A method for controlling the stability of surrounding rock in a shaft perimeter roadway / crosscut repair process

Abstract

This invention discloses a method for controlling the stability of surrounding rock during the repair process of main roadways / stone gates around mine shafts, belonging to the field of surrounding rock control technology in mining tunnels. This invention obtains the physical and mechanical parameters of the surrounding rock, the characteristic parameters of the loosened zone of the roadway, and the parameters of the surrounding rock's approach, thereby dividing the roadway into severely, moderately, and lightly deformed sections; constructs a three-dimensional numerical model and assigns and verifies parameters to quantitatively predict the disturbance impact of roadway repair excavation on the shaft; and implements differentiated repair construction based on an anchor-frame-filling composite support system for each deformed section; it monitors the state of the shaft wall, support, and surrounding rock in real time throughout the construction process, presets early warning thresholds, establishes a multi-level construction response mechanism, and dynamically adjusts construction control strategies. Through the coordinated efforts of quantitative identification of surrounding rock conditions, quantitative prediction of construction disturbances, and dynamic process control, this invention systematically reduces various uncertainties in the repair construction of roadways around the shaft, effectively ensuring the safety of the shaft structure and the stability of the surrounding rock.

Description

Technical Field

[0001] This invention belongs to the field of mine shaft and tunnel surrounding rock control technology, and specifically relates to a method for controlling the stability of surrounding rock during the repair process of main roadways / stone gates around the shaft. Background Technology

[0002] Coal mine shafts are crucial passageways connecting surface and underground production levels, and their structural safety directly impacts the overall safety of the mine. In deep mines, main roadways, stone gates, and girder gates are typically arranged around the shaft, forming the core transportation and ventilation hub of the mine's bottom yard. These roadway groups are spatially adjacent to and influence each other with the shaft, jointly undertaking important functions such as hoisting, transportation, personnel passage, ventilation, and drainage. Due to complex geological conditions, especially when there are weak interlayers such as mudstone and coal seams in the surrounding rock of the mine's bottom yard roadway groups, these roadways are highly susceptible to large-scale deformation and damage under long-term high stress, mining disturbance, and rheological effects, including roof delamination, sidewall convergence, floor heave, and shaft wall cracking. The original support structure gradually fails, seriously affecting the mine's transportation, ventilation, and personnel safety. Once the surrounding tunnels of the shaft are severely deformed and need repair, the repair excavation is essentially a secondary disturbance process to the damaged surrounding rock. The excavation disturbance will inevitably change the original stress field and displacement field distribution of the adjacent shafts and tunnel groups, which can easily damage the shaft wall structure and threaten the safety of shaft operation.

[0003] While there are numerous engineering practices for repairing ordinary roadways, their application in repairing main roadways and stone passages surrounding shafts faces challenges. Due to the close proximity and complex interactions between the repair area and the shaft, construction plans still largely rely on engineering experience. Under these conditions, the impact of the actual fracture and deformation state of the surrounding rock on support requirements cannot be reliably assessed, leading to the use of similar support parameters in different sections, resulting in insufficient matching with actual working conditions. Furthermore, the disturbance impact of repair excavation on adjacent shafts cannot be quantitatively verified, making it difficult to predict the extent of its impact on shaft structural safety before implementation. The correlation between monitoring data and on-site decisions during construction is weak, and the identification and handling of anomalies largely depend on post-event assessment. These combined factors cause experience-based repair plans to deviate from actual working conditions when addressing specific engineering requirements. Consequently, shaft wall cracking, support failure, and even surrounding rock instability accidents frequently occur, directly threatening the long-term operational safety of the core hub of the shaft's parking area.

[0004] Therefore, the repair and construction of the main roadway / stone gate around the shaft urgently requires a set of safety control methods that can systematically cope with the above uncertainties. Summary of the Invention

[0005] To address the aforementioned problems, the purpose of this invention is to provide a method for controlling the stability of the surrounding rock during the repair process of the main roadway / stone gate around the shaft, thereby achieving precise control of the surrounding rock and safe construction throughout the entire repair process of the main roadway around the shaft.

[0006] The technical solution of this invention is: a method for controlling the stability of surrounding rock during the repair process of the main roadway / stone gate around the shaft, comprising: The physical and mechanical parameters of the surrounding rock, the characteristic parameters of the loosened zone of the tunnel, and the parameters of the surrounding rock approach are obtained. The tunnel is a main tunnel or stone gate to be repaired.

[0007] Based on the characteristic parameters of the loosened zone and the proximity parameters of the surrounding rock in the roadway, the roadway to be repaired area is divided into severely deformed, moderately deformed, and lightly deformed sections by a dual-index joint zoning method, thus obtaining the deformation sections of the roadway to be repaired area.

[0008] A three-dimensional numerical model is constructed based on the actual spatial arrangement of the shaft and the roadway group. The physical and mechanical parameters of the surrounding rock are assigned to each rock stratum unit in the three-dimensional numerical model to simulate the evolution of the stress field and displacement field of the surrounding rock during the entire excavation process of the roadway to be repaired. The three-dimensional numerical model is then verified using the loosened zone characteristic parameters. Based on the verified three-dimensional numerical model, the disturbance impact of the roadway construction activities on the shaft is simulated to obtain the construction disturbance prediction results. If the construction disturbance prediction results meet the safety control requirements of the shaft and adjacent roadways, the subsequent steps are continued; otherwise, the support parameters or construction plan are adjusted and the prediction is repeated until the construction disturbance prediction results meet the safety control requirements of the shaft and adjacent roadways.

[0009] Based on the deformation sections of the roadway to be repaired, and combined with the construction disturbance prediction results, a composite support system of anchor-frame-filling is adopted to carry out differentiated repair construction on the roadway to be repaired.

[0010] The wellbore condition, support stress, and surrounding rock deformation are monitored in real time throughout the entire repair construction process. Preset early warning thresholds and establish a multi-level construction response mechanism to dynamically adjust construction control strategies based on monitoring data.

