Advanced pressure relief method for parallel drilling of roadway

Abstract

A roadway parallel drill hole advanced pressure relief method comprises the steps that one to four rows are sequentially arranged from the near to the far away from a roadway side, and one to three drill holes are formed in each row; the drill holes are drilled in the tunneling direction, the angle is consistent with the dip angle of the coal seam, the hole depth is not smaller than 100 m, and the end hole position is not smaller than 100 m ahead of the tunneling working face; the constructed pressure relief hole group has the width of 2-15m and the height of 2-5m, and is of a rectangular or three-flower-shaped energy absorption structure. Advanced pressure relief of the side of the tunneling roadway can be achieved, and the good overall pressure relief effect is achieved; the drilling construction amount can be reduced, and the tunneling efficiency is improved by about 1 / 3; the damage degree of surrounding rocks within the roadway supporting range can be reduced, the overall strength of the surrounding rocks is improved, and roadway repairing and repairing failure supports are reduced. And the advanced pressure relief hole can realize the functions of one hole for multiple purposes, such as an advanced gas drainage hole, a fault structure exploration hole and a coal seam water injection hole, so that the additional engineering cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of rockburst prevention and control, and in particular to a method for pre-decompression through parallel drilling in roadways. Background Technology

[0002] Rockburst is one of the major hazards in mines, severely restricting safe production. The main prevention and control measures for rockburst are support and pressure relief, among which the construction of large-diameter pressure relief holes is currently the mainstream and primary method.

[0003] In existing technology, the pressure relief drilling locations in the coal seam of the roadway are at the face and sidewalls of the tunneling face in areas with impact hazards. That is, depending on the different impact hazard areas, handheld or column-mounted drilling rigs are used to carry out the drilling in cycles of 4-8 hours per day during tunneling. The spacing between the holes is 1 to 3 meters, the diameter is greater than 100 mm, the hole depth is 15 to 25 meters, the hole opening position is 0.5 to 1.5 meters away from the roadway floor, and the drilling direction is perpendicular to the roadway coal wall and the face. This pressure relief method has certain drawbacks. The main drawback is that it cannot achieve pre-depression. That is, the current pressure relief method is to construct pressure relief holes at a certain distance behind the tunnel face. Due to the limitations of the site conditions, it is impossible to achieve full coverage of the sidewalls, resulting in a high stress zone within 10m behind the face. At the same time, the pressure relief protection zone of the roadway sidewalls is horizontal and flat, and blind spots are likely to appear in the upper shoulder and lower corner areas of the roadway, causing stress concentration. Secondly, the large amount of pressure relief work restricts tunneling efficiency. Due to the limitations of its construction method, it is impossible to achieve advance pressure relief or parallel operation of drilling pressure relief and tunneling support. Only cyclic construction can be used. In actual operation, the three shifts of workers usually tunnel for two shifts and drill pressure relief holes for one shift. Drilling pressure relief accounts for 1 / 3 of the total working time, which seriously restricts production efficiency.

[0004] Finally, the surrounding rock of the roadway support section is significantly damaged. Since the opening location is in the coal wall of the roadway side, the pressure relief hole must pass through the roadway support section, which damages the integrity of the roadway surrounding rock, reduces the overall support strength of the roadway support section, causes severe roadway deformation, broken surrounding rock, and support failure, affecting ventilation, transportation, and roof management. It is also not conducive to improving the coal recovery rate. That is, when the working face is close to the safety coal pillar layout such as water-proof, it is necessary to reserve a certain range of coal pillar construction pressure relief drilling holes, which reduces the working face layout width and reduces the resource recovery rate. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for pre-pressure relief by parallel drilling in roadways, based on roadway chambers, using directional drilling technology to achieve pressure relief by drilling parallel to the roadway, thereby realizing pre-pressure relief and parallel operation of pressure relief and tunneling support.

