Inter-wall pillar bidirectional pressure relief mining method based on upper and lower wall surrounding rock roadways

Abstract

The invention provides an inter-panel ore pillar bidirectional pressure relief mining method based on hanging wall and footwall surrounding rock roadways, and belongs to the technical field of mining engineering.The inter-panel ore pillar bidirectional pressure relief mining method comprises the steps that S1, a hanging wall pressure relief roadway and a footwall pressure relief roadway are tunneled in stable surrounding rock on one side of a hanging wall and one side of a footwall of an inter-panel ore pillar respectively, and the axes of the two pressure relief roadways are parallel to the walking direction of the inter-panel ore pillar; s2, the hanging wall pressure relief roadway and the footwall pressure relief roadway serve as safe operation spaces, and a rock drilling device drills pressure relief drill holes in the direction of the contact boundary of the ore pillar and the surrounding rock; stress sudden rise caused by stress redistribution of the other side due to single-side pressure relief is avoided in the step S1, the design that pressure relief drill holes are drilled in the step S2 till the pressure relief drill holes completely penetrate through the contact boundary of the ore pillar and the surrounding rock is combined, and therefore a mitigation fissure zone is formed in the contact boundary, stress in the inter-plate ore pillar is effectively released, and the stability of the inter-plate ore pillar is improved. The invention provides the method for releasing the internal stress of the ore pillar, which is low in cost and can maintain the original bearing capacity of the inter-plate ore pillar.

Description

Technical Field

[0001] This invention belongs to the field of mining engineering technology, and in particular relates to a bidirectional decompression mining method based on the inter-panel pillar of the walled and hanging walls. Background Technology

[0002] In the mining industry, the bottom pillar, as a core component supporting the stability of the stope structure, often forms a key part of ore body recovery together with the triangular pillar formed above it. In traditional mining methods, the recovery of the bottom pillar and the triangular pillar typically employs a step-by-step operation: first, the upper triangular pillar is recovered through methods such as medium-deep hole blasting or manual chiseling, and then the bottom pillar is processed separately. However, this step-by-step recovery strategy requires the triangular pillar to be outside the filling material; when the triangular pillar is inside the filling material, there is no effective method for jointly recovering the triangular pillar and its underlying bottom. Summary of the Invention

[0003] In view of the technical problems existing in the background art, this application provides a bidirectional pressure relief mining method for inter-panel pillars based on the upper and lower wall surrounding rock roadways, including: S1. In the stable surrounding rock on the hanging wall and footwall sides of the inter-panel pillar, excavate one hanging wall pressure relief tunnel and one footwall pressure relief tunnel respectively, with the axes of the two pressure relief tunnels parallel to the strike of the inter-panel pillar. S2. Using the upper and lower relief roadways as safe working spaces, the rock drilling equipment drills relief boreholes towards the contact boundary between the pillar and the surrounding rock until it completely penetrates the contact boundary between the pillar and the surrounding rock. S3. The decoupled charge structure is used to charge the pressure relief borehole and detonate it with micro-delay. S4. After blasting and ventilation, personnel enter the decompression roadway to confirm that the expected continuous fracture decompression zone has been formed. Then, the personnel move to the next section or adjacent section and repeat steps S2 and S3 until the construction of the entire pillar design decompression height is completed. S5. Mining is carried out in the stopes adjacent to the pillars between the blocks.

[0004] In some implementations, in step S1, the horizontal distance D between the pressure relief tunnel and the pillar boundary is determined based on the rock mass quality index RQD of the surrounding rock. When RQD > 70%, D is 3.0 to 4.0 meters; when RQD is 50 to 70%, D is 2.5 to 3.5 meters; when RQD < 50%, D is 2.0 to 3.0 meters.

[0005] In some implementations, in step S1, the upper pressure relief tunnel and the lower pressure relief tunnel are on the same horizontal plane.

[0006] In some implementations, in step S1, there is an elevation difference between the upper pressure relief tunnel and the lower pressure relief tunnel.

[0007] In some embodiments, in step S2, the depth of the pressure relief borehole is 1.5 meters to 3.0 meters into the interior of the pillar.

[0008] In some embodiments, in step S2, the pressure relief boreholes are arranged in multiple rows and multiple holes, with the row spacing being 12 to 16 times the borehole diameter and the hole bottom distance being 1.0 to 1.3 times the row spacing.

[0009] In some embodiments, in step S3, the decoupled charge structure is set in a radial direction, and the charge coefficient is optimized according to the relative stress level of the pillar. The charge coefficient is 0.60 to 0.70 at high stress levels, 0.5 to 0.6 at medium stress levels, and 0.4 to 0.5 at low stress levels.

