording and completely resolving the time lag issue in monitoring data. The standardized layout of measuring points and the setting of the monitoring range ensure that the monitoring data comprehensively and accurately reflects the deformation state of the working face and surrounding rock. The real-time linkage between the monitoring data and the construction control terminal allows construction personnel to promptly grasp the dynamics of surrounding rock deformation, providing timely, reliable, and accurate data support for determining the timing of support and adjusting support strategies. This significantly improves the standardization, accuracy, and timeliness of surrounding rock deformation monitoring, ensuring that the monitoring data effectively guides subsequent construction operations.

[0063] In another technical solution, S5, the support intervention time threshold is set differently according to the surrounding rock grade: for Grade V surrounding rock sections, initial shotcrete is completed within 30 minutes after a single cycle of excavation, and steel arch frame is erected within 1 hour; for Grade IV surrounding rock sections, initial shotcrete is completed within 45 minutes after a single cycle of excavation, and steel arch frame is erected within 2 hours; for Grade III surrounding rock sections, initial shotcrete is completed within 1 hour after a single cycle of excavation.

[0064] This implementation method implements differentiated management of support intervention time after tunnel zoning and grading excavation. It is applicable to the collaborative support construction phase of tunnels with different surrounding rock grades. Before implementation, the tunnel surrounding rock grade and construction section have been divided, and the surrounding rock grade corresponding to each construction foundation unit has been clearly defined. At the same time, the personnel, equipment, and materials for support construction have been prepared to ensure that the support operation can be carried out quickly within the preset time. After the tunnel single-cycle excavation operation is completed, the timing starts immediately, and the differentiated support intervention time management standard is implemented according to the surrounding rock grade corresponding to the excavation section. For Class V surrounding rock sections, after the single-cycle excavation is completed, the support construction personnel and equipment must be on standby on site at any time to ensure that the initial shotcrete construction is completed within 30 minutes. The initial shotcrete operation adopts a wet spraying process to ensure the uniformity and density of the concrete spraying. The steel arch frame is erected and fixed within 1 hour after the excavation is completed. The steel arch frame is erected with precise positioning, firm connection, and close fit to the surrounding rock. For Class IV surrounding rock sections, initial shotcrete construction should be completed within 45 minutes of the completion of a single-cycle excavation. This time allows for simple removal of loose rocks from the excavation surface, while simultaneously preparing for the erection of the steel arch frame. The steel arch frame should be erected within 2 hours of excavation completion, with strict control over its spacing and verticality to ensure the stability of the support structure. For Class III surrounding rock sections, where rock stability is good and deformation rate is relatively slow, initial shotcrete construction can be completed within 1 hour of the completion of a single-cycle excavation. No steel arch frame is required; the initial shotcrete alone is sufficient to effectively constrain the surrounding rock. After initial shotcrete construction, the sprayed surface should be inspected promptly to ensure there are no missed areas or voids. Throughout the support intervention process, dedicated personnel are responsible for timing and construction scheduling to ensure each process proceeds strictly according to the preset time nodes. Simultaneously, real-time monitoring data of surrounding rock deformation is used. If abnormal deformation occurs within the preset support intervention time, support construction can be initiated earlier to avoid rock instability due to delayed support, achieving precise matching between support intervention time and surrounding rock grade. The criteria for judging abnormal deformation of the surrounding rock are based on the preset hourly deformation rate warning threshold. If the real-time monitored hourly rate of crown subsidence or surrounding convergence exceeds the corresponding threshold, regardless of whether the excavation completion time has reached the support intervention time threshold, it is judged as abnormal deformation and support / reinforcement work is immediately started.

[0065] Current tunnel support construction technologies fail to establish differentiated support intervention time thresholds based on the varying surrounding rock grades. A uniform intervention time standard is applied to all rock grades. For Grade V rock sections with poor stability, this uniform standard can lead to delayed intervention, causing excessive deformation of the rock under unconstrained conditions and increasing the risk of rock instability. For Grade III rock sections with better stability, premature intervention wastes construction resources and may compromise support quality due to incomplete excavation. Furthermore, current technologies rely solely on experience to determine intervention times without clear quantitative standards. This leads to significant arbitrariness in timing control during construction, hindering precise management of intervention timing and resulting in poor alignment between support and surrounding rock deformation patterns, ultimately impacting the overall support effectiveness.

[0066] This implementation method, based on the differences in stability of the surrounding rock grades, sets precise quantitative support intervention time thresholds for Grade V, IV, and III surrounding rock sections. For Grade V surrounding rock, which has poor stability and rapid deformation, the support intervention time is shortened to achieve rapid support and restraint of surrounding rock deformation. For Grade III surrounding rock, which has good stability and slow deformation, the support time is appropriately delayed, making rational use of construction resources and balancing construction safety and efficiency. Through clear time node control and dedicated personnel scheduling, the support intervention operation is systematic and effectively avoids the problems of premature or delayed support. It achieves precise matching of support intervention timing with the deformation patterns of different surrounding rock grades, significantly improving the scientific and rational nature of support intervention timing. This allows support construction to better adapt to the construction needs of different surrounding rock grades, effectively control surrounding rock deformation, and ensure the construction quality and support effect of the support structure.

[0067] In another technical solution, S6, the support reinforcement mechanism specifically includes: when the hourly deformation rate of the surrounding rock exceeds 1.2 times the hourly deformation rate warning threshold, the spacing of the steel arch frame is reduced by 30% to 50% (based on the steel arch frame spacing of the corresponding surrounding rock grade preset in the five-dimensional corresponding database), and a locking anchor rod (Φ22, mortar locking anchor rod with a length of not less than 4m) is added at the arch foot of the steel arch frame, while the grouting pressure is increased to 1.2 to 1.5 times the conventional grouting pressure preset in the five-dimensional corresponding database.

[0068] This implementation method focuses on the reinforcement construction of tunnels after the surrounding rock deformation exceeds the standard during the segmented and graded excavation and support process. It is applicable to the collaborative support reinforcement stage of tunnels of various surrounding rock grades. Before implementation, real-time monitoring of tunnel surrounding rock deformation has been completed, and the hourly deformation rate warning threshold corresponding to each construction foundation unit has been clearly defined. At the same time, the on-site preparation of materials and equipment such as steel arch frames, anchor bolts, and grouting equipment required for support reinforcement construction has been completed to ensure that the support reinforcement mechanism can be quickly activated and implemented. During the single-cycle excavation of the tunnel and the monitoring of surrounding rock deformation, the real-time calculated hourly deformation rate of the surrounding rock is continuously compared with the preset warning threshold. When the monitoring data shows that the hourly deformation rate of the surrounding rock exceeds 1.2 times the hourly deformation rate warning threshold (this multiple is determined based on a large number of engineering statistics and numerical simulations, and is a typical critical value for the surrounding rock to enter the accelerated deformation stage), the support reinforcement mechanism is immediately activated, and targeted support reinforcement construction is carried out on the basis of the original conventional collaborative support. First, the spacing of the steel arch frames is adjusted to be denser, and the standard of reducing the original steel arch frame spacing by 40% is implemented. If the steel arch frame spacing in conventional support is 0.8 m for Class V surrounding rock and 1.2 m for Class IV surrounding rock, it is adjusted to 0.48 m and 0.72 m respectively after reinforcement. When erecting the steel arch frames, ensure that the alignment with the original steel arch frames is accurate, the connection is firm, and the steel arch frames are closely fitted with the surrounding rock.

[0069] While densifying the steel arch frame, anchor bolts are added at the arch foot of each steel arch frame. High-strength mortar anchor bolts are selected, with a diameter of 22 mm and a length of 4.5 m. Two anchor bolts are installed at each arch foot of each steel arch frame, driven into the surrounding rock at an angle of 45° to 60° to the horizontal. During construction, drilling and grouting are used to penetrate the anchor bolts deep into the surrounding rock, ensuring that the anchor bolts form a firm connection structure with the surrounding rock and the steel arch frame, effectively restraining the displacement and settlement of the arch foot of the steel arch frame. Simultaneously, the grouting pressure was increased to 1.4 times the conventional grouting pressure. For example, if the conventional grouting pressure for Class V surrounding rock is 1.5 MPa and for Class IV surrounding rock is 1.2 MPa, after reinforcement, these were adjusted to 2.1 MPa and 1.68 MPa respectively. During grouting, the grouting speed and volume were controlled to ensure the grout fully filled the fissures in the surrounding rock and the gaps between the steel arch and the surrounding rock, forming a dense grout consolidation body. The entire support reinforcement construction process was carried out concurrently with surrounding rock deformation monitoring. The deformation data of the reinforced surrounding rock was continuously monitored until the hourly deformation rate of the surrounding rock fell back below the warning threshold, confirming that the surrounding rock deformation was effectively controlled. After the support reinforcement construction was completed, the overall stability of the support structure was promptly checked to ensure that the steel arch, anchor bolts, and grout consolidation body formed an integrated and synergistic reinforced support structure that could effectively restrain surrounding rock deformation for a long period, preventing further development of surrounding rock instability.

