Comprehensive control method for surrounding rock deformation in 3D stope under high stress and complex conditions

Abstract

The present invention discloses a comprehensive control method for the deformation of surrounding rock in a three-dimensional stope under high-stress complex conditions, including step A, active support for controlling the deformation of surrounding rock in a deep stope; step B, constructing a three-dimensional stope dynamic pressure and deformation monitoring system based on LabVIEW and intelligent fiber optic sensors; step C, constructing a stope dynamic pressure and deformation visualization and early warning system; step D, constructing a dynamic deformation intelligent monitoring and control system. On the basis of selecting appropriate active support for controlling the deformation of surrounding rock in a deep stope, a three-dimensional stope dynamic pressure and deformation monitoring system based on LabVIEW and intelligent fiber optic sensors is established, combined with remote real-time visualization monitoring and prediction of stope dynamic pressure and deformation breakage, and based on the monitoring data, control technical measures are dynamically and accurately implemented, forming a set of key technologies for controlling the deformation of surrounding rock in a deep high-stress complex condition stope that is safe, economical and feasible.

Description

Technical Field

[0001] The present invention relates to the technical field of surrounding rock deformation control, and particularly to a comprehensive control method for surrounding rock deformation in a three-dimensional stope under deep high-stress complex conditions. Background Technique

[0002] Since the surrounding rock of the deep stope is under high in-situ stress and complex geological environment, its deformation characteristics are quite different from those in the shallow part. The application of the surrounding rock deformation control method and monitoring system in the deep stope is one of the important measures to ensure the safe mining of the deep working face.

[0003] Domestic and foreign experts have carried out some research on the surrounding rock deformation control method and monitoring system in the deep stope. Although it provides theoretical guidance and technical support for the surrounding rock deformation control in the deep stope to a certain extent, there are still some deficiencies. Especially for the dynamic pressure and deformation monitoring system in the stope, the main problems are as follows: when monitoring the mine pressure, it is necessary for people to carry intelligent handheld acquisition instruments, and the monitoring efficiency is not high; only the stress and deformation of the roadway roof are monitored, the used sensors are relatively traditional, the sensor layout is unreasonable, it is greatly affected by the deep mine environment, and the deformation of the two sides and the floor of the roadway is not monitored, and the monitoring data is not comprehensive; only the stress and strain of the surrounding rock of the stope are monitored, and the monitoring data is relatively single; only the bolt stress is monitored, and the bolt automatic pressure regulation is not involved. Summary of the Invention

[0004] The present invention aims to provide a three-dimensional stope dynamic pressure and deformation monitoring system based on LabVIEW and intelligent fiber optic sensors on the basis of selecting a suitable active support for surrounding rock deformation control in the deep stope, combining remote real-time visualization monitoring and prediction of stope dynamic pressure and deformation fracture, and dynamically and accurately implementing control technical measures based on the monitoring data, so as to form a set of key technologies for surrounding rock deformation control in a deep high-stress complex condition stope that is safe, economical and feasible.

[0005] For this reason, the technical solution adopted by the present invention is as follows: a comprehensive control method for surrounding rock deformation in a three-dimensional stope under high-stress complex conditions, including the following steps:

[0006] Step A, active support for surrounding rock deformation control in the deep stope;

[0007] 1) In-situ stress test;

[0008] Original rock stress test sections are set up in both the gob-side entry along the working face and the non-gob-side entry. Select a roadway section with good rock mass integrity. Set the strike of the rock formation as the X direction, the dip as the Y direction, and the direction perpendicular to the XY plane as the Z direction. Drill complete rock samples in six directions: X, Y, Z, X45°Y, Y45°Z, and Z45°X. Calculate using the loads of the characteristic points of the rock acoustic emission effect in these 6 spatial directions to obtain the magnitudes and orientations of the principal stresses at the sampling points, in order to seek the regional in-situ stress variation law;

[0009] Determine the load based on the characteristic points of the acoustic emission effect of each specimen, calculate the stress from the stressed area of the specimen, and the average value of multiple specimens is the stress test value in this direction. Obtain the magnitude and azimuth angle of its principal stress according to the following formula:

[0010] Take a tetrahedral micro-element OABC in the underground rock mass, where OA, OB, and OC coincide with the positive directions of coordinates X, Y, and Z respectively, and its normal direction cosines are l, m, and n. Then the normal stress σ n on the plane ABC can be expressed as: σ n =σ x l 2 +σ y m 2 +σ z n 2 +2τ xy lm+2τ yz mn+2τ zx nl (1)

[0011] It can be expressed in matrix form as: [σ n =[A][σ] (2)

[0012] In the formula, [σ n is the unidirectional normal stress matrix at the kaiser point, [σ] is the measured point stress component matrix, and [A] is the direction cosine product matrix;

[0013] Regard Equation (2) as a system of equations with unknowns l, m, and n, and l, m, and n must satisfy the condition of Equation (3)

[0014] That is: l 2 +m 2 +n 2 =1 (3)

[0015] Then the characteristic equation of Equation (2) can be obtained: σ 3 -I1σ 2 +I2σ-I3=0 (4)

[0016] Among them,

[0017] Substituting the measured unidirectional normal stress values ​​in the six special directions into equation (1), the six stress components can be calculated, namely, σ x , σ y , σ z , τ xy , τ yz , τ zx , substituting into equations (4) and (5), we can obtain the magnitude and direction of the three principal stresses at the point;

[0018] 2) Find the evolution law of the fracture field in the surrounding rock of the mining area;

[0019] Select the mining crack monitoring section at the position of 170-180m ahead of the working face along the goaf and the non-goaf along the goaf, drill holes into the top plate and the two sides of the tunnel on site, use a borehole imaging device to observe the development status of the top plate and the two sides of the cracks, and divide the surrounding rock into elastic zone, strain softening zone, and plastic flow zone;

[0020] Combined with the results of the crack analysis of the rock mass by borehole imaging, the Hawke-Brown criterion and the non-associated flow law are used to find the evolution law of the crack field in the tunnel surrounding rock. The Runge-Kutta method is used for numerical calculation to solve the radius of the strain softening zone and the plastic flow zone, and finally the spatiotemporal evolution law of the deformation and fracture of the tunnel surrounding rock is obtained.