[0010] In some implementations, the delay of the differential detonation in step S3 is 25 ms.

[0011] In some implementations, in step S3, if the stress levels on both sides of the pillar are significantly asymmetrical, the pressure relief tunnel borehole on the side with higher initiation stress is preferentially drilled.

[0012] In some implementations, in step S4, the mining operation is carried out 7 to 15 days after the depressurization operation is completed.

[0013] This application provides a bidirectional pressure relief mining method for inter-panel pillars based on hanging wall and footwall surrounding rock roadways, including: S1. In the stable surrounding rock on the hanging wall and footwall sides of the inter-panel pillar, excavate one hanging wall pressure relief tunnel and one footwall pressure relief tunnel respectively. The axes of the two pressure relief tunnels are parallel to the strike of the inter-panel pillar. S2. Using the upper and lower relief roadways as safe working spaces, the rock drilling equipment drills relief boreholes towards the contact boundary between the pillar and the surrounding rock. S3. A decoupled charge structure is used to charge the pressure relief borehole and initiate the detonation with micro-delay. S4. After blasting and ventilation, personnel enter the decompression roadway to confirm that the expected continuous fracture decompression zone has been formed. Then, the personnel move to the next section or adjacent section and repeat steps S2 and S3 until the construction of the entire pillar design decompression height is completed. S5. Mining is carried out in the stopes adjacent to the pillars between the blocks.

[0014] By creating a dual-lane stress-relieving layout through the upper and lower wall surrounding rock roadways, and simultaneously implementing bidirectional pressure relief for the pillar, the sudden stress increase caused by stress redistribution on the other side due to pressure relief on one side is avoided. Combined with the design of drilling pressure relief boreholes to completely penetrate the contact boundary between the pillar and the surrounding rock, a mild fracture zone is formed at the contact boundary, effectively releasing the stress inside the pillar between the two sides. At the same time, it avoids the high stress generated by the continuous compression of the pillar between the upper and lower wall surrounding rocks from disturbing the bearing capacity stability of the pillar between the two sides. This provides a low-cost method for stress relief inside the pillar that can maintain the original bearing capacity of the pillar between the two sides. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0016] Figure 1 is a schematic diagram of the overall process engineering layout of a bidirectional decompression mining method based on the upper and lower wall surrounding rock roadways provided in the embodiments of this application; Figure 2 is a schematic diagram of the arrangement of pressure relief boreholes in the inter-panel pillar area in a bidirectional pressure relief mining method based on the upper and lower wall surrounding rock provided in an embodiment of this application. Figure 3 is a cross-sectional schematic diagram of the arrangement of pressure relief boreholes in the inter-panel pillar area in a bidirectional pressure relief mining method based on the upper and lower wall surrounding rock provided in the embodiments of this application. Figure 4 is a schematic diagram of the layout of the upper and lower pressure relief roadways when they are at the same level in a bidirectional pressure relief mining method based on the upper and lower wall surrounding rock roadways provided in the embodiments of this application. Figure 5 is a schematic diagram of the layout of the upper and lower pressure relief roadways when there is an elevation difference in the two-way pressure relief mining method based on the upper and lower wall surrounding rock roadways provided in the embodiments of this application. Figure 6 is a schematic diagram of the radially uncoupled charge structure of the pressure relief borehole in a bidirectional pressure relief mining method based on the upper and lower wall surrounding rock roadways provided in the embodiments of this application.

[0017] Explanation of reference numerals in the attached drawings: 1. First stope; 2. Second stope; 3. Hanging wall stress relief roadway; 4. Footing wall stress relief roadway; 5. Inter-panel pillar; 6. Hanging wall surrounding rock; 7. Footing wall surrounding rock; 8. Stress relief borehole; 81. Filler material; 82. Explosive cartridge; 83. Air gap. Detailed Implementation

[0018] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0020] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0021] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0022] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0023] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0024] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0025] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0026] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0027] In some implementations, refer to Figure 1 A bidirectional pressure relief mining method based on inter-panel pillars in the hanging wall and footwall surrounding rock roadways, comprising: S1. In the stable surrounding rock on the hanging wall and footwall sides of the pillar, excavate one hanging wall pressure relief roadway and one footwall pressure relief roadway respectively. The axes of the two pressure relief roadways are parallel to the strike of the pillar. Specifically, roadways are excavated in the stable surrounding rock on the hanging wall and footwall sides of the pillar, so that the pressure relief roadways are located outside the pillar, rather than in the pillar body. This avoids direct excavation or damage to the core structure of the pillar, thus ensuring the integrity of the pillar, protecting its bearing capacity, and preventing pillar instability caused by pressure relief.