[0070] Current technologies for tunnel construction lack clear triggering conditions for support reinforcement when faced with excessive hourly deformation rates of surrounding rock. There are no quantitative standards for determining the level at which support reinforcement should be initiated, relying heavily on the experience of construction personnel. This can lead to problems such as premature reinforcement initiation, wasting construction resources, or delayed reinforcement, failing to effectively control surrounding rock deformation. Furthermore, current support reinforcement technologies lack unified quantitative parameter adjustment standards. There are no clear regulations regarding the spacing of steel arch frames, the increase in grouting pressure, or the addition of anchor bolts. This results in considerable arbitrariness in reinforcement operations, making it difficult to create targeted and coordinated support structures, leading to inconsistent reinforcement effects. In addition, the various reinforcement processes in current technologies lack coordination. Operations such as steel arch frame densification and grouting pressure increases are often carried out in separate steps, resulting in low construction efficiency and an inability to quickly suppress excessive deformation of the surrounding rock. This can easily lead to the expansion of surrounding rock instability problems, affecting the overall safety of tunnel construction.

[0071] This implementation method explicitly uses an hourly deformation rate exceeding 1.2 times the hourly deformation rate warning threshold as the trigger condition for the support reinforcement mechanism, providing a clear quantitative basis for determining the reinforcement initiation and effectively avoiding decision-making errors caused by experience-based judgments. Simultaneously, it clearly quantifies and sets various construction parameters for the support reinforcement mechanism, with specific standards for the reduction in steel arch spacing and the multiple of grouting pressure increase. The specifications and construction requirements for anchor bolts are also uniformly stipulated, ensuring that every step of the support reinforcement construction is systematic and significantly improving the standardization and accuracy of the reinforcement operation. By simultaneously carrying out reinforcement procedures such as steel arch densification, anchor bolt addition, and grouting pressure increase, coordinated construction between these procedures is achieved, greatly improving the efficiency of support reinforcement construction. This allows for the rapid formation of an integrated, reinforced, and coordinated support structure, timely suppressing excessive deformation of the surrounding rock, effectively controlling the development of surrounding rock instability, and ensuring tunnel construction safety. This approach establishes a complete and standardized construction system for tunnel support reinforcement mechanisms, solving the problems of existing technologies lacking clear triggering conditions, quantitative standards for parameter adjustments, and poor construction results. It significantly improves the effectiveness and timeliness of tunnel support reinforcement, allowing the support structure to better adapt to the deformation and changes of the surrounding rock, and further ensuring the construction quality of tunnel zoning and grading excavation and coordinated support.

[0072] In another technical solution, after step S2 and before step S3, a further step is included: adaptive adjustment of geological variations and control of disturbance during multi-segment excavation. Specifically, within the construction foundation unit formed in S1, ground-penetrating radar is used to conduct real-time advance detection of the surrounding rock section, identifying local fracture zones with a longitudinal length ≤10 m and a transverse range ≤1 / 3 of the tunnel excavation cross-section, as well as local water-rich geological variation areas. The criteria for determining local water-rich points is a single-point inflow rate ≤5 L / min, and the criteria for determining local fracture zones is the rock mass integrity coefficient K.v <0.5. Establish an adaptive adjustment library for geological variation and construction technology. When a geological variation area is detected, the final excavation method and support parameters are corrected and determined in real time based on the five-dimensional correspondence database of zoning, level, technology, time sequence, and parameters and the adaptive adjustment library. When a local water-rich geological variation area is detected in a soft rock section, water-blocking grouting is used in conjunction with short-foot zoning and graded excavation, and the grouting pressure is increased to 1.3 to 1.6 times the conventional grouting pressure. When a local fractured zone geological variation area is detected in a hard rock section, controlled blasting is used and advanced pipe roofs are added, with the pipe roof spacing set to 60% to 80% of the conventional pipe roof spacing. Set an excavation interval threshold for parallel construction of multiple sections. The excavation interval after the upper and lower layers of support at the tunnel intersection section is not less than 5 days, and the excavation interval after the support of ordinary parallel sections is not less than 3 days, in order to suppress stress concentration caused by the superposition of excavation disturbances. The adaptive adjustment library is linked with the construction control terminal data. When a geological variation area is detected, the process adjustment command is automatically output to provide adaptive process parameters for the subsequent S3 excavation steps.

[0073] This implementation method focuses on adaptive adjustment of geological variations and control of disturbances during multi-segment excavation in tunnel construction. It is applicable to various types of tunnels undergoing zoned and graded excavation and coordinated support construction. Before implementation, the basic units for tunnel construction have been divided, and a five-dimensional corresponding database of zone, grade, process, time sequence, and parameters has been established. Simultaneously, the ground-penetrating radar detection equipment and construction control terminals have been debugged and deployed, and personnel and equipment for multi-segment construction have been planned in a coordinated manner to ensure efficient integration of detection and process adjustment. After completing the five-dimensional corresponding database and before commencing tunnel excavation, the adaptive adjustment of geological variations and control of disturbances during multi-segment excavation are initiated.

[0074] First, within the defined construction base units, ground-penetrating radar (GPR) is used to conduct short-range, precise advance detection in front of the tunnel face. The detection range is set at 20 m to 30 m in front of the tunnel face. This distance is the conventional effective detection depth of GPR in tunnel advance prediction, which can ensure the accuracy of identifying adverse geological bodies and complement the technology of long-range prediction methods (100 to 150 m) such as TSP / TGP.

[0075] The detection operation shall be carried out in accordance with the following technical requirements: (1) Antenna selection: a shielded antenna with a center frequency of 50 MHz to 100 MHz shall be used to balance detection depth and resolution; (2) Acquisition method: the point measurement method shall be used to continuously collect data along the measurement line of the working face at a point spacing of no more than 20 cm; (3) Parameter calibration: the dielectric constant of the surrounding rock of the working face shall be calibrated on site before detection. Each test unit shall be calibrated no less than 3 times, and the average value shall be used as the basis for electromagnetic wave velocity calculation. The time window and detection depth shall be adjusted accordingly; (4) Data quality: ensure good coupling between the antenna and the working face. Operators shall not wear metal objects to avoid electromagnetic interference. The detection data shall be uploaded to the construction control terminal in real time to accurately identify geological variation areas such as local fracture zones (rock integrity coefficient Kv < 0.5) and local water-rich points (single point water inflow ≤ 5 L / min).

[0076] A geological variation-construction technology adaptive adjustment library is established simultaneously, which is interconnected with the five-dimensional corresponding database. When a geological variation area is detected, the final excavation method and support parameters are corrected and determined in real time based on the preset parameters of the two databases. If a local water-rich point is detected in a soft rock section, a method of water plugging and grouting combined with short-foot excavation in sections and stages is immediately adopted. The water plugging and grouting pressure is increased to 1.5 times the conventional grouting pressure, and the single-cycle excavation footing is adjusted from the conventional 1.5 m to 0.8 m. After the grouting is completed, the excavation operation is carried out after the grout solidifies. If a local fracture zone is detected in a hard rock section, controlled blasting is used during excavation, the amount of explosive charge is reduced and the layout of the blast holes is optimized. At the same time, advanced pipe roof support is added, with the pipe roof spacing set to 70% of the conventional pipe roof spacing and the pipe roof length set to 15 m to ensure the stability of the surrounding rock. For multi-section parallel construction scenarios, strict excavation interval thresholds are set. For tunnel intersections, the timing for excavation of upper and lower layers begins after the completion of the lower layer's support, with an interval of no less than 5 days. The lower layer is constructed first, followed by the upper layer, to avoid secondary disturbance to the lower surrounding rock caused by upper layer excavation. For ordinary parallel sections, the timing begins after the completion of the previous work face's support, with an excavation interval of no less than 3 days. Excavation of adjacent work faces proceeds sequentially, with a rationally planned construction procedure. Throughout the process, the adaptive adjustment database maintains real-time data linkage with the construction control terminal. Upon detecting areas of geological variation, the terminal automatically outputs process adjustment instructions, directly issuing them to the on-site construction teams. This provides accurate adaptive process parameters for subsequent excavation steps, achieving dynamic matching between process parameters and geological conditions. During excavation, geological conditions are continuously re-measured. Radar detection is conducted every 2-3 excavation cycles (approximately 3-5 m advance). If new areas of geological variation are discovered, the above process adjustment procedure is repeated promptly. At the same time, we strictly control the excavation interval time of multi-section construction, and assign dedicated personnel to be responsible for the scheduling of construction procedures to ensure that the excavation construction of each working face strictly follows the preset interval threshold, thereby suppressing the stress concentration problem caused by the superposition of excavation disturbances from the source.

