A method for pre-unloading pressure of floor-type rock burst in thick coal seam tunneling working face

Abstract

The application discloses a kind of thick coal seam heading face floor type rock burst's advance pressure relief method, belong to coal mine safety mining technical field, by designing specific drill rod connecting piece to the adaptation modification of excavating anchor integrated machine drilling machine, it can be connected support anchor rod drill rod or large diameter drill rod according to need, realize the quick switching of heading and drilling pressure relief;By comprehensive index method, complete impact risk assessment and determine the pressure relief area, design pressure relief drilling parameters, use the excavating anchor integrated machine after modification to complete the large diameter drilling pressure relief of head and two sides simultaneously, and complete pressure relief effect test by multiple means.The application realizes the seamless connection of thick coal seam roadway excavation, support, pressure relief three processes, achieves "one machine multi-use", greatly reduces equipment cost and labor intensity, significantly improves pressure relief construction and roadway excavation efficiency, realizes the advance source control of floor type rock burst, effectively reduces the risk of rock burst.

Description

Technical Field

[0001] This invention belongs to the field of coal mine safety mining technology, and specifically relates to an advanced decompression method for bottom plate type rockburst in thick coal seam tunneling faces, which is particularly suitable for tunneling faces of thick coal seams with a thickness of more than 5m that are prone to rockburst, using a tunneling and anchoring integrated machine. Background Technology

[0002] In the process of tunneling through thick coal seams (especially those with a thickness of more than 5m) with a tendency to rockburst, in order to ensure the stability of the roof, the method of tunneling along the roof is usually adopted. A certain thickness of bottom coal is left at the bottom of the tunnel. This bottom coal is the main source of danger of bottom-type rockburst and needs to be reduced by pressure relief treatment to reduce the risk of rockburst.

[0003] In existing technologies, large-diameter drilling is commonly used for pressure relief treatment of bottom coal seams. The conventional construction method involves using handheld or tracked special-purpose drilling rigs to drill pressure relief holes. However, handheld drilling has drawbacks such as high labor intensity, low construction efficiency, long working time for personnel in dangerous areas at the face, and high safety risks. Tracked special-purpose drilling rigs have problems such as high equipment procurement costs, large space occupation in the roadway, inconvenient relocation, and complex process connections. Moreover, neither of these construction methods can be integrated with roadway excavation and support processes, resulting in a disconnect between pressure relief construction and excavation operations. This severely restricts roadway excavation efficiency and fails to achieve proactive source control of bottom-type rockbursts.

[0004] Currently, integrated tunneling and anchoring machines are widely used in thick coal seam roadway excavation. These machines are equipped with drilling rigs that have high drilling power and high hole-forming efficiency, and can simultaneously complete roadway excavation and anchor mesh support operations. However, the existing integrated tunneling and anchoring machines can only be used with small-diameter support anchor drill rods and cannot be directly matched with large-diameter pressure relief drill rods. They do not have the function of pressure relief drilling, and the equipment's functions are not fully utilized. Furthermore, there is no advanced pressure relief implementation plan to match the integrated tunneling and anchoring machines. Therefore, this is one of the research directions in this industry. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides an advanced decompression method for floor-type rockburst in thick coal seam tunneling faces. The aim is to solve the problems of high equipment costs, high labor intensity, low construction efficiency, disconnect between tunneling-support-decompression processes, and inability to achieve simultaneous decompression and pre-decompression treatment in the treatment of floor-type rockburst in thick coal seam tunneling faces using existing construction methods. This method enables multi-purpose equipment and seamless process integration, improving the decompression treatment effect and tunneling efficiency, and reducing the risk of rockburst occurrence.

