Tunnel advance support construction method
By conducting geological surveys and establishing three-dimensional mechanical models in the tunnel construction area, determining the design parameters of the pipe roof, and monitoring in real time during drilling, the problems of rock mechanics properties and groundwater influence in traditional tunnel pre-support methods were solved, achieving more efficient and safer tunnel support.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-18
- Publication Date
- 2026-04-07
AI Technical Summary
Traditional tunnel pre-support methods lack sufficient consideration of the mechanical properties of the rock mass and the groundwater conditions, making it difficult for the support structure to withstand the pressure of the surrounding rock, which easily leads to deformation and damage, endangering construction safety.
By conducting geological surveys in the pre-designated construction area of the tunnel, establishing a three-dimensional mechanical model of the rock mass, determining the design parameters of the pipe roof, and monitoring the parameters in real time during drilling, the pipe roof is installed inside the borehole for advanced support.
It improved the scientific nature and safety of tunnel pre-support, ensured that the support structure met construction requirements, and enhanced the stability of the surrounding rock and the construction progress.
Smart Images
Figure CN121803261A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of tunnel pre-support technology, and in particular to a tunnel pre-support construction method. Background Technology
[0002] During tunnel construction, when encountering fault and fissure areas, the stability of the fractured rock mass is extremely poor, posing many severe challenges to the construction.
[0003] Traditional tunnel pre-support methods have many drawbacks when dealing with such complex geological conditions. In terms of scheme design, traditional designs often rely too heavily on experience and lack precise analysis of the detailed geological characteristics of the surrounding fractured rock mass. For example, using similar support parameters for faults and fissures of different sizes and orientations leads to poor support effectiveness. Furthermore, the influence of factors such as the mechanical properties of the rock mass and groundwater conditions on the support structure is not fully considered, making it difficult for the support structure to withstand actual surrounding rock pressure, easily leading to deformation and failure, thus endangering construction safety. Summary of the Invention
[0004] The main objective of this invention is to propose a method for tunnel pre-support construction, which aims to solve the technical problem that existing technologies do not fully consider the influence of factors such as the mechanical properties of the rock mass and groundwater conditions on the support structure, making it difficult for the support structure to withstand the actual surrounding rock pressure, and making it prone to deformation and damage, thereby endangering construction safety.
[0005] To achieve the above objectives, in a first aspect, the present invention proposes a method for tunnel pre-support construction, comprising the following steps: A geological survey is conducted in the pre-designated construction area of the tunnel to obtain geological information about the pre-designated construction area; wherein, the geological information includes the distribution characteristics of faults and fissures, the mechanical parameters of the rock mass, and the distribution of groundwater; A mechanical model of the rock mass in the pre-designated construction area is established based on the geological information; wherein, the mechanical model includes elastic modulus, Poisson's ratio, and compressive strength; Based on the aforementioned mechanical model, determine the design parameters of the pipe shed; According to the design parameters, drilling is carried out in the preset construction area, and drilling parameters are monitored in real time during the drilling process; wherein, the drilling parameters include drilling depth, drilling diameter and drilling verticality; The pipe roof is installed in the borehole, and advanced support operations are carried out according to the target support scheme.
[0006] In one embodiment, the step of conducting a geological survey in the predetermined construction area of the tunnel to obtain geological information of the predetermined construction area includes: The pre-designated construction area is continuously scanned along the mileage extension direction of the tunnel using ground-penetrating radar to obtain the location, orientation, and scale of the faults and fissures in the tunnel. Core drilling is conducted along the tunnel mileage extension direction to obtain rock mass data of the preset construction area; wherein, the rock mass data includes the lithology, structure and mechanical parameters of the rock mass; The integrity and internal structure of the rock mass were analyzed using acoustic detection equipment to determine groundwater distribution data. Based on the rock mass data and the groundwater distribution data, a geological profile was drawn to obtain the geological information.
[0007] In one embodiment, the step of performing core drilling along the tunnel mileage extension direction to obtain rock mass data of the preset construction area includes: Core drilling is performed along the tunnel mileage extension direction at target intervals to obtain rock mass data of the preset construction area; wherein, the target interval is A, 20m≤A≤30m.
[0008] In one embodiment, the step of establishing a mechanical model of the rock mass of the preset construction area based on the geological information includes: Using numerical simulation software, a three-dimensional mechanical model of the tunnel and surrounding rock mass is established based on the geological information. In the three-dimensional mechanical model, the mechanical parameters of the rock mass, the location characteristics of the faults and fissures, and the boundary conditions of the groundwater are set.