[0006] The pressure relief method includes the following implementation steps: 1. Based on the drilling direction being parallel to the roadway profile, relevant construction measures were developed; the construction sequence was to arrange one to four rows from the nearest to the roadway side, with one to three holes arranged in each row; 2. The first borehole in the first row is located 3 to 6 meters inside the coal wall of the roadway. Its purpose is to preserve the anchor bolt (cable) anchored into the coal pillar within the surrounding rock range; it is 0.5 to 1 meter away from the roadway floor, drilled in the direction of excavation, at the same angle as the dip angle of the coal seam, with a hole depth of not less than 100 meters, and the final hole position is not less than 100 meters ahead of the excavation face; The second borehole in the first row is located about 2 to 3 meters vertically above the first borehole. The construction direction, angle and other parameters are the same as the first borehole. The third borehole in the first row can be determined according to the coal seam thickness or roadway height to ensure that the uppermost pressure relief hole is no more than 1 meter away from the roadway roof. 3. Construct the second and third rows of pressure relief holes sequentially from the first row, 2 to 5 meters away from the first row, using the same parameters; 4. After construction, the pressure relief hole group has a width of 2 to 15m, a height of 2 to 5m, and a rectangular or triangular energy-absorbing structure.

[0007] 5. At the midpoint of the tunneling face, construct one to two advanced pressure relief protection zones with a depth of not less than 100 mm and a travel distance of not less than 100 m in front of the face, spaced at intervals of 2-3 m.

[0008] The beneficial effects of this invention are: 1. The pressure relief holes of the present invention are arranged in a direction parallel to the roadway sidewall and parallel to the roadway axis; based on this feature, it is possible to achieve pressure relief of the sidewall ahead of time and over a long distance, reduce the amount of pressure relief work, and improve tunneling efficiency.

[0009] 2. The present invention employs a dense, three-dimensional group of pressure relief holes to form a highly efficient energy-absorbing structure around the roadway. This structure not only allows the high stress around the roadway to be transferred to the deeper part of the coal body, but also effectively absorbs and blocks the direct damage of high stress and dynamic load on the surrounding rock of the roadway.

[0010] 3. The pre-decompression hole of the present invention can realize the function of "one hole for multiple purposes" and reduce additional engineering costs; that is, the pre-decompression hole can realize the functions of gas pre-drainage hole, fault structure exploration hole, coal seam water injection hole, etc., and reduce additional engineering costs.

[0011] 4. The pressure relief hole construction scheme of the present invention can reserve a certain range of coal pillars in the surrounding rock of the roadway support section, reduce damage and improve the overall strength; that is, it can reduce the degree of damage to the surrounding rock within the roadway support range, improve the overall strength of the surrounding rock, and reduce roadway repair and replacement of failed support. Attached Figure Description

[0012] Figure 1This is a schematic diagram of an embodiment of the parallel borehole pre-pressure relief method for roadways according to the present invention from a frontal view. Figure 2 The present invention provides a method for pre-decompression of parallel boreholes in roadways based on... Figure 1 A diagram illustrating the implementation method from a top-down perspective; Figure label: The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0013] 1. Principle Explanation: Based on the mechanical environment and physical and mechanical properties of coal seams, during the borehole decompression process, coal fractures first start from the borehole wall and extend vertically from the top and bottom ends of the borehole into the coal body, corresponding to the distribution characteristics of the external load on the coal body.

[0014] Based on theoretical analysis and the evolution characteristics of coal fractures under stress relief, when the coal body is not disturbed by mining, its stress environment is approximately equal to the original rock stress. Under the stress relief effect of boreholes, the range of coal fracture expansion (the range of the plastic zone and the fractured zone) is relatively small. When the coal body is disturbed by mining, the mining disturbance actually generates stress loading on the coal body under the stress relief effect of boreholes, which further strengthens the fracture expansion. The fracture expansion under stress loading is a continuous process, and as the range of the fractured zone increases, the stress concentration gradually increases, and the fracture range increases exponentially. This is also the reason why conventional boreholes can still achieve good stress relief effect under current engineering conditions even when the spacing is much larger than the borehole diameter.

[0015] On-site observation of the fractures within the borehole using a peephole revealed that after the construction of the coal seam pressure relief borehole in the tunneling roadway, a loosened fracture ring resembling an "elliptical cylinder" formed along the borehole axis (drilling direction). The fractures were roughly parallel to the borehole axis, and their development was significantly greater vertically than axially. The amount of fracture closure (compressibility) is an important indicator of the coal's resistance to impact and energy absorption. Under a fixed static load on the coal, the larger the angle between the direction of the dynamic load generated deep within the coal (rock) mass and the borehole axis, the more significant the effect of absorbing the dynamic load, i.e., the more significant the energy absorption and impact resistance.