[0006] To achieve the above objectives, the technical solution adopted by this invention is: an advanced decompression method for floor-type rockburst in thick coal seam tunneling faces, used for the prevention and control of floor-type rockburst during the tunneling process of thick coal seam roadways with rockburst tendency, wherein the thick coal seam is a coal seam with a thickness of more than 5m and a bottom coal seam left along the roof during tunneling, and the method uses a large-diameter borehole decompression method to decompress the rockburst hazard area, including the following steps: S1. Modification and overall debugging of drill rod connectors for integrated tunneling and anchoring drilling rigs to match large-diameter drill rods: Design drill rod connectors and install them on the starter head to connect support anchor drill rods or large-diameter drill rods as needed.

[0007] S2. Use the comprehensive index method to evaluate the impact risk and determine the borehole pressure relief area: comprehensively analyze the geological factors and mining technology conditions of the mining area, determine the influence weight of each factor on rockburst, calculate the rockburst risk index corresponding to the geological factors and mining technology conditions respectively, take the maximum value of the two as the comprehensive rockburst risk index, evaluate and predict the rockburst risk level based on the comprehensive index, and determine the impact risk area as the pressure relief borehole construction area.

[0008] S3. Determine the diameter of the face relief borehole and the two side relief boreholes: The diameter of the coal seam borehole is in the range of 100mm~200mm, and the specific value is determined according to the actual working conditions of the mine tunneling face.

[0009] S4. Determine the depth of the face relief borehole and the two side relief boreholes: The depth of the relief borehole must exceed the peak position of the coal face support pressure.

[0010] S5. Determine the spacing D of the pressure relief boreholes: Based on the core principle that the pressure relief zones around each borehole are interconnected and form a continuous weakening zone, the spacing of the pressure relief boreholes is in the range of 1m to 3m.

[0011] S6. Determine the arrangement of pressure relief boreholes: Pressure relief boreholes are divided into two categories: head boreholes and side boreholes. During the working face excavation, the head boreholes are arranged parallel to the roadway axis, and the side boreholes are arranged perpendicular to the roadway sides.

[0012] S7. Use the tunneling and anchoring machine to perform large-diameter drilling for pressure relief at the face and both sides: When the tunneling and anchoring machine is working normally, connect the support anchor drill rod to the starter head through the drill rod connector in step one; when large-diameter drilling for pressure relief is required, remove the support anchor drill rod and connect the large-diameter pressure relief drill rod to the starter head through the drill rod connector in step one; then construct pressure relief drilling holes at the face and both sides according to the preset parameters in steps S3 to S6.

[0013] S8. Pressure Relief Effect Inspection: The pressure relief effect inspection is carried out using the drill cuttings method as the core inspection method, combined with one or two auxiliary monitoring methods such as online stress monitoring, electromagnetic radiation monitoring, and microseismic monitoring. After all indicators do not exceed the critical value, the advanced pressure relief process is completed, and subsequent normal tunneling construction is organized.

[0014] Further, in step S1, the drill pipe connector includes a first connecting section and a second connecting section, which are coaxially connected. The outer diameter of the first connecting section matches the inner diameter of the support anchor drill pipe, and the outer diameter of the second connecting section matches the inner diameter of the large-diameter drill pipe, with the outer diameter of the second connecting section being larger than that of the first connecting section. In use, one end of the second connecting section of the drill pipe connector is fitted onto the starter head. If it is necessary to connect the support anchor drill pipe, the first connecting section is inserted into the tail of the support anchor drill pipe and fixed with a pin. If it is necessary to connect the large-diameter... For the drill rod, the first and second connecting sections are inserted into the tail of the large-diameter drill rod and fixed with pins; the front end of the drill rod is stabilized by a clamp and a drill bit holder; the original drill sleeve of the tunneling and anchoring machine is modified into a drill rod connector that connects two different drill rods, so that it can simultaneously meet the construction requirements of anchor bolt drilling and large-diameter pressure relief drilling; after the drill rod is installed and fixed, the tunneling and anchoring machine is tested under no-load to verify the rotation accuracy, drilling pressure stability and anti-vibration effect of the drilling machine, ensuring that the equipment meets the requirements of large-diameter drilling operations.

