Method for cooling working face by draining water from coal seam roof aquifer

Abstract

The application discloses a method for cooling a working face by draining water from a water-bearing layer in a coal seam roof, calculates the thickness D of a roof loose circle, selects a water inlet and outlet target layer according to the value of the thickness D, drills from the center positions of two drivage roadways of a working face to the water inlet and outlet target layer, and then drills to positions opposite to a cross-cut roadway in the working face; drills from the center positions of the working face to the water inlet and outlet target layer from two sides opposite to the two drivage roadways, and then drills to positions opposite to the cross-cut roadways and is respectively connected with two corresponding drilling tracks; drills from a system roadway of the working face to the water-bearing layer and branches to positions opposite to the cross-cut roadways, drains water from the water-bearing layer, and precipitates and cools the water, injects the water into each drilling track and finally discharges the water to the ground; and the operation is circular until the cooling work of all working faces is completed. The water from the water-bearing layer in the roof is cooled and the heat of a floor at the bottom of the working face is taken away, without the need of transporting cooling materials from the ground into the underground, so that resources are reasonably and efficiently utilized.

Description

Technical Field

[0001] This invention belongs to the technical field of cooling methods, and relates to a method for cooling the working face by draining water from the aquifer in the roof of a coal seam. Background Technology

[0002] In my country, most coal mines face the threat of water hazards from roof aquifers during coal seam mining. To ensure safe mining, it is often necessary to drill holes in the roof aquifers before mining to drain the water, depressurize the aquifers, and then discharge the drained water to the surface through the mine drainage system. Furthermore, according to the geothermal gradient, formation temperature increases with depth; therefore, as mining depth increases, many mine faces face the problem of high-temperature heat hazards.

[0003] In the past, when draining water from roof aquifers, conventional short boreholes were drilled into the aquifer, and the water was directly drained into the roadway along the borehole. The water flowed along the roadway and was then discharged to the surface through the mine drainage system. This method of draining water from roof aquifers is effective, but the water flow along the roadway easily carries coal slurry and dust, becoming coal slurry water. Coal slurry water tends to accumulate in water tanks, and water containing coal slurry can easily damage drainage equipment. The water in the aquifer is not effectively utilized during the draining process. Furthermore, some mines, due to their deep burial, face significant heat hazards during underground operations, severely reducing underground work efficiency and endangering the health of workers. Previously, the treatment of high-temperature heat hazards underground mainly involved increasing ventilation and placing large blocks of ice or other low-temperature materials at the working face to lower the temperature. However, due to the long ventilation path of the mine ventilation system, the ventilation method has limited effect on reducing the temperature of the working face. Placing ice blocks on the working face has a certain cooling effect, but because the working face is large, a large amount of ice blocks and other low-temperature substances need to be replenished, resulting in large transportation losses. After the ice blocks melt, the humidity of the working face increases, reducing the comfort of the working environment. In addition, the temperature difference between the ice blocks and the working face ground temperature is large, which is not conducive to the physical and mental health of the workers. Summary of the Invention

[0004] The purpose of this invention is to provide a method for cooling the working face by draining water from the aquifer in the roof of the coal seam, which solves the problem of significant heat damage faced by underground operations in the prior art.

[0005] The technical solution adopted in this invention is a method for cooling the working face using drainage water from the aquifer in the roof of the coal seam, specifically including the following steps: Step 1: Calculate the thickness D of the loosened zone of the bottom plate and select the target water inlet and outlet layers based on its value; Step 2: Drill from the center of the two tunneling roadways of a working face to the target water inlet / outlet layer, and then drill to the position opposite the cut-in roadway; Step 3: Drill from the center of the working face to the two sides opposite to the two tunneling roadways to the target water inlet and outlet layers, then drill to the position opposite to the cut-in roadway in the working face, and connect with the two drilling trajectories corresponding to Step 2 respectively. Step 4: Drill from the protective coal pillar of the system roadway of the working face to the aquifer and branch to the position opposite to the cut-off roadway, drain the water in the aquifer and let it settle and cool down, inject water into each borehole trajectory and finally discharge it to the surface; Step 5: Repeat steps 2-4 until the cooling of all working surfaces is completed.

[0006] The method of cooling the working face by draining water from the aquifer in the roof of the coal seam is further characterized by the following: In step 1, within each working face planned according to the mining permit's plan area, the theodolite is used to measure the tunnel depth, rock mechanics testing equipment is used to measure the internal friction angle and cohesion of the surrounding rock within the tunnel, a steel ruler or meter ruler is used to measure the tunnel radius, and the thickness D of the loosened zone of the floor is calculated. (1) Where R0 is the tunnel radius; C is the cohesion; φ is the internal friction angle; P i H represents the support resistance; H represents the tunnel burial depth; when some parameters are lacking and the loosening zone thickness cannot be calculated, the loosening zone thickness is considered to be 3m. Based on the thickness of the loosening zone of the floor and the lithology of the surrounding rock in the tunnel, the sandstone layer or limestone layer below the loosening zone is selected as the target layer for water inflow and outflow. In each working face, two chambers are constructed downwards in the protective coal pillar of the system roadway, respectively close to different tunneling roadways, and the bottom of the two chambers is located above the target water inlet and outlet layers.

