Pressure relief and shock absorption method for deep high-stress key pillar

Abstract

The invention discloses a pressure relief and shock absorption method for a deep high-stress key pillar. (a) a top plate is arranged at the top of the ore pillar, four inclined kerfs are alternately arranged in a top plate area around the ore pillar, and the kerfs are symmetrically arranged in a cross shape; (b) eight anchor rod drill holes perpendicular to the top plate are formed in the interval area between the adjacent kerfs and the periphery of the ore pillar, perpendicular anchor rods are arranged in the anchor rod drill holes, and an orthogonal supporting network formed by the perpendicular anchor rods is formed; and (c) preferentially releasing the bending energy of the roof through the kerf, reducing the vertical load of the ore pillar, and meanwhile, forming a pressure arch effect by applying the prestress of the vertical anchor rod, thereby realizing space-time coupling support of the kerf and the anchor rod, and inhibiting roof separation and dynamic disturbance. The invention has the characteristics of excellent stress transfer, strong vibration suppression and excellent overall column stability.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure relief and shock absorption of ore pillars 1 in mine mining, and specifically relates to a method for pressure relief and shock absorption of key ore pillars under high stress in deep mines. Background Technique

[0002] During the mining process of deep high-stress rock masses, the key ore pillars 1 play an important role in supporting the mine structure and ensuring mining safety. They are long-term exposed to high-stress environments and are extremely prone to instability and failure, which in turn threatens the stability of the entire mine structure and the safety of operating personnel. Therefore, protecting the ore pillars from damage is of crucial significance. Traditional methods for treating ore pillars 1 mostly involve pre-cracking or grouting reinforcement (patent numbers: CN117072167B, CN111004008A). Only by reflecting stress waves through pre-cracking, the self-bearing capacity of the ore pillars cannot be improved, and in the long term, it may fail due to rock mass fatigue, or only rely on grouting reinforcement without solving the source of high stress in the deep part (such as roof pressure), and it may still be affected by continuous loads after reinforcement.

[0003] In summary, traditional pressure relief and reinforcement methods, although they can relieve the stress condition of the ore pillars to a certain extent, have limited effects and large construction difficulties, and are difficult to fully meet the high safety requirements for deep hard rock mining. Summary of the Invention

[0004] In order to overcome the above technical problems, the purpose of the present invention is to provide a method for pressure relief and shock absorption of key ore pillars under high stress in deep mines, which has the characteristics of excellent stress transfer, strong vibration suppression, and good overall pillar stability.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0006] A method for pressure relief and shock absorption of key ore pillars under high stress in deep mines, including the following steps;

[0007] (a) Slit 3 setting: A roof 2 is set on the top of the ore pillar 1, and four inclined slits 3 are alternately arranged in the roof 2 area around the ore pillar 1, and the slits 3 are arranged in a cross-symmetric manner;

[0008] (b) Construction of a vertical anchoring system:

[0009] A total of eight bolt holes perpendicular to the roof 2 are set in the interval areas between adjacent slits 3 and around the ore pillar 1, and vertical bolts are set in the bolt holes to form an orthogonal support network composed of vertical bolts;

[0010] (c) Cooperative support mechanism:

[0011] The bending energy of the roof slab 2 is preferentially released through the slits 3, reducing the vertical load on the ore pillar 1. Meanwhile, the prestress of the vertical bolts is applied to form a pressure arch effect, realizing the spatio-temporal coupling support of the slits 3 and the bolts, and suppressing the separation and dynamic disturbance of the roof slab 2.

[0012] In the step (a), the included angle between the slit 3 and the horizontal surface of the roof slab 2 is 40° - 50°, the depth of the slit 3 is 1 / 3 - 1 / 2 of the thickness of the roof slab 2, and the spacing between adjacent slits 3 is 1 / 4 - 1 / 3 of the side length of the ore pillar 1; the slit 3 is an arc structure, and four arc structures form a circular ring structure. In the step (b), the vertical bolts are divided into bolts 4 inside the slits and bolts 5 outside the slits. There are four bolts 4 inside the slits, which are arranged in the interval area between adjacent slits 3, and the bolts 5 outside the slits are arranged outside the slits 3.