[0077] Existing technologies for tunnel zoning and graded excavation and coordinated support construction lack a pre-excavation geological survey, making it impossible to identify local geological variations within the construction foundation unit in a timely manner. During construction, the initial pre-set excavation and support parameters are still used, lacking adaptive adjustment methods to address sudden geological changes such as local fracture zones and water-rich areas. This easily leads to increased excavation disturbance, surrounding rock instability, and increased construction safety risks. Furthermore, the excavation intervals for parallel multi-section construction are not clearly quantified, relying solely on experience to arrange construction procedures. This can result in overlapping excavation times between adjacent work faces, with excavation disturbances compounding each other. Stress concentrations can occur in areas such as tunnel intersections and ordinary parallel sections, leading to problems such as surrounding rock cracking and support structure deformation, affecting overall construction quality. In addition, existing technologies lack a dedicated adaptive adjustment library and standardized criteria for process parameter correction. Even when geological variations are detected, parameter adjustments are highly arbitrary, making it difficult to achieve precise matching between excavation and support processes and geological conditions.

[0078] This implementation method incorporates a ground-penetrating radar (GPR) pre-excavation detection step, enabling precise and timely identification of local geological variations. By establishing a geological variation-construction process adaptive adjustment library and linking it with a five-dimensional corresponding database, real-time correction of excavation and support parameters is achieved. Specific process adjustment standards are set for different geological variations, allowing the construction process to dynamically adapt to geological conditions and effectively reducing construction risks caused by sudden geological changes. Simultaneously, clear quantitative excavation interval thresholds are set for parallel construction in multiple sections, with differentiated interval time regulations for intersecting sections and ordinary parallel sections. Strict process scheduling ensures that interval requirements are implemented, fundamentally suppressing stress concentration caused by superimposed excavation disturbances and improving the stability of multi-section construction. The linkage between the adaptive adjustment library and the construction control terminal allows for rapid and accurate issuance of process adjustment commands, achieving intelligent and dynamic adjustment of the construction process. This solves the technical challenges of existing technologies being unable to cope with local geological variations and superimposed disturbances from multi-section excavation, allowing tunnel construction to better adapt to complex and changing geological conditions. This significantly improves the safety, rationality, and efficiency of construction, ensuring the overall construction effect of zoned and graded excavation and collaborative support of the tunnel.

[0079] In another technical solution, the process of implementing adaptive adjustment of geological variations and multi-section excavation disturbance control also includes dynamic monitoring of environmental parameters and process linkage adjustment, as follows: While using ground-penetrating radar to conduct real-time advanced detection of the surrounding rock section, environmental monitoring points are simultaneously deployed within the construction foundation unit. Water pressure sensors and temperature sensors are used to continuously monitor groundwater pressure and surrounding rock temperature in real time, and the monitoring data is synchronously uploaded to the construction control terminal. Specifically, one environmental monitoring point is deployed every 10 m, with one point each at the arch top, two side walls, and bottom. Water pressure sensors and temperature sensors are used to continuously monitor groundwater pressure and surrounding rock temperature in real time, with a collection frequency of once per minute. Preset groundwater pressure warning thresholds and surrounding rock temperature warning thresholds are set. The groundwater pressure warning threshold is set to 1.2 times the initial water pressure value predicted in the geological survey report of the corresponding section. The surrounding rock temperature warning threshold is set according to the critical failure conditions of the construction quality of cement-based grouting materials and shotcrete: Low temperature warning threshold: surrounding rock temperature below 5℃. The threshold is defined as the critical temperature at which the cement hydration reaction basically stops, the shotcrete cannot set and harden normally, and the strength development of the grout is severely delayed; the high temperature warning threshold is when the surrounding rock temperature is higher than 35℃. This threshold is defined as the critical temperature at which the excessively rapid reaction of the accelerator leads to a surge in the rebound rate of the shotcrete, a decrease in the bond strength between the shotcrete layer and the surrounding rock, and an aggravation of the later strength loss; when the groundwater pressure is detected to exceed the warning threshold, the construction control terminal automatically links to the adaptive adjustment library, using the standard grouting pressure benchmark value for the corresponding surrounding rock grade (Grade III 0.8~1.0 MPa, Grade IV 1.0~1.2 MPa, Grade V 1.2~1.5 MPa) as the initial setting basis, and increases the grouting pressure of the corresponding section by 10%~20% on the basis of the current setting value, while extending the grouting holding time to 30 min~40 min to enhance the water blocking effect;

[0080] When the temperature of the surrounding rock exceeds the warning threshold, the construction control terminal automatically outputs the process adjustment instruction according to the type of over-limit: (1) Low temperature condition (<5℃): Activate the low temperature construction plan. Switch the grouting material to antifreeze grouting material (such as: HSGM-E antifreeze high strength non-shrink grouting material) or add low temperature early strength agent (such as KDJD-1 composite early strength antifreeze agent), and adjust the dosage of quick-setting agent (such as SBT®-N(II) alkali-free liquid quick-setting agent) to 0.8 to 0.9 times the conventional dosage; heat the mixing water of the sprayed concrete to 30℃ to 50℃, take hot air insulation measures for the sprayed rock surface, and ensure that the concrete temperature is not lower than 10℃ when it enters the formwork; after the grouting is completed, cover with insulation blanket and extend the demolding time until the strength reaches the design requirements. (2) High temperature conditions (>35℃): Adjust the dosage of quick-setting agent in the grouting material to 1.1 to 1.2 times the conventional dosage, and shorten the time interval between mixing and spraying the shotcrete to within 30 minutes; if necessary, add ice to the mixing water to cool it down, and control the concrete discharge temperature to not exceed 30℃; spray the sprayed parts to prevent the surface from losing water too quickly and cracking.

[0081] Environmental parameter monitoring data, geological variation detection data, and surrounding rock deformation monitoring data are synchronously stored in the construction control terminal to form a three-dimensional data linkage analysis system of "environment-geology-deformation". This provides data support for the preset of process parameters in subsequent construction sections and avoids support failure and surrounding rock instability caused by dynamic environmental changes.