[0021] 3) Perform fault grouting modification;

[0022] When the fault is within the scope of mining and support, if the fault is not properly treated, it will cause failure of the support system and safety hazards, so the fault needs to be modified; in order to study the modification principle of fault fissure coal-rock mass, while trying to improve the integrity of the shallow coal-rock mass, it is necessary to prevent further damage to the coal-rock mass. On the basis of the previous ground stress test, it is necessary to conduct a statistical analysis of the fracture pressure of the coal-rock mass at the test point to determine the fracture pressure of the coal-rock mass;

[0023] According to the fracture pressure of coal rock mass, the fault is modified by grouting, and the surrounding rock modification effect before and after modification is tested by the mining borehole peep system. The modification of fault fissure coal rock mass must ensure the effective diffusion of slurry, effectively fill the shallow cracks of coal rock mass, and penetrate and expand the deep closed and semi-closed cracks to form an effective coal rock slurry consolidation body support network; if the fault is outside the scope of mining and support, grouting treatment is not required;

[0024] 4) Design the pressure relief process;

[0025] During the mining process of deep mines, if surrounding rock stress concentration occurs, it will cause impact hazards. Before the face is mined, regional hydraulic fracturing pressure relief should be implemented, and then at least one of the following local anti-impact measures should be selected in the local area of the mining and excavation space: coal seam borehole pressure relief, coal seam blasting pressure relief, coal seam water injection, roof blasting pre-splitting, roof hydraulic fracturing, floor borehole or blasting pressure relief;

[0026] Based on the actual conditions and the dynamic monitoring results of the dynamic pressure of roadway surrounding rock, select a suitable pressure relief technology, and arrange pressure sensors at the free ends of anchor cables to monitor the force changes of anchor cables near the pressure relief roadway, so as to monitor the evolution process of the stress field around the roadway after the pressure relief technology and test the pressure relief effect;

[0027] 5) Active support technology for controlling the deformation of stope surrounding rock

[0028] Based on the multi-level control concept of "deep pressure relief, shallow strong support, and roadway surface protection", carry out ultra-strong active support of anchor cables + metal mesh + steel strip, including:

[0029] a. Use the combination of anchor cable steel and shallow filling behind the wall to control the shallow deformation of roadway surrounding rock

[0030] When the shallow surrounding rock is relatively broken, the supporting effect of anchor cables cannot be fully exerted. Therefore, it is necessary to install a metal safety net and a steel strip at the position of the anchor cables outside the rock wall, and use Gubangte filling to reinforce the broken coal and rock mass in the shallow part of the surrounding rock, especially the broken coal and rock mass at the anchor cable tray;

[0031] b. Expand the advanced support distance of the working face and improve the advanced support strength

[0032] By monitoring the mining-induced stress passing through the gateway of the working face, in the sensitive section of the mining-induced stress change within the advanced distance of the working face in the gob-side entry and non-gob-side entry, use the gateway end support for advanced support, and the advanced support distance is not less than half of the sensitive section of the mining-induced stress change;

[0033] c. Use high-strength prestressed anchor bolts to improve the bolt support strength; due to the different effects of mining-induced dynamic pressure on the mined side and the non-mined side of the roadway, adopt an asymmetric layout method of anchor bolts on the mined side and the non-mined side, and the vertical spacing of the high-strength anchor bolts on the mined side is greater than the vertical spacing of the high-strength anchor bolts on the non-mined side;

[0034] Step B: Construct a three-dimensional stope dynamic pressure and deformation monitoring system based on LabVIEW and intelligent fiber optic sensors;

[0035] Three-dimensional stope dynamic pressure and deformation monitoring system based on LabVIEW and intelligent fiber optic sensors, including an array of series-connected fiber Bragg grating surrounding rock pressure sensors, fiber Bragg grating embedded strain sensors and fiber Bragg grating temperature sensors. Each series-connected group is then respectively connected in parallel with a fiber Bragg grating displacement sensor, and connected to a fiber Bragg grating signal management host through an optical cable. The fiber Bragg grating signal management host is connected to a fiber Bragg grating sensing network analyzer through a cable, and the fiber Bragg grating sensing network analyzer is connected to a computer equipped with the three-dimensional stope dynamic pressure and deformation monitoring system through a local area network;

[0036] The fiber Bragg grating displacement sensors are installed near the roof, floor and the middle of both sides of the roadway to monitor the displacement of the roof, floor and both sides of the roadway. The fiber Bragg grating surrounding rock pressure sensors, fiber Bragg grating embedded strain sensors and fiber Bragg grating temperature sensors are installed in series in the coal body boreholes in the lower part of the middle of both sides and at the junction of the roof, floor and coal wall. The boreholes in the roof and floor are diagonally distributed in the roadway to monitor the dynamic pressure of the roof and floor during coal mining. And for the non-mining side, one borehole depth is taken, while for the mining side, three different borehole depths are taken at longitudinal intervals. According to the monitoring data of the mining-induced stress in the adjacent working face gateway, the intelligent fiber optic sensors are arranged in the area with increased mining-induced stress outside the advanced support of the gateway, and the spacing between monitoring points is 20 m;

[0037] Step C: Construct a visualization and early warning system for stope dynamic pressure and deformation;

[0038] Step D: Construct a dynamic deformation intelligent monitoring and control system;

[0039] 1) In the two sides and the top of the surrounding rock of the deep high-stress roadway, active support is carried out by using bolt cables. Among them, the roof of the roadway surrounding rock is supported by combining high-strength bolts and prestressed anchor cables, and both the mining side and the non-mining side are supported by high-strength bolts. And the vertical spacing of the high-strength bolts on the mining side is greater than that on the non-mining side;

[0040] 2) On the sensitive section of the mining-induced stress change in front of the stope working face, starting from outside the advanced support section of the working face gateway, a stress monitoring section is arranged every 15 - 25 meters. The fiber Bragg grating stress sensors are embedded in the high-strength bolts in the middle of both sides and the middle of the roof of the roadway, as well as the prestressed anchor cables in the middle of the roof of the roadway to monitor the mining-induced stress. The high-strength bolts in the middle of both sides and the middle of the roof of the roadway, as well as the prestressed anchor cables in the middle of the roof of the roadway are collectively referred to as stress monitoring bolt cables;

[0041] 3) Configure a dynamic pressure regulating mechanism for all stress monitoring bolt cables;

[0042] A hollow jack and a prestress monitoring element for the bolt and cable are installed between the tray of each stress monitoring bolt and cable and the rock wall. The outside of the tray is locked by a nut, and a metal safety net and a steel strip are installed at the position of the rock wall corresponding to the stress monitoring bolt and cable outside the rock wall. All the hollow jacks are respectively connected to the same multi-channel oil source control system through their respective corresponding high-pressure oil pipes. The multi-channel oil source control system is connected to the built-in human-machine interface through a built-in program controller. The prestress monitoring element of the bolt and cable is connected to the prestress monitoring and display element of the bolt and cable.