[0028] One hanging wall stress relief roadway and one foot wall stress relief roadway are excavated on the hanging wall and foot wall of the pillar, respectively, thus forming a dual-roadway stress release layout on both sides of the pillar. This is because the stress concentration of the pillar between the two sides is not uniformly distributed, but mainly concentrated at the contact boundary between the pillar and the surrounding rock of the hanging wall and the contact boundary between the pillar and the surrounding rock of the foot wall. With one stress relief roadway on each side, stress relief paths can be formed simultaneously from the upper and lower sides of the pillar. Subsequently, stress relief holes are drilled from the two roadways to the contact boundary between the pillar and the surrounding rock and blasted, which can form bidirectional stress relief for the pillar and avoid the sudden increase in stress caused by stress redistribution on the other side due to stress relief on one side.

[0029] For example, refer to Figure 1 An upper pressure relief roadway 3 is excavated in the upper surrounding rock 6 of the first mining area 1, and a lower pressure relief roadway 4 is excavated in the lower surrounding rock 7 of the first mining area 1.

[0030] S2. Using the upper and lower plate pressure relief roadways as safe working spaces, the drilling equipment drills pressure relief boreholes towards the contact boundary between the pillar and the surrounding rock until the contact boundary is completely penetrated. Specifically, the purpose of this step is, on the one hand, to ensure that the drilling operation is carried out in a pressure relief roadway located in stable surrounding rock, avoiding personnel or drilling equipment from directly entering the stress-concentrated pillar body area, thus reducing safety risks such as rock bursts and spalling. The limitation of the borehole completely penetrating the contact boundary between the pillar and the surrounding rock restricts the spatial boundary of the pressure relief effect, so that the effect of the drilling operation on the pillar between the plates is limited to pressure relief, rather than directly damaging the bearing capacity of the pillar by penetrating it, thereby ensuring that the entire pressure relief process is controllable.

[0031] For example, refer to Figure 2 and Figure 3 Drill a pressure relief borehole 8 from the lower plate pressure relief roadway 4 to the interplate pillar 5.

[0032] S3. A decoupled charge structure is used to charge the pressure relief borehole and initiate the explosion with a micro-delay detonation. Specifically, the core of this step is to control the transmission path and intensity of the blasting energy. Decoupled charges reduce direct contact between the explosive and the borehole wall by creating an air gap, thereby buffering the instantaneous impact of the blast shock wave and reducing its damage to the surrounding rock. This allows the energy to be primarily used to create fractures at the contact boundary between the pillar and the surrounding rock. Micro-delay initiation, on the other hand, can control the detonation sequence of adjacent boreholes, allowing the fractures generated in each borehole to connect with each other, ultimately forming a continuous stress relief zone rather than isolated fractures. This effectively releases concentrated stress within the pillar. These fractures essentially establish a stress buffer layer between the pillar and the hanging wall and footwall surrounding rock. As a result, the stress in the hanging wall and footwall surrounding rock that would normally be directly transmitted to the pillar is preferentially absorbed by the fracture zone. The stress energy is dissipated through the fracture closure process. The unabsorbed residual stress is redistributed through the fracture zone to the more peripheral, stable surrounding rock rather than the pillar core, thereby reducing the total load on the pillar and preventing it from becoming unstable due to stress exceeding its bearing capacity.

[0033] S4. After blasting and ventilation, personnel enter the decompression roadway to confirm the formation of the expected continuous fracture decompression zone. Then, the equipment is moved to the next section or adjacent section, repeating steps S2 and S3 until the designed decompression height of the entire pillar is achieved. Specifically, this step is a verification of the decompression quality. Ventilation removes harmful gases generated by the blasting, ensuring personnel safety. Simultaneously, visual inspection and technical testing confirm the continuity and integrity of the fracture decompression zone, preventing incomplete decompression due to deviations in blasting parameters and eliminating stress concentration hazards for subsequent pillar mining. Segmented and repeated construction adapts to the decompression needs of pillars at different heights, ensuring the expected decompression effect is achieved throughout the entire pillar height direction.

[0034] S5. Mining is carried out in the stopes adjacent to the pillars between the blocks.

[0035] For example, mining is carried out in the first stope 1 and the second stope 2, which are adjacent to the pillar 5 between the blocks.

