Unloading and wave absorbing coupling prevention method for rock burst ultra-deep hole blasting of steeply inclined coal seam

Abstract

The invention discloses a rock burst ultra-deep hole blasting unloading wave absorption coupling prevention method for a steeply inclined coal seam, and belongs to the technical field of coal mining, and the method comprises the following steps: step 1, determining an unloading target rock stratum where a working face top plate and / or bottom plate stress concentration area is located in the steeply inclined coal seam; 2, determining a wave absorbing target rock stratum between the unloading target rock stratum and a roadway on the corresponding side of the working face of the steeply inclined coal seam; 3, arranging a plurality of unloading blast hole groups in the roadway; step 4, arranging a wave absorbing blast hole group at the position where the unloading blast hole group is arranged in the roadway; 5, all the wave absorbing blast holes are detonated, and all the unloading blast holes are detonated; and 6, after blasting is completed, the near-surface surrounding rock of the roadway on the corresponding side subjected to blasting serves as a supporting bearing layer for combined supporting. According to the invention, a three-level cooperative control mechanism of source unloading, propagation weakening and terminal bearing is realized, and steeply inclined coal seam clamping type roof and floor rock burst disasters are prevented fundamentally.

Description

Technical Field

[0001] This invention belongs to the field of coal mining technology, specifically relating to a method for preventing rockburst in steeply inclined coal seams by unloading and wave-damping coupling in ultra-deep hole blasting. Background Technology

[0002] Steeply dipping coal seams (dip angle greater than 45°) are subjected to both tectonic stress and mining stress. Their roof and floor failure behaviors differ significantly from those of near-horizontal or gently dipping coal seams, typically exhibiting a "clamping" stress environment. Specifically, thick, hard roof and floor rock masses (such as sandstone and conglomerate, generally greater than 5m thick) possess high elastic modulus and energy storage characteristics, enabling them to accumulate substantial elastic strain energy under deformation-constrained conditions. After the steeply dipping coal seam is mined, the roof and floor are subjected to the combined influence of far-field tectonic stress and mining stress, resulting in a strong lateral compression and confinement effect, i.e., the "clamping effect." Under this effect, the superposition of regional tectonic stress and mining stress leads to the formation of high-stress concentration zones within the roof and floor rock masses.

[0003] When local stress exceeds the ultimate bearing capacity of the rock mass, the accumulated elastic energy is released instantaneously, inducing a roof and floor type rockburst. This type of impact manifests as a sudden bulge and fracture of the roof or floor rock mass, accompanied by strong vibrations. It often causes instability of the surrounding rock in the roadway, damage to the support structure, and even casualties, posing a serious threat to the safe production of coal mines.

[0004] To cope with such disasters, existing anti-impact technologies mainly include passive resistance and local pressure relief.

[0005] In terms of passive resistance, the main approach is to enhance the bearing capacity of the surrounding rock in the roadway to resist the release of impact energy. This can be achieved through passive support methods such as high-strength anchor bolts, anchor cables, U-shaped steel supports, and concrete arches, or in conjunction with active support methods such as high-prestressed anchor cables, hydraulic supports, and grouting reinforcement. While these methods can improve the roadway's deformation resistance in the short term, their control is limited to the near-surface surrounding rock and do not alter the high-energy-storage structure and stress concentration state deep within the thick, hard roof and floor. Therefore, they cannot weaken the underlying cause of rockbursts at the energy source. When energy is released from the deep, high-stress zone, the peak impact load often reaches 3 to 5 times the rated bearing capacity of the support structure, leading to the overall failure of the support system and resulting in unstable and delayed control effects.

[0006] In terms of active stress relief, common practices include drilling shallow holes (generally no more than 5 m deep) in the surface of the roof and floor to carry out blasting stress relief, or arranging stress relief roadways on both sides of the roadway or below the roof and floor to release local stress energy. Shallow hole blasting only acts on shallow rock mass and cannot effectively weaken the high-energy storage structure of deep, thick, and hard rock layers, thus limiting the stress relief range. While excavating stress relief roadways can alleviate stress concentration to some extent, under steeply inclined coal seam conditions, due to narrow space, complex geological structure, high construction difficulty and cost, and the fact that the empty roadway itself can easily become a new stress concentration zone, inducing secondary collapse or impact risk.

[0007] Therefore, existing passive resistance and localized stress relief methods are essentially localized or shallow control measures, unable to fundamentally change the high-stress, high-energy-storage structure formed by the "clamping effect" of steeply inclined, thick, and hard roof and floor slabs. Strengthened support can only delay the instability of the surrounding rock, but cannot weaken the energy at the source of the disaster; shallow-hole blasting or stress-relief tunnels, limited by construction conditions and scope of action, are difficult to reach the core area of ​​stress concentration, resulting in limited treatment effects and remaining risks.