[0015] Furthermore, in step S2, the comprehensive index for assessing the risk level of rockburst at the working face is... Calculate using the following formula: In the formula, The rockburst hazard index is determined by geological factors. The rockburst hazard index is determined by factors related to mining technology. in, and Calculate using the following formulas respectively: (1) (2) In the formula: , which is the evaluation index of the i-th rockburst influencing factor; is the maximum evaluation index of the i-th rockburst influencing factor; n1 is the number of geological factors; n2 is the number of mining technology factors.

[0016] Based on the composite index The degree of rockburst hazard is quantitatively divided into four levels: no rockburst hazard, weak rockburst hazard, moderate rockburst hazard, and strong rockburst hazard.

[0017] Furthermore, in step S4, the depth of the parallel pressure relief borehole at the face is... , This refers to the distance between the peak bearing pressure at the tunneling face and the coal face. The value should be no less than 8m; the depth of the bottom coal depressurization borehole at the face is... , and The included angle is α; the depth of the pressure relief boreholes on both sides of the tunnel. It shall not be less than the distance between the peak value of the roadway side support pressure and the coal wall, and shall not be less than 1.5 to 2 times the width of the roadway.

[0018] Furthermore, in step (5), the spacing D of the pressure relief boreholes is first calculated using formula (3), and then adjusted using empirical analogy to finally determine the spacing. The calculation formula is as follows: (3) In the formula: D is the spacing between pressure relief holes, in meters; k is the hazard correction coefficient for the spacing between pressure relief holes, taken as 18.84 for weak impact hazard areas, 12.56 for moderate impact hazard areas, and 6.28 for strong impact hazard areas; d is the diameter of the pressure relief borehole, in meters; K is the coal deformation modulus index. , where λ is the post-peak softening modulus of the coal body and E is the pre-peak elastic modulus of the coal body.

[0019] Furthermore, in step S6, for the weak and moderate impact hazard zones, two pre-decompression boreholes are constructed at the face of the tunneling roadway, with the specific arrangement as follows: First, conduct parallel pressure relief drilling at the construction face: the borehole is parallel to the roadway axis, and the borehole diameter... At the head of the roadway floor The middle position slightly to the right Construction site, drilling depth ; Each tunnel excavation Distance, i.e., the remaining distance in front of the tunneling working face. When the pressure relief protection zone of a certain length is reached, the next round of drilling can be carried out to achieve drilling as it is excavated.

[0020] Then, construct the coal seam pressure relief borehole at the face: at the face, at a distance from the roadway floor... The middle position slightly to the left Construction site, borehole diameter Drilling depth The drilling angle is α angled to the dip angle of the coal seam to ensure that the final borehole position enters the coal seam floor; each time the roadway is excavated... Based on the distance, the next round of drilling will be carried out to achieve drilling as needed.

[0021] Furthermore, in step S6, the arrangement of the pressure relief boreholes on both sides of the tunnel is as follows: The construction location of the pre-pressure relief drilling on the side of the tunnel lags behind the face by a distance. The span is 5m to 20m, and the construction is completed in one go according to the anti-erosion design requirements.

[0022] The borehole diameter for weak and moderate impact hazard zones is The drilling depth is The drilling spacing is The height of the borehole center from the roadway floor is , Adjustments were made based on the on-site coal seam conditions, and the drilling direction was perpendicular to the roadway axis.

[0023] Furthermore, in step S7, after the tunneling and anchoring machine completes a single cycle of tunneling and support operations, pressure relief drilling is carried out; after the pressure relief drilling reaches the design depth, the drilling rig idles for no less than 5 minutes; if the drilling cannot reach the design depth, the drilling position is changed and construction is restarted until the drilling depth meets the design requirements.