[0036] In addition, there is a collaborative relationship between the various steps: The collaborative relationship between S1, S2, and S3 is reflected in the following aspects: The core of S1 is to construct a pressure relief roadway within a stable surrounding rock, providing a physical space foundation and safety barrier for drilling in S2 and charging and detonating in S3; S2 requires the operation of rock drilling equipment within the pressure relief roadway, and the drilling direction must point towards the contact boundary between the pillar and the surrounding rock. In S1, the axis of the pressure relief roadway is parallel to the pillar strike, and the distance from the pillar boundary is controllable, ensuring that the drilling can fully cover the contact boundary of the pillar and preventing the drilling from failing to reach the target area due to roadway deviation; The charging and detonation of S3 requires personnel and equipment to work within the roadway, and the pressure relief roadway in S1 ensures the safety of personnel and equipment during the operation, providing a stable environment for the blasting operation of S3.

[0037] The collaborative relationship between S3 and S4 is reflected in the following: S3 is the execution link for forming the fracture relief zone, while S4 is the closed-loop link for verifying the quality of the relief zone. Whether the fractures generated by blasting in S3 are continuous and cover the target area needs to be confirmed by ventilation, gas detection, and ground-penetrating radar scanning in S4. If S4 detects that some fractures are not connected, it is necessary to return to S3 to adjust the blasting parameters or to drill and blast again to ensure that the relief zone achieves the expected effect of being continuous and complete. Only after S4 confirms that it is qualified can the next section of S2 and S3 construction begin, to avoid the failure of the subsequent overall pressure relief due to incomplete pressure relief in the previous section.

[0038] The collaborative relationship between the two is reflected in the self-optimization effect between construction execution and quality verification: the blasting effect of S3 depends on the detection feedback of S4, and the verification results of S4 guide the parameter optimization or supplementary construction of S3, forming a cyclical adjustment between work and result verification to ensure that the decompression quality of the entire pillar is controllable.

[0039] This application provides a bidirectional pressure relief mining method for inter-panel pillars based on hanging wall and footwall surrounding rock roadways, including: S1. In the stable surrounding rock on the hanging wall and footwall sides of the inter-panel pillar, excavate one hanging wall pressure relief tunnel and one footwall pressure relief tunnel respectively. The axes of the two pressure relief tunnels are parallel to the strike of the inter-panel pillar. S2. Using the upper and lower relief roadways as safe working spaces, the rock drilling equipment drills relief boreholes towards the contact boundary between the pillar and the surrounding rock. S3. A decoupled charge structure is used to charge the pressure relief borehole and initiate the detonation with micro-delay. S4. After blasting and ventilation, personnel enter the decompression roadway to confirm that the expected continuous fracture decompression zone has been formed. Then, the personnel move to the next section or adjacent section and repeat steps S2 and S3 until the construction of the entire pillar design decompression height is completed. S5. Mining is carried out in the stopes adjacent to the pillars between the blocks.

[0040] By creating a dual-lane stress-relieving layout through the upper and lower wall surrounding rock roadways, and simultaneously implementing bidirectional pressure relief for the pillar, the sudden stress increase caused by stress redistribution on the other side due to pressure relief on one side is avoided. Combined with the design of drilling pressure relief boreholes to completely penetrate the contact boundary between the pillar and the surrounding rock, a mild fracture zone is formed at the contact boundary, effectively releasing the stress inside the pillar between the two sides. At the same time, it avoids the high stress generated by the continuous compression of the pillar between the upper and lower wall surrounding rocks from disturbing the bearing capacity stability of the pillar between the two sides. This provides a low-cost method for stress relief inside the pillar that can maintain the original bearing capacity of the pillar between the two sides.

[0041] In some implementations, refer to Figure 3 In step S1, the horizontal distance D between the pressure relief roadway and the pillar boundary is determined based on the rock mass quality index RQD of the surrounding rock. When RQD > 70%, D is 3.0 to 4.0 meters; when RQD is 50 to 70%, D is 2.5 to 3.5 meters; when RQD < 50%, D is 2.0 to 3.0 meters. Specifically, in scenarios where the surrounding rock mass is intact, fissures are not developed, and bearing capacity is strong, such as when the surrounding rock on the footwall and hanging wall of the pillar is stable biotite granite, or in other metal mines where the rock mass is not tectonically damaged, RQD = 85, D is 3.0 to 4.0 meters, and further optimization is needed based on the roadway cross-sectional dimensions. If the tunnel cross-section is a three-centered arch cross-section with a net width × net height of 4.0 meters × 3.8 meters, D should be 3.5-4.0 meters; if the tunnel cross-section is smaller (e.g., net width < 3.5 meters, suitable for small rock drilling equipment), D can be taken as the lower limit of 3.0-3.5 meters.