[0013] The construction direction of the inclined slit 3 is perpendicular to the direction of the maximum principal stress of the ore body. The width of the slit 3 is controlled to be 5 - 8 cm, and the end of the slit 3 extends to the junction of the unstable rock stratum and the stable bedrock of the roof slab 2, precisely cutting off the stress transfer of the unstable rock stratum and preventing the crack from spreading to the stable bedrock, maintaining the overall stability of the roof slab 2.

[0014] The aperture of the bolt hole is 28 - 32 mm, the length of the anchorage section is not less than 1.5 m, and the full-length anchorage is carried out by using high-strength resin cartridges. The bolt is perpendicular to the axis of the ore pillar 1.

[0015] The vertical bolt adopts a left-handed non-ribbed threaded steel bolt with a yield strength ≥ 600 MPa, and is used in combination with a fast-setting resin cartridge. The prestress of the bolt is applied to 60% - 70% of the yield strength.

[0016] By controlling the depth of the slit 3 within the range of 1 / 3 to 1 / 2 of the thickness of the roof slab 2, a double-layer structure system with clear functional partitions is constructed. The double-layer structure system is divided into a shallow slit area and a deep stable area;

[0017] In the shallow slit area with a depth less than 0.3 times the thickness of the roof slab 2, the rock stratum is allowed to produce controllable slip along the surface of the slit 3, and 60% - 70% of the bending deformation energy in the total energy storage of the roof slab 2 can be released; while the deep stable area maintains the continuity of the rock stratum and forms a stable self-supporting arch structure by using its residual strength exceeding 30 MPa.

[0018] The method is applicable to the key ore pillar 1 in a metal mine with a buried depth exceeding 800 m. The size of the ore pillar 1 satisfies the width / height ratio ≥ 0.5, and the uniaxial compressive strength of the roof slab 2 rock stratum is not greater than 60 MPa.

[0019] The spatio-temporal coupling relationship between the slit 3 and the vertical bolt is as follows:

[0020] First, cut the slot 3 to 80% ± 5% of the design depth, then install vertical anchor bolts and apply prestress, and finally complete the remaining cutting depth of the slot 3. First, the initial cutting of the slot 3 releases part of the stress, providing a stable force application environment for the prestress of the anchor bolts. Then, the anchor bolts promptly form a pressure arch effect to restrain the secondary disturbance caused by the subsequent construction of the slot 3. Finally, a dynamic balance of "stress release - active support" is achieved, avoiding the sudden collapse of the roof 2 caused by one-time cutting of the slot 3.

[0021] The spatial layout of the orthogonal support network needs to meet the following conditions:

[0022] The vertical anchor bolts are evenly distributed around the ore pillar 1 and in the interval area of the slot 3, with a spacing of 1 / 6 - 1 / 5 of the side length of the ore pillar 1. The projection of the axis of the anchor bolts covers more than 90% of the cross-sectional area of the ore pillar 1. Ensure that the support force evenly covers the periphery of the ore pillar 1, forming a continuous pressure arch structure to inhibit local stress concentration. Through the high-density anchor bolt network, enhance the collaborative deformation ability of the ore pillar 1 and the roof 2, effectively resist dynamic disturbances, and improve the overall stability.

[0023] The beneficial effects of the present invention:

[0024] (1) Stress optimization: Through ABAQUS numerical simulation, it shows that under specific geological conditions, this method can reduce the maximum principal stress inside the ore pillar 1 by about 30% - 45%, and the stress concentration coefficient drops from 2.5 to about 1.8.

[0025] (2) Vibration control: The on-site monitoring data shows that through the combined action of the pressure relief of the slot 3 in step (a) and the collaborative support mechanism in step (c), this method realizes the hierarchical release and dynamic constraint of energy, thus effectively reducing the dynamic vibration frequency around the key ore pillar 1 by more than 50% and making the vibration energy attenuation amplitude reach 50% - 60%.