[0024] Furthermore, in step S8, when using the drill cuttings method for inspection, the number of inspection holes shall not be less than 2 per side, the spacing between inspection holes shall not be greater than 10m, and the amount of coal powder and the dynamic phenomenon index shall not exceed the critical value to confirm that there are no abnormalities.

[0025] When using auxiliary monitoring methods for testing, the microseismic testing range is within 50m of the pre-decompression area, and the testing time is not less than 30 minutes; the online stress testing uses the rate of change index of 1-2 sets of stress gauges within 40m of the pre-decompression area, and the testing time is not less than 30 minutes; the electromagnetic radiation testing range is within 50m of the pre-decompression area, and the number of monitoring points is not less than 5.

[0026] After all the above-mentioned drill cuttings inspection and auxiliary monitoring methods showed no abnormalities, normal construction proceeded. If any abnormalities were detected, the handling procedure was carried out in accordance with the warning indicators of the corresponding monitoring method.

[0027] Compared with the prior art, the present invention has the following advantages: 1. This invention adapts and modifies existing tunneling and anchoring integrated drilling machines by designing special drill rod connectors, enabling them to simultaneously perform anchor bolt construction and large-diameter pressure relief drilling functions. This eliminates the need to purchase additional handheld or crawler-mounted special pressure relief drilling machines, significantly reducing equipment procurement and maintenance costs, while also reducing the equipment's occupation of roadway space and improving the utilization rate of roadway working space.

[0028] 2. This invention utilizes an integrated tunneling and anchoring machine to achieve integrated operation of three processes: tunneling, support, and pressure relief. After completing a single tunneling and support cycle, a large-diameter drill rod can be directly switched to carry out pressure relief drilling construction without waiting for a dedicated drilling rig to arrive or be moved. This completely solves the problem of process disconnection in traditional processes, significantly shortens the waiting time for process connection, and at the same time, utilizes the drilling advantage of the high-power drilling rig of the integrated tunneling and anchoring machine to significantly improve the hole formation efficiency of pressure relief drilling, realizes pressure relief as tunneling, and greatly improves the overall tunneling efficiency.

[0029] 3. This invention uses a tunneling and anchoring integrated machine to mechanize the construction of large-diameter pressure relief boreholes, replacing the traditional manual construction method of handheld drilling rigs. This significantly reduces the labor intensity of workers and also reduces the time that workers spend in the dangerous area of ​​head-on impact, thus reducing the safety risks of personnel operations from the source.

[0030] 4. This invention accurately divides the impact hazard level and pressure relief treatment area using a comprehensive index method, designs pressure relief drilling parameters accordingly, and determines the drilling spacing through theoretical calculations combined with empirical analogies to ensure that the pressure relief zones of the drilling holes are interconnected to form a continuous weakening zone. At the same time, the pressure relief effect is completed through the drill cuttings method combined with multi-dimensional monitoring methods to ensure the pressure relief treatment effect, achieve advanced source treatment of base plate type rockburst, and effectively reduce the risk of rockburst occurrence. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the component structure after the drilling rig of the integrated tunneling and anchoring machine in this invention has been adapted and modified.

[0032] Figure 2 for Figure 1 A schematic diagram of the structure of the clamping device component.

[0033] Figure 3 for Figure 1 A schematic diagram of the structure of the drill pipe connector component.

[0034] Figure 4 This is a plan view of the cyclic operation of the decompression drilling at the tunnel face in this invention.

[0035] Figure 5 for Figure 4 Cross-sectional layout of the pressure relief borehole at the middle face.

[0036] Figure 6 This is a plan view of the pressure relief drilling holes on both sides of the tunnel in this invention.

[0037] Figure 7 for Figure 6 A schematic diagram of the AA section.

[0038] In the diagram: A - Clamping device component; B - Drill rod connecting component; 1 - Drill rod; 2 - Drill rod support; 3 - Clamping device; 4 - Center point; 5 - Roadway face; 6 - Roadway floor; 7 - Coal seam floor; 8 - Parallel pressure relief borehole at the face; 9 - Pressure relief borehole at the bottom coal seam at the face; 10 - Roadway roof; 11 - Roadway sidewall; 12 - First connecting section; 13 - Second connecting section. Detailed Implementation

[0039] The present invention will be further described below.

