Method for acquiring ground advanced grouting parameters of deeply-buried system roadway crossing fault fracture zone
By combining the activation deformation law of water-conducting faults and grouting parameters, orthogonal experiments and numerical simulations were used to determine parameters such as grouting pressure, grout mix ratio and section length, solving the support problem of deep-buried roadways passing through fault fracture zones and achieving safe and efficient tunneling.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-05
- Publication Date
- 2026-03-31
AI Technical Summary
In the process of coal mining, when the deep-buried system roadway passes through the fault fracture zone, the traditional support system cannot provide effective support. The selection of grouting parameters lacks scientific basis, resulting in large engineering workload, stagnation of tunneling and insignificant effect of surrounding rock modification. There is a lack of scientific methods to study the law of rock mass instability and water inrush disaster when the system roadway passes through the deep-buried fault fracture zone.
By combining the activation deformation and water inrush law of water-conducting faults in large-section roadways under different modes and grouting parameters, a three-factor, three-level orthogonal test scheme was adopted. The COMSOL software was used to conduct numerical simulation of grout diffusion. The range analysis method was combined to determine key parameters such as grouting pressure, grout ratio and grouting section length, so as to achieve surrounding rock reinforcement.
The system has achieved reasonable determination of grouting parameters, effectively modified the fault fracture zone, ensured the safe passage of the system roadway, eliminated the threat of surrounding rock fracture and water hazards, and improved tunneling efficiency.
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Figure CN121766083A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of water hazard prevention and control technology in underground engineering such as mines, and relates to a method for obtaining the parameters of surface pre-grouting in deep buried system roadways through fault fracture zones. Background Technology
[0002] Before mining coal resources, the first step is to lay out the main systems of roadways, including transportation, ventilation, and tracks. During roadway excavation, complex geological structures are inevitably encountered, the most common being fault fracture zones. Because fault fracture zones have low strength, poor water resistance, high permeability, and are easily deformed, their physical and mechanical properties differ significantly from ordinary rock masses. Roadways traversing fault fracture zones often experience localized additional stress, leading to numerous complex geological hazards, primarily hydrogeological problems such as water inrush and engineering geological problems such as roof falls and support difficulties. Therefore, safely and efficiently traversing fault fracture zones has always been a key issue in roadway excavation. Furthermore, to alleviate the conflict between mining and excavation and improve excavation efficiency, many coal mines use tunnel boring machines (TBMs) for deep system roadway excavation. TBMs have large excavation cross-sections and place higher demands on the mechanical properties of the surrounding rock and fault fracture zones along the tunnel line. Water inrush during excavation will cause significant construction difficulties.
[0003] To address the aforementioned issues, traditional support systems fail to achieve the desired support effect when deep-buried system tunnels cross faults. Furthermore, commonly used downhole grouting control methods suffer from problems such as large workloads, tunneling stagnation, and insignificant surrounding rock modification effects, failing to effectively transform fault fracture zones. Previous determinations of grouting parameters were largely based on engineering experience, lacking research on the main controlling factors influencing grout diffusion and the optimal combination of different grouting parameters. Therefore, the selection of grouting parameters at present is both vague and empirical. Currently, there is no scientific method for obtaining surface-based advanced grouting parameters for system tunnels crossing deep-buried fault fracture zones. Grouting of fault fracture zones only targets the fault fracture zone itself, lacking methods for determining relevant grouting parameters and processes based on the instability and water inrush disaster patterns of system tunnels crossing deep-buried fault fracture zones. Summary of the Invention
[0004] The purpose of this invention is to provide a method for obtaining pre-grouting parameters for deep-buried roadways passing through fault fracture zones. This method combines the activation, deformation, and water inrush patterns of water-conducting faults in large-section roadways under different modes, as well as the diffusion patterns of grout in the surrounding rock under different grouting parameters. It obtains the optimal reinforcement range for pre-grouting of the surrounding rock in deep-buried large-section roadways passing through fault fracture zones. Furthermore, it incorporates research on the reinforcement effect of grouting in deep-buried large-section roadways passing through water-conducting faults, experimentally analyzing the damage characteristics of the surrounding rock reinforcement under various factors such as grouting section length, grouting pressure, and flow rate. By comparing the results before grouting, it analyzes the influence of grouting reinforcement on the stress and strain parameters of the surrounding rock in the fault fracture zone of large-section roadways. Finally, it yields a method for controlling the pre-grouting of rock masses in deep-buried fault fracture zones in system roadways, considering factors such as grouting pressure, grout ratio, grouting section length, reinforcement range, and roadway deformation mechanism.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for obtaining surface pre-grouting parameters for deep-buried system roadways passing through fault fracture zones includes: Step 1: Determine the deformation and damage patterns of the surrounding rock in the fault fracture zone of the deep-buried system roadway; this includes confirming the spatial pattern type of the deep-buried system roadway passing through the fault fracture zone and obtaining the deformation and damage mechanism of the deep-buried system roadway passing through the fault fracture zone; including: ① Physical similarity material model test of the deformation and damage of the surrounding rock in the deep-buried system roadway passing through the fault fracture zone; ② Evolution process of water inrush in the deep-buried system roadway passing through the fault fracture zone; ③ Evolution characteristics of fault water inrush during tunneling; ④ Numerical simulation calculation of rock mass instability in the deep-buried system roadway passing through the fault fracture zone. Step 2: Determination of key parameters for pre-grouting of the ground surface in the deep buried system tunnel through the fault fracture zone; 1) Grout diffusion law in deep buried system roadways through fault fracture zones: A three-factor, three-level orthogonal experimental scheme was adopted to carry out numerical simulation calculations of grout diffusion in fault grouting under three grouting parameters: grouting pressure, grouting section length, and grout specific gravity. The probe function of COMSOL was used to record the grouting pressure and permeability around the rock borehole. The simulation results were used to analyze the variation of grout diffusion range and permeability. By studying the changes in grout diffusion distance and fault permeability during the grouting process, the characteristics of grout diffusion were clarified. 2) Sensitivity analysis of key parameters for grouting in the fractured zone of a water-conducting fault; the range analysis method was used to conduct a sensitivity analysis of the simulation results of grouting in the fractured zone of a water-conducting fault, which can be specifically expressed as follows: ; In the formula, For the first The number of times the experiment was repeated at the horizontal level; For the first Factor selection At the horizontal level, the first The observed values from this experiment; For each factor, the range of its effect values at each level is calculated to characterize the significance of that factor: ; In the formula, This refers to the level value of this factor; The larger the value, the more significant the influence of the factor on the experimental results; The range analysis method was used to calculate the range of grout diffusion radius, diffusion area and permeability along the fault. Based on the calculation results, the sensitivity of different parameters to grout diffusion radius, diffusion area and fault permeability was ranked, so as to obtain the combination of key grouting parameters to guide grouting reinforcement projects.