[0042] In scenarios where the surrounding rock has a few fissures and localized broken blocks, but can still maintain its overall stability, such as granite slightly affected by tectonic structures or limestone with well-developed bedding, the corresponding RQD is 50% to 70%. In this case, D should be taken as 2.5 to 3.5 meters, with priority given to the lower limit or median value. Because the integrity of the surrounding rock is slightly poor, reducing D can reduce the exposure length of the roadway in moderately stable surrounding rock and reduce the risk of roadway deformation. If there is a local fracture zone near the pillar boundary, D can be slightly adjusted to 3.0-3.5 meters to avoid the roadway directly crossing the fracture zone.

[0043] In scenarios where the surrounding rock has well-developed fissures, numerous fractured interlayers, and poor inherent stability, such as gneiss or weathered basalt heavily influenced by tectonic activity, corresponding to construction conditions where RQD < 50, D should be taken as 2.0 to 3.0 meters. This ensures that the stress relief roadway is as close as possible to the surrounding rock near the relatively intact pillar boundary, reducing the roadway's extension distance within the fractured surrounding rock. Simultaneously, it is necessary to consider the actual geological conditions at the pillar boundary and avoid obvious fracture zones within the rock strata. If there are thick layers of argillaceous interlayers within 1.5 meters of the pillar boundary, D can be adjusted upwards to 2.5-3.0 meters to ensure that the roadway is located within a relatively intact rock mass.

[0044] Taking the RQD value can prevent the roadway from becoming unstable. When RQD>70%, D is taken as 3.0-4.0 meters, so that the roadway is completely in intact, low-fracture surrounding rock, and can maintain stability without complex support, thus avoiding the interruption of drilling and blasting operations due to roadway collapse. When RQD < 50%, D is taken as 2.0-3.0 meters. By shortening the exposed length of the roadway in the fractured surrounding rock and strengthening the support, the convergence of the roadway sides and the subsidence of the roof and floor can be effectively controlled, and the roadway width can be prevented from shrinking from 4.0 meters to less than 3.5 meters, ensuring the normal passage of the drilling rig and protecting the safety of personnel and equipment.

[0045] In some implementations, refer to Figure 4 In step S1, the upper and lower pressure relief roadways are on the same horizontal plane. Specifically, the dual-roadway pressure relief requires time coordination to achieve stress coordination. A horizontally symmetrical layout can avoid the problem of stress redistribution. Because the projections of the two roadways are aligned, the pressure relief boreholes drilled from the roadway sides act symmetrically on the contact boundaries of the upper and lower walls of the pillar, allowing the high stress on both sides of the pillar to be released synchronously in the same time period and the same spatial area, avoiding the risk of one side being pressure-relieved first and the other side experiencing a sudden increase in stress due to asymmetrical borehole positions. For example, an upper pressure relief roadway 3 is excavated in the upper surrounding rock 6 of the first mining area 1, and a lower pressure relief roadway 4 is excavated in the lower surrounding rock 7 of the first mining area 1. The ground elevation of the upper pressure relief roadway 3 is the same as that of the lower pressure relief roadway 4, and the dimensions of the lower pressure relief roadway 4 are the same as those of the upper pressure relief roadway 3.

[0046] In steeply dipping ore bodies, the compressive stress on the pillars from the hanging wall and footwall is mostly symmetrically distributed. The stress relief roadway projected onto the same vertical plane can evenly offset the compressive stress on both sides through symmetrical fracture zones, making the stress distribution inside the pillar more uniform.

[0047] In some implementations, refer to Figure 5 In step S1, there is an elevation difference between the upper and lower pressure relief roadways. Specifically, when the forces on both sides of a pillar are significantly asymmetrical, such as asymmetrical in-situ stress, asymmetrical surrounding rock quality, or asymmetrical pillar shape, the upper and lower pressure relief roadways need to be staggered vertically according to the asymmetrical forces on the pillar to match the asymmetrical forces and avoid insufficient pressure relief on the high-stress side or excessive pressure relief on the low-stress side.

[0048] For example, an upper pressure relief roadway 3 is excavated in the upper rock 6 of the first mining area 1, and a lower pressure relief roadway 4 is excavated in the lower rock 7 of the first mining area 1. When the stress is significantly higher at the upper side of the inter-panel pillar 5, the upper pressure relief roadway 3 is designed to be 3 meters higher than the lower pressure relief roadway through the elevation difference design. This allows the location of the upper borehole to be closer to the high stress area of ​​the upper plate. The fracture zone formed after blasting can better cover the stress peak area of ​​the upper plate, which is better than symmetrical arrangement.