[0026] (3) Stability improvement: The numerical simulation and on-site test results show that through the rigid support of the vertical anchoring system in step (b) and the stress optimization collaborative action of the collaborative support mechanism in step (c), this method constructs an integrated structure system of "pressure relief - support", significantly reducing the roof separation by about 70% - 85% and greatly improving the overall stability coefficient of the ore pillar 1 by 40% - 60%.

[0027] (4) Economic benefits: According to the estimation of the actual application situation in the mine, this method can extend the service life of the mine by about 3 - 5 years and significantly reduce the economic losses caused by production stoppage accidents due to the instability of the ore pillar 1.

[0028] In summary, the method for relieving pressure and reducing shock of the key ore pillar 1 in deep hard rock proposed by the present invention has significant beneficial effects. It can not only improve the stability and mining safety of the ore pillar 1, but also extend the service life of the mine, promote the sustainable development of the mine, and has wide applicability. These beneficial effects make the present invention have important application value and popularization prospects in the field of mine mining technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of slotting and anchoring of the present invention.

[0030] Figure 2 It is a finite element numerical simulation model diagram of slotting and anchoring of the present invention.

[0031] Figure 3 It is a force analysis diagram of the ore pillar in the finite element numerical simulation of the present invention.

[0032] Figure 4 It is a displacement analysis diagram of the ore pillar in the finite element numerical simulation of the present invention.

[0033] Figure 5 It is a force analysis diagram of the roof point layout of the present invention.

[0034] Figure 6 It is a force analysis diagram of the ore pillar point layout of the present invention.

[0035] Figure 7 It is a force analysis diagram of the bolt in the finite element numerical simulation of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0036] The present invention will be further described in detail below with reference to the drawings.

[0037] A method for relieving pressure and reducing shock of a key ore pillar under high stress in deep mines is realized through the following steps:

[0038] I. Slotting-anchoring collaborative support mechanism

[0039] 1. Principle of stress redirection:

[0040] (1) Principle of stress redirection: Based on the Griffith strength theory, a weak structural plane is artificially constructed in the roof 2 rock stratum by prefabricating inclined slots 3 at a specific angle (the typical angle is 45°). This design causes a significant stress concentration effect at the tip of the slot 3, thereby realizing the active regulation of the original rock stress field.

[0041] Specifically manifested as: in terms of vertical stress unloading, the stress component in the vertical direction of the slot 3 surface transfers to both sides, forming a pressure relief zone with a width about 1.5 to 2 times the length of the slot 3; in terms of horizontal stress release, the tectonic stress is effectively dissipated through rock stratum dislocation, and microseismic monitoring data shows that the vibration energy density in the slot 3 area can be reduced by 50% to 60%.

[0042] (2) Energy dissipation system: Adopting the gradient design concept, by controlling the depth of the slit 3 within the range of 1 / 3 to 1 / 2 of the thickness of the roof 2, a double-layer structure system with clear functional partitions is constructed.

[0043] The double-layer structure system is divided into a shallow slit area and a deep stable area;

[0044] Among them, in the shallow slit area where the depth is less than 0.3 times the thickness of the roof 2, the rock formation is allowed to produce controllable slip along the surface of the slit 3, and 60% to 70% of the bending deformation energy in the total energy storage of the roof 2 can be released; while the deep stable area maintains the continuity of the rock formation and forms a stable self-supporting arch structure by using its residual strength exceeding 30 MPa.

[0045] (3) In terms of optimizing engineering parameters, a systematic design criterion is established: First, the angle of the slit 3 should be controlled within the range of 40° to 50° and maintain a specific angle with the direction of the maximum principal stress to ensure the optimization of the energy release path; Second, the width of the slit 3 is precisely controlled within 5 to 8 cm by using the diamond chain saw cutting process to achieve the best balance between construction efficiency and rock mass damage control; Finally, the spacing of the slit 3 is designed according to 1 / 4 to 1 / 3 of the side length of the ore pillar 1 to effectively prevent the formation of a dangerous isolated rock mass structure in the roof 2 rock formation.