[0006] Optionally, in step 1, the numerical simulation calculation of rock mass instability in the deep-buried system tunnel through the fault fracture zone includes: Based on the physical model test of similar materials in the deep buried system tunnel passing through the fault fracture zone, the following methods were adopted. Numerical calculation models for tunneling through deeply buried fault fracture zones were established under different spatial pattern types of tunneling roadways. Appropriate water pressure was applied to the confined aquifer strata at the bottom, and data such as surrounding rock stress, displacement, and plastic height were calculated during tunnel excavation. The instability law of the rock mass in the deeply buried fault fracture zone during system tunnel excavation was analyzed. The rock mass within the fault fracture zone was considered as an aggregate of loose rock and weak infill material, and a numerical calculation model was adopted. The built-in random function randomly distributes these loose rocks and weak infill materials within the fault; The model is constrained by top surface stress, lateral stress, and bottom surface normal displacement. The permeability boundary condition is set as a fixed water pressure applied to the top of the limestone aquifer. Equivalent plastic strain is used. The damage is described as shown in equation (1); (1); In the formula: , and These are the three principal plastic strains of the rock mass; The damage variable value of the rock mass; Material parameters of the rock mass; When rock mass is damaged, elastic modulus and cohesion With damage variables The change can be simplified to a linear relationship, as shown in equation (2); and its permeability Then with damage variables It exhibits an exponential growth relationship, as shown in equation (3); (2); (3); In the formula, and Here are the initial elastic modulus and cohesion of the rock mass, in G·Pa and MPa, respectively; and The residual elastic modulus and cohesion of the rock mass; The initial permeability coefficient of the rock mass is given in m / s. is the coefficient of change in rock permeability, dimensionless.
[0007] Optionally, in step 1, ① the physical similarity material model test for deformation and damage of surrounding rock in the fault fracture zone of the deep buried system tunnel includes: Based on the physical and mechanical properties of the surrounding rock strata and the characteristics of the fault fracture zone, a physical similarity material model test containing the fault fracture zone was constructed. A certain water pressure was applied in the aquifer, and the model was buried in a deep environment. Physical model tests were carried out to expose the fault fracture zone in the system roadway. By simulating the tunnel excavation, the stress, strain and water pressure changes in the surrounding rock and near the fault fracture zone were monitored. The deformation and damage laws of the surrounding rock of the fault fracture zone were analyzed based on the distance from the fault fracture zone.
[0008] Optionally, in step 1, step ②, the evolution process of water inrush through the fault fracture zone in the deep-buried system roadway includes: In the early stages of tunnel excavation, the distribution of faults and water pressure did not change significantly. At the bottom of the fault, due to the influence of confined water, the water flowed upward along the fault, and the water level at the fault was significantly higher than at other locations. During the excavation process, the height of the confined water in the floor and fault evolved. Due to the reduced pressure of the overlying strata, monitoring data showed a decrease in stress in the floor rock mass near the goaf below the tunnel. At the same time, the confined water rose further along the fault. Affected by the tunnel excavation, the original stress balance of the surrounding rock was broken, and the high-pressure water damaged the rock mass below the floor and expanded along the original fractures of the fault.
[0009] Optionally, in step 1, ③ the evolution characteristics of fault water inrush during tunneling include stress evolution characteristics, water pressure evolution characteristics, and confined water height evolution characteristics.
[0010] Optionally, step 3 is also included: verifying the effect of pre-grouting reinforcement of fault fracture zones based on numerical simulation results after grouting. Based on the physical and mechanical properties of the surrounding rock in the fault fracture zone after grouting reinforcement, utilizing Numerical simulation software was used to conduct numerical simulation calculations on the stability of the surrounding rock in the fault fracture zone of the deep buried system roadway after grouting reinforcement. The stress and displacement data of the surrounding rock in different directions were monitored, the deformation and damage law of the surrounding rock in the fault fracture zone after reinforcement was analyzed, and the influence of grouting reinforcement on the stress and strain parameters of the surrounding rock in the fault fracture zone of the large cross-section roadway was analyzed compared with that before grouting.