[0043] 4) Intelligent regulation of roadway dynamic deformation

[0044] The built-in human-machine interface receives the stress signals of the bolts and cables monitored by the fiber Bragg grating stress sensors in real time and dynamically adjusts the prestress of the bolts and cables. By setting the threshold of the increase in mining-induced stress through the built-in program controller, it is judged whether the received data exceeds the threshold. If it exceeds, in the section where the mining-induced stress increases, the prestress of the bolts and cables located in the stress increase section is automatically increased. Through the built-in program controller, the multi-channel oil source control system is driven to supply pressure to the hollow jacks, and the prestress of the bolts and cables in the high stress area is increased by controlling the stroke of the hollow jacks, and axial prestress is directly applied to the bolts and cables without radial torque conversion, so that the applied prestress can be maintained for a long time during the use of the bolts and cables. Increasing the prestress of the bolts and cables can transfer the stress in the high stress area to the adjacent low stress area and transform it into uniform distribution, reducing the local deformation of the surrounding rock under high stress conditions.

[0045] As an optimization of the above solution, in step C, the stope dynamic pressure and deformation visualization and early warning system includes a stope surrounding rock stability determination system and a visualization and early warning system. The stope surrounding rock stability determination system includes a comparison module and a determination module, and the visualization and early warning system includes a visualization module and an early warning module.

[0046] 1) Construct a stope surrounding rock stability determination system

[0047] The comparison module analyzes the displacement deformation and dynamic pressure changes of the two sides and the roof and floor of the roadway by the three-dimensional stope dynamic pressure and deformation monitoring system, establishes a non-linear prediction model for the stability of the stope surrounding rock, and derives the critical criterion for the deformation and instability failure of the roadway. The determination module compares the real-time monitored data with the data derived by the comparison module to judge whether there is a risk of surrounding rock deformation and fracture.

[0048] 2) Construct a visualization and early warning system

[0049] The visualization module uses digital technology to draw dynamic prediction curves and monitoring curves and display them on the screen. The early warning module gives an early warning according to the determination result of the determination module on the surrounding rock deformation and fracture, and uses the dynamic deformation regulation method to regulate the bolt prestress.

[0050] Further preferably, the specification of the high-strength bolt is φ20×2400mm, the spacing between rows of the high-strength bolts on the roof of the roadway surrounding rock is 1200×1000mm, the spacing between rows of the high-strength bolts on the mining side is 800×1000mm, and the spacing between rows of the high-strength bolts on the non-mining side is 1600×1000mm; the specification of the prestressed anchor cable is φ22×6000mm, and the spacing between rows is 1300×2900mm.

[0051] Further preferably, water supply pipes, compressed air pipes, fire prevention and extinguishing pipes, and drainage pipes are installed from top to bottom on the non-mining side, and a water channel is arranged at the bottom of the non-mining side.

[0052] Advantages of the present invention: As the mining depth of the mine continues to increase, the geological conditions of the mine continue to become more complex, and the problem of surrounding rock deformation control becomes increasingly prominent. It is very necessary to actively support the surrounding rock of the deep stope, to monitor and predict the dynamic pressure and deformation of the surrounding rock of the deep stope in real time, and to accurately control the deformation of the surrounding rock of the deep stope. By applying the surrounding rock deformation control method of the stope, the stability of the roadway surrounding rock can be enhanced, and the deformation of the roadway during mining can be reduced; by applying the dynamic pressure and deformation monitoring system of the surrounding rock of the stope, the dynamic pressure and deformation data of the surrounding rock can be monitored in real time, providing a data source for subsequent analysis and processing; by applying the visualization and early warning method of the dynamic pressure and deformation of the surrounding rock of the stope, a large amount of data can be processed, the dynamic pressure and deformation trend of the surrounding rock of the deep stope can be analyzed, the visualization monitoring of the data can be realized, and early warning can be carried out before the occurrence of danger; by applying the dynamic deformation intelligent monitoring system and regulation method, the dynamic pressure change of the surrounding rock of the stope can be intelligently monitored, and the sectional dynamic regulation of the roadway deformation and stress can be realized. Description of the Drawings

[0053] Figure 1 It is a flowchart of the implementation steps of the present invention.

[0054] Figure 2 It is a schematic diagram of the azimuth angle of on-site sampling.

[0055] Figure 3 It is a schematic diagram of a three-dimensional stope dynamic pressure and deformation monitoring system based on LabVIEW and intelligent fiber optic sensors.

[0056] Figure 4 It is a flowchart of a three-dimensional stope dynamic pressure and deformation platform based on LabVIEW.

[0057] Figure 5 It is the layout position of the sensors in the three-dimensional stope dynamic pressure and deformation monitoring system.

[0058] Figure 6 It is a three-dimensional stope dynamic pressure and deformation monitoring system.

[0059] Figure 7It is the working principle diagram of the stope surrounding rock stability determination system.

[0060] Figure 8 It is the working principle diagram of the visualization and early warning system.

[0061] Figure 9 It is the layout position of fiber Bragg grating sensors in the roadway.

[0062] Figure 10 It is the structural schematic diagram of the dynamic pressure regulating bolt.

[0063] Figure 11 It is the intelligent control flow chart of the dynamic deformation of the roadway. Specific implementation mode

[0064] The present invention will be further described below through embodiments in conjunction with the accompanying drawings:

[0065] A comprehensive control method for the deformation of the three-dimensional stope surrounding rock under high-stress complex conditions includes the following steps:

[0066] Step A: Active support for the control of the deformation of the deep stope surrounding rock;

[0067] 1) Original rock stress test;

[0068] Original rock stress test sections are set in both the gob-side entry and the non-gob-side entry of the working face. A roadway section with better rock mass integrity is selected. Let the strike direction of the rock formation be the X direction, the dip direction be the Y direction, and the direction perpendicular to the XY plane be the Z direction.