[0007] Step 2 is implemented as follows: Step 2.1: Drilling rigs, chillers, and water pumps are evenly distributed in two chambers of a working face; Step 2.2: The drilling rig is a long-distance directional drilling rig; the drilling rig drills vertically downwards from 0m-0.5m away from the center of the two tunnels to the target water inlet and outlet layer, forming two water inlet holes, and then drills along the direction parallel to the tunnels to the position opposite to the cut-in tunnel, forming two first boreholes.

[0008] Step 3 is implemented as follows: Step 3.1: The drilling rig drills downwards from the center of the working face to the target water inlet and outlet layers on both sides opposite to the two tunneling roadways and 1m-30m away from the center of the working face, forming two return water holes. It then drills along the direction parallel to the tunneling roadways to the position opposite to the cut-in roadway, forming two second boreholes. Step 3.2, the area formed by the extension line of the first borehole starting from the end point of the first borehole, the extension line of the second borehole starting from the end point of the second borehole, and the line connecting the end points of the first and second boreholes is taken as the arc docking area. Step 3.3: Design two first arc trajectories that drill from the end point of the corresponding first borehole to the arc docking area, and two second arc trajectories that drill from the end point of the corresponding second borehole to the arc docking area. The end points of the first arc trajectories and the end points of the corresponding second arc trajectories are all docked together, and the docking position is the docking point. Step 3.4: The two drilling rigs drill along the corresponding first arc trajectory to the docking point, forming two first arc segments. They advance and retreat 5m-10m along the direction of the corresponding first arc segment at the corresponding docking point and repeat 3-5 times. Then they drill along the corresponding second arc trajectory to the docking point, forming two second arc segments. Step 3.5: Connect each water pump to the bottom of its corresponding inlet hole via a water pipe; connect the drainage pipe to the bottom of each return hole via a water pipe; connect the drainage pipe to the mine drainage system; move the two drilling rigs to their respective chambers. Step 3.6: The same arrangement is carried out in both chambers where drilling rigs are located: a tee is installed at the drill rod joint of the drilling rig, and a water tank is built 2m-5m away from the drilling rig. The opening of the water tank is covered with a cover plate, and a through hole adapted to the size of the water pipe is opened on the cover plate. The water pipe passes through the through hole to connect the water tank and the tee, and the water tank, chiller and water pump are connected through the water pipe. Step 4 is implemented as follows: Step 4.1: The two drilling rigs drill upwards from their respective chambers to the aquifer and then branch out horizontally within the aquifer to positions opposite the cut-in tunnel in the working face, forming two third boreholes. The distance between the two third boreholes is equal to the distance between the branches on the third boreholes, both being 30m-40m. The calculation method for the number of branches and the value in meters (m) on the two third boreholes is as follows: (2) in, d1 is the average spacing between all adjacent branches and the spacing between the two third boreholes, and d2 is the length of the cut-in tunnel. Step 4.2: Drain the water in the aquifer, allowing the water to flow through the two tees and into the corresponding water tanks via water pipes. Let the water stand and settle until all impurities in the water have completely sunk to the bottom of the water tanks. Step 4.3: Transfer the water from the two water tanks to the corresponding chillers through water pipes, and use the chillers to cool the water to 1℃-5℃; Step 4.4: Water is injected into the corresponding inlet hole by the corresponding water pump. The water flows through the first borehole, the first arc segment, the second arc segment, and the second borehole, and then flows out through the return hole and into the drainage pipeline. It is then discharged to the surface through the mine drainage system.

[0009] After the mining work of the working face to be cooled is completed in step 5, the two chillers, two water pumps and two drilling rigs are moved to the corresponding positions of another working face that has not been cooled for the next cooling work.

[0010] The beneficial effects of this invention are: Compared with existing technologies, the present invention utilizes the geothermal gradient law of the coal seam roof aquifer to cool the working face. It leverages the temperature difference between the drained water from the coal seam roof aquifer and the underlying rock strata below the working face, using a chiller to cool the water and remove heat from the underlying rock strata, thus achieving the goal of cooling the working face and fully utilizing the value of the drained water from the coal seam roof. Using a long-distance directional drilling rig to drain the water from the coal seam roof aquifer facilitates water flow collection, preventing water from ordinary drilling from accumulating in some roadways and forming coal slurry. This allows for the separation of clean and dirty water in the mine, reducing damage to the drainage system. Utilizing the drained water from the coal seam roof for underground circulating cooling eliminates the need to transport cooling materials from the surface into the mine, enabling on-site material sourcing, efficient resource utilization, reducing mine transportation workload, and preventing excessive humidity in the roadways due to ice evaporation. The cooling pipeline system has a simple structure and does not interfere with the tunneling work, thus improving mining efficiency. The cooling pipeline system is easy to maintain and has low safety risks. Attached Figure Description