[0082] This implementation method focuses on the dynamic monitoring of environmental parameters and the coordinated adjustment of processes during tunnel construction. It is applicable to geological variation detection and subsequent excavation and support stages in various tunnels undergoing zonal and graded excavation and coordinated support construction. Before implementation, the construction foundation unit division was completed, and the ground-penetrating radar detection equipment and construction control terminal were debugged and deployed. Simultaneously, the calibration and deployment planning of water pressure sensors and temperature sensors were completed to ensure that environmental parameter monitoring and advanced geological detection were carried out synchronously, and that data could be exchanged and linked in real time. While using ground-penetrating radar to conduct real-time advanced detection of the surrounding rock section, environmental monitoring points were simultaneously deployed within the construction foundation unit. One point was deployed every 10 m along the tunnel axis, and one point was deployed at the arch, both sidewalls, and the bottom. Water pressure sensors and temperature sensors were used to continuously monitor groundwater pressure and surrounding rock temperature in real time, respectively, at a collection frequency of once per minute. The monitoring data was uploaded to the construction control terminal in real time via wireless transmission, achieving synchronous transmission and real-time display with geological variation detection data. Groundwater pressure and surrounding rock temperature warning thresholds are preset in the construction control terminal. The groundwater pressure warning threshold is set to 1.2 times the predicted water pressure value in the previous exploration of the corresponding section. The surrounding rock temperature warning threshold is set to 5℃~35℃. The low temperature warning threshold is set to the critical temperature value at which the cement hydration reaction in cement-based grouting materials and shotcrete basically stops, i.e., 5℃. The high temperature warning threshold is set to the critical temperature value at which the rapid reaction of the accelerator leads to a decrease in the bond strength between the shotcrete layer and the surrounding rock, i.e., 35℃. During construction, the control terminal continuously compares and judges the real-time collected environmental parameters. When the groundwater pressure is detected to exceed the warning threshold, the construction control terminal automatically links with the geological variation-construction process adaptive adjustment library to increase the grouting pressure of the corresponding section by 15% on the basis of the current set adjustment value, and at the same time extend the grouting holding time to 35 minutes. The water pressure change is continuously monitored during the grouting process until the water pressure falls back below the warning threshold, thereby enhancing the effect of water blocking and rock stabilization. When the surrounding rock temperature exceeds the warning threshold of 5℃ to 35℃, adjustments are made in two levels: When the surrounding rock temperature is >35℃, the dosage of the accelerator in the grouting material is adjusted to 1.1 to 1.2 times the conventional dosage to accelerate the solidification speed; when the surrounding rock temperature is <5℃, the low-temperature construction plan is activated, antifreeze grouting material is used, and the dosage of the accelerator is adjusted to 0.8 to 0.9 times the conventional dosage. At the same time, insulation covering measures are taken for the grouting area to ensure the normal solidification of the grouting material and the support strength. All environmental parameter monitoring data are synchronously stored in the database of the construction control terminal along with geological variation detection data and surrounding rock deformation monitoring data, forming a three-dimensional data linkage analysis system of environment-geology-deformation. Construction personnel can retrieve historical data through the terminal for analysis, providing comprehensive and accurate data support for the preset excavation and support process parameters of subsequent construction sections.Throughout the construction process, dedicated personnel were assigned to conduct real-time inspections of the environmental monitoring equipment, promptly addressing issues such as sensor malfunctions and data transmission interruptions to ensure the continuity of environmental parameter monitoring. Simultaneously, the location and density of monitoring points were adjusted in a timely manner based on changes in on-site geological conditions, ensuring that environmental parameter monitoring accurately matched construction needs and fundamentally preventing support failure and surrounding rock instability caused by dynamic environmental changes.

[0083] Current technologies for tunnel zoning and graded excavation and collaborative support construction only focus on geological conditions and surrounding rock deformation, neglecting systematic monitoring of key environmental parameters such as groundwater pressure and surrounding rock temperature. They lack dedicated environmental monitoring equipment and routine monitoring procedures, making it impossible to promptly grasp changes in environmental parameters during construction. Furthermore, current technologies lack a linkage adjustment mechanism between environmental parameters and construction processes. Once process parameters such as grouting pressure and grout material ratios are set, they are not adjusted, ignoring the impact of water pressure changes on water plugging effectiveness and temperature changes on grout material setting speed and support strength. This can easily lead to incomplete water plugging, abnormal grout material setting, and insufficient support structure strength, ultimately causing support failure, surrounding rock instability, and increased construction safety risks. In addition, various construction data in current technologies are independent, lacking supplementary environmental data to support geological and deformation data. The reference basis for parameter presets is relatively singular, making it difficult to achieve precise and scientific adjustments to the construction process.

[0084] This implementation method, by simultaneously conducting real-time monitoring of environmental parameters during advanced geological exploration and deploying standardized monitoring points and sensors, achieves continuous acquisition and real-time transmission of groundwater pressure and surrounding rock temperature, filling the gap in environmental parameter monitoring during tunnel construction. By pre-setting quantified environmental parameter early warning thresholds, an automatic linkage adjustment mechanism between environmental parameters and construction techniques is established, enabling dynamic and precise adjustment of grouting pressure, holding time, and grouting material ratio. This effectively avoids the adverse effects of water pressure and temperature changes on support performance, strengthens water blocking and support effects, and ensures the stability of the support structure. Simultaneously, the integration of environmental parameter data with geological and deformation data forms a three-dimensional data linkage analysis system, providing a more comprehensive reference for the pre-setting and adjustment of construction technique parameters. This significantly improves the scientific rigor and accuracy of technique adjustments, solving the technical problems of existing technologies that do not consider the impact of environmental parameters and lack a process linkage adjustment mechanism. This allows tunnel construction to better adapt to complex environmental changes, further enhancing construction safety and support reliability, and ensuring the overall construction quality of tunnel zoning and tiered excavation and coordinated support.

[0085] In another technical solution, after the completion of S3 single-cycle excavation and monitoring and before the support step, a pretreatment step for the surrounding rock interface is also included, specifically:

[0086] The working face and surrounding rock surfaces are cleaned with pumice and high-pressure air washing to remove loose rock fragments and dust;

[0087] Before the initial shotcrete, an interface adhesive is sprayed onto the surrounding rock interface to form a bonding reinforcement layer.

[0088] Before the initial shotcrete application is completed and reaches its final set (preferably within 2 hours), a comprehensive survey of the density between the initial shotcrete and the surrounding rock should be conducted using a radar interface detection device. The detection frequency should be no less than one measuring point per square meter, with a focus on areas prone to voids, such as the arch crown and arch foot. When voids are detected, the voided areas should be filled with additional initial shotcrete or pressure grouting to ensure a tight bond and coordinated deformation between the initial shotcrete and the surrounding rock.

[0089] This implementation method focuses on the pretreatment of the surrounding rock interface before tunnel support construction. It is applicable to the collaborative support construction phase after the zoning and grading excavation of various tunnels. Before implementation, single-cycle excavation and real-time monitoring of surrounding rock deformation have been completed, and on-site debugging and preparation of pumice removal tools, high-pressure air guns, interface adhesives, radar interface detection devices, and shotcrete equipment have been completed to ensure that each pretreatment process can be carried out seamlessly. After completing single-cycle excavation and monitoring of surrounding rock deformation, and before performing various support construction operations, the surrounding rock interface pretreatment process is officially initiated. First, a comprehensive pumice removal is carried out on the working face and the surrounding rock surface. Loose rock blocks and unstable rocks on the excavation face are gradually removed from top to bottom using tools such as crowbars and small hammers. During the cleaning process, on-site protection is carried out to prevent pumice from falling and causing construction hazards, ensuring that there is no obviously loose rock mass on the excavation face. After the loose rocks were removed, a high-pressure air gun was used to perform high-pressure air washing on the entire excavation face. The air pressure of the air gun was set to 0.6 MPa, and it was moved evenly along the excavation face to thoroughly remove dust, rock debris, and loose soil adhering to the surrounding rock surface, ensuring the cleanliness of the excavation face and laying the foundation for subsequent bonding construction. After the high-pressure air washing was completed and the cleanliness of the excavation face was confirmed, an interface adhesive was evenly sprayed onto the entire excavation face before the initial shotcrete construction. The spraying was done using an atomized spraying method, and the spray thickness was controlled at 0.3 mm to ensure that the adhesive could fully and evenly cover the surrounding rock surface without any missed areas or exposed substrate. After spraying, the surface was left to stand for 5 minutes to allow the adhesive to fully penetrate and bond with the surrounding rock surface, forming a dense bonding reinforcement layer, which improves the bonding strength between the subsequent initial shotcrete and the surrounding rock. Following initial shotcreting, a radar interface detection device was immediately used to monitor the density between the shotcrete and the surrounding rock in real time. The detection frequency was one detection point per square meter, comprehensively scanning the contact interface between the shotcrete and the surrounding rock to accurately identify void areas. If void areas were detected, targeted filling measures were taken promptly according to the size of the void areas. Small void areas (void area less than 0.5 m²) were addressed accordingly. 2In areas where there are large voids (void areas greater than or equal to 0.5 m²), initial shotcrete is directly applied using shotcrete equipment for filling. 2 The affected area was filled using pressure grouting at a pressure of 0.8 MPa until the voids were completely filled and compacted. Only after a second inspection confirming the interface was free of voids and gaps could subsequent support construction procedures such as steel arch erection and secondary shotcreting proceed. This ensured a tight bond between the initial shotcrete and the surrounding rock, enabling coordinated deformation. Throughout the entire surrounding rock interface pretreatment process, seamless transitions were maintained, and on-site inspections were conducted after each step to ensure construction quality met standards. Dedicated personnel recorded pretreatment construction data to provide a reference for subsequent construction in similar surrounding rock sections.