[0011] The beneficial effects of this invention are: The present invention provides a method for obtaining surface advanced grouting parameters for deep-buried system tunnels passing through fault fracture zones. The grouting parameters are determined based on the rock mass disaster and water inrush mechanism of the system tunnel passing through the deep-buried fault fracture zone and the grouting diffusion law of the water-conducting fault. This makes the determination of parameters such as grouting pressure, grout specific gravity, and grouting section length more reasonable, effectively realizing the grouting modification of the fault fracture zone, thereby enabling the system tunnel to safely pass through the fault fracture zone. Attached Figure Description
[0012] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1 The diagram illustrates the spatial relationship between the tunnel excavation roadway and the fault fracture zone: a) is a schematic diagram of the intersection with the normal fault, b) is a schematic diagram of the intersection with the reverse fault, and c) is a schematic diagram of the parallel relationship with the fault fracture zone. Figure 2 Three-dimensional design drawings for similar materials; Figure 3 The evolution characteristics of the height rise of the confined water in the floor and fault during the tunneling process; Figure 4 This describes the evolution process of the water inrush channel; Figure 5 This is the stress evolution curve of the roof during the tunneling process; Figure 6 This is the stress evolution curve of the bottom plate during the tunneling process; Figure 7 This is the stress evolution curve of the fault fracture zone during the tunneling process; Figure 8 The curve shows the evolution of water pressure during the tunneling process; Figure 9 The curves show the evolution of the rise height of the confined water in the floor and fault during the tunneling process; a is a three-dimensional view of the model's appearance; b is a diagram of the geological structure. Figure 10 For numerical simulation models; Figure 11 This is a schematic diagram showing the relationship between rock mass damage changes and stress-strain curves. Detailed Implementation
[0013] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0014] This invention discloses a method for obtaining surface pre-grouting parameters for deep-buried system roadways crossing fault fracture zones. Based on the spatial relationship between the fault and the roadway, it summarizes and generalizes the types of roadway excavation patterns across faults, including normal faults, reverse faults, and parallel faults. The method investigates the activation, deformation, and water inrush laws of water-conducting faults during deep-buried system roadway excavation, as well as the diffusion law of grout in fault fracture zones. It clarifies the variation laws of grout diffusion distance and fault permeability during grouting, and uses range analysis to identify the main controlling factors affecting grout diffusion distance, diffusion area, and fault permeability coefficient. Comparing the results before grouting, numerical simulation is used to verify the grouting reinforcement effect. Finally, a method for obtaining surface pre-grouting parameters for deep-buried system roadways crossing fault fracture zones is derived, considering factors such as grouting pressure, grout ratio, grouting section length, reinforcement range, and roadway deformation mechanism. This method can achieve advanced modification of the fractured zone of the water-conducting fault, ensure the safe passage of large-section roadways through the fractured zone, eliminate the threat of fractured surrounding rock and water hazards, achieve efficient roadway excavation, and alleviate the contradiction between mining and excavation.
[0015] The method for obtaining surface pre-grouting parameters for deep-buried system roadways crossing fault fracture zones according to the present invention includes: Step 1: Determine the deformation and damage patterns of the surrounding rock in the fault fracture zone of the deep-buried system roadway; this includes confirming the spatial pattern type of the deep-buried system roadway passing through the fault fracture zone and obtaining the deformation and damage mechanism of the deep-buried system roadway passing through the fault fracture zone; including: ① Physical similarity material model test of the deformation and damage of the surrounding rock in the deep-buried system roadway passing through the fault fracture zone; ② Evolution process of water inrush in the deep-buried system roadway passing through the fault fracture zone; ③ Evolution characteristics of fault water inrush during tunneling; ④ Numerical simulation calculation of rock mass instability in the deep-buried system roadway passing through the fault fracture zone. Step 2: Determination of key parameters for pre-grouting of the ground surface in the deep buried system tunnel through the fault fracture zone; 1) Grout diffusion law in deep buried system roadways through fault fracture zones: A three-factor, three-level orthogonal experimental scheme was adopted to carry out numerical simulation calculations of grout diffusion in fault surrounding rock under three grouting parameters: grouting pressure, grouting section length, and grout specific gravity. The probe function of COMSOL was used to record the grouting pressure and permeability around the rock borehole. The simulation results were used to analyze the variation of grout diffusion range and permeability. By studying the grout diffusion law and diffusion distance under different influencing factors, the influence characteristics of different influencing factors were clarified. 2) Sensitivity analysis of key parameters for grouting in the fractured zone of a water-conducting fault; the range analysis method was used to conduct a sensitivity analysis of the simulation results of grouting in the fractured zone of a water-conducting fault, which can be specifically expressed as follows: ; In the formula, For the first The number of times the experiment was repeated at the horizontal level; For the first Factor selection At the horizontal level, the first The observed values from this experiment; For each factor, the range of its effect values at each level is calculated to characterize the significance of that factor: ; In the formula, This refers to the level value of this factor; The larger the value, the more significant the influence of the factor on the experimental results; Range analysis was used to calculate the range of grout diffusion radius, diffusion area and permeability along the fault. Based on the calculation results, the factors affecting the sensitivity of grout diffusion radius, diffusion area and permeability along the fault were ranked, so as to obtain the key parameters of grouting for active grouting control.
[0016] In step 1, the numerical simulation calculation of rock mass instability in the deep-buried system tunnel passing through the fault fracture zone includes: based on the physical model test of similar materials of the deep-buried system tunnel passing through the fault fracture zone, using... Numerical calculation models for tunneling through deeply buried fault fracture zones were established under different spatial pattern types of tunneling roadways. Appropriate water pressure was applied to the confined aquifer strata at the floor, and data such as surrounding rock stress, displacement, and plastic zone height were calculated during tunnel excavation. The instability law of the rock mass in the deeply buried fault fracture zone of the system roadway was analyzed. The rock mass within the fault fracture zone was considered as an aggregate of loose rock and weak infill material, and a numerical calculation model was adopted. The built-in random function randomly distributes these loose rocks and weak infill materials within the fault; The model is constrained by top surface stress, lateral stress, and bottom surface normal displacement. The permeability boundary condition is set as a fixed water pressure applied to the top of the limestone aquifer. Equivalent plastic strain is used. The damage is described as shown in equation (1); (1); In the formula: , and These are the three principal plastic strains of the rock mass; The damage variable value of the rock mass; Material parameters of the rock mass; When rock mass is damaged, elastic modulus and cohesion With damage variables The change can be simplified to a linear relationship, as shown in equation (2); and its permeability Then with damage variables It exhibits an exponential growth relationship, as shown in equation (3); (2); (3); In the formula, and Here are the initial elastic modulus and cohesion of the rock mass, in G·Pa and MPa, respectively; and The residual elastic modulus and cohesion of the rock mass; The initial permeability coefficient of the rock mass is given in m / s. is the coefficient of change in rock permeability, dimensionless.