[0049] In some implementations, refer to Figure 3 In step S2, the depth of the stress relief borehole is 1.5 to 3.0 meters into the interior of the pillar. The stress concentration zone of the deep pillar is usually distributed within 1.0-2.5 meters inward from the contact boundary. A borehole depth of 1.5-3.0 meters can completely cover this area, and after blasting, a continuous fracture stress relief zone can be formed to release the stress at the contact boundary. Moreover, the supporting capacity of the pillar depends on the intact core area inside. A borehole depth of 1.5-3.0 meters only acts on the shallow boundary of the pillar and does not touch the core area, so it does not affect the core bearing capacity of the pillar.

[0050] In some implementations, refer to Figure 2 In step S2, the pressure relief borehole 8 adopts a multi-row, multi-hole arrangement, with the row spacing being 12 to 16 times the borehole diameter and the bottom hole distance being 1.0 to 1.3 times the row spacing.

[0051] In some implementations, refer to Figure 6In step S3, the decoupled charge structure is set radially, and the charge coefficient is optimized according to the relative stress level of the pillar. The charge coefficient is 0.60 to 0.70 for high stress levels, 0.5 to 0.6 for medium stress levels, and 0.4 to 0.5 for low stress levels. Specifically, the relative stress level of the pillar and borehole parameters are determined through preliminary exploration to ensure parameter matching. Using the ratio (σc / σ1) of the uniaxial compressive strength of the pillar rock to the maximum principal stress (σ1) of the original rock as an indicator, the relative stress level is divided into high stress, medium stress, and low stress levels. High stress level corresponds to σc / σ1 < 2, where stress concentration at the pillar boundary is significant, requiring stronger blasting energy to fracture the rock; medium stress level corresponds to 2 ≤ σc / σ1 ≤ 3, where stress concentration is moderate, and energy needs to be balanced for pressure relief and protection; low stress level corresponds to σc / σ1 > 3, where stress concentration is weak, and energy needs to be controlled to avoid excessive damage. For example, when using emulsion explosive cartridge 82, the diameter of the cartridge must match the diameter of the pressure relief borehole 8 to ensure that the radial decoupling coefficient K (borehole diameter / cartridge diameter) is controlled between 2.0 and 3.0. If K is too small (<2.0), it will easily lead to excessive energy concentration and crush the rock mass; if K is too large (>3.0), the energy will be dispersed and it will not be able to effectively crack the rock.

[0052] For example, when the rock mass σc=120MPa and σ1=70MPa (σc / σ1≈1.71<2): K=0.65, the charge length = 6.0 (i.e., the borehole length, determined by the horizontal distance D of the pressure relief tunnel and the borehole depth L) × 0.65 (K, i.e. the charge coefficient) = 3.9m, 10 rolls of Φ40mm charge cartridges are required (3.9m / 0.4m≈9.75, rounded up to 10 rolls, weighing 6.0kg).

[0053] The air gap of 83 and the decoupled structure can reduce the peak value of the blast shock wave and prevent the rock mass at the boundary of the pillar from being crushed. At the same time, the fracture extends radially along the borehole to form a continuous pressure relief zone, which not only releases stress but also avoids damage to the core bearing area of ​​the pillar. The refined blasting coefficient design can adapt to the pressure relief requirements under different stress conditions, so as to make the blasting energy release reasonable and thus ensure the smooth progress of the pillar stress release work.

[0054] In some implementations, the delay for micro-detonation in step S3 is 25 ms.

[0055] In some implementations, in step S3, if the stress levels on both sides of the pillar are significantly asymmetrical, the pressure relief borehole on the side with higher stress is preferentially detonated. Specifically, the boundary of the pillar on the high-stress side is prone to stress blockage, and the stress cannot be released naturally, accumulating to the critical value of the rock compressive strength. Preemptive detonation can quickly break the blockage with blasting energy, reducing the stress on the high-stress side boundary from a supercritical state to a safe threshold, avoiding the occurrence of spalling or rockburst on the high-stress side first. If detonated simultaneously with the low-stress side, the energy on the low-stress side may be absorbed by the high-stress side, resulting in incomplete pressure relief on the high-stress side.

[0056] Furthermore, if the stress on both sides of the pillar is asymmetrical, during synchronous detonation, the low-stress side will release stress first because the shelter is easily disturbed. The peak stress that has not been released on the high-stress side will quickly transfer to the low-stress side. Prioritizing the detonation of the high-stress side can complete the release of high stress before the detonation of the low-stress side, avoiding the transfer of high stress to the already depressurized low-stress side, and ensuring that the stress on both sides is released within its own area.