[0090] Current technologies for tunnel support construction often involve a rather crude approach to the treatment of the surrounding rock excavation face. Only large, easily visible loose rocks are removed, without a comprehensive and meticulous cleaning of the surface or specialized dust control. The remaining loose rock fragments and dust on the surrounding rock surface directly affect the bonding effect between the support structure and the surrounding rock. Furthermore, current technologies lack a pre-concrete bonding reinforcement step before initial shotcrete application. The bonding between the initial shotcrete and the surrounding rock relies solely on the material properties of the shotcrete itself, resulting in low bond strength. Moreover, the lack of post-construction testing of the interface density between the initial shotcrete and the surrounding rock makes it impossible to detect interface voids in a timely manner, leading to gaps and delamination between the initial shotcrete and the surrounding rock. The aforementioned problems prevent the support structure and the surrounding rock from deforming in tandem. The surrounding rock is prone to local stress concentration after being subjected to stress, and the initial shotcrete is prone to cracking and falling off, which greatly reduces the overall stability of the support structure and may even lead to construction hazards such as support failure and surrounding rock instability. Existing technologies lack targeted solutions and can only provide post-hoc remedial measures after obvious support problems occur, resulting in poor construction effectiveness and safety.

[0091] This implementation method, through a standardized and refined pretreatment process for the surrounding rock interface, achieves comprehensive control over all stages, from pumice removal and high-pressure air washing to adhesive spraying, density testing, and void filling. Thorough pumice removal and high-pressure dust removal of the excavation face ensure the cleanliness and integrity of the surrounding rock surface. By atomizing and controlling the specific spraying thickness of the interface adhesive, the bonding strength between the initial shotcrete and the surrounding rock is effectively improved. A radar interface detection device enables comprehensive detection of interface density, and void areas are promptly filled, fundamentally preventing interface voiding. This method ensures a tight bond between the initial shotcrete and the surrounding rock, allowing the support structure to deform and share stress in tandem with the surrounding rock. It effectively eliminates the vulnerability of the support structure caused by interface voids, significantly improving the overall stability and reliability of the support structure. It solves the technical problems of existing technologies, such as rough and ineffective surrounding rock interface treatment, poor adhesion, susceptibility to voids, and lack of detection and remedial measures. This makes the foundational aspects of tunnel support construction more standardized and robust, further guaranteeing the quality and effectiveness of subsequent overall support construction and enhancing the safety of tunnel construction.

[0092] In another technical solution, when switching to the next construction section in S7 and repeating steps S3 to S6, a continuous connection step for the inter-cycle support structure is also included, specifically:

[0093] The steel arch frame and anchor bolts of the current cycle are connected to the steel arch frame and anchor bolts of the next cycle by lap joint, with an lap length of not less than 50cm.

[0094] Reinforcing steel plates are added at the overlap points, and the overlap area is thickened with shotcrete to form a locally reinforced section.

[0095] At the same time, the deformation monitoring data of the previous and subsequent cycles are linked and compared to ensure that the support structure of adjacent construction sections is subjected to continuous stress without sudden stress changes.

[0096] This implementation method focuses on the continuous connection of inter-cycle support structures during tunnel construction. It is applicable to the cyclical connection construction phase of various tunnels involving zoned and graded excavation and coordinated support. Before implementation, the excavation and reinforced coordinated support of the current construction section have been completed, and preliminary preparations for the excavation of the next construction section have been completed. Materials such as steel arch frames, anchor bolts, reinforcing connecting steel plates, and shotcrete are prepared to ensure rapid and standardized progress in the connection construction. When the current cycle of excavation and reinforced coordinated support is completed, and preparations are made to switch to the next construction section and repeat the excavation, monitoring, and support process, the continuous connection procedure of the inter-cycle support structure is formally initiated. First, the steel arch frames and anchor bolts are overlapped. The steel arch frames and anchor bolts at the end of the current cycle are connected to those at the beginning of the next cycle using an overlapping connection. The overlap length is strictly controlled to 50 cm. During the overlap process, the axis of the steel arch frames is aligned, and the anchor bolts are laid in the same direction, ensuring that the structure at the connection point is straight and free from misalignment or displacement. Reinforcing steel plates were added at the overlap between the steel arch frame and the anchor bolts. The steel plates, 20 mm thick, were cut to size according to the cross-sectional dimensions of the steel arch frame and welded to both the inner and outer sides of the overlap. Welding was ensured to be full and free of incomplete welds, allowing the steel arch frames of the previous and subsequent cycles to form a strong, integrated connection through the reinforcing steel plates, thus improving the structural strength of the overlap. After welding the steel plates, a thicker shotcrete layer was applied to the entire overlap area, increasing the thickness by 5 cm from the standard shotcrete thickness. During spraying, the concrete was ensured to evenly cover the overlap and the reinforcing steel plates, fully filling the gaps and forming a locally reinforced section, integrating the support structure of the overlap with the surrounding area. After the physical connection of the support structure was completed, the deformation data of the surrounding rock from the previous and subsequent cycles were quantitatively compared and analyzed. The specific method is as follows: Extract the crown settlement monitoring data from the last monitoring cycle of the current cycle (i.e., within 24 consecutive hours after the completion of the current cycle's support) and calculate its average rate v1; simultaneously extract the crown settlement monitoring data from the first monitoring cycle of the next cycle (i.e., within 24 consecutive hours after the completion of the next cycle's excavation) and calculate its average rate v2; similarly calculate the average rates w1 and w2 of the peripheral convergence. Calculate the ratio of the deformation rate difference between adjacent cycles for crown settlement and peripheral convergence using the formulas Δv = |v1 - v2| / v1 × 100% and Δw = |w1 - w2| / w1 × 100%, respectively. When Δv ≥ 50% or Δw ≥ 50%, it is determined that there is a stress abrupt change between adjacent cycles, indicating abnormal stress in the overlapping area. At this point, secondary reinforcement measures should be taken immediately for the overlapping parts, including but not limited to densifying the steel arch frame (reducing the spacing by 30% to 50%), adding anchor bolts (Φ22, with a length of not less than 4 m), and pressure grouting of the area (increasing the grouting pressure to 1.2 to 1.5 times the conventional level) to ensure that the support structure of adjacent construction sections is continuously stressed without stress abrupt changes.

[0097] In existing technologies for tunnel zoning and graded excavation and coordinated support construction, there is a lack of standardized construction requirements for the connection of support structures between adjacent construction cycles. The connection of steel arches and anchor bolts lacks clear lap methods and length specifications, often employing simple butt joints or even directly leaving construction joints, resulting in weak structural strength at the connection points. Furthermore, existing technologies do not employ specific reinforcement measures at the lap joints of the support structures, lacking the construction steps for adding reinforcing steel plates and thickening shotcrete. These connection points easily become weak points in the support structure, prone to cracking, deformation, and even detachment under the pressure of the surrounding rock. In addition, existing technologies do not perform linked analysis of deformation monitoring data from previous and subsequent cycles, making it impossible to detect stress abrupt changes at the connection points in a timely manner. Even if abnormal stress occurs in the support structure, it is difficult to detect and address it immediately, easily leading to discontinuity in the stress distribution of support structures in adjacent construction sections, which can cause local instability of the surrounding rock, affecting the overall support effect and construction safety of the tunnel. Moreover, the connection construction in existing technologies relies heavily on construction experience, lacking unified construction standards, resulting in inconsistent construction quality and difficulty in ensuring the integrity of the support system.