[0011] Furthermore, the specific steps for constructing the three-dimensional numerical model are as follows: based on the actual spatial relationship and cross-sectional dimensions of the shaft and the surrounding tunnel group, a three-dimensional geometric model including the shaft, the tunnel to be repaired, and the surrounding tunnel group is established, and the three-dimensional geometric model is meshed to obtain a mesh model; a three-dimensional numerical model is established based on the mesh model, and the three-dimensional numerical model is used to simulate the evolution of the surrounding rock stress field and displacement field.

[0012] Furthermore, after establishing the three-dimensional numerical model, boundary conditions, initial stress fields, and parameter values ​​are set sequentially for the three-dimensional numerical model.

[0013] The specific steps for setting the boundary conditions and initial stress field of the three-dimensional numerical model are as follows: constrain the vertical displacement at the bottom of the three-dimensional numerical model, constrain the normal displacement around the perimeter, and apply the equivalent load of the overburden at the top; set up the initial geostress field according to the actual burial depth of the mine and the geostress test results; when the repair area is affected by the fault structure, additional tectonic stress components are applied.

[0014] The physical and mechanical parameters of the surrounding rock include its density, compressive strength, tensile strength, elastic modulus, Poisson's ratio, cohesion, and internal friction angle. After setting the boundary conditions and initial stress field, the density, compressive strength, tensile strength, elastic modulus, Poisson's ratio, cohesion, and internal friction angle of the surrounding rock are assigned to the corresponding rock strata units in the three-dimensional numerical model according to the lithology of the strata, thus completing the parameter assignment.

[0015] Furthermore, the specific steps for verifying the three-dimensional numerical model are as follows: After assigning values ​​to the parameters of the three-dimensional numerical model, the excavation simulation is carried out in stages according to the actual formation sequence of the shaft, the existing roadway group, and the roadway to be repaired. At each excavation stage, support structure parameters and support boundary conditions consistent with the existing support conditions on site are applied simultaneously. After each excavation and support simulation is completed, the three-dimensional numerical model is calculated to a state of mechanical equilibrium. The stress distribution data, displacement change data, and loosening zone development data of the surrounding rock of the shaft and adjacent roadways at each stage are extracted step by step. The displacement change data and loosening zone development data of the surrounding rock obtained by the three-dimensional numerical model simulation are compared with the measured surrounding rock approach parameters and loosening zone characteristic parameters on site. If the data deviation exceeds the threshold, the parameters of the three-dimensional numerical model, boundary conditions, and existing support parameters are iteratively corrected until the simulation results match the actual surrounding rock response law on site, thus completing the verification of the three-dimensional numerical model.

[0016] Furthermore, the specific construction process of the anchor-frame-filling composite support system is as follows: based on the construction disturbance impact range predicted by the three-dimensional numerical model, reinforcement support is first implemented on the roadways before and after the repair area, as well as the roadways around the shaft and the gate; after completing the reinforcement support, the severely deformed section is brushed and expanded, and initial support of anchor bolts / cables is implemented; then, a U-shaped steel shed is erected and backfilling is carried out to form a composite support structure supported by anchor bolts / cables, U-shaped steel sheds and backfilling bodies.

[0017] Furthermore, the specific implementation method of the differentiated repair construction is as follows: based on the differences in the degree of surrounding rock fragmentation, the development range of the loosened zone, and the magnitude of deformation in the severely deformed, moderately deformed, and lightly deformed sections of the roadway to be repaired, the spacing between anchor bolts / cables and the spacing of U-shaped steel sheds in each section are differentiated; wherein, the spacing between anchor bolts / cables in the severely deformed section is 0.6 to 0.8 times that in the moderately deformed section, the spacing between anchor bolts / cables in the moderately deformed section is 0.6 to 0.8 times that in the lightly deformed section, and the spacing of U-shaped steel sheds is set differently according to the same proportion.

[0018] Furthermore, the specific steps for conducting the real-time monitoring are as follows: real-time monitoring of the circumferential strain data and vertical strain data of the well wall concrete at the inner edge of the well wall above the shaft gate; real-time monitoring of the stress change data of the support structure at the bottom of the well to obtain real-time monitoring data.

[0019] Furthermore, the multi-level construction response mechanism is divided into three control levels: normal response level, early warning response level, and over-limit response level. Based on the comparison results of the real-time monitoring data and the preset early warning threshold, the construction progress speed, support reinforcement scheme, and monitoring frequency adjustment strategy corresponding to the three control levels are matched accordingly.

[0020] Furthermore, the specific control strategies for the regular response level, early warning response level, and over-limit response level are as follows: When real-time monitoring data fails to reach the preset warning threshold, a normal response level is triggered to maintain the repair and construction process.

[0021] When real-time monitoring data approaches the preset warning threshold or when the surrounding rock shows a slight abnormal response, the warning response level is triggered, the repair construction progress is reduced, and the monitoring frequency is increased.

[0022] When real-time monitoring data exceeds the preset warning threshold, or when the surrounding rock deformation or support stress abnormally intensifies, an over-limit response is triggered, repair work is stopped, and temporary reinforced support is set at the connection between the roadway and the shaft. Construction can only resume after the real-time monitoring data returns to stability and the surrounding rock is judged to be stabilizing.