[0009] In one embodiment, the step of determining the design parameters of the pipe shed based on the mechanical model includes: The stress and strain of the rock mass under different pipe roof design parameters are simulated in the three-dimensional mechanical model to analyze the displacement, stress distribution and pressure changes of the rock mass under different pipe roof design parameters. The design parameters of the pipe shed are determined based on the simulation results; wherein the design parameters include the diameter, length, spacing and external angle of the pipe shed.
[0010] In one embodiment, after the step of drawing a geological profile based on the rock mass data and the groundwater distribution data to obtain the geological information, the method further includes: Waterproofing measures are designed based on the groundwater distribution data; wherein, the waterproofing measures include setting a water-stop ring around the outer periphery of the pipe roof.
[0011] In one embodiment, prior to the steps of installing the pipe roof within the borehole and performing advance support operations according to the target support scheme, the method further includes: Based on the waterproofing measures and the grouting scheme of the pipe roof, the target support scheme is obtained; The steps of installing the pipe roof into the borehole and performing advance support operations according to the target support scheme include: The pipe roof is installed inside the borehole, and grouting is performed through the grouting holes of the pipe roof according to the target support plan to complete the advanced support operation.
[0012] In one embodiment, the step of drilling in the preset construction area according to the design parameters and monitoring the drilling parameters in real time during the drilling process includes: According to the design parameters, the drilling rig is moved to the designed hole position, and the position and angle of the drilling rig are adjusted so that the drilling rig is consistent with the designed drilling direction; The drilling rig uses an automatic guidance system to control the verticality and azimuth of the borehole for drilling operations. During the drilling process, a mud circulation system is used to inject mud into the borehole for wall protection and slag removal. After the borehole reaches the designed depth, it is cleaned to remove rock cuttings and debris. Drilling is then carried out in the pre-defined construction area, and drilling parameters are monitored in real time during the drilling process.
[0013] In one embodiment, the step of real-time monitoring of drilling parameters during the drilling process includes: The drilling parameters are measured once after drilling to a preset depth, wherein the preset depth is 2-3 meters. If the verticality deviation is detected to exceed the allowable range, the drilling direction is adjusted, whereby the allowable range is a verticality deviation of no more than 1%. In the hole cleaning step, the thickness of the sediment at the bottom of the hole is controlled to not exceed 50 mm.
[0014] In one embodiment, the step of grouting through the grouting holes of the pipe roof according to the target support scheme includes: The pipe shed is processed by shaping the front end of the pipe shed into a cone shape and drilling the grouting holes on the pipe wall of the pipe shed; The processed pipe roof is pushed into the borehole using a pipe roof installation device, while maintaining the verticality and orientation of the pipe roof during the pushing process; The segmented pipe sheds are connected and fixed, and fixing devices are installed at the pipe sheds and the openings; Grouting material is injected through the grouting hole. During the grouting process, the grouting pressure and grouting volume are monitored. Grouting is stopped when the grouting volume reaches the calculated value and the grouting pressure reaches the designed final pressure.
[0015] The technical solution of this invention involves conducting geological surveys in a pre-designated construction area of the tunnel to obtain geological information about the area. Based on this information, a mechanical model of the rock mass in the pre-designated construction area is established. This mechanical model includes the elastic modulus, Poisson's ratio, and compressive strength. Based on the mechanical model, design parameters for the pipe roof are determined. Drilling is then carried out in the pre-designated construction area according to these parameters, with real-time monitoring of drilling parameters during the drilling process. The pipe roof is then installed within the borehole, and advanced support operations are performed according to the target support scheme. This invention allows for the comprehensive consideration of the mechanical shape of the rock mass and groundwater conditions in the pre-designated construction area to provide advanced support, thereby ensuring that the advanced support structure meets construction requirements and improves construction safety. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.
[0017] Figure 1 The flowchart is for the tunnel pre-support construction method provided by the present invention.
[0018] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0020] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.
[0021] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.
[0022] During tunnel construction, the stability of fractured rock masses is insufficient when encountering fault and fissure areas. Traditional advanced support methods rely too heavily on experience-based judgments during the design phase, lacking a systematic analysis of the geological characteristics of the surrounding rock mass. This results in support parameters being set in a way that fails to adapt to actual geological conditions. Specifically, similar support parameters are used for faults and fissures of different sizes and orientations, without adequately considering the mechanical properties of the rock mass and the distribution of groundwater. Consequently, the support structure cannot effectively resist the surrounding rock pressure, leading to frequent deformation and failure, and threatening construction safety.