[0040] like Figure 1 As shown, this embodiment is applied to the 3105 return airway tunneling face of a certain mine. The specific working conditions are as follows: the average thickness of the coal seam being mined in this working face is 8.2m, the uniaxial compressive strength of the coal seam is 16.8MPa, and it has a strong tendency to impact; the roadway is tunneled along the roof, leaving 3.2m of bottom coal, the net width of the roadway is 5.2m, and the net height is 3.5m. The EBZ260M-2 roadheader-anchor integrated machine is used to complete the roadway tunneling and anchor mesh support operations. During the tunneling process, there is a significant risk of bottom-type rockburst.

[0041] This embodiment specifically includes the following steps: S1. Modification and overall debugging of drill rod connectors for integrated tunneling and anchoring drilling rigs to match large-diameter drill rods. To address the limitation of existing drilling rigs in integrated tunneling and anchoring machines, which can only accommodate small-diameter anchor rods, a specialized stepped drill rod connector was designed. This connector comprises a first connecting section and a second connecting section, coaxially connected. The outer diameter of the first connecting section matches the inner diameter of the support anchor rod, while the outer diameter of the second connecting section matches the inner diameter of the large-diameter drill rod, and the outer diameter of the second connecting section is larger than that of the first connecting section. In use, one end of the second connecting section is fitted onto the starter head. If a support anchor rod needs to be connected, the first connecting section is inserted into the tail of the support anchor rod and secured with a pin. If a large-diameter drill rod needs to be connected, both the first and second connecting sections are inserted into the tail of the large-diameter drill rod and secured with pins. The drill rod's front end is stabilized and limited by a clamp and a drill bit holder. The existing drill sleeve of the integrated tunneling and anchoring machine is modified to accommodate two different drill rods, enabling it to simultaneously meet the construction requirements of φ22mm support anchor drilling and φ150mm large-diameter pressure relief drilling. After the drill rod is installed and fixed, the tunneling and anchoring machine is tested under no-load conditions. It is run continuously under no-load for 10 minutes to verify the rotation accuracy, drilling pressure stability and anti-vibration effect of the drilling machine. After the test is qualified, it is ready for on-site construction.

[0042] S2. Use the comprehensive index method to evaluate the impact hazard and determine the borehole pressure relief zone. A comprehensive analysis was conducted on the geological factors and mining technology conditions of the working face. Geological factors included coal seam thickness, coal seam impact tendency, roof strata structure, and geological formations. Mining technology conditions included working face depth, roadway dimensions, tunneling speed, and bearing pressure distribution. The weights and evaluation indices of each influencing factor were determined using an expert scoring method, and the geological impact hazard index was calculated for each factor. Impact risk index of mining technology factors The composite index is obtained by taking the maximum of the two values. Based on industry regulations, the area was assessed as a medium-impact hazard zone and designated as a pressure relief drilling area.

[0043] S3. Determine the diameter of the pressure relief borehole. Based on the hardness of the coal seam, the impact hazard level, and the drilling capacity of the integrated tunneling and anchoring machine, the diameter of the pressure relief boreholes at the face and both sides was determined to be 150mm.

[0044] S4. Determine the depth of the pressure relief borehole. Through on-site stress monitoring, it was determined that the peak pressure of the face support was 10m away from the coal wall, and the peak pressure of the roadway side support was 7m away from the coal wall.