[0069] As shown by Figure 2 the azimuth of the on-site sampling, intact rock samples are drilled in six directions of X, Y, Z, X45°Y, Y45°Z, and Z45°X. The loads of the characteristic points of the rock acoustic emission effect in these 6 spatial directions are used for calculation to obtain the magnitudes and azimuths of the principal stresses at the sampling points. Since this method has the advantages of simplicity, intuitiveness, and relative economy compared with the traditional stress contact method and hydraulic fracturing, it is convenient for a large number of tests, and this method is adopted to seek the regional in-situ stress change law.

[0070] The load of each specimen is determined according to the characteristic points of the acoustic emission effect of the specimen, and the stress is calculated from the stress area of the specimen. The average value of multiple specimens is the stress test value in this direction, and the magnitude and azimuth angle of its principal stress are obtained according to the following formula:

[0071] Take a tetrahedral microelement OABC in the underground rock mass, where OA, OB, and OC coincide with the positive directions of coordinates X, Y, and Z respectively, and the cosines of its normal directions (i.e., the three principal directions of X, Y, and Z) are l, m, and n. Then the normal stress σ on the plane ABC n can be expressed as:

[0072] σn = σ x l 2 + σ y m 2 + σ z n 2 + 2τ xy lm + 2τ yz mn + 2τ zx nl (1)

[0073] In matrix form, it can be expressed as: [σ n = [A][σ] (2)

[0074] Wherein, [σ n is the unidirectional normal stress matrix at the kaiser point, [σ] is the stress component matrix at the measurement point, and [A] is the direction cosine product matrix.

[0075] Regarding Equation (2) as a system of equations with l, m, and n as unknowns, and l, m, and n must satisfy the condition of Equation (3)

[0076] That is: l 2 + m 2 + n 2 = 1 (3)

[0077] Then the characteristic equation of Equation (2) can be obtained: σ 3 - I1σ 2 + I2σ - I3 = 0 (4)

[0078] Among them,

[0079] Substituting the measured unidirectional normal stress values in 6 special directions into Equation (1), 6 stress components can be calculated, namely σ x , σ y , σ z , τ xy , τ yz , τ zx . Substituting them into Equations (4) and (5), the magnitudes and directions of the 3 principal stresses at this point can be obtained.

[0080] 2) Find the evolution law of the fracture field of the stope surrounding rock;

[0081] Select the mining-induced fracture monitoring section at the position 170 - 180 m ahead of the working face along the gob-side entry and non-gob-side entry. Drill holes in the roof and two sides of the roadway on-site, and use a borehole imager to observe the fracture development state of the roof and two sides. Since in many actual conditions, such as in jointed rock masses, the linear Mohr-Coulomb criterion is not very applicable, and the non-linear Hoek-Brown criterion is more applicable, the non-linear yield criterion is used to study the surrounding rock deformation of the working face, and the surrounding rock is divided into an elastic zone, a strain-softening zone, and a plastic flow zone.

[0082] Combined with the fracture analysis results of the rock mass by borehole imaging, the Hoek-Brown criterion and the non-associated flow rule are used to find the evolution law of the fracture field of the roadway surrounding rock. The parameters of the surrounding rock in the softened area change with the increase of plastic deformation. It is difficult to obtain the stress by the analytical method, so the Runge-Kutta method is used for numerical calculation to solve the radii of the strain-softening area and the plastic flow area, and finally the spatio-temporal evolution law of the deformation and fracture of the roadway surrounding rock is obtained.

[0083] 3) Carry out fault grouting modification;

[0084] When the fault is within the influence range of coal mining and support, if the fault is not properly treated, it will cause the failure of the support system and potential safety hazards. Therefore, it is necessary to transform the fault. In order to study the modification principle of the fault fracture coal-rock mass, while improving the integrity of the shallow coal-rock mass as much as possible and preventing further damage to the coal-rock mass, it is necessary to statistically analyze the fracture pressure of the coal-rock mass at the test points based on the previous in-situ stress test to determine the fracture pressure of the coal-rock mass.

[0085] The fault is grouted and modified according to the fracture pressure of the coal-rock mass, and the modification effect of the surrounding rock before and after modification is inspected through the mine borehole peephole system. The modification of the fault fracture coal-rock mass should not only ensure the effective diffusion of the slurry, effectively fill the shallow fractures of the coal-rock mass, but also penetrate and expand the deep closed and semi-closed fractures to form an effective support network of the coal-rock mass slurry solidified body; if the fault is outside the influence range of coal mining and support, no grouting treatment is required.

[0086] 4) Carry out pressure relief process design;

[0087] If the stress concentration of the surrounding rock occurs during the mining process in deep mines, it will cause impact hazards. Before the coal face is mined, regional hydraulic fracturing pressure relief should be implemented, and then at least one targeted and effective local anti-impact measure such as coal seam borehole pressure relief, coal seam blasting pressure relief, coal seam water injection, roof blasting pre-splitting, roof hydraulic fracturing, floor borehole or blasting pressure relief should be selected in the local mining space.

[0088] Based on the comprehensive actual conditions and the dynamic monitoring results of the dynamic pressure of the roadway surrounding rock, select a suitable pressure relief process, and arrange pressure sensors at the free ends of the bolt and cable to monitor the force changes of the bolt and cable near the pressure relief roadway, so as to monitor the evolution process of the stress field around the roadway after the pressure relief process and inspect the pressure relief effect.

[0089] 5) Active support technology for controlling the deformation of the surrounding rock in the stope

[0090] Based on the multi-level control concept of "deep pressure relief, shallow strong support, and roadway surface protection", carry out ultra-strong active support of bolt + cable + metal mesh + steel strip, including:

[0091] a. Controlling the shallow deformation of roadway surrounding rock by using the shallow filling behind the combined wall of anchor cable steel

[0092] When the shallow surrounding rock is relatively broken, the supporting effect of bolts and anchor cables cannot be fully exerted. Therefore, it is necessary to install a metal safety net and steel strip at the positions of bolts and anchor cables outside the rock wall, and use Gubangte filling to reinforce the shallow broken coal and rock mass of the surrounding rock, especially the broken coal and rock mass at the bolt and anchor cable trays.