[0046] 2. Anchoring support mechanism

[0047] (1) Compression arch formation mechanism:

[0048] By applying a prestress of 300 to 350 kN through vertical bolts, using the bonding effect between the anchor body and the rock mass, a compression arch structure with load-bearing capacity is formed in the roof 2 rock formation. Its mechanical model can be simplified as a pressure arch under a uniformly distributed load. According to the Prandtl theory, the height h p of the pressure arch is calculated by B / 2f (where B represents the width of the ore pillar 1 and f is the Prandtl coefficient), and a relationship model of bolt spacing - arch height - stability coefficient is established. Finally, numerical simulation verification shows that when the bolt spacing does not exceed 1 / 5 of the side length of the ore pillar 1, the formed pressure arch can completely cover the height of the ore pillar 1 and effectively shield the load action in the vertical direction.

[0049] (2) Optimization design of the support network:

[0050] In terms of material selection, high-strength deformed steel bars with a yield strength not less than 600 MPa are used to meet the requirements of the deep high-stress environment. The anchoring parameters are designed as follows: the anchoring section length is 1.5 m to ensure penetration into the stable rock formation; the free section length is 0.5 m to provide a necessary buffer space for the deformation of the roof 2. At the same time, a double-speed resin cartridge system combining ultra-fast setting and fast setting is adopted to ensure that the anchoring force of a single bolt reaches more than 200 kN.

[0051] (3) Prestressing application strategy:

[0052] Adopt the step-by-step tensioning process. The initial anchoring torque is controlled at 300 N·m (corresponding to a prestress of 100 kN), and the final anchoring torque is increased to 500 N·m (corresponding to a prestress of 300 kN). In terms of time effect control, based on the creep characteristics of the rock mass, the installation of rock bolts is selected within the 24-hour golden window period 80% after the completion of the slot 3 project. At this time, the rock mass is in a quasi-stable state, which is most conducive to the effectiveness of the anchoring system.

[0053] 3. Synergy mechanism

[0054] The analysis of the space-time coupling effect shows that there is an optimal synergy time window of 24 to 48 hours between the construction of slot 3 and the rock bolt support. If the support project is implemented too early and the anchoring is carried out before the completion of slot 3, it will limit the necessary deformation of the rock mass, thus significantly reducing the pressure relief effect; on the contrary, if the support is implemented too late and the anchoring is carried out after the rock mass has undergone irreversible deformation, it will cause the support system to bear excessive load pressure.

[0055] Based on the principle of energy balance, a quantitative relationship model between the pressure relief energy of slot 3 and the support energy of rock bolts is established.

[0056]

[0057]

[0058] In the formula: σ max is the maximum principal stress, V 卸压 is the pressure relief volume, θ is the angle of slot 3, P i is the prestress of the i-th rock bolt, and ΔL i is the elongation of the rock bolt.

[0059] In terms of enhancing the synergy efficiency, it is mainly reflected in the following two dimensions:

[0060] (1) In terms of stress synergy, the slot 3 project can reduce the vertical stress by 20% to 30%. At the same time, the rock bolt system effectively bears the horizontal stress increment, optimizing the total stress concentration coefficient from the initial 2.5 to 1.5 to 1.8;

[0061] (2) In terms of deformation synergy, the slot 3 structure allows a controllable deformation of no more than 5 mm per day, while the rock bolt system effectively restricts the separation displacement, increasing the integrity coefficient of the roof 2 by 30% to 45%.

[0062] II. Optimization of key technical parameters

[0063] The optimization of key parameters needs to follow the three principles of "geological adaptation, mechanical balance, and dynamic feedback":

[0064] (1) Geological adaptation: The parameters need to match the characteristics of deep rock masses (such as uniaxial compressive strength > 40 MPa), the distribution of in-situ stress fields (lateral pressure coefficient λ = 0.8 - 1.2), and the geometric characteristics of ore pillar 1 (width-to-height ratio > 0.5).

[0065] (2) Mechanical equilibrium: Establish a mechanical model of the support system through numerical simulation with ABAQUS to ensure the dynamic balance between the pressure relief energy of the slotted seam 3 and the support energy of the bolt.

[0066] (3) Dynamic feedback: Based on on-site monitoring data (displacement, stress, microseismicity), use the Bayesian optimization algorithm to dynamically adjust the parameters. The specific key parameter selections are shown in Table 1.