[0045] Determine the depth of parallel pressure relief drilling at the face. Ensure that the drilling depth exceeds the peak position of the support pressure, and always maintain a pressure relief protection zone of not less than 10m in front of the tunneling face; the depth of the bottom coal pressure relief drilling at the face. The downward inclination angle α between the borehole and the roadway axis is -12°, ensuring that the final borehole position penetrates the bottom coal and enters the coal seam floor by no less than 0.5m; the depth of the pressure relief boreholes on both sides of the roadway... It meets the requirement of exceeding the peak position of the support pressure and not less than 1.5 times the roadway width.

[0046] S5. Determine the spacing D of the pressure relief boreholes. Laboratory mechanical tests revealed that the pre-peak elastic modulus of the coal face was E=1.2GPa, and the post-peak softening modulus was λ=0.3GPa. The deformation modulus index of the coal face was calculated. For the medium impact hazard zone, the hazard correction factor k is taken as 12.56, and the borehole diameter d = 0.15m. Substitute these values ​​into formula (3) to calculate: Based on field experience and analogy, the final drilling spacing at the face was determined to be 2m, and the spacing between the pressure relief drilling holes on both sides of the roadway was also determined to be 2m, to ensure that the pressure relief zones of each drilling hole are interconnected and form a continuous weakening zone.

[0047] S6. Determine the arrangement of the pressure relief boreholes. ① Drilling layout at the tunnel face: Two pre-decompression boreholes were drilled at the tunnel face, and the specific layout is as follows: Parallel pressure relief drilling at the face: The borehole is parallel to the roadway axis, with a diameter of 150mm. It is drilled 0.5m to the right of the middle position of the roadway, 1.7m from the roadway floor, and the drilling depth is 20m. The next round of drilling is carried out every 10m of roadway excavation, that is, when there is 10m of pressure relief protection zone left in front of the excavation working face, so as to achieve drilling as excavation progresses.

[0048] Decompression borehole at the face: The borehole is constructed 0.5m to the left of the middle position of the roadway, 1.7m from the roadway floor. The borehole diameter is 150mm, the borehole depth is 22m, the borehole is inclined downward at 3°, and the final borehole position enters the coal seam floor 0.8m. The next round of borehole construction is carried out simultaneously every 10m of roadway excavation.

[0049] ② Drilling layout on both sides of the roadway: The drilling position of the pressure relief drilling on the mining side of the roadway is 10m behind the face and is completed in one go; the drilling diameter is 150mm, the drilling depth is 10m, the drilling spacing is 2m, the center of the drilling is 1.5m away from the roadway floor, the construction direction is perpendicular to the roadway axis, and the construction is carried out perpendicular to the roadway side into the coal body.

[0050] S7. Use a tunneling and anchoring machine to perform large-diameter borehole pressure relief. After the tunneling and anchoring machine completes a single tunneling cycle (10m advance) and full-face anchor mesh support operation, the machine is stopped and locked. The support anchor drill rod is removed, and the φ150mm large-diameter pressure relief drill rod is connected to the starter head through the drill rod connector in step one. After being firmly fixed with pins, the machine is moved to a position 10m behind the face to construct the pressure relief drill holes on both sides.

[0051] After each borehole reaches the designed depth, the drilling rig is kept idle for 6 minutes to fully remove coal dust from the borehole, expand the development range of pressure relief fractures in the borehole, and improve the pressure relief effect. If hard rock is encountered during construction and drilling cannot reach the designed depth, a new borehole is opened within 0.5m of the original borehole until the borehole depth meets the design requirements.

[0052] S8. Pressure Relief Effect Inspection Using the drill cuttings method as the core inspection method, three inspection holes were constructed on each side of the pressure relief area. The inspection holes were spaced 8m apart, with a diameter of 42mm and a depth of 12m. Coal dust was collected and weighed every meter, and dynamic phenomena such as stuck drill, drill suction, and abnormal noise in the hole were recorded simultaneously. The inspection results showed that the amount of coal dust per meter in each inspection hole was lower than the critical value for the area, and there were no abnormal dynamic phenomena, indicating that the pressure relief effect met the standards.