[0093] b. Expanding the advanced support distance of the working face and increasing the advanced support strength

[0094] By monitoring the mining-induced stress in the gateway along the working face, in the sensitive sections of the mining-induced stress change within the advanced distance of the working face for the gob-side entry and non-gob-side entry, the advanced support is carried out by using the gateway end support, and the advanced support distance is not less than half of the sensitive section of the mining-induced stress change. The increase in the advanced support distance can significantly reduce the deformation amount and deformation speed of the roadway roof, floor and two sides, and the increase in the advanced support strength can reduce the deformation amount of the roadway surrounding rock.

[0095] c. Using high-strength prestressed bolts to increase the bolt support strength; due to the different influences of mining-induced dynamic pressure on the mined side and the non-mined side of the roadway, the asymmetric layout method of bolts on the mined side and the non-mined side is adopted, and the vertical spacing of the high-strength bolts on the mined side is greater than the vertical spacing of the high-strength bolts on the non-mined side.

[0096] If the yield strength of the used bolts is insufficient, it will often lead to the bolts being pulled off during use, resulting in bolt failure, and thus it is necessary to add bolts or anchor cables, which is neither safe nor economical and also time-consuming. Therefore, the numerical simulation method is used to simulate and calculate the forces of different high-strength prestressed bolts during roadway support, select high-strength prestressed bolts with appropriate yield strength and tensile strength, and apply appropriate prestress, which can greatly increase the prestress during installation and the bolts will not be pulled off, forming an effective active support and reducing the surrounding rock deformation.

[0097] Due to the different influences of mining-induced dynamic pressure on the mined side and the non-mined side of the roadway, considering the support safety and economy, the asymmetric layout method of bolts is adopted, high-strength prestressed bolts are used, different support models are designed, and through numerical simulation calculation, the overall deformation process of the roadway section, the forces of bolts and anchor cables, the deformations of bolts and anchor cables, the deformation of the surrounding rock in the middle of the two sides of the roadway, and the economic benefits in different support models are compared, and the support system with the highest cost performance is selected.

[0098] Step B: Construct a three-dimensional mining-induced dynamic pressure and deformation monitoring system based on LabVIEW and intelligent fiber optic sensors;

[0099] As Figure 3As shown in the figure, a three-dimensional stope dynamic pressure and deformation monitoring system based on LabVIEW and intelligent fiber optic sensors includes an array of series-connected fiber Bragg grating surrounding rock pressure sensors 9, fiber Bragg grating embedded strain sensors 10, and fiber Bragg grating temperature sensors 11. Each series-connected group is then respectively connected in parallel with a fiber Bragg grating displacement sensor 8 and connected to a fiber Bragg grating signal management host 6 through an optical cable 7. The fiber Bragg grating signal management host 6 is connected to a fiber Bragg grating sensing network analyzer 4 through a cable 5, and the fiber Bragg grating sensing network analyzer 4 is connected to a computer 1 carrying the three-dimensional stope dynamic pressure and deformation monitoring system 2 through a local area network 3. The flow chart of the three-dimensional stope dynamic pressure and deformation platform based on LabVIEW is as Figure 4 shown.

[0100] The fiber Bragg grating displacement sensor 8, fiber Bragg grating surrounding rock pressure sensor 9, fiber Bragg grating embedded strain sensor 10, and fiber Bragg grating temperature sensor 11 are used to measure roof separation, surrounding rock deformation, monitor the internal pressure, strain, and temperature of the surrounding rock. Design appropriate sensor positions. The schematic diagram of the sensor positions is as Figure 5 shown. ① is the installation position of the fiber Bragg grating displacement sensor, and ② is the installation positions of the fiber Bragg grating surrounding rock pressure sensor, fiber Bragg grating embedded strain sensor, and fiber Bragg grating temperature sensor. The fiber Bragg grating displacement sensor is installed near the middle of the roadway roof, floor, and two sides to monitor the displacement of the roadway roof, floor, and two sides. The fiber Bragg grating surrounding rock pressure sensor, fiber Bragg grating embedded strain sensor, and fiber Bragg grating temperature sensor are installed in series in the coal body boreholes in the middle and lower part of the two sides and at the junction of the roof, floor, and coal wall. The boreholes in the roof and floor are diagonally distributed in the roadway to monitor the dynamic pressure of the roadway roof and floor during coal mining. The fiber Bragg grating surrounding rock pressure sensor, fiber Bragg grating embedded strain sensor, and fiber Bragg grating temperature sensor installed on the two sides of the roadway are located in the coal body boreholes in the middle and lower part of the roadway. Such an arrangement is to reduce the influence of the boreholes on the displacement sensors in the middle of the roadway, facilitate the on-site layout by workers, and it is beneficial to combine and analyze the data monitored by the displacement sensors by arranging the remaining sensors near the displacement sensors in the middle and lower part of the roadway. Since the mining side of the roadway is greatly affected by mining stress, in order to make the monitoring of the dynamic pressure of the mining side more accurate, a single borehole depth is taken for the non-mining side, and three different borehole depths are taken at intervals along the longitudinal direction for the mining side. During the installation process of the optical cable, a protection device should be used to protect it to prevent damage due to excessive pulling force. According to the monitoring data of the mining stress in the adjacent working face gate roadway, the intelligent fiber optic sensors are arranged in the increased mining stress area outside the advanced support of the gate roadway, and the spacing between the monitoring points is 20 m.

[0101] Mark the length identification inside the fiber Bragg grating roadway and the roadway position at the sensor layout location in the roadway. One is to facilitate the scientific and efficient management of the monitoring data, and the other is to facilitate the maintenance of the sensors by the staff.

[0102] Based on the optimization algorithm of LabVIEW and intelligent fiber Bragg grating sensors, a three-dimensional stope dynamic pressure and deformation monitoring system is established. The three-dimensional stope dynamic pressure and deformation monitoring system is composed of four related subsystems as shown in Figure 6 and consists of: a sensor system, a data acquisition system, a data transmission system, and a three-dimensional stope dynamic pressure and deformation remote monitoring system.