[0023] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention provides objective evidence for identifying the surrounding rock condition by acquiring physical and mechanical parameters of the surrounding rock and quantitative indicators such as the loosening zone and the amount of movement of the tunnel, overcoming the shortcomings of traditional zoning methods which lack objective quantitative evidence; by constructing a three-dimensional numerical model verified by on-site measurements, it quantitatively predicts the disturbance impact of repair excavation on the shaft, making the formulation of construction plans based on evidence and avoiding blind construction due to insufficient prediction; by combining zoning results with numerical simulation data, a differentiated repair is implemented using an anchor-frame-filling composite support system, ensuring that the support strength is precisely matched with the actual deformation and fragmentation degree of the surrounding rock, avoiding support redundancy or insufficiency; on this basis, through the linkage of real-time monitoring throughout the process and a graded response mechanism, the safety management of the construction process shifts from passive response to proactive control. The synergistic effect of these methods systematically reduces the uncertainties caused by unclear identification of the surrounding rock condition, unclear disturbance impact, mismatched support plans, and delayed abnormal responses during the repair construction of tunnels around the shaft, thereby improving the overall reliability of the construction plan and effectively ensuring the safety of the shaft structure and the stability of the surrounding rock. Attached Figure Description

[0024] Figure 1 This is a flowchart of the present invention; Figure 2 This is a schematic diagram of the anchor-frame (single layer)-filling composite support system according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the anchor-frame (double layer)-filling composite support system according to an embodiment of the present invention; Figure 4 This is a diagram illustrating the arrangement of reinforcing support anchor cables in an application example of the present invention. Detailed Implementation

[0025] The following is combined Figures 1 to 4 The specific embodiments of the present invention will be described in detail below. Since the geological conditions, surrounding rock stress, and rheological deformation failure mechanisms of the main roadway and the stone gate are the same, the disturbance transmission law during repair excavation is also the same. Therefore, the method for controlling the stability of the surrounding rock during the repair process of the main roadway around the shaft is also applicable to the stone gate around the shaft.

[0026] Example like Figure 1 The method for controlling the stability of surrounding rock during the repair process of the main roadway / stone gate around the shaft, as shown, includes: Obtain the physical and mechanical parameters of the surrounding rock, the characteristic parameters of the loosened zone of the tunnel, and the parameters of the surrounding rock approach. The tunnel is the main tunnel or stone gate to be repaired.

[0027] Based on the characteristic parameters of the loosened zone and the convergence parameters of the surrounding rock, a dual-index joint zoning discrimination is performed on the roadway to be repaired area, dividing the roadway to be repaired area into severely deformed, moderately deformed, and slightly deformed sections, thus obtaining the deformation sections of the roadway to be repaired area. Among them, the characteristic parameter of the loosened zone is the thickness of the loosened zone of the surrounding rock, which can be determined by combining borehole inspection, sonic testing, distributed optical fiber (BOTDR) or ground-penetrating radar detection. The larger the thickness of the loosened zone of the surrounding rock, the more fully developed the surrounding rock fractures and the wider the damage range. The convergence parameters of the surrounding rock include the convergence of the sidewalls and the convergence of the roof and floor. It is measured by setting up measuring points on the key cross sections of the roadway to be repaired and using the cross-point method, or by using distributed optical fiber (BOTDR), fiber optic grating (FBG) and other means to obtain the displacement distribution data of the surrounding rock at various depths. The larger the convergence of the surrounding rock, the more severe the roadway cross section shrinkage and the higher the degree of surrounding rock deformation.

[0028] The thickness of the loosened zone and the amount of surrounding rock movement are used as indicators for determining severely deformed sections. When the thickness of the loosened zone exceeds the upper limit of a preset threshold, or the amount of surrounding rock movement reaches a level of deformation that affects the normal production and use of the roadway, the area is determined to be a severely deformed section and designated as a repair and construction area. The threshold ranges for the loosened zone thickness and the surrounding rock movement are determined based on the surrounding rock conditions, the functional positioning of the roadway, and on-site production requirements.

[0029] Areas that do not meet the criteria for severe deformation can be further divided into medium-deformation or light-deformation sections based on on-site measured data, the degree of deformation of the surrounding rock, and the production and use needs of the roadway. These sections are used for construction organization and support parameter optimization and are not considered areas that must be repaired.

[0030] A three-dimensional numerical model was constructed based on the actual spatial arrangement of the shaft and the tunnel group. The physical and mechanical parameters of the surrounding rock were assigned to each rock stratum unit in the three-dimensional numerical model to simulate the evolution of the stress field and displacement field of the surrounding rock during the entire excavation process of the tunnel to be repaired area. The three-dimensional numerical model was checked using the characteristic parameters of the loosened zone. Based on the checked three-dimensional numerical model, the disturbance effect of the construction activities of the tunnel to be repaired on the shaft was simulated, and the construction disturbance prediction results were obtained.

[0031] When the construction disturbance prediction results meet the safety control requirements of the shaft and adjacent roadways, differentiated repair construction is carried out based on each deformation section of the roadway to be repaired using an anchor-frame-filling composite support system; otherwise, the support parameters or construction plan are adjusted, and the construction disturbance prediction is carried out again until the construction disturbance prediction results meet the safety control requirements of the shaft and adjacent roadways.

[0032] The wellbore condition, support stress, and surrounding rock deformation are monitored in real time throughout the entire repair construction process. Preset early warning thresholds and establish a multi-level construction response mechanism to dynamically adjust construction control strategies based on monitoring data.

[0033] Preferably, the specific steps for constructing a three-dimensional numerical model are as follows: based on the actual spatial relationship and cross-sectional dimensions of the shaft and the surrounding tunnel group, a three-dimensional geometric model including the shaft, the tunnel to be repaired, and the surrounding tunnel group is established, and the three-dimensional geometric model is meshed to obtain a mesh model; a three-dimensional numerical model is established based on the mesh model, and the three-dimensional numerical model is used to simulate the evolution of the stress field and displacement field of the surrounding rock.

[0034] Preferably, after establishing the three-dimensional numerical model, the boundary conditions, initial stress field settings, and parameter assignments are performed on the three-dimensional numerical model in sequence.

[0035] The specific steps for setting the boundary conditions and initial stress field of the three-dimensional numerical model are as follows: constrain the vertical displacement at the bottom of the three-dimensional numerical model, constrain the normal displacement around the perimeter, and apply the equivalent load of the overburden at the top; set up the initial geostress field according to the actual burial depth of the mine and the geostress test results; when the repair area is affected by the fault structure, additional tectonic stress components are applied.