[0023] For example, at kilometer marker K18+500 of a tunnel project, a high-angle fault exists in the construction area. Within this fault zone, the rock mass is fractured and groundwater activity is significant. In this scenario, traditional methods failed to conduct a detailed investigation of the geological information of the area. The design parameters for the pipe roof were uniformly set, and drilling parameters were not monitored in real time during drilling operations. As a result, the borehole verticality deviation exceeded the allowable range, the pipe roof installation position deviated from design requirements, the stability of the surrounding rock was further weakened, local instability events were triggered, and the construction process was forced to stop.
[0024] This invention proposes a method for tunnel pre-support construction.
[0025] Please see Figure 1 To facilitate understanding, this method for tunnel pre-support construction includes the following steps: S100. Conduct a geological survey in the pre-designated construction area of the tunnel to obtain geological information of the pre-designated construction area; wherein, the geological information includes the distribution characteristics of faults and fissures, the mechanical parameters of the rock mass, and the distribution of groundwater; S200. Establish a mechanical model of the rock mass in the preset construction area based on the geological information; wherein, the mechanical model includes elastic modulus, Poisson's ratio, and compressive strength; S300. Based on the aforementioned mechanical model, determine the design parameters of the pipe shed; S400. Drilling is carried out in the preset construction area according to the design parameters, and drilling parameters are monitored in real time during the drilling process; wherein, the drilling parameters include drilling depth, drilling diameter and drilling verticality; S500. Install the pipe roof into the borehole and carry out advance support operations according to the target support scheme.
[0026] Specifically, the first step is to conduct a geological survey in the pre-designated construction area of the tunnel to obtain detailed geological information about the area. The methods for conducting this geological survey can be varied. For example, traditional engineering geological exploration methods can be used, such as on-site reconnaissance, geological sketching, trench excavation, or limited borehole sampling, to obtain surface and shallow geological data. Conventional geophysical exploration techniques, such as resistivity methods and shallow seismic methods, can also be used to conduct preliminary exploration of the underground rock mass structure to identify potential faults and fractures. In some cases, experienced geological engineers can be relied upon to conduct a preliminary assessment and evaluation of the geological conditions of the pre-designated construction area, combining regional geological data and historical engineering experience. Through these methods, geological information including the distribution characteristics of faults and fractures, the mechanical parameters of the rock mass, and the distribution of groundwater can be obtained.
[0027] Subsequently, a mechanical model of the rock mass in the pre-designated construction area is established based on the obtained geological information. The establishment of this mechanical model is grounded in a deep understanding of the rock mass properties. For example, empirical formulas or simplified theoretical models can be used, combined with geological survey data, to estimate mechanical parameters such as the rock mass's elastic modulus, Poisson's ratio, and compressive strength. In some cases, scaled-down physical models can be created to simulate the rock mass's stress-deformation behavior through laboratory tests. Alternatively, a two-dimensional plane strain model can be used for simplified mechanical calculations to preliminarily analyze the stress-strain state of the rock mass. These mechanical models provide a theoretical basis for subsequent pipe roof design.
[0028] Based on this, the design parameters of the pipe roof are determined according to the established mechanical model. Determining the pipe roof design parameters is a crucial step in ensuring the support effect. For example, parameters such as the diameter, length, spacing, and outward angle of the pipe roof can be initially determined by referring to engineering experience or industry standard recommendations under similar geological conditions. Alternatively, appropriate pipe roof parameters can be selected based on the rock mass type and surrounding rock grade by consulting empirical charts or design manuals. Alternatively, simplified mechanical calculation methods such as beam theory or arch effect theory can be used to conduct a preliminary analysis of the stress situation of the surrounding rock under different pipe roof parameters, thereby determining more reasonable design parameters.
[0029] Furthermore, based on the determined design parameters, drilling is carried out in the pre-designed construction area, and drilling parameters are monitored in real time during the drilling process. The quality of the drilling directly affects the installation effect of the pipe roof. For example, during the drilling process, the verticality and orientation of the borehole can be manually controlled and adjusted by the experience of the drilling rig operator and simple measuring tools, such as spirit levels and inclinometers. Monitoring of drilling parameters can be done periodically, for example, by measuring the drilling depth, diameter, and verticality every time a relatively long distance is drilled (e.g., 5 or 10 meters). In some cases, the quality and stability of the borehole can also be initially judged by visually observing the cuttings produced and the swaying of the drill rod.
[0030] Finally, the pipe roof is installed inside the borehole, and advance support work is carried out according to the target support plan. The installation and support of the pipe roof is the final step in achieving surrounding rock reinforcement. For example, the pipe roof can be directly pushed or jacked into the borehole, and then filled with simple cement mortar to achieve bonding between the pipe roof and the surrounding rock. In grouting operations, segmented grouting can be used, but the grouting process may lack precise pressure and flow control. Alternatively, a single grouting hole can be used for one-time grouting, but this method may make it difficult to ensure uniform distribution and penetration of the grouting material along the entire length of the pipe roof.