[0103] Data acquisition system: The system first records the analog signal after being transformed by the sensor and amplified by the amplifier, and then records the digital signal after analog-to-digital conversion. The data acquisition work of this system is mainly completed by the fiber Bragg grating sensing network analyzer.

[0104] Data transmission system: It realizes the function of real-time monitoring, transmits the monitoring data to the control room by wired and wireless means, displays it on the computer screen, and finally stores it in the monitoring database.

[0105] Three-dimensional stope dynamic pressure and deformation remote monitoring system: This system combines the characteristics of the monitoring target, and reasonably and effectively stores the stress, strain, and temperature data of the bolt and cable in the management system. This management system can conveniently obtain data from the data measurement system and can be conveniently called by different users, reducing the accumulation of invalid data and ensuring the reliability of the storage of necessary information.

[0106] Step C: Construct a stope dynamic pressure and deformation visualization and early warning system.

[0107] The visualization and early warning system has been applied and can be directly borrowed. In step C, the adopted stope dynamic pressure and deformation visualization and early warning system is improved on the existing visualization and early warning system. Its working principle diagrams are shown in Figure 7 and Figure 8 respectively, and include a stope surrounding rock stability determination system and a visualization and early warning system. The stope surrounding rock stability determination system includes a comparison module and a determination module, and the visualization and early warning system includes a visualization module and an early warning module:

[0108] 1) Construct a stope surrounding rock stability determination system

[0109] The comparison module analyzes the displacement deformation and dynamic pressure changes of the two sides and the roof and floor of the roadway by the three-dimensional stope dynamic pressure and deformation monitoring system, establishes a non-linear prediction model for the stability of the stope surrounding rock, and derives the critical criterion for the deformation and instability failure of the roadway; the determination module compares the real-time monitored data with the data derived by the comparison module to judge whether there is a risk of surrounding rock deformation and fracture.

[0110] 2) Construct a visualization and early warning system

[0111] The visualization module uses digital technology to draw dynamic prediction curves and monitoring curves and display them on the screen; the early warning module gives early warnings according to the determination results of the surrounding rock deformation and fracture by the determination module, and uses the dynamic deformation control method to control the prestress of the bolts.

[0112] Step D: Construct a dynamic deformation intelligent monitoring and control system.

[0113] 1) As Figure 9 shown, active support is carried out on both sides and the top of the surrounding rock of deep high-stress roadways using bolts and cable bolts; among them, the roof of the roadway surrounding rock is supported by combining high-strength bolts and prestressed cable bolts, and both the mined side and the non-mined side are supported by high-strength bolts, and the vertical spacing of the high-strength bolts on the mined side is greater than that of the high-strength bolts on the non-mined side.

[0114] 2) On the sensitive section of the mining-induced stress change in front of the working face of the stope, starting from outside the advanced support section of the working face gateway, a stress monitoring section is arranged every 15 - 25 meters. The fiber Bragg grating stress sensors are buried in the high-strength bolts in the middle of both sides of the roadway, the middle of the roof, and the prestressed cable bolts in the middle of the roadway roof. As Figure 9 shown in ①, the fiber Bragg grating stress sensors are used to monitor the mining-induced stress. The high-strength bolts in the middle of both sides of the roadway, the middle of the roof, and the prestressed cable bolts in the middle of the roadway roof are collectively referred to as stress monitoring bolt and cable bolts.

[0115] 3) Configure dynamic pressure regulating mechanisms for all stress monitoring bolt and cable bolts;

[0116] As Figure 10 shown, a hollow jack 13 and a bolt and cable bolt prestress monitoring element 14 are installed between the tray 12 of each stress monitoring bolt and cable bolt and the rock wall, and the outside of the tray 12 is locked by a nut 15. A metal safety net 16 and a steel strip 17 are installed at the position of the stress monitoring bolt and cable bolt outside the rock wall; all the hollow jacks 13 are respectively connected to the same multi-channel oil source control system 19 through their corresponding high-pressure oil pipes 18. The multi-channel oil source control system 19 is connected to the built-in human-machine interface 21 through the internal program controller 20, and the bolt and cable bolt prestress monitoring element 14 is connected to the bolt and cable bolt prestress monitoring and display element 22.

[0117] 4) Intelligent control of roadway dynamic deformation.

[0118] As Figure 11As shown, the built-in human-machine interface receives in real time the stress signals of the bolt and cable monitored by the fiber Bragg grating stress sensor, and dynamically adjusts the prestress of the bolt and cable; the mining-induced stress increase threshold is set through the internal program controller to judge whether the received data exceeds the threshold. If it exceeds, in the mining-induced stress increase section, the prestress of the bolts and cables located in the stress increase section is automatically increased. Through the internal program controller, the multi-channel oil source control system is driven to supply pressure to the hollow jack, and the prestress of the bolts and cables in the high-stress area is increased by controlling the stroke of the hollow jack, and axial prestress is directly applied to the bolts and cables without radial torque conversion, so that the applied prestress can be maintained for a long time during the use of the bolts and cables; through the automatic pressure regulation function, the stress in the high-stress area can be transferred to the adjacent low-stress area and transformed into uniform distribution, reducing the local deformation of the surrounding rock under the high-stress state.

[0119] Preferably, in combination with Figure 5 、 Figure 9 As shown, the specification of the high-strength bolt is φ20×2400mm, the spacing and row spacing of the high-strength bolts on the roof of the roadway surrounding rock are 1200×1000mm, the spacing and row spacing of the high-strength bolts on the mining side are 800×1000mm, and the spacing and row spacing of the high-strength bolts on the non-mining side are 1600×1000mm; the specification of the prestressed cable is φ22×6000mm, and the spacing and row spacing are 1300×2900mm.

[0120] In addition, water supply, compressed air, fire prevention and drainage pipelines are installed from top to bottom on the non-mining side, and a water ditch is arranged at the bottom of the non-mining side.