[0017] In step 1, ① the physical similarity material model test for deformation and damage of the surrounding rock of the deep-buried system roadway through the fault fracture zone includes: based on the physical and mechanical properties of the surrounding rock strata and the characteristics of the fault fracture zone, a physical similarity material model test containing the fault fracture zone is built, and a certain water pressure is applied in the aquifer. In the deep-buried environment of the model, a physical model test is carried out to expose the fault fracture zone in the system roadway. By simulating the tunneling of the system roadway, the stress, strain and water pressure changes of the surrounding rock and the fault fracture zone are monitored, and the deformation and damage law of the surrounding rock of the fault fracture zone is analyzed based on the distance from the fault fracture zone.
[0018] In step 1, the evolution of water inrush in the deep-buried system roadway through the fault fracture zone includes: In the early stage of roadway excavation, the distribution of fault and water pressure did not change significantly. Due to the influence of confined water at the bottom of the fault, the water flow developed upward along the fault, and the water level at the fault was significantly higher than other locations. During the excavation process, the height of the confined water in the floor and fault evolved. Due to the reduced pressure of the overlying strata, the monitoring data showed a decrease in stress in the floor rock mass near the goaf below the roadway. At the same time, the confined water rose further along the fault. Affected by the roadway excavation, the original stress balance of the surrounding rock of the roadway was broken, and the high-pressure water damaged the rock mass below the floor and expanded and developed along the original fractures of the fault.
[0019] In step 1, ③ the evolution characteristics of fault water inrush during the tunneling process include stress evolution characteristics, water pressure evolution characteristics, and confined water height evolution characteristics.
[0020] Step 3 also includes: verifying the effect of pre-grouting reinforcement of fault fracture zones based on numerical simulation results after grouting. Based on the physical and mechanical properties of the surrounding rock in the fault fracture zone after grouting reinforcement, utilizing Numerical simulation software was used to conduct numerical simulation calculations on the stability of the surrounding rock in the fault fracture zone of the deep buried system roadway after grouting reinforcement. The stress and displacement data of the surrounding rock in different directions were monitored, the deformation and damage law of the surrounding rock in the fault fracture zone after reinforcement was analyzed, and the influence of grouting reinforcement on the stress and strain parameters of the surrounding rock in the fault fracture zone of the large cross-section roadway was analyzed compared with that before grouting.
[0021] Example 1: The specific implementation of this invention includes the following steps: Step 1: Determine the deformation and damage patterns of the surrounding rock in the fault fracture zone of the deep-buried system roadway. 1) Spatial pattern types of deep-buried system roadway excavation roadways crossing fault fracture zones Because different types of fault fracture zones have different geostress environments and water conductivity characteristics, the surrounding rock deformation and fault activation damage characteristics generated when a tunnel exposes different fault fracture zones are different. Therefore, different spatial relationships between tunnels and fault fracture zones are defined, with normal faults and reverse faults being the main types. Figure 1 This study summarizes and generalizes the different types of fault fracture zones and their characteristics in tunnel excavation.
[0022] 2) Deformation and damage mechanism of deep-buried fault fracture zone in deep-buried system roadway ① Physical similarity material model test of deformation and damage of surrounding rock in deep buried fault fracture zone of deep buried system roadway Based on the physical and mechanical properties of the surrounding rock strata and the characteristics of the fault fracture zone, a physical similarity material model test containing the fault fracture zone was constructed. A certain water pressure was applied in the aquifer, and the model was buried in a deep environment. Physical model tests were carried out to expose the fault fracture zone in the system roadway. By simulating the roadway excavation, the stress, strain and water pressure changes in the surrounding rock and near the fault fracture zone were monitored. The deformation and damage laws of the surrounding rock of the fault fracture zone were analyzed based on the distance from the fault fracture zone.
[0023] (1) System composition The simulated test system for deep-buried tunnel excavation through a deep-buried fault fracture zone consists of four parts: a test bench system; a servo loading system; a hydraulic control system; and a computer data acquisition system. During the test, the spatiotemporal evolution of deformation and damage in the surrounding rock of the excavation fault can be visually displayed. The model size is designed to be 1200mm (length). 910mm (width) 300mm (height) (2) Model design The fault morphology was simulated according to a geometric similarity ratio of 150. Uniformly distributed loads were applied to the upper part of the model and in the horizontal direction to simulate the stress state of the actual surrounding rock. Displacement constraints were achieved using plexiglass at the front and back of the model, which allowed for clear observation of the fault rock failure and the seepage of confined water along the fractures during the experiment, while also realizing the three-dimensional stress state of the deep, real rock strata.
[0024] A. Additional load design Based on the tunnel excavation situation, geological conditions, and theoretical analysis, the simulated water pressure is approximately 8 MPa. The test requires applying overburden pressure at a depth of approximately 800 m in the vertical direction.
[0025] Stress compensation was achieved by applying loads to the model using a servo loading system in the simulation test bench. The overlying load was 0.13 MPa. A corresponding water pressure of 0.053 MPa was automatically supplied via the test bench's high-water-pressure loading system. Fixed constraints were implemented on both sides using displacement limiting mechanisms. The model design is as follows: Figure 2 As shown.