[0031] In this embodiment, geological surveys are conducted in the pre-designated construction area of the tunnel to obtain geological information about the area. A mechanical model of the rock mass in the pre-designated construction area is then established based on this information. This mechanical model includes the elastic modulus, Poisson's ratio, and compressive strength. Based on the mechanical model, design parameters for the pipe roof are determined. Drilling is then carried out in the pre-designated construction area according to these parameters, and drilling parameters are monitored in real time during the drilling process. The pipe roof is then installed inside the borehole, and advanced support operations are performed according to the target support scheme. This allows the invention to fully integrate the mechanical shape of the rock mass and groundwater conditions in the pre-designated construction area to provide advanced support, thereby ensuring that the advanced support structure meets construction requirements and improves construction safety.
[0032] In one embodiment, the step of conducting a geological survey in the predetermined construction area of the tunnel to obtain geological information of the predetermined construction area includes: The pre-designated construction area is continuously scanned along the mileage extension direction of the tunnel using ground-penetrating radar to obtain the location, orientation, and scale of the faults and fissures in the tunnel. Core drilling is conducted along the tunnel mileage extension direction to obtain rock mass data of the preset construction area; wherein, the rock mass data includes the lithology, structure and mechanical parameters of the rock mass; The integrity and internal structure of the rock mass were analyzed using acoustic detection equipment to determine groundwater distribution data. Based on the rock mass data and the groundwater distribution data, a geological profile was drawn to obtain the geological information.
[0033] In this embodiment, a multi-dimensional, high-precision geological survey system is formed by organically combining the macroscopic detection capabilities of ground-penetrating radar (GPR), the direct acquisition capabilities of borehole coring, and the detailed analysis capabilities of acoustic detection. Continuous scanning by GPR can initially delineate potential geological anomaly areas, providing precise borehole layout guidance for subsequent coring, making coring more targeted and efficient. Borehole coring provides the most direct and reliable lithological, structural, and mechanical parameters, which can be used to calibrate and verify the results of GPR and acoustic detection, improving the accuracy of their interpretation. Acoustic detection further refines the integrity of the rock mass and the distribution of groundwater, especially between potential blind spots in GPR or between coring points. Finally, all these complementary data are integrated into a geological profile map, forming a comprehensive, accurate, and intuitive view of subsurface geological information. This comprehensive survey method overcomes the limitations of single survey methods, ensuring the comprehensiveness and reliability of geological information, thus providing a solid foundation for subsequent rock mechanics model establishment and the determination of pipe roof design parameters.
[0034] In one embodiment, the step of performing core drilling along the tunnel mileage extension direction to obtain rock mass data of the preset construction area includes: Core drilling is performed along the tunnel mileage extension direction at target intervals to obtain rock mass data of the preset construction area; wherein, the target interval is A, 20m≤A≤30m.
[0035] In this embodiment, the geological survey includes using ground-penetrating radar to continuously scan the pre-designated construction area along the tunnel's mileage extension direction to obtain the location, orientation, and scale of faults and fissures in the tunnel; conducting core drilling along the tunnel's mileage extension direction to obtain rock mass data for the pre-designated construction area, including the lithology, structure, and mechanical parameters of the rock mass; using acoustic detection equipment to analyze the integrity and internal structure of the rock mass to determine groundwater distribution data; and drawing a geological profile based on the rock mass data and groundwater distribution data to obtain the geological information. However, if the core drilling spacing is not clearly defined, uneven distribution or insufficient density of sampling points may occur, making it impossible for the obtained rock mass data to fully and accurately reflect the geological characteristics of the pre-designated construction area of the tunnel, thereby affecting the accuracy of subsequent mechanical models and design parameters.
[0036] In one embodiment, the step of establishing a mechanical model of the rock mass of the preset construction area based on the geological information includes: Using numerical simulation software, a three-dimensional mechanical model of the tunnel and surrounding rock mass is established based on the geological information. In the three-dimensional mechanical model, the mechanical parameters of the rock mass, the location characteristics of the faults and fissures, and the boundary conditions of the groundwater are set.