[0011] Figure 1 This is a plan view of the working face in the method of cooling the working face by draining water from the aquifer in the roof of the coal seam according to the present invention; Figure 2 This is a diagram showing the equipment layout of the working face in the method of cooling the working face by draining water from the aquifer in the roof of the coal seam according to the present invention. Figure 3 This is a diagram showing the borehole trajectory of the working face and the target water inlet / outlet layers in the method of cooling the working face by draining water from the aquifer in the coal seam roof in this invention. Figure 4 This is a cross-sectional view of the tunnel, water inlet, connection point, and water outlet in the method of cooling the working face by draining water from the aquifer in the roof of the coal seam according to the present invention. Figure 5 This is a cross-sectional view of the drainage borehole in the method of cooling the working face by draining water from the aquifer in the roof of the coal seam according to the present invention. Figure 6 This is a diagram showing the water tank layout in the method of cooling the working face by draining water from the aquifer in the coal seam roof according to the present invention.

[0012] In the diagram, 1. Chamber, 2. Drilling rig, 3. T-junction, 4. Roof, 41. Aquifer, 42. Water-resistant layer, 5. First borehole, 6. Second borehole, 7. Coal seam, 8. Refrigeration unit, 9. Water pump, 10. Water pipe, 11. Working face, 111. Excavation roadway, 112. Cut-in roadway, 113. Retreat roadway, 114. System roadway protective coal pillar, 115. Mining area, 12. Target water inlet / outlet layer, 13. Water inlet, 14. Connection point, 15. Return water hole, 16. Drainage pipeline, 17. First arc segment, 18. Second arc segment, 19. Protective coal pillar between working faces, 20. Floor, 21. Water sump, 22. Third borehole, 23. System roadway, 24. Arc connection area, 25. Cover plate, 26. Through hole. Detailed Implementation

[0013] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0014] The method of cooling the working face by draining water from the aquifer in the roof of the coal seam specifically includes the following steps: Step 1: Refer to Figure 1 Within each working face 11 planned according to the mining permit's plan, the theodolite is used to measure the tunnel depth, rock mechanics testing equipment is used to measure the internal friction angle and cohesion of the surrounding rock within the tunnel, and a steel ruler or meter ruler is used to measure the tunnel radius. The thickness D of the loosened zone of the floor is then calculated. (1) Where R0 is the tunnel radius; C is the cohesion; φ is the internal friction angle; P i H represents the support resistance; H represents the roadway burial depth; when some parameters are lacking and the loosening zone thickness cannot be calculated, the loosening zone thickness is considered to be 3m. Based on the thickness of the loosening zone of the floor plate and the lithology of the surrounding rock in the roadway, the sandstone layer or limestone layer below the loosening zone is selected as the target layer 12 for water inflow and outflow. In the system roadway protection coal pillar 114 in each working face 11, two chambers 1 are constructed downwards, respectively close to different excavation roadways 111, and the bottom of the two chambers 1 is located above the target layer 12 for water inflow and outflow.

[0015] Step 2: Refer to Figure 2 Drilling rig 2, refrigeration unit 8, and water pump 9 are evenly distributed in two chambers 1 of a working face 11; drilling rig 2 is a long-distance directional drilling rig; refer to Figure 3 Drilling rig 2 drills vertically downwards from a position 0m-0.5m from the center of the two tunnels 111 to the target water inlet / outlet layer 12, forming two water inlet holes 13. It then drills along a direction parallel to the tunnels 111 to a position opposite to the cut-in tunnel 112, forming two first boreholes 5.