[0067] Table 1 Optimization of key technical parameters

[0068]

[0069] This embodiment aims to simulate the stress state of the key ore pillar 1 during the deep hard rock mining process through the ABAQUS finite element analysis software and verify the effectiveness of the proposed pressure relief and shock absorption method. As a powerful numerical simulation tool, ABAQUS can accurately simulate the stress conditions of ore pillar 1 under complex geological structures and mining conditions, providing a scientific decision-making basis for mine mining.

[0070] As Figure 1 shown, it is a schematic diagram of the anchoring of the slotted seam in the deep rock mass, showing the relative positional relationship between the ore pillar 1, the roof 2, the slotted seam 3, and the bolts. The left side is the front view of the anchoring of the slotted seam 3 in the ore pillar 1, and the right side is the cross-sectional view of the ore pillar 1. In the figure, 1 is the ore pillar, 2 is the roof, 3 is the slotted seam, 4 is the bolt inside the slotted seam, 5 is the bolt outside the slotted seam. According to on-site investigation and planning, the present invention adopts an inner-to-outer diameter ratio of the slotted seam 3 of 1.6:2.2 - 1.8:2.5. While ensuring a rock mass swelling deformation space of more than 15%, the radius of the plastic zone is controlled within 1.2 times the depth of the slotted seam 3, effectively protecting the stable bedrock. The angle of the slotted seam 3 is preferably 40° - 50° (the best is 45° ± 5°), and this design increases the shear stress transfer efficiency by 20% - 25%. The supporting bolts with a length of 1.0 - 1.2 m (protruding 0.1 - 0.2 m from the surface of the slotted seam 3) are matched with an opening depth of 0.9 - 1.1 m, which not only ensures an uplift force of more than 150 kN but also reduces the stress concentration coefficient by 0.3 - 0.5 through the stress buffer step, finally constructing a safe and efficient integrated pressure relief - support system.

[0071] As Figure 2 shown, it is the ABAQUS finite element numerical simulation geometric model diagram of the slotted seam anchoring of the present invention, showing the geometric model, the definition of material properties, and the setting of boundary conditions. The specific steps for establishing the model are as follows:

[0072] (1) Establish a geometric model

[0073] First, according to the actual geological conditions and mining design of deep hard rock mines, using the modeling function of ABAQUS, a geometric model of the key ore pillar 1 and the surrounding rock mass is established. The model should accurately reflect the shape and size of ore pillar 1 and the distribution characteristics of the surrounding rock mass. The top and bottom plates have the same size, with a length and width of 10.5 m and a thickness of 2 m. The radius of ore pillar 1 is 1.5 m and the height is 5 m.

[0074] (2) Define material properties

[0075] According to the mechanical properties and experimental results of deep hard rock, accurate material properties are defined for ore pillar 1 and the rock mass in the model. Take the elastic modulus E as 54.77 GPa, the Poisson's ratio as 0.18, and the density ρ = 2820 Kg / m 3 , the cohesion is 28.16 MPa, and the internal friction angle φ = 63.238°.

[0076] (3) Set boundary conditions and loads

[0077] According to the actual situation of mine exploitation, reasonable boundary conditions and loads are set for the model. To reflect the interaction between ore pillar 1 and the surrounding rock mass, the surrounding rock pressure is applied to the top and bottom plates of the model; to reflect the influence of ore pillar 1 on ore seismicity, earthquake and the cyclic disturbance of the surrounding stope operation, cyclic loads are applied in the horizontal direction to fully simulate its actual environment.

[0078] (4) Apply the pressure relief and shock absorption method

[0079] Apply the pressure relief and shock absorption method proposed by the present invention in the model, that is, preset the position of the cut seam 3 on the key ore pillar 1, and form the cut seam 3 by cutting. The ratio of the inner and outer circles of the cut seam 3 is 1.71:2.4, and the angle of the cut seam 3 is 45°; at the same time, install bolts near the cut seam 3 or at other key positions of the key ore pillar 1 for reinforcement treatment.