[0036] The physical and mechanical parameters of the surrounding rock include its density, compressive strength, tensile strength, elastic modulus, Poisson's ratio, cohesion, and internal friction angle. After setting the boundary conditions and initial stress field, numerical simulation software is used to assign the density, compressive strength, tensile strength, elastic modulus, Poisson's ratio, cohesion, and internal friction angle of the surrounding rock to the corresponding rock elements in the three-dimensional numerical model according to the lithology of the formation, thus completing the parameter assignment. The creep model is selected as the constitutive model for numerical calculation.

[0037] Preferably, the specific steps for verifying the three-dimensional numerical model are as follows: After assigning the parameters of the three-dimensional numerical model, the excavation simulation is carried out in stages according to the actual formation sequence of the shaft, the existing roadway group, and the roadway to be repaired. At each excavation stage, the support structure parameters and support boundary conditions consistent with the existing support conditions on site are applied simultaneously. After each excavation and support simulation is completed, the three-dimensional numerical model is calculated to the mechanical equilibrium state, and the stress distribution data, surrounding rock displacement change data, and loosening zone development data of the surrounding rock and adjacent roadways at each stage are extracted step by step. The surrounding rock displacement change data and loosening zone development data obtained by the three-dimensional numerical model simulation are compared with the surrounding rock approach parameters and loosening zone characteristic parameters measured on site. If the data deviation is large, the three-dimensional numerical model parameters, boundary conditions, and existing support parameters are iteratively corrected until the simulation results match the actual surrounding rock response law on site, and the three-dimensional numerical model verification is completed.

[0038] Preferably, the construction process of the anchor-frame-filling composite support system is as follows: based on the construction disturbance impact range predicted by the three-dimensional numerical model, reinforcement support is first implemented on the roadways before and after the repair area, as well as the roadways around the shaft and the gate; after the reinforcement support is completed, the severely deformed section is brushed and expanded, and initial support of anchor bolts / cables is implemented; then, a U-shaped steel shed is erected and backfilling is carried out to form a composite support structure supported by anchor bolts / cables, U-shaped steel sheds and backfilling.

[0039] Preferably, the specific implementation method of differentiated repair construction is as follows: based on the differences in the degree of surrounding rock fragmentation, the development range of the loosened zone, and the magnitude of deformation in the severely deformed, moderately deformed, and lightly deformed sections of the roadway to be repaired, the spacing between anchor bolts / cables and the spacing of U-shaped steel sheds are differentiated for each section. In this embodiment, the spacing between anchor bolts in the severely deformed section is 800mm×800mm, the spacing between anchor cables is 1200mm×600mm, and the spacing of U-shaped steel sheds is 450mm; the spacing between anchor bolts in the moderately deformed section is set at 900mm×900mm, the spacing between anchor cables is set at 1400mm×700mm, and the spacing of U-shaped steel sheds is set at 550mm; the spacing between anchor bolts in the lightly deformed section is set at 1000mm×1000mm, the spacing between anchor cables is set at 1600mm×800mm, and the spacing of U-shaped steel sheds is set at 650mm. Based on the above specific values, the anchor / cable spacing in severely deformed sections is 0.6 to 0.8 times that in moderately deformed sections, and the anchor / cable spacing in moderately deformed sections is 0.6 to 0.8 times that in lightly deformed sections. The spacing of the U-shaped steel canopies is differentiated according to the same proportion. It should be noted that support parameters may also include the number of U-shaped steel canopy layers and the type of U-shaped steel canopy. For example, the number of U-shaped steel canopy layers in severely and moderately deformed sections is double, while the number of U-shaped steel canopy layers in lightly deformed sections is single, or different types of U-shaped steel canopies can be used, ensuring that the support strength is higher for sections with higher deformation.

[0040] Reinforcement support: Before the repair construction, based on the construction disturbance impact range predicted by the three-dimensional numerical model, reinforcement support is implemented in the roadways before and after the repair area, as well as the roadways around the shaft and the gate, in order to improve the overall bearing capacity of the adjacent roadways and reduce the disturbance impact of the repair construction on the shaft and the surrounding rock.

[0041] Initial support using anchor bolts / cables: After completing the reinforcement support, the heavily deformed section is sculpted and expanded, and broken surrounding rock and failed support components are removed. After sculpting and expansion, a full-section initial support system consisting of anchor bolts / cables, steel strips, and anchor mesh is used to reinforce and constrain the shallow part of the surrounding rock. The arrangement of anchor bolts / cables and support parameters can be adjusted according to the surrounding rock conditions, the range of the loosened zone, and numerical simulation results to meet the stability requirements of the surrounding rock. The support design is based on the heavily deformed section, and the designed support parameters are used for the heavily deformed section; for the moderately deformed section, the support density can be appropriately increased while meeting the support design principles and the stability requirements of the surrounding rock.

[0042] U-shaped steel canopy support: U-shaped steel canopies possess a certain load-bearing capacity and compressibility. As the surrounding rock deforms, they provide lateral restraint to the filling material, placing it in a triaxial stress state, inhibiting crack formation, and improving the mechanical properties of the filling material. After initial anchor / cable support is completed, U-shaped canopies are erected based on the degree of surrounding rock fragmentation, the extent of loosened zone development, the characteristics of continuous roadway deformation, and the support load-bearing requirements. U-shaped steel canopies can be used in single-layer or double-layer support configurations. Figure 2 As shown, for roadways with relatively low surrounding rock deformation and where single-layer support can meet the requirements for load bearing and deformation control, a single-layer U-shaped steel canopy can be erected on the initial support of anchor bolts / cables. Post-erection filling transforms the surrounding rock load from local contact to continuous transmission, improving the overall load-bearing capacity of the support structure. For example... Figure 3 As shown, for roadways with severely fractured surrounding rock, significant continuous deformation, high support load requirements, or unsuitability for repeated maintenance, a double-layer U-shaped steel canopy can be adopted. In the double-layer structure, the first layer of the U-shaped steel canopy prioritizes bearing the initial deformation load of the surrounding rock and releases some of the surrounding rock stress through its own compressibility; the second layer of the U-shaped steel canopy serves as the load-bearing skeleton, forming a synergistic force-bearing structure with the backfill material, further improving the support system's adaptability to continuous deformation of the surrounding rock and preventing stress concentration in the surrounding rock from causing instability of the support structure. The layout, number of layers, model, and other parameters of the U-shaped steel canopy are comprehensively determined based on the surrounding rock conditions, numerical simulation results, and roadway usage requirements.