[0016] Step 3: Drilling rig 2 drills downwards from the center of the working face 11, opposite to the two tunneling roadways 111 on both sides and 1m-30m from the center of the working face, down to the target water inlet / outlet layer 12, forming two return water holes 15. It then drills parallel to the tunneling roadways 111 to a position opposite to the cut-in roadway 112, forming two second boreholes 6. The area formed by the extension line of the first borehole 5 starting from the end point of the first borehole 5, the extension line of the second borehole 6 starting from the end point of the second borehole 6, and the line connecting the end points of the first and second boreholes 6 is designated as the arc docking area 24. Two first arc trajectories are designed, drilling from the corresponding end point of the first borehole 5 to the arc docking area 24, and two second arc trajectories are designed, drilling from the corresponding end point of the second borehole 6 to the arc docking area 24. The end points of the first and second arc trajectories are all docked together at docking point 14. (Refer to...) Figure 4 Two drilling rigs 2 drill along their respective first arc trajectories to the docking point 14, forming two first arc segments 17. They then advance and retreat 5m-10m along their respective first arc segments 17 at the docking point 14, repeating this cycle 3-5 times. Finally, they drill along their respective second arc trajectories to the docking point 14, forming two second arc segments 18. The bottom of each water pump 9 and its corresponding inlet hole 13 is connected via water pipe 10. Similarly, the bottom of each drainage pipe 16 and each return hole 15 is connected via water pipe 10. The drainage pipe 16 is also connected to the mine drainage system. (Refer to...) Figure 5 Move the two drilling rigs 2 to their respective chambers 1; make the same arrangement in both chambers 1 where the drilling rigs 2 are located: install a tee 3 at the drill rod joint of the drilling rig 2, and construct a water tank 21 at a distance of 2m-5m from the drilling rig 2, referring to... Figure 6 The opening of the water tank 21 is covered with a cover plate 25. The cover plate 25 has a through hole 26 that matches the size of the water pipe 10. The water pipe 10 passes through the through hole 26 to connect the water tank 21 and the tee 3. The water tank 21, the chiller 8 and the water pump 9 are connected through the water pipe 10.

[0017] Step 4: Refer to Figure 5 Two drilling rigs 2 drill upwards from their respective chambers 1 to the aquifer 41 and then branch out horizontally within the aquifer 41 to positions opposite the cut-in tunnel 112 in the working face 11, forming two third boreholes 22. The distance between the two third boreholes 22 is equal to the distance between the branches on the third boreholes 22, both being 30m-40m. The calculation method for the number of branches and the length of meters on the two third boreholes 22 is as follows: (2) in, d2 is the average distance between all adjacent branches and the distance between the two third boreholes, and d2 is the length of the cut-in tunnel 112; the water in the aquifer 41 is drained, and the water flows through the two tees 3 and through the water pipe 10 to the corresponding water tank 21. The water is allowed to settle until the impurities in the water are completely settled to the bottom of the water tank 21; the water in the two water tanks 21 is transported to the corresponding chiller 8 through the water pipe 10, and the chiller 8 is used to cool the water to 1℃-5℃; the water is injected into the corresponding inlet hole 13 through the corresponding water pump 9, and the water flows through the first borehole 5, the first arc segment 17, the second arc segment 18, and the second borehole 6, and then flows out through the return water hole 15 and into the drainage pipe 16, and is discharged to the surface through the mine drainage system.

[0018] Step 5: After the mining work of the cooled working face 11 is completed, move the two chillers 8, the two water pumps 9 and the two drilling rigs 2 to the corresponding positions of another uncooled working face 11 to carry out the next cooling work. Repeat steps 2-4 until the cooling work of all working faces 11 is completed.

[0019] The working principle of this invention is: The drilling rig drills from the chamber 1 of the working face 11 to the aquifer 41, allowing the water in the aquifer 41 to flow into the water tank 21. After sedimentation in the water tank 21, impurities in the water can be reduced. In each working face 11, a hole is drilled to the water inlet / outlet target layer 12 and drills horizontally along the water inlet / outlet target layer 12 to form a drilling trajectory. After the water is drained, it is cooled by the chiller 8 and flows through the drilling trajectory, which will carry away the heat of the rock strata of the bottom plate 20 below the working face 11, achieving the goal of cooling the working face 11 and giving full play to the value of draining water from the coal seam roof.

[0020] Example 1: The method of cooling the working face by draining water from the aquifer in the roof of the coal seam specifically includes the following steps: Step 1: Within each working face 11 planned according to the mining license's plan, use a theodolite to measure the tunnel depth, use rock mechanics testing equipment to measure the internal friction angle and cohesion of the surrounding rock within the tunnel, use a steel ruler or meter ruler to measure the tunnel radius, and calculate the thickness D of the loosened zone of the floor. (1) Where R0 is the tunnel radius; C is the cohesion; φ is the internal friction angle; P i H represents the support resistance; H represents the roadway burial depth; based on the thickness of the loosened zone of the floor and the lithology of the surrounding rock in the roadway, the sandstone or limestone layer below the loosened zone is selected as the target layer 12 for water inflow and outflow; in the system roadway protection coal pillar 114 in each working face 11, two chambers 1 are constructed downwards, respectively close to different excavation roadways 111, and the bottom of the two chambers 1 is located above the target layer 12 for water inflow and outflow.

[0021] Step 2: Drilling rig 2, chiller 8 and water pump 9 are evenly distributed in two chambers 1 of a working face 11; Drilling rig 2 is a long-distance directional drilling rig; Drilling rig 2 drills vertically downward from the center of the two tunnels 111 to the target water inlet / outlet layer 12, forming two water inlet holes 13, and drills along the direction parallel to the tunnels 111 to the position opposite to the cut-in tunnel 112, forming two first boreholes 5.