[0008] Based on this, this application proposes a deep-hole blasting unloading and wave-damping coupling prevention method for rockbursts in steeply inclined coal seams. This method realizes a three-level coordinated control mechanism of source unloading, propagation weakening, and terminal bearing, fundamentally preventing rockburst disasters caused by the clamping of the roof and floor in steeply inclined coal seams, and ensuring long-term stable and safe and efficient mining of the roadway. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preventing rockburst in steeply inclined coal seams by unloading and wave-damping coupling in ultra-deep hole blasting.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: A method for preventing rockburst in steeply inclined coal seams by unloading and wave-damping coupling during ultra-deep hole blasting includes the following steps: Step 1: Determine the target rock strata for unloading in the stress concentration zone of the roof and / or floor of the working face in a steeply inclined coal seam; Step 2: Determine the wave-damping target rock layer between the unloading target rock layer and the corresponding side roadway of the steeply inclined coal seam working face; Step 3: Evenly arrange several unloading blast hole groups along the length of the tunnel. Each unloading blast hole group includes several unloading blast holes. The unloading blast holes extend through the wave-damping target rock layer and penetrate the unloading target rock layer. Step 4: Set up wave-damping blast hole groups at the locations where unloading blast hole groups are set up in the tunnel. Each wave-damping blast hole group includes several wave-damping blast holes, and the bottom of the wave-damping blast holes penetrates the target rock layer. Step 5: Detonate each wave-damping blast hole to generate a dense crack zone, forming a wave-damping layer blast weakening zone, and constructing an energy dissipation zone that can absorb and attenuate dynamic loads of rockburst and blast seismic waves. Each unloading borehole is detonated to generate a network of through-hole blasting fractures, forming a blasting weakening zone in the unloading layer, destroying the integrity of the target rock layer and eliminating its high-energy storage structure, weakening the potential energy of rockburst generation, and reducing energy accumulation. In the energy transfer path of unloading borehole blasting, the energy dissipation zone absorbs and attenuates the dynamic load of the rock pressure and the blasting seismic wave. Step 6: After the blasting is completed, the surrounding rock near the surface of the corresponding side roadway that was blasted is used as a support bearing layer for joint support to improve the long-term stability of the roadway surrounding rock against dynamic loads.

[0011] Preferably, the distance L1 between the wave-damping target rock layer and the corresponding side tunnel is 10-15m.

[0012] Preferably, an intact rock layer is preserved between the unloading target rock layer and the wave-dissipating target rock layer on the corresponding side.

[0013] Preferably, 1 to 2 sets of wave-damping blast holes are added between adjacent unloading blast hole sets.

[0014] Preferably, the spacing L2 between adjacent unloading borehole groups is 20-30m, and the spacing L3 between adjacent wave-damping borehole groups does not exceed 10m.

[0015] Preferably, the wave-damping holes in the wave-damping hole group are arranged in an alternating pattern.

[0016] Preferably, the diameter of the wave-damping blast hole and the unloading blast hole is not less than 50mm, and the blocking length of the wave-damping blast hole and the unloading blast hole is not less than one-third of the blast hole length and not less than 6m.

[0017] Preferably, the unloading borehole includes a first charge section, a sealing section, a second charge section, and a plugging section; the first charge section is located within the target rock layer for unloading, the second charge section is located within the target rock layer for wave dissipation, the sealing section is located between the first charge section and the second charge section, and the plugging section is located between the second charge section and the borehole opening.

[0018] Preferably, all the explosives in the wave-damping boreholes and the second charge section within the unloading borehole are detonated simultaneously to create an initial weakened zone, followed by simultaneous detonation of the explosives in the first charge section within the unloading borehole.

[0019] Preferably, in the unloading borehole, the interval between the first charge section and the second charge section is 50-100 ms.

[0020] The beneficial effects of this invention are: (1) The present invention first generates a dense crack zone in the target rock layer through blasting with wave-absorbing blast holes, forming a wave-absorbing layer blast weakening zone, and constructing an energy dissipation zone that can absorb and attenuate the dynamic load of rockburst and the blast seismic wave; then, in the target rock layer, a through-type blast crack network is generated through unloading blast holes, forming an unloading layer blast weakening zone, destroying the integrity of the target rock layer and eliminating its high energy storage structure, weakening the potential energy of rockburst generation, reducing energy accumulation, and at the same time, in the energy transmission path of the target rock layer through unloading blast holes, the energy dissipation zone absorbs and attenuates the dynamic load of rockburst and the blast seismic wave; and the near-surface surrounding rock of the roadway is used as a support bearing layer for joint support to enhance the stability of the terminal surrounding rock. Ultimately, a three-tiered coordinated control mechanism of source unloading, propagation weakening, and terminal bearing is achieved. This mechanism can effectively relieve pressure in deep stress concentration areas, dissipate wave energy in the central energy transmission path, and form a stable support barrier in the near-surface roadway area. This forms a comprehensive, multi-level rockburst prevention and control system that fundamentally prevents rockburst disasters caused by steeply inclined coal seams sandwiched between roof and floor, ensuring long-term stability and safe and efficient mining of roadways. The three-tiered coordinated control mechanism of source unloading, propagation weakening, and terminal bearing breaks through the limitations of traditional shallow local pressure relief and passive reinforcement support, realizing a fundamental shift in rockburst prevention and control from passive management to proactive prevention. This can significantly improve the long-term stability of roadways and the level of safe production in the mine.