[0080] Based on the running function of ABAQUS, numerical simulation is carried out on the model. During the simulation process, the stress state, displacement and deformation of ore pillar 1 and the stress of the bolts should be closely monitored. After the simulation is completed, the simulation results are analyzed in detail to evaluate the effectiveness of the pressure relief and shock absorption method.

[0081] As Figure 3 shown, it is the analysis diagram of the stress state of ore pillar 1 in the finite element numerical simulation of the present invention. The simulation results visually show the stress situation of the key ore pillar 1 during the mining process. Figure 3 Figures 3a and 3b respectively show the stress states of ore pillar 1 under stable load and cyclic load, and the two are basically the same. Figure 3 Figures 3c and 3d respectively present the stress states of ore pillar 1 after the cut seam 3 under stable load and cyclic load, showing that the stress on ore pillar 1 is significantly reduced. Figure 3Figures e and 3f show the stress states of ore pillar 1 under stable load and cyclic load after slotting 3 and anchoring. After applying the pressure relief and shock absorption method, the internal stress distribution of ore pillar 1 becomes more uniform, and the degree of stress concentration is significantly reduced. This indicates that the pressure relief and shock absorption method can effectively relieve the stress on ore pillar 1 and reduce the risk of failure.

[0082] As Figure 4 shown, it is the finite element displacement analysis diagram of ore pillar 1 of the present invention, which intuitively shows the displacement state of the key ore pillar 1 during the mining process. Figure 4 Figures a and 4b respectively present the displacement changes of ore pillar 1 under stable load and cyclic load, and the two are consistent. Figure 4 Figures c and 4d show that after slotting 3 in ore pillar 1, the displacement under stable load and cyclic load is significantly reduced. Figure 4 Figures e and 4f show the displacement changes of ore pillar 1 after slotting 3 and anchoring under the corresponding loads. The simulation results show that after applying the pressure relief and shock absorption method, the displacement deformation of the key ore pillar 1 is significantly reduced. The method of the present invention can reduce the stress concentration degree inside ore pillar 1 by 30% and the displacement deformation by 25%, significantly improving the overall stability of ore pillar 1.

[0083] As Figure 5 shown, this figure intuitively shows the stress analysis results of the layout points of the roof 2 in the present invention. To study the stress change characteristics of the roof 2 in the original state, slotting 3 state and anchoring state, the random layout point method is used to monitor the stress change, and the data is plotted into a curve graph. The curve graph clearly reflects the stress change conditions of the roof 2 in the three states at different time points. The specific numerical analysis is as follows:

[0084] Original state: Within the monitoring time range, the average stress value of the roof 2 is 8.5 MPa, the stress fluctuation range is relatively large, and the maximum stress value reaches 9.3 MPa.

[0085] Slotting 3 state: After the slotting 3 treatment, the stress level of the roof 2 drops significantly, the average stress value drops to 3.7 MPa, a decrease of 65.4% compared with the original state. The maximum stress value also correspondingly decreases to 4.2 MPa.

[0086] Anchoring state: After the anchoring treatment on the basis of slotting 3, the stress of the roof 2 is further reduced. The average stress value is only 3.3 MPa, a decrease of 61.1% compared with the original state and a decrease of 10.3% compared with the slotting 3 state. The maximum stress value drops to 4.1 MPa.

[0087] This comparison result intuitively shows the significant effect of slotting 3 and anchoring treatment in reducing the stress of the roof 2. Especially in the anchoring state, the stress state of the roof 2 is effectively controlled, proving the effectiveness of the present invention in the pressure relief and shock absorption of the roof 2.

[0088] As Figure 6As shown in the figure, the figure shows the analysis results of the stress distribution of the ore pillar 1 in the present invention. To intuitively understand the stress distribution of the ore pillar 1 in the original state, the state of the cut seam 3, and the anchored state, the random point distribution technology is adopted. Multiple points are selected on the surface of the ore pillar 1 for mechanical loading simulation, and the time-stress curve is drawn. The specific numerical analysis is as follows:

[0089] Original state: In the original state of the ore pillar 1, the internal stress distribution is uneven, the average stress value is 14.2 MPa, and the maximum stress value reaches 18.5 MPa.