[0037] In this embodiment, a three-dimensional mechanical model of the tunnel and surrounding rock mass is constructed using numerical simulation software based on comprehensive geological information obtained from geological surveys. This model precisely sets the mechanical parameters of the rock mass, the location characteristics of faults and fissures, and the boundary conditions of groundwater, thus overcoming the limitations of traditional two-dimensional or simplified models in accurately reflecting complex geological conditions. Specifically, the geological survey provides key data such as the distribution characteristics of faults and fissures, the mechanical parameters of the rock mass, and the distribution of groundwater. These data serve as input, and the numerical simulation software transforms discrete geological information into a continuous three-dimensional spatial model. In the three-dimensional mechanical model, the mechanical parameters of the rock mass are precisely assigned, enabling the model to realistically reflect the strength and deformation characteristics of different rock strata. Simultaneously, the precise location characteristics of faults and fissures, as structural weak points in the rock mass, are incorporated into the model, allowing it to capture the controlling effect of these weak points on stress distribution and deformation patterns. Furthermore, the boundary conditions for groundwater are set, enabling the model to consider the influence of pore water pressure and seepage on the stability of the rock mass. In this way, the three-dimensional mechanical model can comprehensively consider the coupled effects of multiple geological factors, providing a rock mass mechanical response prediction that is closer to actual engineering conditions, and offering a more reliable basis for determining subsequent pipe roof design parameters. This method makes the prediction of the stress-strain state, displacement trend, and potential instability modes of the rock mass during tunnel excavation and support more refined and accurate, thereby effectively improving the scientific nature and safety of the advanced support scheme.
[0038] In one embodiment, the step of determining the design parameters of the pipe shed based on the mechanical model includes: The stress and strain of the rock mass under different pipe roof design parameters are simulated in the three-dimensional mechanical model to analyze the displacement, stress distribution and pressure changes of the rock mass under different pipe roof design parameters. The design parameters of the pipe shed are determined based on the simulation results; wherein the design parameters include the diameter, length, spacing and external angle of the pipe shed.
[0039] In this embodiment, detailed geological information was obtained through geological surveys, and a three-dimensional mechanical model of the tunnel and surrounding rock mass was established based on this information. This three-dimensional mechanical model can realistically reflect the rock mass characteristics under complex geological conditions. Based on this, this application further proposes a method for accurately determining pipe roof design parameters using this three-dimensional mechanical model. Specifically, this method systematically simulates the stress and strain of the rock mass under different pipe roof design parameters (including diameter, length, spacing, and external angle) within the three-dimensional mechanical model. This means that designers no longer rely on experience or simplified calculation models, but can intuitively and quantitatively observe the impact of different pipe roof configurations on rock mass displacement, stress distribution, and the stress state of the pipe roof itself through numerical simulation. For example, when the pipe roof diameter increases or the spacing decreases, the simulation results will show a decrease in rock mass displacement, a more uniform stress distribution, and changes in the pressure borne by the pipe roof. Through in-depth analysis of these simulation results, designers can evaluate the support effect and safety of each pipe roof design scheme. Finally, based on these detailed simulation analysis results, combined with engineering design specifications and safety requirements, the most suitable pipe roof design parameters for the current geological conditions and construction requirements can be scientifically and rationally determined. This parameter determination method based on refined numerical simulation enables the pipe roof design to make full use of information from previous geological surveys and mechanical models, thereby achieving precise design of tunnel pre-support under complex geological conditions and effectively improving the reliability and economy of the support.
[0040] In one embodiment, after the step of drawing a geological profile based on the rock mass data and the groundwater distribution data to obtain the geological information, the method further includes: Waterproofing measures are designed based on the groundwater distribution data; wherein, the waterproofing measures include setting a water-stop ring around the outer periphery of the pipe roof.
[0041] In this embodiment, by installing a water-stop ring around the outer periphery of the pipe roof, groundwater can be effectively prevented from seeping into the tunnel along the interface between the pipe roof and the borehole wall. When groundwater attempts to flow along the outer wall of the pipe roof, the water-stop ring forms a tight sealing barrier, stopping the water flow. This not only protects the pipe roof structure from groundwater erosion, but more importantly, it creates a relatively dry and stable environment for subsequent pipe roof grouting operations, preventing the grouting material from being diluted or washed away by groundwater. This significantly improves the density and consolidation effect of the grouting, ensuring the overall stability and durability of the advanced support. This waterproof design based on accurate groundwater data makes the support scheme more targeted and reliable.
[0042] In one embodiment, prior to the steps of installing the pipe roof within the borehole and performing advance support operations according to the target support scheme, the method further includes: Based on the waterproofing measures and the grouting scheme of the pipe roof, the target support scheme is obtained; The steps of installing the pipe roof into the borehole and performing advance support operations according to the target support scheme include: The pipe roof is installed inside the borehole, and grouting is performed through the grouting holes of the pipe roof according to the target support plan to complete the advanced support operation.