[0043] Post-scaffolding backfilling: After the U-shaped steel canopy is erected, high-ductility concrete is used to fill the gap between the U-shaped steel canopy and the surrounding rock or existing support structure. When using a double-layer U-shaped steel canopy, the reserved space between the two layers can also be filled. The backfill material, together with the U-shaped steel canopy and anchor / cable support, forms a synergistic load-bearing system, uniformly transferring the force of the surrounding rock to the support, changing the stress on the support from point contact to surface contact, avoiding local stress concentration that could lead to instability and failure; at the same time, it isolates the surrounding rock from water and air, reducing the weakening of the surrounding rock strength. The strength grade of the backfill material is determined based on the calculation results of the surrounding rock pressure.

[0044] Preferably, the specific steps for real-time monitoring are as follows: real-time monitoring of the circumferential strain data and vertical strain data of the well wall concrete at the inner edge of the well wall above the shaft gate; real-time monitoring of the stress change data of the support structure at the bottom of the well to obtain real-time monitoring data.

[0045] Preferably, the multi-level construction response mechanism is divided into three control levels: normal response level, early warning response level, and over-limit response level. Based on the comparison results of real-time monitoring data and preset early warning thresholds, the construction progress speed, support reinforcement scheme, and monitoring frequency adjustment strategy corresponding to the three control levels are matched accordingly.

[0046] It should be noted that the preset warning thresholds are determined based on the mechanical properties of the shaft wall concrete and engineering safety requirements, and include two categories: shaft wall concrete strain warning thresholds and roadway displacement warning thresholds. The shaft wall concrete strain warning threshold is determined based on the design strength grade of the shaft wall concrete and with reference to relevant industry standards; the value should ensure that the concrete structure does not undergo macroscopic cracking at this strain level. The roadway displacement warning threshold is determined based on the roadway cross-section design requirements and mine safety production regulations. Specific warning values ​​are calibrated in engineering applications by combining the shaft structure safety assessment results and historical monitoring baseline data.

[0047] Preferred control strategies for standard response levels, early warning response levels, and over-limit response levels are as follows: When real-time monitoring data fails to reach the preset warning threshold, a normal response level is triggered to maintain the repair and construction process.

[0048] When real-time monitoring data approaches the preset warning threshold or a minor abnormal response occurs in the surrounding rock, a warning response level is triggered, reducing the repair construction speed and increasing the monitoring frequency. Specifically, when real-time monitoring data reaches 60%–80% of the preset warning threshold, a warning response level is triggered, reducing the repair construction speed, increasing the monitoring frequency to more than twice the normal frequency, and feeding the monitoring data during the warning phase back to the calibrated three-dimensional coupled numerical model for verification analysis to assess whether the current support scheme can effectively control the surrounding rock deformation. If the verification results indicate that the current support scheme still meets the control requirements, construction continues under reduced speed conditions; if the verification results indicate that the current support scheme's control effect is insufficient, the support parameters are adjusted accordingly before construction continues.

[0049] When real-time monitoring data exceeds the preset warning threshold, or when the surrounding rock deformation or support stress abnormally intensifies, an over-limit response is triggered, repair work is stopped, and temporary reinforced support is installed at the connection between the roadway and the shaft. Construction can only resume after the real-time monitoring data returns to a stable range and a safety assessment confirms that the conditions for resuming construction are met. Specifically, when real-time monitoring data reaches or exceeds the preset warning threshold, an over-limit response level is triggered, repair work is immediately stopped, and temporary reinforced support (such as I-beam stacks, grouting reinforcement rings, etc.) is installed at the connection between the roadway and the shaft. Simultaneously, the over-limit monitoring data is fed back to the three-dimensional coupled numerical model for recalculation, analyzing the causes of the over-limit (such as unreasonable support parameters, local stress redistribution caused by construction disturbance, etc.). Based on this, the support scheme parameters are adjusted (such as increasing the spacing between anchor bolts and cables, changing the number of U-shaped steel canopy layers, increasing grouting pressure, etc.). The adjusted support scheme is then re-simulated and verified in the numerical model, and construction can only resume after confirming that the control requirements are met.

[0050] Application examples Taking the repair project of the No. 2 track gate in a mine's bottom yard as an example, the repair construction was carried out using the implementation method.

[0051] The No. 2 track gate is located near the shaft head gate and is an important transportation and ventilation tunnel in the bottom yard. Affected by factors such as long-term rheological changes in high-stress soft rock, disturbance from the excavation of adjacent tunnels, and insufficient bearing capacity of the original support, some sections of the tunnel have experienced convergence of the sidewalls, movement of the roof and floor plates, support deformation, and reduction of cross-section, which has affected the normal production and use of the tunnel. Repair and reinforcement of the severely deformed sections are required.

[0052] I. On-site parameter acquisition and determination of severely deformed sections First, a field survey and surrounding rock stability test were conducted on the No. 2 track gate and its adjacent tunnels. Indoor rock mechanics tests were carried out through on-site sampling to obtain the physical and mechanical parameters of the surrounding rock, including density, compressive strength, tensile strength, elastic modulus, Poisson's ratio, cohesion, and internal friction angle. Among them, fine sandstone has a density of approximately 2600 kg / m³, an elastic modulus of 14.2 GPa, a Poisson's ratio of 0.13, a cohesion of 7.84 MPa, an internal friction angle of 49.9°, and a tensile strength of 5.57 MPa; sandy mudstone has a density of 2580 kg / m³, an elastic modulus of 13.6 GPa, a Poisson's ratio of 0.23, a cohesion of 5.91 MPa, an internal friction angle of 42.4°, and a tensile strength of 4.07 MPa; mudstone has a density of 2600 kg / m³, an elastic modulus of 5.55 GPa, a Poisson's ratio of 0.26, a cohesion of 4.04 MPa, an internal friction angle of 40.8°, and a tensile strength of 1.98 MPa. Subsequently, borehole inspection and ground-penetrating radar were used to test the loosened zone of the surrounding rock to obtain the development range of the loosened zone. The "cross" point method was used to determine the movement of the surrounding rock in the roadway, providing a basis for the subsequent determination of severely deformed sections and the assignment of parameters for the three-dimensional numerical model.