[0021] (2) This invention uses unloading blast holes that extend to the bottom of the unloading target rock layer to carry out ultra-deep hole blasting, forming a continuous blast fracture network, transforming the high stiffness unloading target rock layer into a low stiffness pressure relief body, effectively releasing deep stress and reducing the elastic strain energy that can be accumulated, thereby weakening the conditions for the formation of rockburst from the energy source, that is, weakening the high energy storage structure of the unloading target rock layer at the source and reducing the potential energy of rockburst generation.

[0022] (3) This invention uses wave-absorbing blast holes extending to the target rock layer at the bottom of the holes to form dense crack zones by dense ultra-deep hole blasting, which increases the damping of the rock medium and reduces the wave impedance, thus constructing an energy dissipation zone that can absorb and attenuate dynamic carrier energy. This weakens the energy of blasting seismic waves and stress waves from the propagation path, thus establishing a wave energy dissipation barrier and significantly reducing the transmission efficiency of blasting and impact dynamic loads to the roadway. Attached Figure Description

[0023] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.

[0024] Figure 1 This is a schematic flowchart of the method for preventing rockburst in steeply inclined coal seams by unloading and wave-damping coupling in ultra-deep hole blasting according to the present invention. Figure 2This is a schematic diagram of the unloading of target rock layers in both the top plate and the bottom plate in Embodiment 1 of the present invention; Figure 3 yes Figure 2 Top view of the working surface; Figure 4 This is a schematic diagram of the unloading target rock layer when only the top plate exists in Embodiment 2 of the present invention; Figure 5 yes Figure 4 Top view of the working surface; Figure 6 This is a schematic diagram of the unloading target rock layer when only the bottom plate exists in Embodiment 3 of the present invention; Figure 7 yes Figure 6 Top view of the working surface; in: 1. Steeply inclined coal seam; 2. Target rock stratum for unloading; 3. Roadway; 4. Target rock stratum for wave damping; 5. Unloading blast hole; 51. First charging section; 52. Separation section; 53. Second charging section; 54. Blocking section; 6. Wave damping blast hole; 7. Intact rock stratum; 8. Near-surface surrounding rock; 9. Wave damping layer blasting weakened zone; 10. Unloading layer blasting weakened zone. Detailed Implementation

[0025] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, 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.

[0026] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0027] In this invention, terms such as "upper," "lower," "bottom," and "top" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are merely relational terms determined for the convenience of describing the structural relationship of the various components or elements of this invention, and do not specifically refer to any component or element in this invention, and should not be construed as limiting this invention.

[0028] In this invention, terms such as "connected" and "linked" should be interpreted broadly, indicating a fixed connection, an integral connection, or a detachable connection; a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can determine the specific meaning of these terms in this invention based on the specific circumstances, and they should not be construed as limitations on the invention.

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] like Figure 1 As shown, the method for preventing rockburst in steeply inclined coal seams by unloading and wave-damping coupling through ultra-deep hole blasting includes the following steps: Step 1: Determine the target unloading rock stratum 2 where the stress concentration zone of the roof and / or floor of the steeply inclined coal seam 1 is located. Specifically, the target unloading rock stratum 2 for the roof is selected within a 100m thick roof layer, and the target unloading rock stratum 2 for the floor is selected within a 100m thick floor layer. Taking the determination of the target unloading rock stratum 2 for the roof as an example: First, find all rock strata within a 100m thick roof layer that meet the requirements of a rock stratum thickness greater than 10m and a uniaxial compressive strength greater than 50MPa. Among these rock strata, monitor the microseismic signals through a microseismic monitoring system, and identify the rock stratum that emits the maximum vibration energy due to its own fracture as the target unloading rock stratum 2 for the roof. Step 2: Determine the wave-damping target rock layer 4 between the unloading target rock layer 2 and the corresponding side roadway 3 of the steeply inclined coal seam working face; Step 3: Evenly arrange several unloading blast hole groups along the length of tunnel 3 within tunnel 3. Each unloading blast hole group includes several unloading blast holes 5. The unloading blast holes 5 extend through the wave-damping target rock layer 4 and penetrate the unloading target rock layer 2, that is, the bottom of the hole reaches the interface between the unloading target rock layer 2 and the next rock layer. The openings of each unloading blast hole 5 in the unloading blast hole group are close to each other, and the bottoms are diverging away from each other. The distance between the centers of the bottoms of two adjacent unloading blast holes 5 in the unloading blast hole group is 20-30m. The unloading blast holes 5 use directional drilling technology to control the blast hole trajectory. When encountering broken or soft interlayers, protective pipes are installed to ensure the quality of hole formation and the safety of explosive loading. Step 4: At the location where the unloading blast hole group is set up in the tunnel 3, a wave-damping blast hole group is set up. Each wave-damping blast hole group includes several wave-damping blast holes 6. The bottom of the wave-damping blast hole 6 penetrates the wave-damping target rock layer 4, that is, the bottom of the hole reaches the interface between the wave-damping target rock layer 4 and the next rock layer. The openings of the wave-damping blast holes 6 in the wave-damping blast hole group are close to each other, and the bottoms are diverging away from each other. The distance between the centers of the bottoms of two adjacent wave-damping blast holes 6 in the wave-damping blast hole group is 5 to 10 m. Step 5: Detonate each wave-damping borehole 6 to generate a dense crack zone, forming a wave-damping layer blast weakening zone 9, and constructing an energy dissipation zone that can absorb and attenuate dynamic loads of rockburst and blast seismic waves. Each unloading borehole 5 is detonated to generate a network of through-hole blasting fractures, forming a blasting weakening zone 10 in the unloading layer, which destroys the integrity of the target rock layer and eliminates its high energy storage structure, weakens the potential energy of the rock burst, and reduces energy accumulation. In the energy transfer path of the blasting in borehole 5, the energy dissipation zone absorbs and attenuates the dynamic load of the rock pressure and the blasting seismic wave. Step 6: After the blasting is completed, the surrounding rock 8 near the surface of the corresponding side roadway 3 that was blasted is used as a support bearing layer for joint support to improve the long-term stability of the roadway surrounding rock against dynamic loads.