[0098] This implementation method, by clearly defining the overlapping method and specific overlapping length of the steel arch frame and anchor bolts between cycles, ensures a unified construction standard for the connection of the support structure, effectively avoiding problems such as misalignment and weak connection. Adding reinforcing steel plates at the overlapping locations and thickening the shotcrete creates locally reinforced sections, significantly improving the structural strength of the connection points and fundamentally eliminating weak points in the support between cycles. Simultaneously, by comparing the deformation monitoring data of the preceding and following cycles, the stress state of the connection points can be grasped in a timely manner, effectively avoiding construction risks caused by sudden stress changes and ensuring continuous and smooth stress transmission in the support structures of adjacent construction sections. This method allows the support structures of each cycle in tunnel construction to form a complete and continuous whole, solving the technical problems of lack of standards for support connection between cycles, weak structure, and discontinuous stress in existing technologies. It significantly improves the integrity and stability of the support system, allowing the support structure to bear the surrounding rock pressure more evenly, effectively controlling the overall deformation of the surrounding rock of the tunnel, and further ensuring the construction quality and safety of the tunnel's zonal and graded excavation and coordinated support. Example

[0099] This embodiment is applicable to the construction of large-section highway tunnel projects. The tunnel is designed with a cross-sectional span of 15m and a height of 12m. The surrounding rock along the route is mainly Class IV, with local intersections of Class V soft rock with water-rich areas and Class III hard rock sections. The construction method of zoned and graded excavation and coordinated support is adopted for the entire tunnel construction. This method solves the problems of mismatched excavation and support sequence, inaccurate control of surrounding rock deformation, and lack of closed-loop management in traditional construction. The specific implementation steps and quantitative parameters are as follows:

[0100] Construction foundation unit division: Based on the geological survey data of the tunnel project, the tunnel is longitudinally divided into continuous construction sections of 20m each. Each construction section is precisely divided into Class III, Class IV, and Class V surrounding rock sections according to geological conditions. At the same time, each construction section is transversely divided into an upper bench area (excavation height 6m), a lower bench area (excavation height 5m), and a core soil area (cross-sectional area accounting for 30%) according to cross-sectional structure. The core soil area has a reserved width of 4m and adopts a reserved bench excavation. Vertically, it is divided into 2 to 3 benches, each bench height of 1.5m to 2.0m. The construction follows the principle of "step-by-step demolition and protection as demolition is carried out", which ultimately forms a standardized construction foundation unit with longitudinal grading and transverse zoning to ensure the stability of the tunnel face excavation.

[0101] Five-dimensional database construction: Pre-set quantitative parameters for all dimensions for different surrounding rock grades and construction zones, stored in data tables. Core parameters are set in layers according to "hourly thresholds (real-time judgment) + daily thresholds (long-term control)". All grouting pressure adjustments are based on conventional grouting pressure benchmark values ​​(Grade III 0.8–1.0 MPa, Grade IV 1.0–1.2 MPa, Grade V 1.2–1.5 MPa), specifically as follows: Grade III surrounding rock: 2 m excavation advance for the upper bench, 2.5 m for the lower bench, initial shotcrete thickness 8 cm; shotcrete is the main support method, steel arches are not defaulted to; if the surrounding rock integrity coefficient Kv < 0.5 or the real-time deformation rate exceeds the warning threshold by 80% during construction, it is determined that I14 type steel arches need to be added, spaced 1.5 m apart, and erected within 2 hours after excavation; hourly warning thresholds: arch crown settlement ≤ 0.1 mm / h, perimeter convergence ≤ 0.15 mm / h. mm / h; Daily control thresholds: crown settlement ≤ 2 mm / d, perimeter convergence ≤ 3 mm / d. Class IV surrounding rock: upper bench excavation advance 1.5 m, lower bench 2 m, initial shotcrete thickness 10 cm; I16 type steel arch frame is selected, spacing 1.2 m, lightweight steel arch frame is arranged at the edge of the core soil area; hourly warning thresholds: crown settlement ≤ 0.2 mm / h, perimeter convergence ≤ 0.25 mm / h; daily control thresholds: crown settlement ≤ 4 mm / d, perimeter convergence ≤ 5 mm / d. Class V surrounding rock: Excavation advance of 1 m for both upper and lower steps, initial shotcrete thickness of 12 cm; I18 type steel arch frames are selected, spaced 0.8 m apart, with steel arch frames arranged at 1 m intervals in the core soil area and anchor bolts installed; hourly warning thresholds: arch crown settlement ≤ 0.3 mm / h, perimeter convergence ≤ 0.35 mm / h; daily control thresholds: arch crown settlement ≤ 6 mm / d, perimeter convergence ≤ 7 mm / d. Support intervention time thresholds: set according to the grade of surrounding rock: Class V surrounding rock: initial shotcrete completed within 30 minutes, steel arch frame erection completed within 1 hour; Class IV surrounding rock: initial shotcrete completed within 45 minutes, steel arch frame erection completed within 2 hours; Class III surrounding rock: initial shotcrete completed within 1 hour. All thresholds are simultaneously included in the database for unified management.

[0102] Geological Variation and Excavation Disturbance Control: After the database was built and before excavation, ground-penetrating radar was used to conduct advanced detection of the surrounding rock sections within the construction foundation unit. The detection range covered the entire unit and 20 m in front of the tunnel face, accurately identifying geological variation areas such as local fracture zones (rock integrity coefficient Kv < 0.5) and local water-rich points (single-point water inflow ≤ 5 L / min). A geological variation-construction technology adaptive adjustment library was established, achieving data linkage with the five-dimensional corresponding database. In soft rock water-rich areas, water-blocking grouting was used first, followed by short-cut excavation in different zones and grades. The short-cut excavation was 50%~60% of the conventional excavation cut for the corresponding surrounding rock grade, and the grouting pressure was increased to 1.5 times the conventional grouting pressure. In hard rock fracture zones, controlled blasting was used, and advanced pipe roofs were added. The pipe roof spacing was 70% of the conventional pipe roof spacing, and the pipe roof length was 15. m; When constructing multiple sections in parallel, set a quantitative excavation interval threshold, with the timing starting on the day the support is completed and accepted; the excavation interval between upper and lower layers at tunnel intersections shall not be less than 5 days, and the excavation interval between ordinary parallel sections shall not be less than 3 days, to suppress stress concentration in the surrounding rock caused by the superposition of excavation disturbances; the adaptive adjustment library is linked with the construction control terminal in real time, and automatically outputs process adjustment instructions after detecting areas of geological variation to guide subsequent excavation construction.

[0103] Dynamic monitoring of environmental parameters and process linkage: While conducting advanced geological exploration, an environmental monitoring point is set up every 10 m along the tunnel axis within the construction foundation unit. One water pressure sensor and one temperature sensor are installed at the arch crown, both side walls, and the bottom. The sensors penetrate 5 cm into the surrounding rock surface, collecting data once per minute. The monitoring data is uploaded to the construction control terminal in real time. The groundwater pressure warning threshold is 1.2 times the predicted water pressure value; the surrounding rock temperature warning threshold is 5℃~35℃, where <5℃ is the low-temperature warning threshold (cement hydration reaction stagnation) and >35℃ is the high-temperature warning threshold (accelerator reaction too rapid). When groundwater pressure exceeds the limit, the grouting pressure is increased by 15% based on the geological variation adjustment, and the grouting holding time is extended to 35 minutes to enhance the water-blocking effect. When the surrounding rock temperature exceeds the limit, adjustments are made according to the working conditions: for low-temperature conditions (<5℃), antifreeze grouting materials are switched, and the dosage of accelerator is adjusted to 0.8-0.9 times the conventional dosage, supplemented by hot air insulation measures; for high-temperature conditions (>35℃), the dosage of accelerator is adjusted to 1.15 times the conventional dosage, ice is added to the mixing water to cool it down, and the concrete discharge temperature is controlled not to exceed 30℃. The monitoring data of environmental parameters such as groundwater pressure and surrounding rock temperature are synchronously stored in the construction control terminal along with geological variation detection data and surrounding rock deformation monitoring data, forming a three-dimensional data linkage analysis system of "environment-geology-deformation", providing comprehensive data support for the preset of process parameters in subsequent construction sections.

[0104] Zonal and graded excavation and non-contact monitoring: According to the excavation method and advance parameters preset in the five-dimensional corresponding database, the current construction section is excavated in a zonal and graded manner in the order of "upper bench area → lower bench area → core soil area". The advance is strictly controlled in single-cycle excavation. The core soil area follows the principle of "step-by-step demolition and support as demolition", with one level of support removed and one level removed to minimize the time when the core soil surface is exposed without support. Non-contact monitoring: After the single-cycle excavation is completed, a total station is used for non-contact real-time monitoring. Monitoring points are evenly distributed within a 10 m range at the tunnel face and behind it, with 3 points on the arch crown and 4 points on each of the two side walls. The total station collects spatial location data of the monitoring points at a frequency of once per minute. The construction control terminal calculates the arch crown settlement rate and the surrounding convergence rate in real time. All monitoring and calculation data are uploaded to the terminal simultaneously, comprehensively and accurately reflecting the deformation state of the surrounding rock and providing real-time data basis for determining the timing of support. If the construction site space is limited, a laser point cloud device can be used for monitoring, with a scanning cycle of once every 5 minutes, to achieve the same monitoring effect.