[0053] Field test results show that the surrounding rock in a local section of the No. 2 track gate is significantly fractured, with a loosening zone depth of approximately 2.4m. The cross-section of the roadway in this section is significantly smaller than the original design cross-section, with the local net width reduced from the design value of 5400mm to approximately 3600mm. The deformation of the roof, floor, and sidewalls is also significant, and it can no longer meet the requirements for normal production and use of the roadway. Considering the extent of the loosening zone development, the degree of roadway cross-section contraction, and the roadway's transportation and ventilation functions in the mine's bottom yard, this section is determined to be a severely deformed section and is designated as the repair area for this application example, with a repair length of approximately 45m.

[0054] For the adjacent areas of the No. 2 track gate, far from the severely deformed section, the deformation of the surrounding rock is relatively small and does not significantly affect the normal use of the roadway. These areas can be classified as moderately deformed sections based on the measured deformation and production needs. For areas further away from the repair area and where the surrounding rock is basically stable, these areas can be classified as lightly deformed sections. In this application example, the repair work mainly targets the severely deformed section. The moderately and lightly deformed sections are not considered as areas that must be repaired, but are only used as a reference range for construction organization, disturbance analysis, and support parameter optimization.

[0055] II. Three-dimensional numerical model construction, verification, and disturbance prediction Based on the physical and mechanical parameters of the surrounding rock, the spatial relationship of the tunnel, and the results of the field survey obtained in Step 1, a three-dimensional geometric model including the No. 2 track gate, the surrounding ventilation shaft, the gate and the chamber group was established using Rhino three-dimensional modeling software. The calculation range of the model is 150m×200m×80m. After completing the mesh generation, the model was imported into FLAC3D numerical simulation software to establish a three-dimensional numerical model for simulating the evolution of the stress field and displacement field of the surrounding rock.

[0056] After the model is established, it is simulated step by step according to the actual formation sequence of the shaft, existing roadway group, and roadway to be repaired. Support structure parameters consistent with those on site are applied simultaneously to ensure that the excavation process and support status in the model are consistent with the actual on-site conditions. After calculation, results such as the displacement changes of the surrounding rock in the shaft and adjacent roadways, and the development range of the loosened zone are extracted and compared with the on-site monitoring data obtained in step one. If there are deviations between the simulation results and the on-site deformation characteristics and the development range of the loosened zone, the physical and mechanical parameters of the surrounding rock, boundary conditions, and existing support parameters are iteratively corrected until the simulation results are basically consistent with the on-site monitoring results, thus completing the verification of the three-dimensional numerical model.

[0057] The model verification results show that the simulated cross-sectional shrinkage characteristics of the severely deformed section of the No. 2 track roadway are basically consistent with the field measurement results, indicating that the established three-dimensional numerical model can well reflect the deformation characteristics of the surrounding rock on site and can be used for subsequent repair construction disturbance prediction and analysis.

[0058] After completing the model verification, the anchor-frame-filling composite support scheme determined in step three is input into the verified three-dimensional numerical model to predict and analyze the disturbance impact on the shaft, gate, and adjacent roadways during the repair construction process, and obtain response results such as shaft displacement, shaft wall strain, and surrounding rock deformation of adjacent roadways. When the construction disturbance prediction results meet the safety control requirements of the shaft structure and the stability control requirements of the roadway, the repair construction is implemented. If the construction disturbance prediction results exceed the preset control requirements, the support parameters or construction scheme are adjusted, and numerical simulation verification is carried out again until the construction disturbance prediction results meet the safety control requirements before the repair construction is implemented.

[0059] III. Repair and Construction of Severely Deformed Sections After the three-dimensional numerical model was verified and it was confirmed that the repair work met the safety control requirements for the disturbance to the shaft and adjacent roadways, the repair work was carried out on the section that was identified as severely deformed.

[0060] This application example uses an anchor-frame-fill composite support system for repair. Based on the surrounding rock conditions and support requirements of the severely deformed section of the mine, this application example selects a single-layer U-shaped steel shed as the frame structure in the composite support system. Through anchor / cable support, the U-shaped steel shed, and backfilling, a synergistic load-bearing structure is formed, improving the overall stability of the surrounding rock in the repair area.

[0061] (1) Reinforcement support Based on the predicted impact range of construction disturbance from the three-dimensional numerical model, anchor cable combined with grouting reinforcement support was implemented in the roadways before and after the repair area, as well as in the shaft and the roadways surrounding the gate. Figure 4 As shown, the roof reinforcement uses Φ21.8mm×9200mm anchor cables, with 3 cables per row and a row spacing of 2400mm×1600mm; the side reinforcement uses Φ21.8mm×6200mm anchor cables, with 1 cable per side and a row spacing of 1600mm. This reinforcement improves the overall bearing capacity of adjacent roadways and reduces disturbance to the shaft and girder area during repair work.

[0062] (2) Initial support of anchor bolts / cables.

[0063] After the reinforcement and support are completed, the severely deformed section is enlarged and brushed. The enlargement size is determined according to the deformation of the roadway on site, so that the roadway cross-section after repair meets the design requirements.

[0064] During the screeding process, the outer slurry skin, broken surrounding rock, and failed support components of the roof and sidewalls are removed first, and the original anchor bolts, anchor mesh, and steel strips are dismantled. In the broken surrounding rock area, the construction process of "first initial spraying, then installation of anchor bolts and hanging of mesh" is adopted.