[0026] B. Model material ratio A non-hydrophilic similarity simulation material was prepared using paraffin wax and petrolatum as binders, and river sand, calcium carbonate, and other aggregates to match the properties of the roof and floor rocks. Based on the physical and mechanical properties of the mine strata, the mass ratio range of the similarity simulation material components was determined, ensuring that the compressive strength and permeability coefficient of the similar material were controlled within the range of 0.04–0.60 MPa and 2.87 × 10⁻⁶ MPa, respectively. -7 ~9.37×10 - 5 cm / s. The tunnel strata used in this experiment were made of fine sandstone; the floor slab was made of non-hydrophilic simulated material, consisting of calcium carbonate, sand, paraffin, etc.; the roof slab was made of ordinary similar simulated material composed of sand, gypsum, calcium carbonate, and water. The material ratios of each rock stratum are shown in Table 1.
[0027] Table 1. Material ratios for similar simulations
[0028] C. Deployment of stress sensors The plan is to deploy 18 stress sensors and 7 water pressure sensors. Specifically, points A1-A8 will monitor stress changes in the roadway roof and floor; points A9-A14 will monitor stress changes in the fault's two sides; points A15-A18 will monitor stress changes in the roadway roof and floor; points B1-B4 will monitor the variation of seepage water pressure within the floor rock mass; and points B5-B7 will monitor the variation of seepage water pressure within the fault fracture zone. Figure 2 The sensors in the fault fracture zone are spaced 6 cm apart to measure stress changes near the fault fracture zone at different distances. The sensors in the fault footwall are spaced 10 cm apart.
[0029] (3) Model laying Before laying the model, the similar simulation test system needs to be debugged to achieve its optimal working state. Then, the sealing rubber gasket is placed on the bottom to prevent water from overflowing along the gaps and interfaces. Grease is applied to the left and right sides of the model to reduce the boundary friction caused by the movement of the top and bottom rock layers. The contact area between the test platform and the plexiglass is sealed with sealant. The similar model is laid by manually compacting and filling.
[0030] Next, according to the corresponding simulated material ratio requirements, materials were selected, specimens were processed, and performance requirements were tested; similar simulated materials were configured in large proportions according to the test requirements; sealant was applied to some parts of the test platform, and lubricant was applied to the front and rear plexiglass plates to reduce friction; stress sensors were installed on the rock strata of the model base as needed for the test; materials were laid from bottom to top according to the dimensions of each layer; mica powder was spread between each rock layer, and each layer of similar simulated material was compacted; after the similar simulated material was laid, an external load was applied to compact the model and increase its density; the model was placed for 3-5 days for room temperature curing.
[0031] Finally, after the model is laid out, external vertical and horizontal loads are applied, and after curing at room temperature for one week, a pre-set water pressure is applied to start the excavation of the tunnel.
[0032] (4) Model excavation After one week of model curing, external vertical loads, horizontal loads, and water pressure were applied before tunneling began. Once the loads and water pressure reached the preset values, they were stabilized. Each tunneling operation involved 5 cm of tunneling with a 0.5-hour interval, for a total of 18 simulated tunneling operations.
[0033] (5) Analysis of water inrush process and characteristics in deep-buried fault fracture zone during tunnel excavation ② Evolution of water inrush in deep-buried system roadways through deep-buried fault fracture zones In the initial stage of tunnel excavation, the distribution of faults and water pressure did not change significantly. At the bottom of the fault, due to the influence of confined water, the water flowed upwards along the fault, and the water level at the fault was significantly higher than at other locations. The evolution of the rise in height of the confined water in the floor and fault during excavation was as follows: Figure 3 As shown, when the tunnel advanced to 20cm, the stress in the floor rock mass near the goaf decreased due to the reduced pressure from the overlying strata. Simultaneously, pressurized water rose further along the fault. Affected by the tunnel excavation, the original stress balance of the surrounding rock was disrupted, and the high-pressure water caused damage to the rock mass below the floor, extending and developing along the existing fractures of the fault.
[0034] When the tunnel was excavated to 55cm, the floor slab delamination and cracks continued to expand, especially near the fault. When the tunnel was excavated to 60cm, a water inrush point appeared above the fault, and water continued to gush out. Figure 4As shown, the water inrush is turbid, the soil within the fault is washed out, and the surrounding rock near the fault fractures and collapses. The water inrush phenomenon follows the "principle of least resistance," meaning the location of the water inrush point is closest to the highest point at the upper end of the fault. The location of the water inrush point directly above the fault can also be referred to as the "principle of least path." When the tunnel is excavated to 65cm, as the water inrush channel continues to expand and evolve, and the number of water inrush points continues to increase, the water inrush volume in the mining area further increases, eventually evolving into a water inrush disaster. When the tunnel is excavated to 75cm, the water inrush channel is fully developed, and the water inrush volume gradually stabilizes.
[0035] ③ Evolution characteristics of fault water inrush during deep-buried system tunnel excavation (a) Stress evolution characteristics Combination Figure 5-7 The stress in the surrounding rock of the tunnel roof showed a decreasing trend, which is consistent with the phenomenon observed in the experiment where the tunnel roof delaminated due to the excavation, followed by bending, subsidence, and compaction of the overlying strata, resulting in the disappearance of the delamination. Due to tunnel excavation, the stress on the floor strata decreased from above, leading to a reduction in stress. When the surrounding rock collapsed, the stress began to increase. The stress monitoring data of the hanging wall (A13) and footwall (A14) showed different trends. Before mining 45cm, A13 showed a trend of increasing stress, which then began to decrease; A14 remained relatively stable. The monitoring data indicate that tunnel excavation did not affect the stress sensors inside the aquitard beneath the floor, and that confined water was the main influencing factor on the stress changes in the sensors.