[0016] Based on the above, the present invention employs the method of constructing multiple rows of dense vertical boreholes in the direction parallel to the roadway sidewalls to form a pressure-relieving "energy-absorbing wall" of a certain thickness and height around the roadway and perpendicular to the direction of dynamic load. This "wall" can not only transfer high stress to the deep part of the coal body, but also play a role in efficiently absorbing and blocking the direct damage of high stress of coal (rock) to the surrounding rock of the roadway. 2. Implementation method: The pressure relief method includes the following implementation steps: 1. Based on the drilling direction being parallel to the roadway profile, relevant construction measures were developed; the construction sequence was to arrange one to four rows from the nearest to the roadway side, with one to three holes arranged in each row; 2. The first borehole in the first row is located 3 to 6 meters inside the coal wall of the roadway. Its purpose is to preserve the anchor bolt (cable) anchored into the coal pillar within the surrounding rock range; it is 0.5 to 1 meter away from the roadway floor, drilled in the direction of excavation, at the same angle as the dip angle of the coal seam, with a hole depth of not less than 100 meters, and the final hole position is not less than 100 meters ahead of the excavation face; The second borehole in the first row is located about 2 to 3 meters vertically above the first borehole. The construction direction, angle and other parameters are the same as the first borehole. The third borehole in the first row can be determined according to the coal seam thickness or roadway height to ensure that the uppermost pressure relief hole is no more than 1 meter away from the roadway roof. 3. Construct the second and third rows of pressure relief holes sequentially from the first row, 2 to 5 meters away from the first row, using the same parameters; 4. After construction, the pressure relief hole group has a width of 2 to 15m, a height of 2 to 5m, and a rectangular or triangular energy-absorbing structure.

[0017] 5. At the midpoint of the tunneling face, construct one to two advanced pressure relief protection zones with a depth of not less than 100 mm and a travel distance of not less than 100 m in front of the face, spaced at intervals of 2-3 m.

[0018] Furthermore, as the tunneling face advances, before the final position of the advanced pressure relief holes at the face and roadway sides is less than 20m from the face, the construction of the advanced long pressure relief holes at the face and both sides is repeated according to the above construction plan.

[0019] Furthermore, the starting point for the drilling is in the chamber or connecting roadway area. This allows for parallel operations of pressure relief and tunneling support.

[0020] Furthermore, after the pressure relief hole is constructed, the pressure relief effect of the pressure relief area is inspected. The methods can include coal powder drill cuttings method, online stress, micro-vibration or CT inversion to inspect the effect.

[0021] Furthermore, for stress concentration areas discovered during the pressure relief effect inspection, the borehole spacing and number of boreholes parameters should be optimized in a timely manner, and the construction plan should be adjusted to eliminate stress concentration areas.

[0022] Furthermore, the equipment used for constructing the pressure relief hole is a directional drilling rig, using a directional drill bit with a diameter of not less than 100mm and corresponding drill rods; Furthermore, the hole depth is adjusted according to the geological conditions of the coal seam; its range is 100-200m.

[0023] 3. Detailed description of construction effects based on construction principles: 1. This invention employs a three-dimensional pressure relief mode to improve the overall pressure relief effect. The pressure relief borehole arrangement of this invention is based on the energy absorption characteristics of fractures generated in different directions around the pressure relief boreholes, transforming the existing single, flat, and inefficient pressure relief mode into a three-dimensional, efficient pressure relief mode that extends vertically and horizontally. Specifically, a group of dense, three-dimensional pressure relief boreholes is constructed around the roadway, causing the fractures between the boreholes to intersect and overlap, expanding the range and extent of the fractures and forming a three-dimensional, efficient pressure relief "energy-absorbing wall" of a certain thickness and height, increasing the overall impact resistance by more than two times.