[0043] In this embodiment, before installing the pipe roof and carrying out pre-support work, a comprehensive target support plan is systematically obtained based on the designed waterproofing measures and the pipe roof grouting scheme. This target support plan organically integrates geological information obtained from the geological survey, mechanical model analysis results, pipe roof design parameters, waterproofing measures (such as water-stop rings), and grouting strategies to form a unified construction guideline. In the actual pre-support operation, after the pipe roof is installed in the borehole, precise grouting is carried out through the pre-set grouting holes on the pipe roof, strictly following this target support plan. Under the set pressure and flow rate, the grouting material is evenly injected into the annular space between the pipe roof and the surrounding rock, as well as into the fissures of the surrounding rock, through the grouting holes. This process not only fills the gaps, making the pipe roof and the surrounding rock form a whole, significantly improving the strength and stability of the surrounding rock, but also works synergistically with waterproofing measures (such as water-stop rings) to effectively block groundwater channels, ensuring the long-term stability and waterproofing effect of the support structure. This strategy of planning before implementation transforms the proactive support operation from a passive response to an active control, ensuring the scientific nature and effectiveness of the construction.
[0044] In one embodiment, the step of drilling in the preset construction area according to the design parameters and monitoring the drilling parameters in real time during the drilling process includes: According to the design parameters, the drilling rig is moved to the designed hole position, and the position and angle of the drilling rig are adjusted so that the drilling rig is consistent with the designed drilling direction; The drilling rig uses an automatic guidance system to control the verticality and azimuth of the borehole for drilling operations. During the drilling process, a mud circulation system is used to inject mud into the borehole for wall protection and slag removal. After the borehole reaches the designed depth, it is cleaned to remove rock cuttings and debris. Drilling is then carried out in the pre-defined construction area, and drilling parameters are monitored in real time during the drilling process.
[0045] In this embodiment, the precision and efficiency of drilling operations are significantly improved by introducing a series of refined control and auxiliary technologies. First, before drilling begins, the drilling rig is precisely moved to the designed borehole position according to pre-determined design parameters. The position and angle of the drilling rig are adjusted to ensure its main axis is strictly aligned with the designed drilling direction. This initial alignment lays the foundation for subsequent precise drilling, avoiding cumulative errors caused by initial deviations. During drilling, the drilling rig's automatic guidance system plays a crucial role. This system monitors the drill bit's attitude and position in real time and compares it with the preset drilling trajectory. Once a deviation in the verticality or azimuth of the borehole is detected, the automatic guidance system immediately issues a command to drive the correction mechanism on the drill bit or drill rod to make fine adjustments, thereby dynamically correcting the drilling direction and ensuring that the drilling trajectory always extends along the designed path. This closed-loop control mechanism greatly improves drilling precision, enabling the pipe roof to be accurately placed in the surrounding rock according to design requirements, thus ensuring the integrity and stability of the support structure. Meanwhile, to address potential borehole instability and cuttings accumulation under complex geological conditions, this scheme employs a mud circulation system during drilling. This system continuously injects mud with specific rheological properties into the borehole. The mud forms a thin, dense filter cake on the borehole wall, effectively isolating the borehole wall from formation water, preventing collapse and loosening of the borehole wall, and providing excellent wall protection. Furthermore, the circulating mud flow promptly carries the cuttings generated by the drill bit to the surface, preventing their accumulation at the bottom of the borehole, ensuring smooth drilling, and extending the lifespan of the drill bit. Once the borehole reaches the predetermined design depth, a thorough cleaning operation is performed. This step aims to remove residual mud filter cake, cuttings, and any other debris, providing a clean channel for the subsequent installation of the pipe roof and grouting operations. A clean channel not only facilitates accurate pipe roof placement but also ensures that the grouting material can fully penetrate the surrounding rock fissures, forming a dense grout body, thereby maximizing the support effect of the pipe roof. Through the synergistic effect of the above series of steps, this solution can effectively solve the problems of insufficient precision, borehole instability and poor slag removal in traditional drilling construction, provide a high-quality drilling foundation for tunnel pre-support, and thus improve the reliability and safety of the entire support system.
[0046] In one embodiment, the step of real-time monitoring of drilling parameters during the drilling process includes: The drilling parameters are measured once after drilling to a preset depth, wherein the preset depth is 2-3 meters. If the verticality deviation is detected to exceed the allowable range, the drilling direction is adjusted, whereby the allowable range is a verticality deviation of no more than 1%. In the hole cleaning step, the thickness of the sediment at the bottom of the hole is controlled to not exceed 50 mm.