[0090] State of the cut seam 3: After the treatment of the cut seam 3, the stress level of the ore pillar 1 decreases, the average stress value drops to 9.8 MPa, a decrease of 30.9% compared with the original state. The maximum stress value also decreases to 15.3 MPa.

[0091] Anchored state: After the anchoring treatment on the basis of the cut seam 3, the stress level of the ore pillar 1 decreases significantly. The average stress value is only 9.5 MPa, a decrease of 33.1% compared with the original state, and also a decrease of 3% compared with the state of the cut seam 3. The maximum stress value drops to 12.6 MPa.

[0092] This result shows that through the cut seam 3 and the anchoring treatment, the present invention effectively reduces the stress level of the ore pillar 1 and improves the stability of the ore pillar 1. This is of great significance for extending the service life of the ore pillar 1 and ensuring the safe production of the mine.

[0093] As Figure 7 shown, through the analysis of the stress condition of the anchor bolt in the present invention, it is found that the anchor bolt plays a significant role in pressure relief and shock absorption. Specifically, within the cut seam 3, the stress on the 4 anchor bolts is small, and the average stress value is 130 kPa, only 50% of the average stress value of the anchor bolt 5 outside the cut seam; while outside the cut seam 3, the other 4 anchor bolts bear greater stress, and the average stress value reaches 260 kPa. This stress difference enables the anchor bolts to interact with each other, effectively dispersing the internal stress of the ore pillar 1 and reducing the burden on the ore pillar 1. Further analysis shows that the stress dispersion effect of the anchor bolt plays a key role in enhancing the stability of the ore pillar 1. By comparing the ore pillar 1 with and without anchor bolt support, it is found that the anchor bolt support improves the overall stability of the ore pillar 1 by 30%. Specifically, through its tensile strength and yield strength, the anchor bolt significantly enhances the bearing capacity of the ore pillar 1 and prevents the failure of the ore pillar 1 caused by excessive stress.

[0094] In this embodiment, the stress state of the key ore pillar 1 during the deep hard rock mining process was successfully simulated using the ABAQUS finite element analysis software, and the effectiveness of the proposed pressure relief and shock absorption method was verified. The simulation results show that this method can significantly reduce the stress concentration degree inside the ore pillar 1, reduce the displacement deformation amount, and improve the overall stability of the ore pillar 1. Therefore, this method has broad application prospects and popularization value in deep hard rock mining. At the same time, this embodiment also provides a scientific decision-making basis for mine mining, which helps to achieve safe and efficient mining of the mine.

[0095] The present invention combines slot cutting 3 for pressure relief and bolt reinforcement, which not only reduces the stress on the ore pillar 1 but also improves its anti-deformation ability, forming a more durable protection mechanism. Protecting the ore pillar 1 is not only crucial for the smooth progress of mine production but also directly related to the life safety of operating personnel and the sustainable development of the environment. This comprehensive technical route provides an innovative solution to the problem of protecting the ore pillar 1 in deep mine mining.

Claims

1. A method for pressure relief and shock absorption of key pillars in deep high-stress areas, characterized in that, It includes the following steps; (a) A roof slab (2) is set at the top of the ore pillar (1), and four inclined cut slots (3) are alternately arranged in the area of the roof slab (2) around the ore pillar (1) in a cross-symmetrical layout; (b) A total of eight bolt holes perpendicular to the roof slab (2) are set in the interval areas between adjacent cut slots (3) and around the ore pillar (1), and vertical bolts are set in the bolt holes to form an orthogonal support network composed of vertical bolts; (c) The bending energy of the roof slab (2) is preferentially released through the cut slots (3) to reduce the vertical load of the ore pillar (1). At the same time, the pressure arch effect is formed by applying the prestress of the vertical bolts, realizing the time-space coupling support of the cut slots (3) and the bolts, and suppressing the separation layer and dynamic disturbance of the roof slab (2).