[0036] (b) Characteristics of water pressure evolution Combination Figure 8 Water pressure sensors B1, B2, and B3 are located inside the fault from bottom to top, while water pressure sensor B4 is located inside the floor. As the tunnel continues to advance, the area affected by the excavation gradually moves forward. The fault at the water pressure monitoring point undergoes gradual damage under the combined effects of stress and water pressure, resulting in a decrease in water pressure and an increase in water inflow. When the confined water is sequentially guided to the location of the water pressure sensors, the water pressure value decreases. Water pressure sensors B5 and B6 show no water inflow and no significant change in value. (c) Evolution characteristics of confined water height Combination Figure 9 When the tunnel was excavated from 30cm to 55cm, the water pressure in the floor changed significantly, the fault water level rose further, and the confined water was guided upwards along the fault. The water level along the rising fault was higher than at other locations and gradually surged upwards. At 35cm, the confined water rise height was 8.43cm; the floor rise height was 4.38cm. At 45cm, the confined water rise height was 19.93cm; the floor rise height was 13.73cm. At 60cm, after the water inrush, the confined water rise height tended to stabilize.
[0037] ④ Numerical simulation calculation of rock mass instability in fault fracture zone of system roadway buried too deep.
[0038] Based on the physical model test of similar materials in the fault fracture zone of the system tunnel at excessive depth, FLAC was used. 3D Numerical calculation models for tunneling through deeply buried fault fracture zones were established under different modes (referring to the three different spatial mode types of tunnel excavation through fault fracture zones in step 1). Appropriate water pressure was applied to the confined aquifer at the bottom, and the stress, displacement, and plastic damage information of the surrounding rock were monitored. The instability law of the rock mass in the deeply buried fault fracture zone during tunnel excavation was analyzed. Figure 3 As shown. The model is designed with a width of 150m, a height of 50m, and a thickness of 40m. The rock mass within the fault fracture zone is considered as an aggregate of loose rock and weak infill, and FLAC is used. 3D The built-in random function randomly distributes these loose rocks and weak infill within the fault.
[0039] Combination Figure 10 Based on the proposed numerical simulation scheme, the numerical simulation steps for this study are determined as follows: (1) Establish a numerical simulation model for large-section tunnel excavation through faults, and classify the fault rock mass into two categories: loose rock and weak filling material; (2) Set the model mechanics and seepage boundary conditions, define the mechanics and seepage parameters of various types of rocks, and calculate the initial stress to reach equilibrium; (3) Excavate the roadway at a rate of 10m and construct a support structure. The model dynamically changes various rock mechanics parameters, permeability coefficient and porosity values according to the damage size. Finally, the equilibrium is achieved through fluid-solid coupling calculation or the surrounding rock of the roadway undergoes deformation, instability and failure.
[0040] In the model, top surface stress, lateral stress and bottom surface normal displacement constraints are set. The model permeability boundary condition is set to apply a fixed water pressure at the top of the limestone aquifer. When simulating tunnel excavation, the excavation advance is set to 10.0m each time and the water pressure in this area is set to 0.
[0041] For rock materials described using the Mohr-Coulomb criterion, under the combined effects of tunneling disturbance stress and seepage water pressure, plastic deformation and damage will occur simultaneously after reaching the bearing limit. Therefore, the equivalent plastic strain can be used. The damage is described as shown in Equation (1).
[0042] (1) In the formula: , and These are the three principal plastic strains of the rock mass; The damage variable value of the rock mass; These are the material parameters of the rock mass.
[0043] Combination Figure 11 When the rock mass is damaged, the change in its internal friction angle φ is very small, and the elastic modulus is... and cohesion With damage variables The change can be simplified to a linear relationship, as shown in equation (2); and its permeability Then with damage variables It exhibits an exponential growth relationship, as shown in equation (3).
[0044] (2); (3); In the formula, and The initial elastic modulus and cohesion of the rock mass; and The residual elastic modulus and cohesion of the rock mass; The initial permeability coefficient of the rock mass; This is the coefficient of change in rock mass permeability.
[0045] Simulations were conducted using the following different schemes: (1) Scheme 1: The fault dip angle is 80° (normal fault), and the water pressure at the bottom plate is 8MPa; (2) Scheme 2: The fault dip angle is 30° (normal fault), and the water pressure at the bottom plate is 8MPa; (3) Scheme 3: The fault dip angle is 55° (normal fault), and the water pressure at the bottom plate is 8MPa; (4) Scheme 4: The fault dip angle is 30° (reverse fault), and the bottom plate water pressure is 8MPa; (5) Scheme 5: The fault dip angle is 55° (reverse fault), and the bottom plate water pressure is 8MPa; (6) Scheme 6: The fault dip angle is 80° (reverse fault), and the bottom plate water pressure is 8MPa; Step 2: Determination of key parameters for pre-grouting of deep-buried system tunnels across fault fracture zones 1) Establishment of grouting model for deep-buried fault fracture zone Numerical simulations of grout diffusion in fault-bounded rock under different grouting parameters (grouting pressure, grouting section length, and grout specific gravity) were conducted using the two-phase Darcy law physical field and fluid-solid coupling field in the porous media and groundwater module of COMSOL software. The variation characteristics of grout diffusion range within the fault under different grouting parameters were summarized and analyzed, and the response sensitivity characteristics of grout diffusion range to different parameters were explored.