[0031] Before and after the blasting, borehole inspection, microseismic monitoring, stress monitoring, and inter-well seismic wave testing were used to quantitatively evaluate the blasting crack propagation range, the stress release effect of the unloading target rock layer 2, and the wave velocity attenuation effect of the wave-dissipating target rock layer 4, in order to verify the anti-scour effect.

[0032] Preferably, the distance L1 between the wave-damping target rock layer 4 and the corresponding side tunnel 3 is 10-15m.

[0033] Preferably, a complete rock layer 7 is retained between the unloading target rock layer 2 and the wave-dissipating target rock layer 4 on the corresponding side. In order to weaken the impact of the seismic waves generated by the blasting of the unloading target rock layer 2 on the near-surface surrounding rock 8, a complete rock layer 7 of a certain thickness should be retained between the unloading target rock layer 2 and the wave-dissipating target rock layer 4. The complete rock layer 7 can be multiple layers of medium-hard rock or a single thick complete rock layer, which is used to attenuate and dissipate the seismic waves from the blasting of the unloading target rock layer 2.

[0034] Preferably, 1 to 2 sets of wave-damping blast holes are added between adjacent unloading blast hole sets to increase the density of blast fractures in the wave-damping target rock layer 4, thereby reducing the energy transfer efficiency of the dynamic load to the roadway when the dynamic load or rockburst occurs in the unloading target rock layer 2.

[0035] Preferably, the spacing L2 between adjacent unloading borehole groups is 20-30m, and the spacing L3 between adjacent wave-damping borehole groups does not exceed 10m. Within roadway 3, if the openings of all unloading boreholes 5 in each unloading borehole group are located within a pre-defined unloading area, then L2 is the distance between the center points of adjacent unloading areas; similarly, if the openings of all wave-damping boreholes 6 in each wave-damping borehole group are located within a pre-defined wave-damping area, then L3 is the distance between the center points of adjacent wave-damping areas. Figure 3 , Figure 5 , Figure 7 In the diagram, point A represents the center point of the unloading area, and point B represents the center point of the wave-damping area.

[0036] Preferably, the wave-damping boreholes 6 in the wave-damping borehole group are arranged in an interlaced manner, that is, the central axes of the wave-damping boreholes 6 in the wave-damping borehole group are spatially skewed, that is, the central axes of any two wave-damping boreholes 6 in the wave-damping borehole group are not in the same plane, so as to form a continuous interwoven burst crack network and improve the wave energy dissipation and absorption capacity.

[0037] Preferably, the diameter of the wave-damping borehole 6 and the unloading borehole 5 is not less than 50mm, and the blocking length of the wave-damping borehole 6 and the unloading borehole 5 is not less than one-third of the borehole length and not less than 6m.

[0038] Preferably, the unloading borehole 5 includes a first charge section 51, a sealing section 52, a second charge section 53, and a plugging section 54; the first charge section 51 is located within the unloading target rock layer 2, the second charge section 53 is located within the wave-damping target rock layer 4, the sealing section 52 is located between the first charge section 51 and the second charge section 53, and the plugging section 54 is located between the second charge section 53 and the borehole opening.

[0039] Preferably, all the explosives in the wave-damping boreholes 6 and the second charge section 53 in the unloading borehole 5 are detonated simultaneously to form an initial weakened zone. Then, the explosives in the first charge section 51 in the unloading borehole 5 are detonated simultaneously. That is, the explosives in the wave-damping target rock layer 4 are detonated first to form a wave-damping layer blasting weakened zone 9, reducing the impact of the explosive blasting in the unloading target rock layer 2 on the near-surface surrounding rock 8.