[0057] In some implementations, in step S4, the mining operation is carried out 7 to 15 days after the decompression operation is completed. Specifically, after the decompression blast, the stress between the pillar and the surrounding rock is in a state of transient imbalance. It needs to undergo creep deformation over a period of time, and the residual stress gradually transfers to the more stable surrounding rock. During this period, mining will cause the untransferred residual stress to superimpose with the mining disturbance, resulting in a secondary increase in the pillar stress, thereby inducing spalling.

[0058] The specific waiting time needs to be preliminarily determined and differentiated based on the rock mass creep characteristics, the stress level before decompression, and the decompression effect. For example, based on the rock mass quality index (RQD) and uniaxial compressive strength (σc) of the surrounding rock and pillar, the rock mass creep state is classified. RQD > 70% and σc > 150 MPa indicate high-hardness, stable rock mass with slow creep deformation, requiring a longer time for stress redistribution; the stabilization period is 12-15 days. 50% ≤ RQD ≤ 70% and 100 MPa ≤ σc ≤ 150 MPa indicate medium-hardness rock mass with a moderate creep rate; the stabilization period is 8-12 days. RQD < 50% and σc < 100 MPa indicate low-hardness rock mass, prone to short-term creep, with faster stress redistribution; the stabilization period is 7-8 days. Furthermore, the lower the relative stress level of the pillar before decompression, the shorter the stabilization period can be; conversely, a higher relative stress level requires a longer stabilization period to ensure sufficient stress release.

[0059] In some implementations, refer to Figures 1 to 6 For example, please provide a workflow for a bidirectional decompression mining method based on inter-panel pillars in the upper and lower wall surrounding rock roadways: The 8th section of a tungsten mine has a burial depth of H=1100m. The ore body is a steeply dipping, thick quartz vein type ore body with an average true thickness of 28m and a dip angle of 75°. The stope is arranged along the strike of the ore body, with a section height of 60m and a designed pillar width W=18m between the hanging walls. The surrounding rock of both the hanging wall and footwall is stable biotite granite with a rock mass quality index RQD=85 and a uniaxial compressive strength σc=160MPa. In-situ stress measurements show that the maximum principal stress of the original rock is σ1=35MPa, with a nearly horizontal direction.

[0060] Tunnel Design: Due to the extremely stable surrounding rock (RQD=85>70), according to the present invention, the horizontal distance D between the hanging wall stress relief tunnel and the pillar boundary is determined to be 3.5m. Both tunnels are designed with a three-centered arch cross-section, with specifications of: net width × net height = 4.0m × 3.8m, to meet the needs of transporting and operating large drilling rigs. The two tunnels are located at the same elevation in the vertical direction, and their axes are aligned vertically.

[0061] Tunnel excavation and support: Construction was carried out using an integrated tunneling and anchoring unit, with a cycle advance of 2.0m. The basic support method employed was "short anchor bolts + shotcrete." Φ22mm×2400mm threaded steel resin anchor bolts were installed, spaced 1.5m×1.5m apart in a staggered pattern. C25 shotcrete was applied to a thickness of 80mm.

[0062] A rock drilling rig is used, equipped with a Φ102mm drill bit. According to the requirements of this invention, the borehole must penetrate into the ore pillar. The borehole depth is determined to be L = 3.5m (D) + 2.5m (depth into the ore body) = 6.0m.

[0063] Hole parameters: Row spacing: Take 14 times the borehole diameter, i.e., 0.102m × 14 ≈ 1.43m, rounded to 1.4m. Four boreholes are arranged in each row. Bottom-of-hole distance: Take 1.2 times the row spacing, i.e., 1.4m × 1.2 ≈ 1.7m. The borehole direction is perpendicular to the roadway sidewall, directly pointing to the contact boundary between the pillar and the surrounding rock.

[0064] Explosive selection: Use emulsion explosive rolls with a diameter of Φ40mm (each roll is 400mm long and weighs 0.6kg).

[0065] Charge structure: Calculated stress level: σc / σ1=160 / 35≈4.57>3, which belongs to the low stress level. According to the present invention, the charge coefficient is taken as 0.45.

[0066] The length of the charge per hole is 6m × 0.45 = 2.7m. The number of charge rolls required per hole is approximately 2.7m / 0.4m ≈ 6.75 rolls, which is rounded up to 7 rolls (4.2kg).

[0067] A radially decoupled charge is used, with a decoupling coefficient K = 10² / 40 = 2.55. The borehole opening is properly filled with drill bituminous rock powder, with a filling length of not less than 1.5 m.