[0024] 2. The boreholes of this invention adopt a matrix-type, high-density, low-total-depth three-dimensional arrangement, which is less than 1 / 3 of the total drilling depth of existing technologies. Utilizing mature directional drilling technology, the construction efficiency is 2 to 3 times that of conventional methods while maintaining the same pressure relief effect. Furthermore, it allows for the advanced construction of pressure relief holes over long distances, especially in medium-hard or higher coal seams, where up to 500m can be constructed in a single operation. This eliminates the need for pressure relief work every month or even every two months, significantly reducing production time and increasing tunneling efficiency by 30% to 50%. These holes can also serve as functional holes for advanced gas drainage in mining faces, fault exploration, and coal seam water injection, achieving "multi-purpose use" and indirectly reducing additional construction costs.

[0025] 3. Existing technologies require the pressure relief holes to penetrate the roadway support section because the opening location is in the coal wall of the roadway sidewall. This damages the integrity of the surrounding rock and reduces the overall strength of the surrounding rock in the roadway support section. The present invention, however, places the borehole at a certain distance from the coal wall, leaving a coal pillar within the roadway support area. This reduces the damage and deformation to the surrounding rock in the roadway support section and improves the overall strength of the surrounding rock.

[0026] 4. Existing technologies require additional width of pressure-relief coal pillars when working near safety coal pillars, which wastes coal resources to some extent, especially in thick coal seams. The present invention arranges boreholes within a coal pillar 6 to 15 meters from the roadway side, which is 1 / 3 to 2 / 3 lower than existing technologies (generally 20 to 25 meters). Furthermore, the borehole arrangement range can be adjusted based on the pressure-relief effect, further improving coal recovery rate. The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of the invention is defined by the appended claims rather than the foregoing description, and all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0027] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for pre-decompression in parallel drilling of roadways, characterized in that: The implementation steps include the following: Step 1. Based on the drilling direction being parallel to the roadway profile, develop relevant construction measures; the construction sequence is to arrange one to four rows from the nearest to the roadway side, with one to three holes arranged in each row; Step 2. The first borehole in the first row is 3 to 6 meters inside the coal wall of the roadway and 0.5 to 1 meter from the roadway floor. Drill along the direction of excavation, with the angle consistent with the dip angle of the coal seam. The depth of the hole is not less than 100 meters, and the final hole position is not less than 100 meters ahead of the excavation face. The second borehole in the first row is located about 2 to 3 meters vertically above the first borehole. The construction direction, angle and other parameters are the same as the first borehole. The third borehole in the first row can be determined according to the coal seam thickness or roadway height to ensure that the uppermost pressure relief hole is no more than 1 meter away from the roadway roof. Step 3. Construct the second and third rows of pressure relief holes sequentially from the first row, 2 to 5 meters away from the first row, using the same parameters. Step 4. After construction, the pressure relief hole group is 2 to 15m wide and 2 to 5m high, and its shape is a rectangular or triangular energy-absorbing structure; Step 5. Construct 1 to 2 advanced pressure relief protection zones with a depth of not less than 100 mm and a travel distance of not less than 100 m in front of the face at intervals of 2-3 m in the middle of the tunneling face.

2. The method for pre-decompression in parallel drilling of roadways according to claim 1, characterized in that, As the tunneling face advances, before the final position of the advanced pressure relief holes at the face and roadway sides is less than 20m from the face, the construction of the advanced long pressure relief holes at the face and both sides will be repeated according to the above construction plan.

3. The method for pre-decompression in parallel drilling of roadways according to claim 1, characterized in that, The starting point for the drilling operation is in the chamber or connecting tunnel area.

4. The method for pre-decompression in parallel drilling of roadways according to claim 1, characterized in that, After the pressure relief hole is constructed, the pressure relief effect of the pressure relief area should be checked. The methods can be coal powder drill cuttings method, online stress, micro-vibration or CT inversion to check the effect.

5. The method for pre-decompression in parallel drilling of roadways according to claim 1, characterized in that, For stress concentration areas found during the pressure relief effect inspection, the borehole spacing and number of boreholes parameters should be optimized in a timely manner, and the construction plan should be adjusted to eliminate the stress concentration areas.

6. The method for pre-decompression in parallel drilling of roadways according to claim 1, characterized in that, The equipment used for constructing the pressure relief hole is a directional drilling rig, using a directional drill bit with a diameter of not less than 100mm and corresponding drill rods.

7. The method for pre-decompression in parallel drilling of roadways according to claim 1, characterized in that, The hole depth is adjusted according to the geological conditions of the coal seam; its range is 100-200m.

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