[0040] Preferably, in the unloading borehole 5, the interval between the first charging section 51 and the second charging section 53 is 50-100ms.

[0041] Example 1: like Figures 2-3 As shown, when stress concentration zones exist in both the roof and floor of the working face in a steeply inclined coal seam 1, i.e., when there are corresponding unloading target rock layers 2, the method for preventing rockburst from occurring in a steeply inclined coal seam using ultra-deep hole blasting unloading and wave-damping coupling includes the following steps: Step 1: Determine the target rock layer 2 for unloading, which is located in the stress concentration zone of the roof and floor of the working face in the steeply inclined coal seam 1. The lithology of the target rock layer 2 for unloading is sandstone or fine-grained rock.

[0042] Step 2: Determine the wave-absorbing target rock layer 4 between the unloading target rock layer 2 and the corresponding side roadway 3 of the steeply inclined coal seam working face. The lithology of the wave-absorbing target rock layer 4 is mainly mudstone, siltstone, or weakened zone of interbedded coal, which has good wave energy absorption characteristics. The distance L1 between the wave-absorbing target rock layer 4 of the roof and the corresponding side roadway 3 is 12m, and the distance L1 between the wave-absorbing target rock layer 4 of the floor and the corresponding side roadway 3 is 10m. In order to weaken the influence of the seismic waves generated by the blasting of the unloading target rock layer 2 on the near-surface surrounding rock 8, a complete rock layer 7 with a thickness of 20m should be retained between the unloading target rock layer 2 and the wave-absorbing target rock layer 4 to attenuate and dissipate the seismic waves from the blasting of the unloading target rock layer 2.

[0043] Step 3: Several unloading blast hole groups are evenly arranged along the length of the tunnel 3. Each unloading blast hole group includes 3 unloading blast holes 5. The unloading blast holes 5 extend through the wave-damping target rock layer 4 and penetrate the unloading target rock layer 2. The openings of the unloading blast holes 5 in the unloading blast hole group are close to each other, and the bottoms of the holes are diverging away from each other. The unloading blast holes 5 use directional drilling technology to control the trajectory of the blast holes. When encountering broken or soft interlayers, protective pipes are set to ensure the quality of hole formation and the safety of explosive loading.

[0044] The spacing L2 between adjacent unloading borehole groups is 20m. The borehole diameter of unloading borehole 5 is 90mm. The length of the blocking section 54 in unloading borehole 5 is 10m, and the length of the sealing section 52 is 20m. The first charging section 51 and the second charging section 53 both adopt a coupled charging structure. The explosive is a coal mine permitted emulsion explosive.

[0045] Step 4: At the locations where unloading blast hole groups are set up in tunnel 3, wave-damping blast hole groups are installed. Each wave-damping blast hole group includes 15 wave-damping blast holes 6, the bottom of which penetrates the target rock layer 4. The openings of the wave-damping blast holes 6 in each wave-damping blast hole group are close to each other, while the bottoms are diverging away. To ensure image clarity, Figure 2 The 15 wave-damping holes 6 in the wave-damping hole group are not fully drawn; only a few wave-damping holes 6 are drawn for illustration. One additional set of wave-damping boreholes is added between adjacent unloading borehole sets, with a spacing L3 of 10m between adjacent wave-damping borehole sets. The borehole diameter of wave-damping borehole 6 is 75mm, and the explosive charge adopts a coupled charging method.

[0046] Step 5: Detonate each wave-damping borehole 6 to generate a dense crack zone, forming a wave-damping layer blast weakening zone 9, and constructing an energy dissipation zone that can absorb and attenuate dynamic loads of rockburst and blast seismic waves. Each unloading borehole 5 is detonated to generate a network of through-hole blast fractures, forming a blast weakening zone 10 in the unloading layer. This destroys the integrity of the target rock layer and eliminates its high-energy-storage structure, weakening the potential energy of the rockburst and reducing energy accumulation.

[0047] In this process, all the explosives in the wave-damping boreholes 6 and the second charge section 53 in the unloading borehole 5 are detonated simultaneously to form an initial weakened zone. Then, the explosives in the first charge section 51 in the unloading borehole 5 are detonated simultaneously. The explosives in the wave-damping target rock layer 4 are detonated first to form a wave-damping layer blasting weakened zone 9, reducing the impact of the explosive blasting in the unloading target rock layer 2 on the near-surface surrounding rock 8.

[0048] In the unloading borehole 5, the interval between the first charging section 51 and the second charging section 53 is 50ms.

[0049] Several monitoring and verification tasks were conducted before and after the blasting: crack propagation morphology was observed using borehole inspection technology; microseismic monitoring systems were used to capture blast-induced microseismic events in real time; the stress release amplitude of the unloaded target rock layer 2 was monitored using a ground stress tester; and the wave velocity attenuation effect of the wave-damping target rock layer 4 was evaluated through inter-well seismic wave testing. If the test results show that the dominant frequency of the blasting seismic wave is below 50Hz and the peak vibration velocity at the free face of the tunnel does not exceed 2cm / s, then the control requirements are met.