[0046] The proposed model has a width of 200m, a height of 100m, and a thickness of 30m. It considers the vertical stress on the overlying rock strata and the horizontal stress on both sides. The bottom boundary of the model is set to fixed displacement. The perimeter of the model is set as a non-flux boundary, i.e., an impermeable boundary, so that grouting slurry will not overflow from the perimeter. The data is imported into COMSOL through interpolation functions, and each point in the COMSOL model is assigned a specific value to represent the initial permeability. The fracture zone is characterized by changing the permeability of the surrounding rock of the fault. 2) Simulation scheme for grout diffusion in fault surrounding rock under different grouting parameters To study the grouting diffusion law in fault fracture zones and provide a scientific basis for safe tunnel excavation, enabling successful passage through faults, this simulation scheme adopted a three-factor, three-level orthogonal experimental design. The three influencing factors were the grout water-cement ratio, grouting pressure, and grouting section length. The grout water-cement ratios were 1:1, 2:1, and 3:1; the grouting pressures were 12 MPa, 16 MPa, and 20 MPa; and the grouting section lengths within the fault zone were 10 m, 20 m, and 30 m. The influencing factors and levels of the orthogonal experimental design are shown in Table 4, the numerical model calculation parameters are shown in Table 5, and the specific simulation scheme of the orthogonal experiment is shown in Table 6. This simulation utilized the probe function of COMSOL to record data on the grouting pressure and permeability around the borehole in the rock mass. The cloud map results generated by COMSOL software and the data results were used to analyze the variation law of grouting pressure and permeability. By studying the grout diffusion law and diffusion distance under different influencing factors, the influence characteristics of different influencing factors were clarified, and the grouting reinforcement effect of fault fracture zones was determined.
[0047] Table 4 Numerical Simulation Factors-Level Table
[0048] Table 5 Numerical Model Calculation Parameters
[0049] Table 6 Numerical Simulation Operating Conditions Table
[0050] 3) Analysis of key parameters for grouting in the fractured zone of the water-conducting fault To further clarify the main controlling factors in the grouting process of the fractured zone of the water-conducting fault, a sensitivity analysis was conducted on the simulation results of grouting in the fractured zone of the water-conducting fault using range analysis. Range analysis, also known as intuitive analysis, is characterized by its simplicity, low workload, and clear, intuitive results. Through range analysis, the primary and secondary factors affecting the physical and mechanical parameters can be identified.
[0051] (3) Analysis of the diffusion radius of slurry along the fault Range analysis was used to calculate the range of grout diffusion radius, diffusion area, and permeability along the fault. The average diffusion radius of each factor at the same level was taken. Based on the calculation results, a visual analysis diagram of the influence of each factor on the grout diffusion distance along the fault was obtained. This led to a ranking of the sensitivity of the three factors to parameters such as grout diffusion distance, diffusion area, and permeability, revealing the main controlling factors for grout diffusion radius, diffusion area, and permeability along the fault.
[0052] Step 3: Verify the effect of pre-grouting reinforcement of fault fracture zones based on numerical simulation results after grouting. Based on the deformation and damage patterns of the surrounding rock in the fractured zone during large-section roadway excavation under different modes, this study analyzes the damage range of the surrounding rock in the fault fractured zone under different modes. According to the grout diffusion range of the surrounding rock in the fault fractured zone under different grouting parameters, the combination of grouting parameters that can cover a reasonable range of reinforcement for the surrounding rock in the fault fractured zone of a large-section roadway is determined, thus identifying the optimal reinforcement range for the fault fractured zone under different parameters. Based on the physical and mechanical properties of the surrounding rock in the fault fractured zone after reinforcement, numerical simulation calculations of roadway excavation in the fault fractured zone after grouting reinforcement are carried out using FLAC3D numerical simulation software. Stress and displacement data of the surrounding rock in different directions are monitored, and the deformation and damage patterns of the surrounding rock in the fault fractured zone after reinforcement are analyzed. Compared with before grouting, the influence of grouting reinforcement on the stress and strain parameters of the surrounding rock in the fault fractured zone during large-section roadway excavation is analyzed. Therefore, the optimal combination of grouting parameters is determined.
[0053] Numerical simulations of parameters such as shear stress, displacement, and plastic zone after grouting reinforcement, compared with those before grouting, show that the grouting parameters of this invention are determined based on the mechanism of rock mass catastrophic water inrush in the fault fracture zone of the system roadway and the grouting diffusion law of the water-conducting fault. This makes the determination of parameters such as grouting pressure, grout ratio, grouting reinforcement range, and grouting section length more reasonable, effectively realizing the grouting modification of the fault fracture zone, thereby enabling the system roadway to safely pass through the fault fracture zone.
[0054] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.
Claims
1. A method for obtaining surface pre-grouting parameters for deep-buried system roadways crossing fault fracture zones, characterized in that, include: Step 1: Determine the deformation and damage patterns of the surrounding rock in the fault fracture zone of the deep-buried system roadway; This includes confirming the spatial pattern type of deep-buried system roadways passing through fault fracture zones and obtaining the deformation and damage mechanism of deep-buried system roadways passing through fault fracture zones; including: ① physical similarity material model test of deformation and damage of surrounding rock in deep-buried system roadways passing through fault fracture zones; ② evolution process of water inrush in deep-buried system roadways passing through fault fracture zones; ③ evolution characteristics of fault water inrush during tunneling; ④ numerical simulation of rock mass instability in deep-buried system roadways passing through fault fracture zones. Step 2: Determination of key parameters for pre-grouting of the ground surface in the deep buried system tunnel through the fault fracture zone; 1) Grout diffusion law in deep buried system roadways through fault fracture zones: A three-factor, three-level orthogonal experimental scheme was adopted to carry out numerical simulation calculations of grout diffusion in fault grouting under three grouting parameters: grouting pressure, grouting section length, and grout specific gravity. The probe function of COMSOL was used to record the grouting pressure and permeability around the rock borehole. The changes in grout diffusion range and permeability were analyzed. By studying the changes in grout diffusion distance and fault permeability during the grouting process, the characteristics of grout diffusion were clarified. 2) Sensitivity analysis of key parameters for grouting in the fractured zone of a water-conducting fault; the range analysis method was used to conduct a sensitivity analysis of the simulation results of grouting in the fractured zone of a water-conducting fault, which can be specifically expressed as follows: ； In the formula, For the first The number of times the experiment was repeated at the horizontal level; For the first Factor selection At the horizontal level, the first The observed values from this experiment; For each factor, the range of its effect values at each level is calculated to characterize the significance of that factor: ； In the formula, This refers to the level value of this factor; The larger the value, the more significant the influence of the factor on the experimental results; The range analysis method was used to calculate the range of grout diffusion radius, diffusion area and permeability along the fault. Based on the calculation results, the sensitivity of different parameters to grout diffusion radius, diffusion area and fault permeability was ranked, so as to obtain the combination of key grouting parameters to guide grouting reinforcement projects.