[0047] In this embodiment, a refined monitoring and control mechanism is introduced during the drilling process to ensure the quality of the drilling. Specifically, instead of simple real-time monitoring, drilling parameters are measured every preset depth (e.g., 2-3 meters). This periodic, high-frequency measurement method can promptly capture changes in the drilling status, providing immediate data for subsequent decision-making. When the verticality deviation of the borehole exceeds the allowable range (e.g., no more than 1%), the system or operator can respond quickly and make precise adjustments to the drilling direction, effectively avoiding the accumulation of borehole deviation and ensuring the straightness and design accuracy of the borehole. Furthermore, in the cleaning stage after the borehole reaches the design depth, this solution further clarifies the strict control standard that the thickness of the sediment at the bottom of the borehole should not exceed 50 mm. This standard ensures the cleanliness of the environment at the bottom of the borehole, providing the necessary conditions for the accurate installation of the pipe roof and the full filling of the grouting material. Through the aforementioned synergistic effects—periodic measurement, timely correction, and strict borehole cleaning quality control—this scheme significantly improves the construction accuracy and quality of boreholes, laying a solid foundation for the effective installation of pipe roofs and grouting operations, thereby ensuring the overall effectiveness and safety of tunnel pre-support.
[0048] In one embodiment, the step of grouting through the grouting holes of the pipe roof according to the target support scheme includes: The pipe shed is processed by shaping the front end of the pipe shed into a cone shape and drilling the grouting holes on the pipe wall of the pipe shed; The processed pipe roof is pushed into the borehole using a pipe roof installation device, while maintaining the verticality and orientation of the pipe roof during the pushing process; The segmented pipe sheds are connected and fixed, and fixing devices are installed at the pipe sheds and the openings; Grouting material is injected through the grouting hole. During the grouting process, the grouting pressure and grouting volume are monitored. Grouting is stopped when the grouting volume reaches the calculated value and the grouting pressure reaches the designed final pressure.
[0049] In this embodiment, the aforementioned problems were effectively solved through meticulous processing, precise installation, and strict grouting control of the pipe roof. First, the pipe roof was processed, with its front end shaped into a cone, and grouting holes drilled in the pipe wall. The cone-shaped front end effectively reduced resistance when the pipe roof entered the borehole, ensuring smooth advancement, while the grouting holes in the pipe wall provided the necessary channel for the uniform diffusion of subsequent grouting material. Second, a pipe roof installation device was used to push the processed pipe roof into the borehole, maintaining its verticality and orientation throughout the process. This ensured that the pipe roof was precisely positioned according to design requirements, avoiding uneven support or localized failure due to installation deviations, thus laying a solid foundation for subsequent grouting operations. Furthermore, for segmented pipe roofs, they were integrated into a continuous whole through connection and fixing, with fixing devices installed at the pipe roof and borehole opening. This not only ensured the integrity and stability of the pipe roof structure, preventing displacement under grouting or ground stress, but also provided a reliable sealing interface for grouting, preventing grout from overflowing from the borehole opening. Finally, grouting material is injected through the grouting holes of the pipe roof, and the grouting pressure and volume are monitored in real time during the grouting process. Grouting is stopped when the grouting volume reaches the calculated value and the grouting pressure reaches the design final pressure. This precisely controlled grouting method ensures that the grouting material can fully and evenly fill the fissures and voids in the surrounding rock, avoiding under-grouting or over-grouting, thereby maximizing the consolidation strength and waterproof performance of the surrounding rock. Through the above series of refined operations, the scheme of this application significantly improves the accuracy of pipe roof installation and the quality of grouting on the basis of the original tunnel pre-support method, making the pre-support structure more stable and reliable, effectively enhancing the overall stability of the tunnel surrounding rock, and providing a more solid safety guarantee for tunnel construction.
[0050] The above description is merely an exemplary embodiment of the present invention and does not limit the scope of the present invention. Any equivalent structural transformations made based on the technical concept of the present invention and the contents of the specification and drawings of the present invention, or direct / indirect applications in other related technical fields, are included within the protection scope of the present invention.
Claims
1. A method for tunnel pre-support construction, characterized in that, Includes the following steps: A geological survey is conducted in the pre-designated construction area of the tunnel to obtain geological information about the pre-designated construction area; wherein, the geological information includes the distribution characteristics of faults and fissures, the mechanical parameters of the rock mass, and the distribution of groundwater; A mechanical model of the rock mass in the pre-designated construction area is established based on the geological information; wherein, the mechanical model includes elastic modulus, Poisson's ratio, and compressive strength; Based on the aforementioned mechanical model, determine the design parameters of the pipe shed; According to the design parameters, drilling is carried out in the preset construction area, and drilling parameters are monitored in real time during the drilling process; wherein, the drilling parameters include drilling depth, drilling diameter and drilling verticality; The pipe roof is installed in the borehole, and advanced support operations are carried out according to the target support scheme.