[0022] Step 3: Drilling rig 2 drills downwards from the center of the working face 11, opposite to the two tunneling roadways 111 on both sides and 1m away from the center of the working face, down to the target water inlet / outlet layer 12, forming two return water holes 15. It then drills along a direction parallel to the tunneling roadways 111 to a position opposite to the cut-in roadway 112, forming two second boreholes 6. The area formed by the extension line of the first borehole 5 starting from the end point of the first borehole 5, the extension line of the second borehole 6 starting from the end point of the second borehole 6, and the line connecting the end points of the first borehole 5 and the second borehole 6 is designated as the arc docking area 24. Two first arc trajectories are designed, drilling from the corresponding end points of the first borehole 5 to the arc docking area 24, and two second arc trajectories are designed, drilling from the corresponding end points of the second borehole 6 to the arc docking area 24. The end points of the first arc trajectories and the corresponding end points of the second arc trajectories are all docked together, with the docking point being the docking point 14. The two drilling rigs 2 respectively drill along the corresponding first... Drill along the arc trajectory to the docking point 14, forming two first arc segments 17. At the corresponding docking point 14, drill forward and backward 5m along the direction of the corresponding first arc segment 17, repeating this cycle 3 times. Then drill along the corresponding second arc trajectory to the docking point 14, forming two second arc segments 18. Connect the bottom of each water pump 9 and the corresponding inlet hole 13 to the bottom of each water pipe 10. Connect the bottom of the drainage pipe 16 and each return hole 15 to the bottom of each water pipe 10. Connect the drainage pipe 16 and the mine drainage system. Connect; move the two drilling rigs 2 to their respective chambers 1; make the same arrangement in both chambers 1 where the drilling rigs 2 are located: install a tee 3 at the drill rod joint of the drilling rig 2, build a water tank 21 2m away from the drilling rig 2, cover the opening of the water tank 21 with a cover plate 25, and open a through hole 26 on the cover plate 25 that matches the size of the water pipe 10. The water pipe 10 passes through the through hole 26 to connect the water tank 21 and the tee 3, and connects the water tank 21, the chiller 8 and the water pump 9 through the water pipe 10.

[0023] Step 4: The two drilling rigs 2 drill upwards from their respective chambers 1 to the aquifer 41 and branch out horizontally within the aquifer 41 to positions opposite to the cut-in tunnel 112 in the working face 11, forming two third boreholes 22. The distance between the two third boreholes 22 is equal to the distance between the branches on the third boreholes 22, both being 30m. The calculation method for the number of branches and the length of meters on the two third boreholes 22 is as follows: (2) in, d2 is the average distance between all adjacent branches and the distance between the two third boreholes, and d2 is the length of the cut-in tunnel 112; the water in the aquifer 41 is drained, and the water flows through the two tees 3 and through the water pipe 10 to the corresponding water tank 21. The water is allowed to settle until the impurities in the water are completely settled to the bottom of the water tank 21; the water in the two water tanks 21 is transported to the corresponding chiller 8 through the water pipe 10, and the chiller 8 is used to cool the water to 1℃; the water is injected into the corresponding inlet hole 13 through the corresponding water pump 9, and the water flows through the first borehole 5, the first arc segment 17, the second arc segment 18, and the second borehole 6, and then flows out through the return water hole 15 and into the drainage pipe 16, and is discharged to the surface through the mine drainage system.

[0024] Step 5: After the mining work of the cooled working face 11 is completed, move the two chillers 8, the two water pumps 9 and the two drilling rigs 2 to the corresponding positions of another uncooled working face 11 to carry out the next cooling work. Repeat steps 2-4 until the cooling work of all working faces 11 is completed.

[0025] Example 2: The method of cooling the working face by draining water from the aquifer in the roof of the coal seam specifically includes the following steps: Step 1: Within each working face 11 planned according to the mining license's plan, use a theodolite to measure the tunnel depth, use rock mechanics testing equipment to measure the internal friction angle and cohesion of the surrounding rock within the tunnel, use a steel ruler or meter ruler to measure the tunnel radius, and calculate the thickness D of the loosened zone of the floor. (1) Where R0 is the tunnel radius; C is the cohesion; φ is the internal friction angle; P i H represents the support resistance; H represents the roadway burial depth; based on the thickness of the loosened zone of the floor and the lithology of the surrounding rock in the roadway, the sandstone or limestone layer below the loosened zone is selected as the target layer 12 for water inflow and outflow; in the system roadway protection coal pillar 114 in each working face 11, two chambers 1 are constructed downwards, respectively close to different excavation roadways 111, and the bottom of the two chambers 1 is located above the target layer 12 for water inflow and outflow.

[0026] Step 2: Drilling rig 2, chiller 8 and water pump 9 are evenly distributed in two chambers 1 of a working face 11; Drilling rig 2 is a long-distance directional drilling rig; Drilling rig 2 drills vertically downward from 0.25m away from the center of the two tunnels 111 to the target water inlet / outlet layer 12, forming two water inlet holes 13, and drills along a direction parallel to the tunnels 111 to the position opposite to the cut-in tunnel 112, forming two first boreholes 5.