[0053] Simultaneously, online stress monitoring was used for auxiliary verification. Monitoring data from two sets of stress gauges within a 30m radius of the decompression area were retrieved and continuously monitored for 40 minutes. The stress change rate was lower than the warning threshold, and there was no abnormal increase in stress. Finally, it was confirmed that the decompression effect was qualified, and subsequent tunneling operations were organized normally on site.

[0054] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for pre-decompression of floor-type rockburst in a thick coal seam tunneling face, characterized in that, Includes the following steps: S1. Design a drill pipe connector and install it on the starter head to connect the support anchor drill pipe or large-diameter drill pipe as needed. S2. Comprehensively analyze the geological factors and mining technology conditions of the mining area, determine the influence weight of each factor on rockburst, calculate the rockburst hazard index corresponding to the geological factors and mining technology conditions respectively, take the maximum value of the two as the comprehensive rockburst hazard index, evaluate and predict the rockburst hazard level based on the comprehensive index, and determine the rockburst hazard area as the pressure relief drilling construction area. S3. Determine the range of values ​​for the diameter of the coal seam borehole; S4. Determine the depth of the face relief borehole and the two side relief boreholes, and the depth of the relief boreholes must exceed the peak position of the coal wall support pressure. S5. The spacing of the pressure relief boreholes is determined based on the core principle that the pressure relief zones around each borehole are interconnected and form a continuous weakening zone. S6. Pressure relief boreholes are divided into two categories: head boreholes and side boreholes. During the working face excavation, the head boreholes are arranged parallel to the roadway axis, and the side boreholes are arranged perpendicular to the roadway sides. S7. When the drilling rig of the integrated tunneling and anchoring machine is working normally, connect the support anchor drill rod to the starter head through the drill rod connector in step one; when it is necessary to perform pressure relief drilling of large diameter holes, remove the support anchor drill rod and connect the large diameter pressure relief drill rod to the starter head through the drill rod connector in step one; then construct pressure relief drilling holes at the face and both sides according to the preset parameters of steps S3 to S6. S8. Using the drill cuttings method as the core inspection method, and combining it with one or two auxiliary monitoring methods such as online stress monitoring, electromagnetic radiation monitoring, and microseismic monitoring, the pressure relief effect is inspected. The advanced pressure relief process is completed after all indicators do not exceed the critical value.

2. The method for pre-decompression of bottom-plate rockburst in thick coal seam tunneling faces according to claim 1, characterized in that, In step S1, the drill pipe connector includes a first connecting section and a second connecting section, which are coaxially connected. The outer diameter of the first connecting section matches the inner diameter of the support anchor drill pipe, and the outer diameter of the second connecting section matches the inner diameter of the large-diameter drill pipe. The outer diameter of the second connecting section is larger than that of the first connecting section. In use, one end of the second connecting section of the drill pipe connector is fitted onto the starter head. If it is necessary to connect the support anchor drill pipe, the first connecting section is inserted into the tail of the support anchor drill pipe and fixed with a pin. If it is necessary to connect the large-diameter drill pipe, the first connecting section and the second connecting section are inserted into the tail of the large-diameter drill pipe and fixed with a pin.

3. The method for pre-decompression of bottom-plate rockburst in thick coal seam tunneling faces according to claim 1, characterized in that, In step S2, the comprehensive index for assessing the risk level of rockburst at the working face is... Calculate using the following formula: In the formula, The rockburst hazard index is determined by geological factors. The rockburst hazard index is determined by factors related to mining technology. Based on the composite index The degree of rockburst hazard is quantitatively divided into four levels: no rockburst hazard, weak rockburst hazard, moderate rockburst hazard, and strong rockburst hazard.