[0105] Rock Interface Pretreatment: After excavation and deformation monitoring are completed and before support construction, a comprehensive and meticulous pretreatment process is carried out on the working face and surrounding excavation faces to ensure that the initial shotcrete adheres tightly to the surrounding rock and deforms in tandem. Loose Rock Removal and High-Pressure Air Washing: Loose rock blocks and unstable rocks are manually removed from top to bottom on the excavation face. A high-pressure air gun with a pressure of 0.6 MPa is used to blow away dust and rock debris from the surrounding rock surface, ensuring that there is no loose rock mass or dust adhering to the excavation face. Interface Bonding Enhancement: An interface adhesive is sprayed onto the surrounding rock interface using an atomized spraying method. The wet film thickness is controlled at 0.3 mm. After spraying, the interface is left to stand for 5 minutes to allow the adhesive to fully penetrate and bond with the surrounding rock surface, forming a dense bonded reinforcement layer. Density Testing and Void Filling: After the initial shotcrete construction is completed, a radar interface detection device is used to test the interface density at a frequency of one detection point per square meter. Small void areas (<0.5 m²) are filled. 2 Directly fill with sprayed concrete for large areas of voids (≥0.5 m). 2 Grouting with 0.8 MPa pressure was used for filling. Only after two rounds of testing confirmed that there were no voids or gaps at the interface could the subsequent support process begin.

[0106] Support Timing Determination and Coordinated Support: The construction control terminal prioritizes the hourly deformation rate of the surrounding rock as the first priority and the excavation completion time as the second priority, using a dual-threshold coordinated determination of support timing. Specific determination and execution rules are as follows: If the hourly deformation rate of the surrounding rock does not exceed the hourly warning threshold, wait until the excavation completion time reaches the support intervention time threshold, then execute conventional coordinated support according to the preset parameters in the five-dimensional database; if the excavation completion time has exceeded the support intervention time threshold but the deformation rate still does not exceed the limit, immediately execute conventional coordinated support without further waiting; Conventional coordinated support strictly follows the process parameters corresponding to the surrounding rock grade: the initial shotcrete uses a wet spraying process to ensure uniform spraying and density; the steel arch frame is erected to ensure accurate positioning, straight axis, and close fit with the surrounding rock, with full welds at welded joints and no incomplete or missing welds, ensuring the quality of the support structure formation.

[0107] Implementation of the support reinforcement mechanism: When monitoring detects that the hourly deformation rate of the surrounding rock exceeds 1.2 times the hourly warning threshold, the support reinforcement mechanism is immediately activated. Based on conventional coordinated support, triple reinforcement measures are implemented, with all reinforcement procedures carried out simultaneously to quickly form a reinforced and coordinated support structure.

[0108] Steel arch frame densification: The spacing between steel arch frames is reduced by 40% (based on the preset spacing in the five-dimensional database). For Class V surrounding rock, the spacing is adjusted from 0.8 m to 0.48 m, and for Class IV surrounding rock, from 1.2 m to 0.72 m. During installation, precise alignment and secure connection with the existing steel arch frames are ensured. Additional anchor bolts are added: Two Φ22, 4.5 m long mortar anchor bolts are installed at the arch foot of each steel arch frame, driven into the surrounding rock at an angle of 45°–60° to the horizontal. This ensures a strong connection between the anchor bolts and the surrounding rock and steel arch frame, restraining arch foot displacement and settlement. Grouting pressure is increased: The grouting pressure is increased to 1.4 times the conventional grouting pressure benchmark. During grouting, the grouting speed and volume are controlled to ensure the grout fully fills the fissures in the surrounding rock and the gaps between the steel arch frame and the surrounding rock, forming a dense grout-consolidated body. During the reinforcement construction process, the deformation of the surrounding rock is continuously monitored until the hourly deformation rate of the surrounding rock falls back to within the hourly warning threshold, confirming that the deformation of the surrounding rock has been effectively controlled.

[0109] Continuous connection of support structures between cycles: After the current cycle of excavation and support construction is completed and accepted, and before switching to the next construction section, continuous connection construction of the support structures between cycles is carried out to ensure the continuity of stress and no stress abrupt changes in the support structures of adjacent sections. Overlap connection: The steel arches and anchor bolts of the current cycle and the next cycle are connected by overlap, with the overlap length strictly controlled at 50 cm, ensuring that the steel arch axis is aligned and the anchor bolts are laid in the same direction, without misalignment or offset. Local reinforcement: 20 mm thick reinforcing steel plates are welded to both the inner and outer sides of the overlap location, with full welds and no incomplete welds. The overlap area is thickened by 5 cm on top of the conventional shotcrete thickness to form a local reinforced section, allowing the overlap part to form an integral whole with the surrounding support structure. Stress mutation prevention and control: The monitoring data such as the arch settlement rate, the surrounding convergence rate, and the total deformation of the previous and subsequent cycles are compared in a linked manner. If the difference in deformation rate between adjacent cycles is ≥50%, it is determined to be a stress mutation. The steel arch frame at the overlapping part is immediately densified, the locking foot anchor is added, and pressure grouting is carried out to fill the gap. Secondary reinforcement measures are taken in a timely manner to ensure that the support structure is continuously subjected to force and smoothly transmitted.

[0110] Closed-loop construction progress: After completing all excavation, monitoring, pretreatment, support / reinforcement, and connection construction stages of the current construction cycle, a comprehensive inspection and acceptance of the support structure construction quality is conducted. Once confirmed as qualified, the process moves to the next construction section, repeating the entire process of zoned and graded excavation – non-contact monitoring – surrounding rock interface pretreatment – ​​support timing determination – conventional collaborative support / support reinforcement – ​​inter-cycle support connection, advancing the tunnel construction progress section by section. Throughout the construction process, dedicated personnel are assigned to manage work sequence scheduling and quality control, promptly recording data from each construction stage and synchronously updating the corresponding five-dimensional database to achieve dynamic optimization of construction parameters. Ultimately, a closed-loop construction system is formed, encompassing tunnel excavation, monitoring, support, reinforcement, and data feedback. This effectively controls surrounding rock deformation, avoids problems such as surrounding rock instability and uneven stress on the support structure, and ensures the overall construction quality and safety of the tunnel.

[0111] This embodiment integrates the various stages of tunnel excavation and collaborative support into an organic whole through systematic construction unit division, standardized parameter preset, dynamic process adjustment, and closed-loop management of the entire process. Compared with traditional construction methods, it achieves multi-dimensional and digital construction management and control, which greatly improves the safety, standardization and reliability of tunnel construction. It is applicable to the construction of various tunnel projects such as highways, railways and water conservancy projects.