[0068] Digital electronic detonators were used for blasting. All blasting holes in the upper and lower pressure relief tunnels were detonated simultaneously (all with a 0ms delay) to achieve the maximum synergistic impact superposition effect and maximize the pressure relief effect.

[0069] Effect Inspection: After blasting and ventilation, personnel entered the two pressure relief tunnels for inspection. It was observed that obvious radial fissures appeared in the granite mass around the borehole opening. A large amount of rock powder was ejected and accumulated on the tunnel surface. When the drill rod of a rock drilling rig was inserted into the borehole, a significant reduction in resistance was felt, indicating that the internal fissures had fully developed.

[0070] Based on comprehensive assessment, the fracture stress relief zone has been successfully formed.

[0071] Cyclic operation: The drilling rig moves to the next section (usually every 20-30m), and steps S2 and S3 are repeated. After the decompression work of the entire length of this section is completed, it is lowered to the next section for construction, until the entire designed decompression height is completed.

[0072] After all decompression works are completed, mining operations in adjacent panels will be suspended. Given the hardness of the rock mass and the high stress level, a 14-day stress adjustment and stabilization period will be selected. After this period, conventional mining methods will be used to begin mining the ore in the panel adjacent to the pillar.

[0073] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

[0074] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A mining method based on the upper and lower disc surrounding rock roadway between the disc pillar two-way pressure relief mining method, characterized in that, The method comprises the following steps: S1, in the stable surrounding rock on the upper and lower sides of the inter- panel pillar, excavate an upper panel pressure relief roadway and a lower panel pressure relief roadway, respectively, and the axes of the two pressure relief roadways are parallel to the strike of the inter-panel pillar; S2, use the upper panel pressure relief roadway and the lower panel pressure relief roadway as a safe operation space, and drill pressure relief boreholes in the direction of the contact boundary between the pillar and the surrounding rock to completely penetrate the contact boundary between the pillar and the surrounding rock by using rock drilling equipment; S3, use a decoupled charging structure to charge the pressure relief boreholes and initiate them by a millisecond delay; S4, after blasting and ventilation, personnel enter the pressure relief roadway to confirm that the expected continuous crack pressure relief zone has been formed, and then move the equipment to the next section or adjacent section, and repeat steps S2 and S3 until the entire pillar design pressure relief height construction is completed; S5, perform mining in the stope adjacent to the inter-panel pillar.

2. The mining method of claim 1, wherein, In step S1, the horizontal distance D between the pressure relief roadway and the pillar boundary is determined according to the rock mass quality index ROD of the surrounding rock, when RQD>70%, D is 3.0 to 4.0 meters; when RQD is 50 to 70%, D is 2.5 to 3.5 meters; and when RQD<50, D is 2.0 to 3.0 meters.

3. The mining method of claim 2, wherein, In step S1, the upper panel pressure relief roadway and the lower panel pressure relief roadway are on the same horizontal plane.

4. The mining method of claim 2, wherein, In step S1, there is a height difference between the elevations of the upper panel pressure relief roadway and the lower panel pressure relief roadway.

5. The mining method of claim 1, wherein, In step S2, the depth of the pressure relief borehole is 1.5 to 3.0 meters into the pillar.

6. The dual direction pressure relief mining method based on the upper and lower disc surrounding rock roadway and inter-disc pillar according to claim 5, characterized in that, In step S2, the pressure relief borehole uses a multi-row and multi-hole arrangement, the row distance is 12 to 16 times the diameter of the borehole, and the hole bottom distance is 1.0 to 1.3 times the row distance.

7. The dual direction pressure relief mining method based on the upper and lower disc surrounding rock roadway inter-disc pillar of claim 1, characterized in that, In step S3, the setting direction of the decoupled charging structure is radial, and the charging coefficient is optimized according to the corresponding stress level of the pillar, when the stress level is high, the charging coefficient is 0.60 to 0.70, when the stress level is medium, the charging coefficient is 0.5 to 0.6, and when the stress level is low, the charging coefficient is 0.4 to 0.

5.

8. The dual direction pressure relief mining method based on the upper and lower disc surrounding rock roadway inter-disc pillar of claim 1, characterized in that, In step S3, the delay time of the millisecond initiation is 25 ms.

9. The dual direction pressure relief mining method based on the upper and lower disc surrounding rock roadway and inter-disc pillar according to claim 8, characterized in that, In step S3, if the stress levels on both sides of the pillar are significantly asymmetric, the boreholes in the pressure relief roadway on the side with higher stress are preferentially initiated.

10. The mining method of claim 1, wherein, In step S4, the mining engineering is performed 7 to 15 days after the completion of the pressure relief engineering.

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