[0050] Step 6: After the blasting is completed, the surrounding rock 8 near the surface of the corresponding side roadway 3 that was blasted is used as the support bearing layer. High-strength anchor cables, anchor bolts, shotcrete and steel mesh are used for combined support to improve the long-term stability of the roadway surrounding rock against dynamic loads.

[0051] Example 2: like Figures 4-5 As shown, when there is a stress concentration zone in the roof of the working face of a steeply inclined coal seam 1, but no stress concentration zone in the floor of the working face, the method for preventing rockburst from occurring in a steeply inclined coal seam using ultra-deep hole blasting unloading and wave-damping coupling includes the following steps: Step 1: Determine the target rock layer 2 for unloading in the steeply inclined coal seam 1, where the stress concentration zone of the working face roof is located. The lithology of the target rock layer 2 for unloading is sandstone or fine-grained rock.

[0052] Step 2: Determine the wave-absorbing target rock layer 4 between the unloading target rock layer 2 and the corresponding side roadway 3 of the steeply inclined coal seam working face. The lithology of the wave-absorbing target rock layer 4 is mainly mudstone, siltstone or coal seam weakening zone, which has good wave energy absorption characteristics. The distance L1 between the wave-absorbing target rock layer 4 of the roof and the corresponding side roadway 3 is 15m. In order to weaken the influence of the seismic waves generated by the blasting of the unloading target rock layer 2 on the near-surface surrounding rock 8, a complete rock layer 7 with a thickness of 25m should be retained between the unloading target rock layer 2 and the wave-absorbing target rock layer 4 to attenuate and dissipate the seismic waves from the blasting of the unloading target rock layer 2.

[0053] Step 3: Several unloading blast hole groups are evenly arranged along the length of the tunnel 3. Each unloading blast hole group includes 3 unloading blast holes 5. The unloading blast holes 5 extend through the wave-damping target rock layer 4 and penetrate the unloading target rock layer 2. The openings of the unloading blast holes 5 in the unloading blast hole group are close to each other, and the bottoms of the holes are diverging away from each other. The unloading blast holes 5 use directional drilling technology to control the trajectory of the blast holes. When encountering broken or soft interlayers, protective pipes are set to ensure the quality of hole formation and the safety of explosive loading.

[0054] The spacing L2 between adjacent unloading borehole groups is 24m. The borehole diameter of unloading borehole 5 is 90mm. The length of the blocking section 54 in unloading borehole 5 is 15m, and the length of the sealing section 52 is 25m. The first charging section 51 and the second charging section 53 both adopt a coupled charging structure. The explosive is a coal mine permitted emulsion explosive.

[0055] Step 4: At the locations where unloading blast hole groups are set up in tunnel 3, wave-damping blast hole groups are installed. Each wave-damping blast hole group includes 15 wave-damping blast holes 6, the bottom of which penetrates the target rock layer 4. The openings of the wave-damping blast holes 6 in each wave-damping blast hole group are close to each other, while the bottoms are diverging away. To ensure image clarity, Figure 4 The 15 wave-damping holes 6 in the wave-damping hole group are not fully drawn; only a few wave-damping holes 6 are drawn for illustration. Two additional wave-damping borehole groups are added between adjacent unloading borehole groups, with a spacing L3 of 8m between adjacent wave-damping borehole groups. The borehole diameter of wave-damping borehole 6 is 75mm, and the explosive charge adopts a coupled charging method.

[0056] Step 5: Detonate each wave-damping borehole 6 to generate a dense crack zone, forming a wave-damping layer blast weakening zone 9, and constructing an energy dissipation zone that can absorb and attenuate dynamic loads of rockburst and blast seismic waves. Each unloading borehole 5 is detonated to generate a network of through-hole blast fractures, forming a blast weakening zone 10 in the unloading layer. This destroys the integrity of the target rock layer and eliminates its high-energy-storage structure, weakening the potential energy of the rockburst and reducing energy accumulation.

[0057] In this process, all the explosives in the wave-damping boreholes 6 and the second charge section 53 in the unloading borehole 5 are detonated simultaneously to form an initial weakened zone. Then, the explosives in the first charge section 51 in the unloading borehole 5 are detonated simultaneously. The explosives in the wave-damping target rock layer 4 are detonated first to form a wave-damping layer blasting weakened zone 9, reducing the impact of the explosive blasting in the unloading target rock layer 2 on the near-surface surrounding rock 8.

[0058] In the unloading borehole 5, the interval between the first charging section 51 and the second charging section 53 is 75ms.

[0059] Several monitoring and verification tasks were conducted before and after the blasting: crack propagation morphology was observed using borehole inspection technology; microseismic monitoring systems were used to capture blast-induced microseismic events in real time; the stress release amplitude of the unloaded target rock layer 2 was monitored using a ground stress tester; and the wave velocity attenuation effect of the wave-damping target rock layer 4 was evaluated through inter-well seismic wave testing. If the test results show that the dominant frequency of the blasting seismic wave is below 50Hz and the peak vibration velocity at the free face of the tunnel does not exceed 2cm / s, then the control requirements are met.