[0065] The anchor bolts are Φ22mm×2500mm in combination with M3 steel strips for full-section support, with a row spacing of 800mm×800mm. The roof anchors are Φ21.8mm×9200mm, with 7 anchors per row and a row spacing of 1200mm×600mm. The side anchors are Φ21.8mm×6200mm, with 4 anchors per row and a row spacing of 1200mm×600mm. The support parameters are determined based on the design requirements for the heavily deformed section. For the moderately deformed zone, the support density can be appropriately increased, provided that the support design principles and surrounding rock stability requirements are met.

[0066] (3) U-shaped steel shed support.

[0067] After the initial support of the anchor bolts / cables is completed, based on the degree of deformation of the surrounding rock and the support bearing requirements of this application example, a single-layer 36U-shaped steel shed is erected with a shed spacing of 450mm. The design net height of the U-shaped steel shed is 4200mm and the net width is 5400mm.

[0068] After the U-shaped steel shed is erected, a plastic grout barrier is laid on the surface of the steel mesh to serve as a load-bearing and grout barrier layer for the subsequent backfilling material, thus providing conditions for the backfilling construction.

[0069] (4) Filling after racking.

[0070] After laying the plastic sheeting, use a shotcrete machine to spray grout for backfilling. Backfilling should be done uniformly after the entire scaffolding is completed, or the scaffolding can be erected and backfilled in sections according to the site conditions.

[0071] The backfill layer, together with the U-shaped steel shed and anchor / cable support, forms a collaborative load-bearing system, which evenly transfers the surrounding rock load to the support structure, improves the stress state of the U-shaped steel shed, reduces local stress concentration, and improves the overall stiffness and long-term stability of the support system.

[0072] For areas not classified as severely deformed zones, no repair work will be carried out in this application example; for moderately deformed zones, when on-site monitoring indicates that further reinforcement is needed, support parameters such as the spacing between anchor bolts / cables, the number of layers, model, and spacing of U-shaped steel canopies can be appropriately changed, provided that the support design principles are met, to achieve differentiated support.

[0073] IV. Construction Monitoring and Multi-level Response Before the repair work, concrete surface strain sensors were installed on the east, west, and south sides of the shaft wall at the entrance of the air intake shaft, and surrounding rock displacement monitoring points were installed at key locations in the bottom of the shaft to monitor the compressive strain and tensile strain of the shaft wall concrete and the daily deformation of the roadway in real time throughout the entire process.

[0074] Based on the concrete design strength grade and shaft structure safety control requirements of this application example, and referring to historical monitoring baseline data, a construction monitoring and early warning system is established. Specifically, the early warning threshold for compressive strain of the shaft wall concrete is set at -2000με, the early warning threshold for tensile strain is set at 240με, and the early warning threshold for daily deformation of the roadway is set at 2mm.

[0075] During the repair work, the monitoring system continuously collects data on the compressive strain and tensile strain of the well wall concrete and the daily deformation of the roadway at a set frequency, and performs dynamic evaluation based on the multi-level response mechanism established in this invention. When the monitoring data at a local monitoring point reaches the early warning response condition for a short period of time, the early warning response mechanism is immediately activated, the repair work progress speed is reduced, the monitoring frequency is increased, and the real-time monitoring data is fed back to the verified three-dimensional numerical model for review and analysis. Based on the review results, the construction organization and local support parameters are optimized and adjusted, and numerical simulation verification and safety assessment are carried out again.

[0076] After assessment and confirmation that the adjusted support scheme met the requirements for shaft structure safety and surrounding rock stability control, normal construction resumed. Subsequent monitoring results showed that all monitoring data gradually stabilized and none reached the over-limit response threshold; no over-limit response level was triggered throughout the entire construction process.

[0077] After the construction was completed, the monitoring data of the whole process were statistically analyzed. The results showed that all monitoring indicators were within the safe control range, which verified that the method of the present invention can effectively ensure the safety of roadway repair construction around the shaft.

[0078] This application example demonstrates that by adopting the integrated control method proposed in this invention, which includes "judgment of severely deformed sections, verification of three-dimensional numerical models, prediction of repair disturbances, anchor-frame-filling composite support, and real-time monitoring and response," the entire process of repairing severely deformed roadways around the shaft can be safely controlled, and the repair of severely deformed sections can be completed under the premise of ensuring the structural safety of the shaft and surrounding roadways.

[0079] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and do not limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the protection scope of the present invention.

Claims

1. A method for controlling the stability of surrounding rock during the repair process of a main roadway / stone gate around a shaft, characterized in that, include: Obtain the physical and mechanical parameters of the surrounding rock, the characteristic parameters of the loosened zone of the tunnel, and the parameters of the surrounding rock approach. The tunnel is the main tunnel or stone gate to be repaired. Based on the characteristic parameters of the loosened zone and the surrounding rock migration parameters, the roadway to be repaired area is divided into severely deformed, moderately deformed and lightly deformed sections, thus obtaining the deformation sections of the roadway to be repaired area. A three-dimensional numerical model is constructed based on the actual spatial arrangement of the shaft and the roadway group. The physical and mechanical parameters of the surrounding rock are assigned to each rock stratum unit in the three-dimensional numerical model to simulate the evolution of the stress field and displacement field of the surrounding rock during the entire excavation process of the roadway to be repaired. The three-dimensional numerical model is checked using the loosened zone characteristic parameters. Based on the checked three-dimensional numerical model, the disturbance impact of the roadway construction activities on the shaft is simulated to obtain the construction disturbance prediction results. If the construction disturbance prediction results meet the safety control requirements of the shaft and adjacent roadways, the subsequent steps are continued; otherwise, the support parameters or construction plan are adjusted and the prediction is repeated until the construction disturbance prediction results meet the safety control requirements of the shaft and adjacent roadways. Based on the deformation sections of the roadway to be repaired, and combined with the construction disturbance prediction results, a composite support system of anchor-frame-filling is adopted to carry out differentiated repair construction on the roadway to be repaired. The wellbore condition, support stress, and surrounding rock deformation are monitored in real time throughout the entire repair construction process. Preset early warning thresholds and establish a multi-level construction response mechanism to dynamically adjust construction control strategies based on monitoring data.