2. The tunnel pre-support construction method as described in claim 1, characterized in that, The step of conducting a geological survey in the predetermined construction area of the tunnel to obtain geological information of the predetermined construction area includes: The pre-designated construction area is continuously scanned along the mileage extension direction of the tunnel using ground-penetrating radar to obtain the location, orientation, and scale of the faults and fissures in the tunnel. Core drilling is conducted along the tunnel mileage extension direction to obtain rock mass data of the preset construction area; wherein, the rock mass data includes the lithology, structure and mechanical parameters of the rock mass; The integrity and internal structure of the rock mass were analyzed using acoustic detection equipment to determine groundwater distribution data. Based on the rock mass data and the groundwater distribution data, a geological profile was drawn to obtain the geological information.
3. The tunnel pre-support construction method as described in claim 2, characterized in that, The step of conducting core drilling along the tunnel mileage extension direction to obtain rock mass data of the preset construction area includes: Core drilling is performed along the tunnel mileage extension direction at target intervals to obtain rock mass data of the preset construction area; wherein, the target interval is A, 20m≤A≤30m.
4. The tunnel pre-support construction method as described in claim 3, characterized in that, The step of establishing a mechanical model of the rock mass in the preset construction area based on the geological information includes: Using numerical simulation software, a three-dimensional mechanical model of the tunnel and surrounding rock mass is established based on the geological information. In the three-dimensional mechanical model, the mechanical parameters of the rock mass, the location characteristics of the faults and fissures, and the boundary conditions of the groundwater are set.
5. The tunnel pre-support construction method as described in claim 4, characterized in that, The step of determining the design parameters of the pipe shed based on the mechanical model includes: The stress and strain of the rock mass under different pipe roof design parameters are simulated in the three-dimensional mechanical model to analyze the displacement, stress distribution and pressure changes of the rock mass under different pipe roof design parameters. The design parameters of the pipe shed are determined based on the simulation results; wherein the design parameters include the diameter, length, spacing and external angle of the pipe shed.
6. The tunnel pre-support construction method as described in claim 2, characterized in that, After the step of drawing a geological profile based on the rock mass data and the groundwater distribution data to obtain the geological information, the method further includes: Waterproofing measures are designed based on the groundwater distribution data; wherein, the waterproofing measures include setting a water-stop ring around the outer periphery of the pipe roof.
7. The tunnel pre-support construction method as described in claim 6, characterized in that, Before the step of installing the pipe roof into the borehole and performing advance support operations according to the target support scheme, the method further includes: Based on the waterproofing measures and the grouting scheme of the pipe roof, the target support scheme is obtained; The steps of installing the pipe roof into the borehole and performing advance support operations according to the target support scheme include: The pipe roof is installed inside the borehole, and grouting is performed through the grouting holes of the pipe roof according to the target support plan to complete the advanced support operation.
8. The tunnel pre-support construction method as described in claim 7, characterized in that, The step of drilling in the preset construction area according to the design parameters, and monitoring the drilling parameters in real time during the drilling process, includes: According to the design parameters, the drilling rig is moved to the designed hole position, and the position and angle of the drilling rig are adjusted so that the drilling rig is consistent with the designed drilling direction; The drilling rig uses an automatic guidance system to control the verticality and azimuth of the borehole for drilling operations. During the drilling process, a mud circulation system is used to inject mud into the borehole for wall protection and slag removal. After the borehole reaches the designed depth, it is cleaned to remove rock cuttings and debris. Drilling is then carried out in the pre-defined construction area, and drilling parameters are monitored in real time during the drilling process.
9. The tunnel pre-support construction method as described in claim 8, characterized in that, The step of real-time monitoring of drilling parameters during the drilling process includes: The drilling parameters are measured once after drilling to a preset depth, wherein the preset depth is 2-3 meters. If the verticality deviation is detected to exceed the allowable range, the drilling direction is adjusted, whereby the allowable range is a verticality deviation of no more than 1%. In the hole cleaning step, the thickness of the sediment at the bottom of the hole is controlled to not exceed 50 mm.
10. The tunnel pre-support construction method as described in claim 9, characterized in that, The step of grouting through the grouting holes of the pipe roof according to the target support scheme includes: The pipe shed is processed by shaping the front end of the pipe shed into a cone shape and drilling the grouting holes on the pipe wall of the pipe shed; The processed pipe roof is pushed into the borehole using a pipe roof installation device, while maintaining the verticality and orientation of the pipe roof during the pushing process; The segmented pipe sheds are connected and fixed, and fixing devices are installed at the pipe sheds and the openings; Grouting material is injected through the grouting hole. During the grouting process, the grouting pressure and grouting volume are monitored. Grouting is stopped when the grouting volume reaches the calculated value and the grouting pressure reaches the designed final pressure.