[0027] Step 3: Drilling rig 2 drills downwards from the center of the working face 11, opposite to the two tunneling roadways 111 on both sides and 15.5m from the center of the working face, down to the target water inlet / outlet layer 12, forming two return water holes 15. It then drills parallel to the tunneling roadways 111 to a position opposite to the cut-in roadway 112, forming two second boreholes 6. The area formed by the extension line of the first borehole 5 starting from the end point of the first borehole 5, the extension line of the second borehole 6 starting from the end point of the second borehole 6, and the line connecting the end points of the first and second boreholes 6 is designated as the arc docking area 24. Two first arc trajectories are designed, drilling from the corresponding end points of the first borehole 5 to the arc docking area 24, and two second arc trajectories are designed, with the end points of the first and second arc trajectories docking together at docking point 14. The two drilling rigs 2 drill along the corresponding first arc trajectories... The drill is driven along an arc trajectory to docking point 14, forming two first arc segments 17. At the corresponding docking point 14, the drill moves 7.5m forward and backward along the direction of the corresponding first arc segment 17, repeating this cycle 4 times. Then, the drill is driven along the corresponding second arc trajectory to docking point 14, forming two second arc segments 18. The bottom of each water pump 9 and its corresponding inlet hole 13 is connected via water pipe 10. Similarly, the bottom of the drainage pipe 16 and each return hole 15 is connected via water pipe 10. The drainage pipe 16 and the mine drainage system are also connected. Connect; move the two drilling rigs 2 to their respective chambers 1; make the same arrangement in both chambers 1 where the drilling rigs 2 are located: install a tee 3 at the drill rod joint of the drilling rig 2, build a water tank 21 at a distance of 3.5m from the drilling rig 2, cover the opening of the water tank 21 with a cover plate 25, and open a through hole 26 on the cover plate 25 that matches the size of the water pipe 10, the water pipe 10 passes through the through hole 26 to connect the water tank 21 and the tee 3, and connect the water tank 21, the chiller 8 and the water pump 9 through the water pipe 10.

[0028] Step 4: The two drilling rigs 2 drill upwards from their respective chambers 1 to the aquifer 41 and branch out horizontally within the aquifer 41 to positions opposite to the cut-in tunnel 112 in the working face 11, forming two third boreholes 22. The distance between the two third boreholes 22 is equal to the branch spacing on the third borehole 22, both being 35m. The calculation method for the number of branches and the length of meters on the two third boreholes 22 is as follows: (2) in, d2 is the average distance between all adjacent branches and between the two third boreholes, and d2 is the length of the cut-in tunnel 112; the water in the aquifer 41 is drained, and the water flows through the two tees 3 and through the water pipe 10 to the corresponding water tank 21. The water is allowed to settle until the impurities in the water are completely settled to the bottom of the water tank 21; the water in the two water tanks 21 is transported through the water pipe 10 to the corresponding chiller 8, and the chiller 8 is used to cool the water to 3°C; the water is injected into the corresponding inlet hole 13 through the corresponding water pump 9, and the water flows through the first borehole 5, the first arc segment 17, the second arc segment 18, and the second borehole 6, and then flows out through the return water hole 15 and into the drainage pipe 16, and is discharged to the surface through the mine drainage system.

[0029] Step 5: After the mining work of the cooled working face 11 is completed, move the two chillers 8, the two water pumps 9 and the two drilling rigs 2 to the corresponding positions of another uncooled working face 11 to carry out the next cooling work. Repeat steps 2-4 until the cooling work of all working faces 11 is completed.

[0030] Example 3: Step 1: Within each working face 11 planned according to the mining license's plan, use a theodolite to measure the tunnel depth, use rock mechanics testing equipment to measure the internal friction angle and cohesion of the surrounding rock within the tunnel, use a steel ruler or meter ruler to measure the tunnel radius, and calculate the thickness D of the loosened zone of the floor. (1) Where R0 is the tunnel radius; C is the cohesion; φ is the internal friction angle; P i H represents the support resistance; H represents the roadway burial depth; based on the thickness of the loosened zone of the floor and the lithology of the surrounding rock in the roadway, the sandstone or limestone layer below the loosened zone is selected as the target layer 12 for water inflow and outflow; in the system roadway protection coal pillar 114 in each working face 11, two chambers 1 are constructed downwards, respectively close to different excavation roadways 111, and the bottom of the two chambers 1 is located above the target layer 12 for water inflow and outflow.

[0031] Step 2: Drilling rig 2, chiller 8 and water pump 9 are evenly distributed in two chambers 1 of a working face 11; Drilling rig 2 is a long-distance directional drilling rig; Drilling rig 2 drills vertically downward from 0.5m away from the center of the two tunnels 111 to the target water inlet / outlet layer 12, forming two water inlet holes 13, and drills along a direction parallel to the tunnels 111 to the position opposite to the cut-in tunnel 112, forming two first boreholes 5.