2. The method for controlling the stability of surrounding rock during the repair process of the main roadway / stone gate around the shaft as described in claim 1, characterized in that, The specific steps for constructing the three-dimensional numerical model are as follows: based on the actual spatial relationship and cross-sectional dimensions of the shaft and the surrounding tunnel group, a three-dimensional geometric model including the shaft, the tunnel to be repaired, and the surrounding tunnel group is established, and the three-dimensional geometric model is meshed to obtain a mesh model; a three-dimensional numerical model is established based on the mesh model, and the three-dimensional numerical model is used to simulate the evolution of the stress field and displacement field of the surrounding rock.

3. The method for controlling the stability of surrounding rock during the repair process of the main roadway / stone gate around the shaft as described in claim 2, characterized in that, After establishing the three-dimensional numerical model, the boundary conditions, initial stress field settings, and parameter assignments are performed on the three-dimensional numerical model in sequence. The specific steps for setting the boundary conditions and initial stress field of the three-dimensional numerical model are as follows: constrain the vertical displacement at the bottom of the three-dimensional numerical model, constrain the normal displacement around the perimeter, and apply the equivalent load of the overburden at the top; set up the initial geostress field according to the actual burial depth of the mine and the geostress test results; when the repair area is affected by the fault structure, additional tectonic stress components are applied. The physical and mechanical parameters of the surrounding rock include its density, compressive strength, tensile strength, elastic modulus, Poisson's ratio, cohesion, and internal friction angle. After setting the boundary conditions and initial stress field, the density, compressive strength, tensile strength, elastic modulus, Poisson's ratio, cohesion, and internal friction angle of the surrounding rock are assigned to the corresponding rock strata units in the three-dimensional numerical model according to the lithology of the strata, thus completing the parameter assignment.

4. The method for controlling the stability of surrounding rock during the repair process of the main roadway / stone gate around the shaft as described in claim 3, characterized in that, The specific steps for verifying the three-dimensional numerical model are as follows: After assigning the parameters of the three-dimensional numerical model, the excavation simulation is carried out in stages according to the actual formation sequence of the shaft, the existing roadway group, and the roadway to be repaired. At each excavation stage, the support structure parameters and support boundary conditions consistent with the existing support conditions on site are applied simultaneously. After each excavation and support simulation is completed, the three-dimensional numerical model is calculated to the mechanical equilibrium state. The stress distribution data, displacement change data, and loosening zone development data of the surrounding rock of the shaft and adjacent roadways at each stage are extracted step by step. The displacement change data and loosening zone development data of the surrounding rock obtained by the three-dimensional numerical model simulation are compared with the measured surrounding rock approach parameters and loosening zone characteristic parameters on site. If the data deviation exceeds the threshold, the three-dimensional numerical model parameters, boundary conditions, and existing support parameters are iteratively corrected until the simulation results match the actual surrounding rock response law on site, and the three-dimensional numerical model verification is completed.

5. The method for controlling the stability of surrounding rock during the repair process of the main roadway / stone gate around the shaft as described in claim 1, characterized in that, The specific construction process of the anchor-frame-filling composite support system is as follows: Based on the construction disturbance impact range predicted by the three-dimensional numerical model, reinforcement support is first implemented on the roadways before and after the repair area, as well as the roadways around the shaft and the gate; after the reinforcement support is completed, the severely deformed section is brushed and expanded, and initial support of anchor bolts / cables is implemented; then, a U-shaped steel shed is erected and backfilling is carried out to form a composite support structure supported by anchor bolts / cables, U-shaped steel sheds and backfilling.

6. The method for controlling the stability of surrounding rock during the repair process of the main roadway / stone gate around the shaft as described in claim 5, characterized in that, The specific implementation method of the differentiated repair construction is as follows: based on the differences in the degree of surrounding rock fragmentation, the development range of the loosened zone, and the magnitude of deformation in the severely deformed, moderately deformed, and lightly deformed sections of the roadway to be repaired, the spacing between anchor bolts / cables and the spacing of U-shaped steel sheds in each section are differentiated; wherein, the spacing between anchor bolts / cables in the severely deformed section is 0.6 to 0.8 times that in the moderately deformed section, the spacing between anchor bolts / cables in the moderately deformed section is 0.6 to 0.8 times that in the lightly deformed section, and the spacing of U-shaped steel sheds is set differently according to the same proportion.

7. The method for controlling the stability of surrounding rock during the repair process of the main roadway / stone gate around the shaft as described in claim 1, characterized in that, The specific steps for conducting the real-time monitoring are as follows: real-time monitoring of the circumferential strain data and vertical strain data of the well wall concrete at the inner edge of the well wall above the shaft gate; real-time monitoring of the stress change data of the support structure at the bottom of the well to obtain real-time monitoring data.

8. The method for controlling the stability of surrounding rock during the repair process of the main roadway / stone gate around the shaft as described in claim 7, characterized in that, The multi-level construction response mechanism is divided into three control levels: normal response level, early warning response level, and over-limit response level. Based on the comparison results of the real-time monitoring data and the preset early warning threshold, the construction progress speed, support reinforcement scheme and monitoring frequency adjustment strategy corresponding to the three control levels are matched accordingly.

9. The method for controlling the stability of surrounding rock during the repair process of the main roadway / stone gate around the shaft as described in claim 8, characterized in that, The specific control strategies for the standard response level, early warning response level, and over-limit response level are as follows: When real-time monitoring data fails to reach the preset warning threshold, a routine response is triggered to maintain the repair and construction process. When real-time monitoring data approaches the preset warning threshold or when the surrounding rock shows a slight abnormal response, an early warning response is triggered, the speed of repair construction is reduced, and the monitoring frequency is increased. When real-time monitoring data exceeds the preset warning threshold, or when the surrounding rock deformation or support stress abnormally intensifies, an over-limit response is triggered, repair work is stopped, and temporary reinforced support is set at the connection between the roadway and the shaft. Construction can only resume after the real-time monitoring data returns to stability and the surrounding rock is judged to be stabilizing.

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