2. A method for relieving pressure and reducing shock in key deep high-stress ore pillars according to claim 1, characterized in that In the step (a), the included angle between the cut slot (3) and the horizontal surface of the roof slab (2) is 40° - 50°, the depth of the cut slot (3) is 1 / 3 - 1 / 2 of the thickness of the roof slab (2), and the distance between adjacent cut slots (3) is 1 / 4 - 1 / 3 of the side length of the ore pillar (1); the cut slot (3) is an arc structure, and four arc structures form a circular ring structure.

3. A method for relieving pressure and reducing vibration of a key pillar in deep high-stress areas according to claim 1, characterized in that In the step (b), the vertical bolts are divided into bolts inside the cut slots (4) and bolts outside the cut slots (5). There are four bolts inside the cut slots (4), which are set in the interval areas between adjacent cut slots (3), and the bolts outside the cut slots (5) are set outside the cut slots (3).

4. A method for pressure relief and shock absorption of key pillars in deep high-stress areas according to claim 1, characterized in that, The construction direction of the inclined cut slot (3) is perpendicular to the direction of the maximum principal stress of the ore body. The width of the cut slot (3) is controlled to be 5 - 8 cm, and the end of the cut slot (3) extends to the junction of the unstable rock stratum and the stable bedrock of the roof slab (2), precisely cutting off the stress transfer of the unstable rock stratum and preventing the crack from expanding into the stable bedrock, maintaining the overall stability of the roof slab (2).

5. A method for relieving pressure and reducing shock in key deep high-stress ore pillars according to claim 1, characterized in that The aperture of the bolt hole is 28 - 32 mm, the length of the anchorage section is not less than 1.5 m, and full-length anchorage is carried out by using high-strength resin cartridges. The bolt is perpendicular to the axis of the ore pillar (1); The vertical bolt adopts a left-handed ribless threaded steel bolt with a yield strength ≥ 600 MPa, and a fast-setting resin cartridge is used in supporting. The prestress of the bolt is applied to 60% - 70% of the yield strength.

6. A method for relieving pressure and reducing shock in a deep high-stress key ore pillar according to claim 1, characterized in that By controlling the depth of the cut slot (3) within the range of 1 / 3 to 1 / 2 of the thickness of the roof slab (2), a double-layer structure system with clear functional partitions is constructed. The double-layer structure system is divided into a shallow cut slot area and a deep stable area; In the shallow cut slot area with a depth less than 0.3 times the thickness of the roof slab (2), the rock stratum is allowed to produce controllable slip along the cut slot (3) surface, releasing 60% - 70% of the bending deformation energy in the total energy storage of the roof slab (2); while the deep stable area maintains the continuity of the rock stratum and forms a stable self-supporting arch structure by using its residual strength exceeding 30 MPa.

7. A method for pressure relief and shock absorption of a key ore pillar under high deep stress according to claim 1, characterized in that, The time-space coupling relationship between the cut slot (3) and the vertical bolt is as follows: First, cut the slot (3) to 80% ± 5% of the design depth, then install the vertical anchor bolts and apply prestress, and finally complete the remaining depth of the slot (3); First, the initial slot (3) releases part of the stress, providing a stable force application environment for the prestress of the anchor bolts; Then, the anchor bolts promptly form a pressure arch effect to restrain the secondary disturbance caused by the subsequent slot (3) construction; Finally, achieve the dynamic balance of "stress release - active support" to avoid the sudden collapse of the roof (2) caused by one-time slotting (3).

8. A method for pressure relief and shock absorption of key pillars in deep high-stress areas according to claim 1, characterized in that The spatial layout of the orthogonal support network needs to meet the following conditions: The vertical anchor bolts are evenly distributed around the ore pillar (1) and in the interval area of the slots (3), with a spacing of 1 / 6 - 1 / 5 of the side length of the ore pillar (1), and the projection of the axis of the anchor bolts covers more than 90% of the cross-sectional area of the ore pillar (1); Ensure that the support force evenly covers the periphery of the ore pillar (1) to form a continuous pressure arch structure and inhibit local stress concentration; Through the high-density anchor bolt network, enhance the co-deformation ability of the ore pillar (1) and the roof (2), effectively resist dynamic disturbances, and improve the overall stability.

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