2. The method for obtaining surface pre-grouting parameters for deep-buried system roadways crossing fault fracture zones according to claim 1, characterized in that, In step 1, step ④, the numerical simulation calculation of rock mass instability in the deep-buried system tunnel through the fault fracture zone, includes: Based on the physical model test of similar materials in the deep buried system tunnel passing through the fault fracture zone, the following methods were adopted. Numerical calculation models for tunneling through deeply buried fault fracture zones were established under different spatial pattern types of tunneling roadways. Appropriate water pressure was applied to the confined aquifer strata at the bottom, and data such as surrounding rock stress, displacement, and plastic height were calculated during tunnel excavation. The instability law of the rock mass in the deeply buried fault fracture zone during system tunnel excavation was analyzed. The rock mass within the fault fracture zone was considered as an aggregate of loose rock and weak infill material, and a numerical calculation model was adopted. The built-in random function randomly distributes these loose rocks and weak infill materials within the fault; The model is constrained by top surface stress, lateral stress, and bottom surface normal displacement. The permeability boundary condition is set as a fixed water pressure applied to the top of the limestone aquifer. Equivalent plastic strain is used. The damage is described as shown in equation (1); (1)； In the formula: , and These are the three principal plastic strains of the rock mass; The damage variable value of the rock mass; Material parameters of the rock mass; When rock mass is damaged, elastic modulus and cohesion With damage variables The change can be simplified to a linear relationship, as shown in equation (2); and its permeability Then with damage variables It exhibits an exponential growth relationship, as shown in equation (3); (2)； (3)； In the formula, and Here, represents the initial elastic modulus and cohesion of the rock mass, with units of G·Pa and MPa, respectively. and The residual elastic modulus and cohesion of the rock mass; The initial permeability coefficient of the rock mass is given in m / s. is the coefficient of change in rock permeability, dimensionless.
3. The method for obtaining surface pre-grouting parameters for deep-buried system roadways crossing fault fracture zones according to claim 1 or 2, characterized in that, In step 1, the physical similarity material model test for deformation and damage of the surrounding rock in the fault fracture zone of the deep buried system roadway includes: Based on the physical and mechanical properties of the surrounding rock strata and the characteristics of the fault fracture zone, a physical similarity material model test containing the fault fracture zone was constructed. A certain water pressure was applied in the aquifer of the bottom plate, and the model was buried in a deep environment. Physical model tests were carried out to expose the fault fracture zone in the system roadway. By simulating the tunnel excavation, the stress, strain and water pressure changes in the surrounding rock and near the fault fracture zone were monitored. The deformation and damage laws of the surrounding rock of the fault fracture zone were analyzed based on the distance from the fault fracture zone.
4. The method for obtaining surface pre-grouting parameters for deep-buried system roadways crossing fault fracture zones according to claim 1 or 2, characterized in that, In step 1, the evolution process of water inrush through the fault fracture zone in the deep buried system roadway includes: In the early stages of tunnel excavation, the distribution of faults and water pressure did not change significantly. At the bottom of the fault, due to the influence of confined water, the water flowed upward along the fault, and the water level at the fault was significantly higher than at other locations. During the excavation process, the height of the confined water in the floor and fault evolved. Due to the reduced pressure of the overlying strata, monitoring data showed a decrease in stress in the floor rock mass near the goaf below the tunnel. At the same time, the confined water rose further along the fault. Affected by the tunnel excavation, the original stress balance of the surrounding rock was broken, and the high-pressure water damaged the rock mass below the floor and expanded along the original fractures of the fault.
5. The method for obtaining surface pre-grouting parameters for deep-buried system roadways crossing fault fracture zones according to claim 1 or 2, characterized in that, In step 1, ③ the evolution characteristics of fault water inrush during tunneling include stress evolution characteristics, water pressure evolution characteristics, and confined water height evolution characteristics.
6. The method for obtaining surface pre-grouting parameters for deep-buried system roadways crossing fault fracture zones according to claim 1 or 2, characterized in that, Step 3 also includes: verifying the effect of pre-grouting reinforcement of fault fracture zones based on numerical simulation results after grouting. Based on the physical and mechanical properties of the surrounding rock in the fault fracture zone after grouting reinforcement, utilizing Numerical simulation software was used to conduct numerical simulation calculations on the stability of the surrounding rock in the fault fracture zone of the deep buried system roadway after grouting reinforcement. The stress and displacement data of the surrounding rock in different directions were monitored, the deformation and damage law of the surrounding rock in the fault fracture zone after reinforcement was analyzed, and the influence of grouting reinforcement on the stress and strain parameters of the surrounding rock in the fault fracture zone of the large cross-section roadway was analyzed compared with that before grouting.