4. The method for pre-decompression of rockburst at the bottom plate of a thick coal seam tunneling face according to claim 3, characterized in that, In step S4, the depth of the parallel pressure relief drilling at the face is: , This refers to the distance from the peak bearing pressure at the tunneling face to the coal face. The value should be no less than 8m; the depth of the bottom coal depressurization borehole at the face is... , and The included angle is α; the depth of the pressure relief boreholes on both sides of the tunnel. It shall not be less than the distance between the peak value of the roadway side support pressure and the coal wall, and shall not be less than 1.5 to 2 times the width of the roadway.

5. The method for pre-decompression of rockburst at the bottom plate of a thick coal seam tunneling face according to claim 3, characterized in that, In step S5, the spacing D of the pressure relief boreholes is first calculated using formula (3), and then adjusted using empirical analogy to finally determine the spacing. The calculation formula is as follows: （3） In the formula: D is the spacing between pressure relief holes, in meters; k is the risk correction coefficient for the spacing between pressure relief holes; d is the diameter of the pressure relief borehole, in meters; and K is the coal deformation modulus index.

6. The method for pre-decompression of bottom-plate rockburst in thick coal seam tunneling faces according to claim 4, characterized in that, In step S6, for the weak and moderate impact hazard zones, two pre-decompression boreholes are drilled at the face of the tunneling roadway, with the specific arrangement as follows: First, conduct parallel pressure relief drilling at the construction face: the borehole is parallel to the roadway axis, and the borehole diameter... At the head of the roadway floor The middle position slightly to the right Construction site, drilling depth ; Each tunnel excavation Distance, i.e., the remaining distance in front of the tunneling working face. When the pressure relief protection zone of a certain length is reached, the next round of drilling can begin. Then, construct the coal seam pressure relief borehole at the face: at the face, at a distance from the roadway floor... The middle position is slightly to the left. Construction site, borehole diameter Drilling depth The drilling angle is α angled to the dip angle of the coal seam to ensure that the final borehole position enters the coal seam floor; each time the roadway is excavated... Distance, proceed with the next round of drilling.

7. The method for pre-decompression of bottom-plate rockburst in thick coal seam tunneling faces according to claim 4, characterized in that, In step S6, the arrangement of the pressure relief boreholes on both sides of the tunnel is as follows: The construction location of the pre-pressure relief drilling on the side of the tunnel lags behind the face by a distance. The span is 5m to 20m, and the construction is completed in one go according to the anti-erosion design requirements; The borehole diameter for weak and moderate impact hazard zones is The drilling depth is The drilling spacing is The height of the borehole center from the roadway floor is , Adjustments were made based on the on-site coal seam conditions, and the drilling direction was perpendicular to the roadway axis.

8. The method for pre-decompression of bottom-plate rockburst in thick coal seam tunneling faces according to claim 1, characterized in that, In step S7, after the tunneling and anchoring machine completes a single cycle of tunneling and support operations, pressure relief drilling is carried out. If the drilling cannot reach the designed depth after the pressure relief drilling reaches the designed depth, the drilling position is changed and the drilling is restarted until the drilling depth meets the design requirements.

9. The method for pre-decompression of rockburst at the bottom plate of a thick coal seam tunneling face according to claim 1, characterized in that, In step S8, when the drill cuttings method is used for inspection, the number of inspection holes shall not be less than 2 per side, the spacing between inspection holes shall not be greater than 10m, and the coal powder quantity and dynamic phenomenon index shall not exceed the critical value to confirm that there is no abnormality. When using auxiliary monitoring methods for testing, the microseismic testing range is within 50m of the pre-decompression area, and the testing time is not less than 30 minutes; the online stress testing uses the rate of change index of 1-2 sets of stress gauges within 40m of the pre-decompression area, and the testing time is not less than 30 minutes; the electromagnetic radiation testing range is within 50m of the pre-decompression area, and the number of monitoring points is not less than 5. After all the above-mentioned drill cuttings inspection and auxiliary monitoring methods showed no abnormalities, normal construction proceeded. If any abnormalities were detected, the handling procedure was carried out in accordance with the warning indicators of the corresponding monitoring method.

Images