[0060] Step 6: After the blasting is completed, the surrounding rock 8 near the surface of the corresponding side roadway 3 that was blasted is used as the support bearing layer. High-strength anchor cables, anchor bolts, shotcrete and steel mesh are used for combined support to improve the long-term stability of the roadway surrounding rock against dynamic loads.

[0061] Example 3: like Figures 6-7 As shown, when there is a stress concentration zone in the floor of the working face of a steeply inclined coal seam 1, but no stress concentration zone in the roof of the working face, the method for preventing rockburst from occurring in a steeply inclined coal seam using ultra-deep hole blasting unloading and wave-damping coupling includes the following steps: Step 1: Determine the target rock layer 2 for unloading in the steeply inclined coal seam 1, where the stress concentration zone of the working face floor is located. The rock type of the target rock layer 2 is sandstone or fine-grained rock.

[0062] Step 2: Determine the wave-absorbing target rock layer 4 between the unloading target rock layer 2 and the corresponding side roadway 3 of the steeply inclined coal seam working face. The lithology of the wave-absorbing target rock layer 4 is mainly mudstone, siltstone or coal seam weakening zone, which has good wave energy absorption characteristics. The distance L1 between the wave-absorbing target rock layer 4 of the floor and the corresponding side roadway 3 is 15m. In order to weaken the influence of the seismic waves generated by the blasting of the unloading target rock layer 2 on the near-surface surrounding rock 8, a complete rock layer 7 with a thickness of 30m should be retained between the unloading target rock layer 2 and the wave-absorbing target rock layer 4 to attenuate and dissipate the seismic waves from the blasting of the unloading target rock layer 2.

[0063] Step 3: Several unloading blast hole groups are evenly arranged along the length of the tunnel 3. Each unloading blast hole group includes 4 unloading blast holes 5. The unloading blast holes 5 extend through the wave-damping target rock layer 4 and penetrate the unloading target rock layer 2. The openings of the unloading blast holes 5 in the unloading blast hole group are close to each other, and the bottoms of the holes are diverging away from each other. The unloading blast holes 5 use directional drilling technology to control the trajectory of the blast holes. When encountering broken or soft interlayers, protective pipes are set to ensure the quality of hole formation and the safety of explosive loading.

[0064] The spacing L2 between adjacent unloading borehole groups is 30m. The borehole diameter of unloading borehole 5 is 90mm. The length of the blocking section 54 in unloading borehole 5 is 15m, and the length of the sealing section 52 is 30m. The first charging section 51 and the second charging section 53 both adopt a coupled charging structure. The explosive is a coal mine permitted emulsion explosive.

[0065] Step 4: At the locations where unloading blast hole groups are set up in tunnel 3, wave-damping blast hole groups are installed. Each wave-damping blast hole group includes 13 wave-damping blast holes 6, the bottom of which penetrates the target rock layer 4. The openings of the wave-damping blast holes 6 in each wave-damping blast hole group are close to each other, while the bottoms are diverging away. To ensure image clarity, Figure 6 The 13 wave-damping holes 6 in the diagram are not fully drawn; only a few wave-damping holes 6 are drawn for illustration. Two additional wave-damping borehole groups are added between adjacent unloading borehole groups, with a spacing L3 of 10m between adjacent wave-damping borehole groups. The borehole diameter of wave-damping borehole 6 is 75mm, and the explosive charge adopts a coupled charging method.

[0066] Step 5: Detonate each wave-damping borehole 6 to generate a dense crack zone, forming a wave-damping layer blast weakening zone 9, and constructing an energy dissipation zone that can absorb and attenuate dynamic loads of rockburst and blast seismic waves. Each unloading borehole 5 is detonated to generate a network of through-hole blast fractures, forming a blast weakening zone 10 in the unloading layer. This destroys the integrity of the target rock layer and eliminates its high-energy-storage structure, weakening the potential energy of the rockburst and reducing energy accumulation.

[0067] In this process, all the explosives in the wave-damping boreholes 6 and the second charge section 53 in the unloading borehole 5 are detonated simultaneously to form an initial weakened zone. Then, the explosives in the first charge section 51 in the unloading borehole 5 are detonated simultaneously. The explosives in the wave-damping target rock layer 4 are detonated first to form a wave-damping layer blasting weakened zone 9, reducing the impact of the explosive blasting in the unloading target rock layer 2 on the near-surface surrounding rock 8.

[0068] In the unloading borehole 5, the interval between the first charge section 51 and the second charge section 53 is 100ms.

[0069] Several monitoring and verification tasks were conducted before and after the blasting: crack propagation morphology was observed using borehole inspection technology; microseismic monitoring systems were used to capture blast-induced microseismic events in real time; the stress release amplitude of the unloaded target rock layer 2 was monitored using a ground stress tester; and the wave velocity attenuation effect of the wave-damping target rock layer 4 was evaluated through inter-well seismic wave testing. If the test results show that the dominant frequency of the blasting seismic wave is below 50Hz and the peak vibration velocity at the free face of the tunnel does not exceed 2cm / s, then the control requirements are met.