[0032] Step 3: Drilling rig 2 drills downwards from the center of the working face 11, 30m away from the center of the two tunneling roadways 111, to the target water inlet / outlet layer 12, forming two return water holes 15. It then drills parallel to the tunneling roadways 111 to a position opposite to the cut-in roadway 112, forming two second boreholes 6. The area formed by the extension line of the first borehole 5 (starting from the end point of the first borehole 5), the extension line of the second borehole 6 (starting from the end point of the second borehole 6), and the line connecting the end points of the first and second boreholes 6 is designated as the arc docking area 24. Two first arc trajectories are designed, drilling from the corresponding end points of the first borehole 5 to the arc docking area 24, and two second arc trajectories are designed, with the end points of the first and second arc trajectories docking together at docking point 14. The two drilling rigs 2 drill along the corresponding first... Drill along the arc trajectory to the docking point 14, forming two first arc segments 17. At the corresponding docking point 14, drill 10m forward and backward along the direction of the corresponding first arc segment 17, repeating this cycle 5 times. Then drill along the corresponding second arc trajectory to the docking point 14, forming two second arc segments 18. Connect the bottom of each water pump 9 and the corresponding inlet hole 13 to the bottom of each water pipe 10. Connect the bottom of the drainage pipe 16 and each return hole 15 to the bottom of each water pipe 10. Connect the drainage pipe 16 and the mine drainage system... Connect the two drilling rigs 2 to their respective chambers 1. Make the same arrangement in both chambers 1 where the drilling rigs 2 are located: install a tee 3 at the drill rod joint of the drilling rig 2, build a water tank 21 5m away from the drilling rig 2, cover the opening of the water tank 21 with a cover plate 25, and open a through hole 26 on the cover plate 25 that matches the size of the water pipe 10. The water pipe 10 passes through the through hole 26 to connect the water tank 21 and the tee 3, and connects the water tank 21, the chiller 8 and the water pump 9 through the water pipe 10.

[0033] Step 4: The two drilling rigs 2 drill upwards from their respective chambers 1 to the aquifer 41 and branch out horizontally within the aquifer 41 to positions opposite to the cut-in tunnel 112 in the working face 11, forming two third boreholes 22. The distance between the two third boreholes 22 is equal to the distance between the branches on the third boreholes 22, both being 40m. The calculation method for the number of branches and the length of meters on the two third boreholes 22 is as follows: (2) in, d2 is the average distance between all adjacent branches and between the two third boreholes, and d2 is the length of the cut-in tunnel 112; the water in the aquifer 41 is drained, and the water flows through the two tees 3 and through the water pipe 10 to the corresponding water tank 21. The water is allowed to settle until the impurities in the water are completely settled to the bottom of the water tank 21; the water in the two water tanks 21 is transported to the corresponding chiller 8 through the water pipe 10, and the chiller 8 is used to cool the water to 5°C; the water is injected into the corresponding inlet hole 13 through the corresponding water pump 9, and the water flows through the first borehole 5, the first arc segment 17, the second arc segment 18, and the second borehole 6, and then flows out through the return water hole 15 and into the drainage pipe 16, and is discharged to the surface through the mine drainage system.

[0034] Step 5: After the mining work of the cooled working face 11 is completed, move the two chillers 8, the two water pumps 9 and the two drilling rigs 2 to the corresponding positions of another uncooled working face 11 to carry out the next cooling work. Repeat steps 2-4 until the cooling work of all working faces 11 is completed.