Claims

1. A comprehensive control method for the deformation of surrounding rock in a three-dimensional stope under high-stress complex conditions, characterized in that, It includes the following steps: Step A: Active support for controlling the deformation of surrounding rock in deep stope; 1) In-situ stress test; In-situ stress test sections are set up in the gob-side entry and non-gob-side entry of the working face. Select a roadway section with better rock mass integrity. Let the strike of the rock stratum be the X direction, the dip be the Y direction, and the direction perpendicular to the XY plane be the Z direction. Drill complete rock samples in six directions: X, Y, Z, X45°Y, Y45°Z, and Z45°X. Calculate using the loads of the acoustic emission effect characteristic points of the rock in six spatial directions to obtain the magnitude and orientation of the principal stress at the sampling point, so as to seek the regional in-situ stress change law; Determine the load according to the acoustic emission effect characteristic point of each specimen, calculate the stress from the stress area of the specimen, and the average value of multiple specimens is the stress test value in the measured direction. The magnitude and azimuth angle of the principal stress are obtained according to the following formula: Take a tetrahedral microelement OABC in the underground rock mass, where OA, OB, and OC coincide with the positive directions of coordinates X, Y, and Z respectively, and the normal direction cosines are l, m, and n. Then the normal stress σ on the plane ABC n is expressed as: σ n = σ x l 2 + σ y m 2 + σ z n 2 + 2τ xy lm + 2τ yz mn + 2τ zx nl(1) It can be expressed in matrix form as: [σ n = [A][σ](2) Wherein, [σ n is the unidirectional normal stress matrix at the Kaiser point, [σ] is the measured point stress component matrix, and [A] is the direction cosine product matrix; Regarding Equation (2) as a system of equations with unknowns \(l\), \(m\), and \(n\), and \(l\), \(m\), and \(n\) must satisfy the condition of Equation (3), that is: \(l\) 2 + \(m\) 2 + \(n\) 2 = 1 (3) Then the characteristic equation of Equation (2) can be obtained: σ 3 - I1σ 2 + I2σ - I3 = 0 (4) Among them, Substitute the measured unidirectional normal stress values in six special directions into Equation (1) to calculate six stress components, namely σ x 、σ y 、σ z 、τ xy 、τ yz 、τ zx . Substitute them into Equations (4) and (5) to obtain the magnitudes and directions of the three principal stresses at this point; 2) Find the evolution law of the fracture field of the surrounding rock in the stope; Select the mining fracture monitoring section at the position 170 - 180 m ahead of the working face in the gob-side entry and non-gob-side entry of the working face. Drill holes in the roof and two sides of the roadway on-site, and use a borehole imager to peep the fracture development state of the roof and two sides. Divide the surrounding rock into an elastic zone, a strain-softening zone, and a plastic flow zone; Combined with the fracture analysis results of the rock mass by borehole imaging, use the Hoek-Brown criterion and the non-associated flow rule to find the evolution law of the fracture field of the roadway surrounding rock, and use the Runge-Kutta method for numerical calculation to solve the radii of the strain-softening zone and the plastic flow zone, and finally obtain the spatio-temporal evolution law of the deformation and fracture of the roadway surrounding rock; 3) Conduct fault grouting modification; When the fault is within the influence range of mining and support, if the fault is not properly treated, it will cause the failure of the support system and potential safety hazards. Therefore, the fault needs to be reformed; in order to study the modification principle of the fault fracture coal-rock mass, while trying to improve the integrity of the shallow coal-rock mass as much as possible and preventing further damage to the coal-rock mass, it is necessary to statistically analyze the fracture pressure of the coal-rock mass at the test points on the basis of the previous in-situ stress test to determine the fracture pressure of the coal-rock mass; Grout and modify the fault according to the fracture pressure of the coal-rock mass, and use a mine borehole peeping system to inspect the modification effect of the surrounding rock before and after modification. The modification of the fault fracture coal-rock mass should not only ensure the effective diffusion of the grout, effectively fill the shallow fractures of the coal-rock mass, but also penetrate and expand the deep closed and semi-closed fractures to form an effective support network of the coal-rock mass grout consolidation body; if the fault is outside the influence range of mining and support, no grouting treatment is required; 4) Conduct pressure relief process design; If stress concentration of the surrounding rock occurs during the mining process in a deep mine, it will cause impact hazards. Before the working face is mined, regional hydraulic fracturing pressure relief should be implemented, and then at least one local impact prevention measure such as coal seam borehole pressure relief, coal seam blasting pressure relief, coal seam water injection, roof blasting pre-splitting, roof hydraulic fracturing, floor borehole or blasting pressure relief should be selected in the local mining and excavation space; Based on the actual conditions and the dynamic monitoring results of the roadway surrounding rock dynamic pressure, select an appropriate pressure relief technology, and arrange pressure sensors at the free ends of the bolt and cable bolts to monitor the stress changes of the bolt and cable bolts near the pressure relief roadway, so as to monitor the evolution process of the stress field around the roadway after the pressure relief technology and test the pressure relief effect; 5) Active support technology for controlling the deformation of the stope surrounding rock Based on the multi-level control concept of "deep pressure relief, shallow strong support, and roadway surface protection", carry out ultra-strong active support of bolt and cable bolts + metal mesh + steel strip, including: a. Control the shallow deformation of the roadway surrounding rock by using the cable bolt steel combined with shallow filling behind the wall When the shallow surrounding rock is relatively broken, the supporting effect of the bolt and cable bolts cannot be fully exerted. Therefore, it is necessary to install a metal safety net and a steel strip at the position of the bolt and cable bolts outside the rock wall to reinforce the broken coal and rock mass in the shallow part of the surrounding rock and the broken coal and rock mass at the bolt and cable bolt trays with Gubangte filling; b. Expand the advanced support distance of the working face and improve the advanced support strength By monitoring the mining-induced stress passing through the gateways of the working face, in the sensitive sections of the mining-induced stress changes in the gob-side entry and non-gob-side entry within the advanced distance of the working face, use the gateway end support for advanced support, and the advanced support distance is not less than half of the sensitive section of the mining-induced stress change; c. Use high-strength prestressed bolts to improve the bolt support strength; due to the different effects of the mining side and the non-mining side of the roadway on the stope dynamic pressure, adopt an asymmetric layout method of bolts on the mining side and the non-mining side. The vertical spacing of the high-strength bolts on the mining side is greater than the vertical spacing of the high-strength bolts on the non-mining side; Step B: Construct a three-dimensional stope dynamic pressure and deformation monitoring system based on LabVIEW and intelligent fiber optic sensors; The three-dimensional stope dynamic pressure and deformation monitoring system based on LabVIEW and intelligent fiber optic sensors includes an array of series-connected fiber Bragg grating surrounding rock pressure sensors, fiber Bragg grating embedded strain sensors, and fiber Bragg grating temperature sensors. Each series-connected group is then connected in parallel with a fiber Bragg grating displacement sensor, connected to the fiber Bragg grating signal management host through an optical cable, the fiber Bragg grating signal management host is connected to the fiber Bragg grating sensing network analyzer through a cable, and the fiber Bragg grating sensing network analyzer is connected to the computer equipped with the three-dimensional stope dynamic pressure and deformation monitoring system through a local area network; The fiber Bragg grating displacement sensors are installed near the roof, floor, and the middle of the two sides of the roadway to monitor the displacement of the roof, floor, and two sides of the roadway; the fiber Bragg grating surrounding rock pressure sensors, fiber Bragg grating embedded strain sensors, and fiber Bragg grating temperature sensors are installed in series in the coal body boreholes in the middle and lower part of the two sides and at the junction of the roof, floor, and coal wall. The boreholes in the roof and floor are diagonally distributed in the roadway to monitor the dynamic pressure of the roof and floor during mining; and one borehole depth is taken for the non-mining side, and three different borehole depths are taken at intervals along the longitudinal direction for the mining side; according to the monitoring data of the mining-induced stress in the adjacent gateway of the working face, the intelligent fiber optic sensors are arranged in the increased mining-induced stress area outside the advanced support of the gateway, and the spacing between the monitoring points is 20m; Step C: Construct a visualization and early warning system for stope dynamic pressure and deformation; Step D: Construct a dynamic deformation intelligent monitoring and control system; 1) Active support is carried out by using bolts and cable bolts on both sides and the top of the surrounding rock of deep high-stress roadways. Among them, the roof of the surrounding rock of the roadway is supported by combining high-strength bolts and prestressed cable bolts. High-strength bolts are used for support on both the mined side and the unmined side, and the vertical spacing of the high-strength bolts on the mined side is greater than that of the high-strength bolts on the unmined side; 2) On the sensitive section of the mining-induced stress change in front of the working face of the stope, a stress monitoring section is arranged every 15 - 25 meters starting from outside the advanced support section of the working face gateway. Fiber Bragg grating stress sensors are buried in the high-strength bolts in the middle of both sides of the roadway, the middle of the roof, and the prestressed cable bolts in the middle of the roadway roof to monitor the mining-induced stress. The high-strength bolts in the middle of both sides of the roadway, the middle of the roof, and the prestressed cable bolts in the middle of the roadway roof are collectively referred to as stress monitoring bolt and cable bolt; 3) Configure a dynamic pressure regulating mechanism for all stress monitoring bolt and cable bolts; Install a hollow jack and a bolt and cable bolt prestress monitoring element between the tray of each stress monitoring bolt and cable bolt and the rock wall, and the outside of the tray is locked by a nut. A metal safety net and a steel strip are installed at the position of the stress monitoring bolt and cable bolt outside the rock wall; all hollow jacks are respectively connected to the same multi-channel oil source control system through their respective high-pressure oil pipes. The multi-channel oil source control system is connected to the built-in human-machine interface through the internal program controller, and the bolt and cable bolt prestress monitoring element is connected to the bolt and cable bolt prestress monitoring display element; 4) Intelligent regulation of roadway dynamic deformation; The built-in human-machine interface receives the stress signals of the bolt and cable bolts monitored by the Fiber Bragg grating stress sensor in real time and dynamically adjusts the prestress of the bolt and cable bolts; set the mining-induced stress increase threshold through the internal program controller, and judge whether the received data exceeds the threshold. If it exceeds, in the mining-induced stress increase section, automatically increase the prestress of the bolt and cable bolts located in the stress increase section. Through the internal program controller, drive the multi-channel oil source control system to supply pressure to the hollow jack, and control the stroke of the hollow jack to increase the prestress of the bolt and cable bolts in the high-stress area, directly applying axial prestress to the bolt and cable bolts without going through radial torque conversion, so that the applied prestress can be maintained for a long time during the use of the bolt and cable bolts; increasing the prestress of the bolt and cable bolts transfers the stress in the high-stress area to the adjacent low-stress area and transforms it into uniform distribution, reducing the local deformation of the surrounding rock under high-stress conditions.