[0070] Step 6: After the blasting is completed, the surrounding rock 8 near the surface of the corresponding side roadway 3 that was blasted is used as the support bearing layer. High-strength anchor cables, anchor bolts, shotcrete and steel mesh are used for combined support to improve the long-term stability of the roadway surrounding rock against dynamic loads.

[0071] While specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, they are not intended to limit the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preventing rock burst in an ultra-deep hole blasting unloading and damping coupling of steeply inclined coal seams, characterized in that, The method comprises the following steps: Step 1, determining the unloading target rock stratum where the stress concentration zone of the roof and / or floor of the working face in the steeply inclined coal seam is located; Step 2, determining the wave-absorbing target rock stratum between the unloading target rock stratum and the corresponding side roadway of the working face in the steeply inclined coal seam; Step 3, uniformly arranging a plurality of unloading blast hole groups in the roadway along the length direction of the roadway, each unloading blast hole group comprising a plurality of unloading blast holes, the unloading blast holes extending through the wave-absorbing target rock stratum and penetrating the unloading target rock stratum; Step 4, arranging a wave-absorbing blast hole group at the position where the unloading blast hole group is arranged in the roadway, each wave-absorbing blast hole group comprising a plurality of wave-absorbing blast holes, the bottom of the wave-absorbing blast hole penetrating the wave-absorbing target rock stratum; Step 5, initiating each wave-absorbing blast hole to generate a dense crack zone and form a wave-absorbing layer blasting weakened zone, thereby constructing an energy dissipation zone capable of absorbing and attenuating the impact ground pressure dynamic load and blasting seismic wave; Step 6, initiating each unloading blast hole to generate a penetrating blast crack network and form an unloading layer blasting weakened zone, thereby destroying the integrity of the unloading target rock stratum, eliminating the high energy storage structure thereof, weakening the impact ground pressure occurrence potential energy and reducing the energy accumulation; In the energy transmission path of the unloading blast hole blasting, the energy dissipation zone absorbs and attenuates the impact ground pressure dynamic load and blasting seismic wave; Step 7, after the blasting is completed, the near-surface surrounding rock of the corresponding side roadway where the blasting is performed is taken as a support bearing layer for combined support, so as to improve the long-term stability of the roadway surrounding rock against dynamic load.

2. The bumping pressure super deep hole blasting unloading and damping coupling prevention method for steeply inclined coal seam according to claim 1, characterized in that, The distance L1 between the wave-absorbing target rock stratum and the corresponding side roadway is 10-15 m.

3. The bumping pressure super deep hole blasting unloading and damping coupling prevention method for steeply inclined coal seam according to claim 1, characterized in that, The complete rock stratum is reserved between the unloading target rock stratum and the wave-absorbing target rock stratum of the corresponding side.

4. The bumping pressure super deep hole blasting unloading and damping coupling prevention method for steeply inclined coal seam according to claim 1, characterized in that, 1-2 wave-absorbing blast hole groups are added between adjacent unloading blast hole groups.

5. The steeply inclined coal seam rock burst ultra-deep hole blasting unloading and damping coupling prevention method of claim 4, wherein, The interval L2 between adjacent unloading blast hole groups is 20-30 m, and the interval L3 between adjacent wave-absorbing blast hole groups is not more than 10 m.

6. The steeply inclined coal seam rock burst ultra-deep hole blasting unloading and damping coupling prevention method of claim 1, wherein, The wave-absorbing blast holes in the wave-absorbing blast hole group are arranged in a staggered manner.

7. The steeply inclined coal seam rock burst ultra-deep hole blasting unloading and damping coupling prevention method of claim 1, wherein, The diameters of the wave-absorbing blast holes and the unloading blast holes are not less than 50 mm, and the plugging length of the wave-absorbing blast holes and the unloading blast holes is not less than one third of the length of the blast hole and not less than 6 m.

8. The bumping pressure super deep hole blasting unloading and damping coupling prevention method for steeply inclined coal seam according to claim 1, characterized in that, The unloading blast hole comprises a first charging section, a partition section, a second charging section and a plugging section, the first charging section is located in the unloading target rock stratum, the second charging section is located in the wave-absorbing target rock stratum, the partition section is located between the first charging section and the second charging section, and the plugging section is located between the second charging section and the blast hole mouth.

9. The steeply inclined coal seam rock burst ultra-deep hole blasting unloading and damping coupling prevention method of claim 8, wherein, The explosives in all wave-absorbing blast holes and the second charging section of the unloading blast hole are initiated simultaneously to form an initial weakened zone, and then the explosives in the first charging section of the unloading blast hole are initiated simultaneously.

10. The bumping pressure super deep hole blasting unloading and damping coupling prevention method for steeply inclined coal seam according to claim 8, characterized in that, The interval between the first charging section and the second charging section in the unloading blast hole is 50-100 ms.

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