Claims

1. A method for cooling the working face using drainage water from the aquifer in the roof of a coal seam, characterized in that, Specifically, the following steps are included: Step 1: Calculate the thickness D of the loosened zone of the bottom plate and select the target layer (12) for water inlet and outlet based on its value. In the system roadway protection coal pillar (114) in each working face (11), construct two chambers (1) that are close to different tunneling roadways (111) respectively, and the bottom of the two chambers (1) is located above the target layer (12) for water inlet and outlet. Step 2: Drilling rig (2), refrigeration unit (8) and water pump (9) are evenly distributed in two chambers (1) of a working face (11). Drilling rig (2) is a long-distance directional drilling rig. Drilling rig (2) drills vertically downward from 0m-0.5m away from the center of the two tunnels (111) to the target water inlet / outlet layer (12) to form two water inlet holes (13). Drilling along the direction parallel to the tunnel (111) to the position opposite to the cut-in tunnel (112) to form two first boreholes (5). Step 3: The drilling rig (2) drills downwards from the center of the working face (11) to the target water inlet / outlet layer (12) on both sides opposite to the two tunneling roadways (111) and 1m-30m away from the center of the working face, forming two return water holes (15). It then drills in a direction parallel to the tunneling roadway (111) to the position opposite to the cut-in roadway (112), forming two second boreholes (6). The extension line of the first borehole (5) starting from the end point of the first borehole (5), the extension line of the second borehole (6) starting from the end point of the second borehole (6), and the first borehole (5) are then drilled downwards to the target water inlet / outlet layer (12), forming two return water holes (15). The area formed by the line connecting the end point of hole (5) and the end point of the second borehole (6) is designated as the arc docking area (24). Two first arc trajectories are designed, drilling from the end point of the corresponding first borehole (5) to the arc docking area (24), and two second arc trajectories are designed, drilling from the end point of the corresponding second borehole (6) to the arc docking area (24). The end points of the first arc trajectories and the corresponding end points of the second arc trajectories are docked together, and the docking position is the docking point (14). The two drilling rigs (2) drill along the corresponding first arc trajectories to the docking point (14), forming... Two first arc segments (17) are drilled along the direction of the corresponding first arc segment (17) at the corresponding docking point (14) for 5m-10m and 3-5 times respectively, and drilled along the corresponding second arc trajectory to the docking point (14) to form two second arc segments (18). The bottom of each water pump (9) and the corresponding water inlet (13) are connected by water pipes (10), the bottom of each drainage pipe (16) and each return water hole (15) are connected by water pipes (10), and the drainage pipes (16) are connected to the mine drainage system. The two drilling rigs (2) are moved respectively. Move to the corresponding chamber (1), and make the same arrangement in both chambers (1) where the drilling machine (2) is located: install a tee (3) at the drill rod joint of the drilling machine (2), build a water tank (21) at a distance of 2m-5m from the drilling machine (2), cover the opening of the water tank (21) with a cover plate (25), and open a through hole (26) on the cover plate (25) that matches the size of the water pipe (10). The water pipe (10) passes through the through hole (26) to connect the water tank (21) and the tee (3), and connect the water tank (21), the chiller (8) and the water pump (9) through the water pipe (10). Step 4: Drill from the system roadway protection coal pillar (114) of the working face (11) to the aquifer (41) and branch to the position opposite to the cut-in roadway (112), drain the water in the aquifer (41) and let it settle and cool down, inject the water into each borehole trajectory and finally discharge it to the surface; Step 5: Repeat steps 2-4 until the cooling of all working surfaces (11) is completed.

2. The method for cooling the working face using drainage water from the aquifer in the roof of the coal seam according to claim 1, characterized in that, In step 1, the theodolite is used to measure the roadway depth in each working face (11) planned according to the mining license plan of the mine, the internal friction angle and cohesion of the surrounding rock in the roadway are measured using rock mechanics testing equipment, the roadway radius is measured using a steel ruler or meter ruler, and the thickness D of the loosened zone of the bottom plate is calculated. （1） Where R0 is the tunnel radius; C is the cohesion; φ is the internal friction angle; Pi is the support resistance; H is the tunnel burial depth; based on the thickness of the loosened zone of the floor and the lithology of the surrounding rock in the tunnel, the sandstone or limestone layer below the loosened zone is selected as the target layer for water inflow and outflow (12).

3. The method for cooling the working face using drainage water from the aquifer in the roof of the coal seam according to claim 1 or 2, characterized in that, Step 4 is implemented in the following steps: Step 4.1: The two drilling rigs (2) drill upwards from their respective chambers (1) to the aquifer (41) and branch out horizontally within the aquifer (41) to a position opposite to the cut-in tunnel (112) in the working face (11), forming two third boreholes (22). The distance between the two third boreholes (22) is equal to the distance between the branches on the third boreholes (22), both being 30m-40m. The calculation method for the number of branches and m on the two third boreholes (22) is as follows: （2） in, d1 is the average spacing between all adjacent branches and the spacing between the two third boreholes, and d2 is the length of the cut-eye tunnel (112); Step 4.2: Drain the water in the aquifer (41) so that the water flows through the two tees (3) and through the water pipe (10) into the corresponding water tank (21). Let the water stand and settle until the impurities in the water completely sink to the bottom of the water tank (21). Step 4.3: The water in the two water tanks (21) is transported to the corresponding chiller (8) through the water pipe (10), and the chiller (8) is used to cool the water to 1℃-5℃; Step 4.4: Water is injected into the corresponding inlet hole (13) by the corresponding water pump (9). The water flows through the first borehole (5), the first arc segment (17), the second arc segment (18), and the second borehole (6), and then flows out through the return hole (15) and into the drainage pipe (16), and is discharged to the ground through the mine drainage system.

4. The method for cooling the working face using drainage water from the aquifer in the roof of the coal seam according to claim 1, characterized in that, After the mining work of the working face (11) to be cooled in step 5 is completed, the two chillers (8), two water pumps (9) and two drilling rigs (2) are moved to the corresponding positions of another working face (11) that has not been cooled for the next cooling work.

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