2. The comprehensive control method for surrounding rock deformation in a three-dimensional stope under high stress and complex conditions according to claim 1 is characterized in that: In step C, the stope dynamic pressure and deformation visualization and early warning system includes a stope surrounding rock stability determination system and a visualization and early warning system. The stope surrounding rock stability determination system includes a comparison module and a determination module, and the visualization and early warning system includes a visualization module and an early warning module; 1) Construct a stope surrounding rock stability determination system The comparison module analyzes the displacement deformation and dynamic pressure changes of both sides and the roof and floor of the roadway by the three-dimensional stope dynamic pressure and deformation monitoring system, establishes a non-linear prediction model of stope surrounding rock stability, and derives the critical criterion for roadway deformation instability and failure; the determination module compares the real-time monitored data with the data derived by the comparison module to judge whether there is a risk of surrounding rock deformation and fracture; 2) Construct a visualization and early warning system The visualization module uses digital technology to draw dynamic prediction curves and monitoring curves and display them on the screen; The early warning module gives early warnings according to the determination results of the surrounding rock deformation and fracture by the determination module, and adjusts the prestress of the bolt using the dynamic deformation control method.

3. The comprehensive control method for surrounding rock deformation in a three-dimensional stope under high stress and complex conditions according to claim 1 is characterized in that: The specifications of the high-strength bolts are φ20×2400mm, the spacing and row spacing of the high-strength bolts on the roof of the roadway surrounding rock are 1200×1000mm, the spacing and row spacing of the high-strength bolts on the mining side are 800×1000mm, and the spacing and row spacing of the high-strength bolts on the non-mining side are 1600×1000mm; the specifications of the prestressed anchor cables are φ22×6000mm, and the spacing and row spacing are 1300×2900mm.

4. The comprehensive control method for surrounding rock deformation in a three-dimensional stope under high stress and complex conditions according to claim 1 is characterized in that: On the non-mining side, water supply, compressed air, fire prevention and drainage pipelines are installed from top to bottom, and a water ditch is set at the bottom of the non-mining side.

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