[0112] Although the technical solutions of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A construction method for zoned and graded excavation and coordinated support of tunnels, characterized in that, Includes the following steps: S1. Based on the geological survey data of the tunnel project, the surrounding rock grade of the tunnel is classified along the axial direction in advance, and the construction sections are divided in combination with the cross-sectional structure, forming a construction basic unit that is classified longitudinally according to the surrounding rock grade and divided laterally according to the cross-sectional structure. S2. For each construction foundation unit, pre-set the excavation method, support structure form, support intervention time threshold and hourly deformation rate warning threshold corresponding to the surrounding rock grade, and establish a five-dimensional corresponding database of zone-grade-process-sequence-parameter. S3: Perform zoned and graded excavation on the current construction section according to the preset excavation method. After completing a single cycle of excavation, conduct real-time monitoring of the arch subsidence and surrounding rock deformation in multiple dimensions of the tunnel face and the surrounding rock behind it. S4: Compare the hourly deformation rate of the surrounding rock obtained from real-time monitoring with the hourly deformation rate warning threshold, and determine whether the current excavation completion time has reached the corresponding support intervention time threshold. S5: If the hourly deformation rate of the surrounding rock does not exceed the hourly deformation rate warning threshold, wait until the excavation completion time reaches the support intervention time threshold, and then execute conventional collaborative support according to the preset support strength and structural form; if the hourly deformation rate of the surrounding rock exceeds the hourly deformation rate warning threshold, proceed to S6. S6: Immediately activate the support reinforcement mechanism; when the hourly deformation rate of the surrounding rock exceeds 1.2 times the hourly deformation rate warning threshold, on the basis of conventional collaborative support, increase the spacing of the steel arch frames, add locking anchor rods, and increase the grouting pressure to form a reinforced collaborative support structure; the support reinforcement mechanism specifically includes: when the hourly deformation rate of the surrounding rock exceeds 1.2 times the hourly deformation rate warning threshold, reduce the spacing of the steel arch frames by 30% to 50%, add locking anchor rods at the arch feet of the steel arch frames, and increase the grouting pressure to 1.2 to 1.5 times the conventional grouting pressure; S7: After completing the current cycle of excavation and support reinforcement, switch to the next construction section and repeat steps S3 to S6 to achieve full tunnel construction section by section; The process, following step S2 and preceding step S3, further includes steps for adaptive adjustment of geological variations and control of disturbance during multi-segment excavation, specifically: Within the construction foundation unit formed in S1, ground-penetrating radar is used to conduct real-time advanced detection of the surrounding rock section to identify local fracture zones and local water-rich geological variation areas. Establish a geological variation-construction technology adaptive adjustment library. When a geological variation area is detected, the final excavation method and support parameters are corrected and determined in real time based on the five-dimensional correspondence database of zoning, level, technology, time sequence and parameter and the adaptive adjustment library. When local water-rich geological variations are detected in soft rock sections, water-blocking grouting is used in conjunction with short-cut, sectional, and graded excavation, and the grouting pressure is increased to 1.3 to 1.6 times the conventional grouting pressure. When localized fracture zones with geological variations are detected in hard rock sections, controlled blasting is employed, and advanced pipe roofs are added, with the pipe roof spacing set to 60%–80% of the conventional pipe roof spacing. For parallel construction in multiple sections, an excavation interval threshold is set. The excavation interval after the upper and lower layers of support at the tunnel intersection is not less than 5 days, and the excavation interval after the support of the ordinary parallel section is not less than 3 days, in order to suppress stress concentration caused by the superposition of excavation disturbances. The adaptive adjustment library is linked with the construction control terminal data. When a geological variation area is detected, it automatically outputs process adjustment instructions to provide adaptive process parameters for the subsequent S3 excavation step.

2. The construction method for tunnel zoning and graded excavation and coordinated support as described in claim 1, characterized in that, In S1, the surrounding rock grade is classified along the tunnel axis, and the construction sections are divided based on the cross-sectional structure, specifically including: The tunnel is divided longitudinally into multiple continuous construction sections. Each construction section is further divided into Class III, Class IV, and Class V surrounding rock zones based on geological survey results. Each construction section is also divided transversely into upper bench zone, lower bench zone, and core soil zone, forming a construction foundation unit with longitudinal grading and transverse partitioning.

3. The construction method for tunnel zoning and graded excavation and coordinated support as described in claim 1, characterized in that, The five dimensions of partitioning, grade, process, time series, and parameters correspond to the database, specifically including: For different surrounding rock grades and different construction zones, excavation advance parameters, initial shotcrete thickness, steel arch frame type and spacing, support intervention time threshold, hourly arch crown settlement rate warning threshold, and hourly peripheral convergence rate warning threshold are preset and stored in the form of data tables. At the same time, a daily deformation rate threshold is preset as a macro-control indicator of the long-term stability trend of the surrounding rock, which is not involved in the real-time determination of the timing of single-cycle support.

4. The construction method for tunnel zoning and graded excavation and coordinated support as described in claim 1, characterized in that, In S3, real-time monitoring is non-contact real-time monitoring, specifically including: Laser point cloud or total station is used to continuously collect data on the surrounding rock of the working face, calculate the crown settlement rate and the surrounding convergence rate in real time, and upload the monitoring data to the construction control terminal in real time.

5. The construction method for tunnel zoning and graded excavation and coordinated support as described in claim 2, characterized in that, In S5, the threshold for support intervention time is set according to the different levels of surrounding rock: After the single-cycle excavation of the Class V surrounding rock section is completed, the initial shotcrete should be completed within 30 minutes and the steel arch frame should be erected within 1 hour. The initial shotcrete should be completed within 45 minutes after the single-cycle excavation of the Class IV surrounding rock section is completed, and the steel arch frame should be erected within 2 hours. The initial shotcrete was completed within one hour after the single-cycle excavation of the Class III surrounding rock section.

6. The construction method for tunnel zoning and graded excavation and coordinated support as described in claim 1, characterized in that, The process of implementing adaptive adjustment of geological variations and multi-section excavation disturbance control also includes dynamic monitoring of environmental parameters and coordinated adjustment of processes, as detailed below: While using ground-penetrating radar to conduct real-time advance detection of the surrounding rock section, environmental monitoring points are simultaneously set up in the construction foundation unit. Water pressure sensors and temperature sensors are used to continuously monitor the groundwater pressure and surrounding rock temperature in real time, and the monitoring data is simultaneously uploaded to the construction control terminal. The groundwater pressure warning threshold and the surrounding rock temperature warning threshold are preset. The groundwater pressure warning threshold is set to 1.2 times the initial water pressure value predicted in the geological survey report of the corresponding section. The surrounding rock temperature warning threshold is set according to the critical failure conditions of the construction quality of cement-based grouting materials and shotcrete, including low temperature warning threshold and high temperature warning threshold. When the groundwater pressure is detected to exceed the warning threshold, the construction control terminal automatically links with the adaptive adjustment database to increase the grouting pressure of the corresponding section by 10% to 20% on the basis of the current set value, and at the same time extend the grouting holding time to 30 to 40 minutes to enhance the water blocking effect. When the temperature of the surrounding rock is detected to be lower than the low temperature warning threshold, the construction control terminal automatically outputs the low temperature construction plan instruction, switches to antifreeze grouting material or adds low temperature early strength agent, and supplements it with heat preservation and curing measures. When the temperature of the surrounding rock is detected to be higher than the high temperature warning threshold, the construction control terminal automatically outputs a high temperature adaptability ratio instruction, adjusts the dosage of quick-setting agent, and takes cooling control measures. Environmental parameter monitoring data, geological variation detection data, and surrounding rock deformation monitoring data are synchronously stored in the construction control terminal to form a three-dimensional data linkage analysis system of "environment-geology-deformation". This provides data support for the preset of process parameters in subsequent construction sections and avoids support failure and surrounding rock instability caused by dynamic environmental changes.

7. The construction method for tunnel zoning and graded excavation and coordinated support as described in claim 1, characterized in that, After the completion of S3 single-cycle excavation and monitoring, and before the support step, a pretreatment step for the surrounding rock interface is also included, specifically: The working face and surrounding rock surfaces are cleaned with pumice and high-pressure air washing to remove loose rock fragments and dust; Before the initial shotcrete, an interface adhesive is sprayed onto the surrounding rock interface to form a bonding reinforcement layer. The density between the initial shotcrete and the surrounding rock is detected in real time by a radar interface detection device. When a void area is detected at the interface, the void area is filled with additional initial shotcrete or pressure grouting to ensure that the initial shotcrete and the surrounding rock are closely bonded and deform together.

8. The construction method for tunnel zoning and graded excavation and coordinated support as described in claim 1, characterized in that, When switching to the next construction section in S7 and repeating steps S3 to S6, a continuous connection step for the inter-cycle support structure is also included, specifically: The steel arch frame and anchor bolts of the current cycle are connected to the steel arch frame and anchor bolts of the next cycle by lap joint, with an lap length of not less than 50cm. Reinforcing steel plates are added at the overlap points, and the overlap area is thickened with shotcrete to form a locally reinforced section. Simultaneously, the monitoring data of the surrounding rock arch subsidence rate, peripheral convergence rate, and total deformation of the previous and subsequent cycles are linked and compared. When the difference in deformation rate between adjacent cycles is ≥50%, it is determined to be a stress mutation, and reinforcement measures are taken in a timely manner to ensure that the support structure of adjacent construction sections is continuously stressed without stress mutation.

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