A method for recovering coal from sidewall compression in open-pit mines with monitored stress displacement

Abstract

This invention discloses a method for recovering coal from side slope pressure in open-pit mines with monitored stress displacement. The method involves mining in soft rock strata; a filling station is set up at the uppermost flat area of ​​the slope crest, and filling pipelines are laid down the slope from the bottom of the filling station to the mining chamber; after mining a chamber, a reinforcing cage is sent into the chamber, equipped with inclinometers and force measuring devices; after the reinforcing cage is sent into the chamber, the filling station injects liquid filling material into the chamber through the filling pipelines, and the liquid filling material solidifies to form in-situ filling piles; the in-situ filling piles replace the soft rock strata, significantly improving the overall stability coefficient of the slope, increasing the final slope angle while maintaining the slope height, and advancing from the bottom of the pit at the slope toe towards the end slope, achieving side slope mining and increasing coal resource recovery; through pre-embedded inclinometers and force measuring devices, the changes in vertical displacement and vertical stress of the slope are monitored continuously during side slope mining.

Description

Technical Field

[0001] This invention relates to a method for recovering coal from sidewall pressure, specifically a method for recovering coal from sidewall pressure in open-pit mines with monitored stress displacement, belonging to the field of mineral mining technology. Background Technology

[0002] Open-pit coal mining is an important method of coal extraction, characterized by high resource recovery rates. Currently, in northern and northwestern my country, many open-pit coal mines contain weak rock strata. These weak rock strata generally have incomplete structures, low cementation, and are characterized by weakness, strong creep, and strong hydrophilicity. The presence of weak rock strata commonly leads to reduced slope stability, and monitoring changes in internal stress and displacement of the slope remains a challenge. This limits the implementation of side-mounted mining techniques, leaving a significant amount of coal resources unextracted. Abandoning mining would represent a substantial resource loss for both enterprises and the nation. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides a stress-displacement-monitored method for coal recovery from side slopes in open-pit mines. This method can improve the physical and mechanical properties of the weak rock layers inside the slope, enhance the overall slope stability, and enable continuous monitoring of changes in vertical displacement and stress during side slope mining. This increases the amount of coal resources recovered and is beneficial for the sustainable development of the mine.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for recovering coal from sidewall pressure in open-pit mines with monitored stress displacement, wherein a longitudinal auger is deployed at the bottom of a weak rock stratum to mine the pit; a filling station is deployed at the uppermost flat plate at the top of the slope, the filling station is filled with liquid filling material, and a filling pipeline is deployed from the bottom of the filling station down the slope to the pit; after the longitudinal auger has finished mining a pit, a reinforcing cage is sent into the pit, and an inclination measuring device is installed at the bottom inner part of the longitudinal axis of the reinforcing cage diameter, and a force measuring device is installed at the top outer part of the longitudinal axis of the reinforcing cage diameter;

[0005] After the steel cage is sent into the mining pit, the filling station injects liquid filling material into the mining pit through the filling pipeline. After the liquid filling material solidifies, it forms an in-situ filling pile.

[0006] In-situ filling piles replace weak rock layers, significantly improving the overall stability coefficient of the slope. With the slope height unchanged, the final slope angle is increased, allowing for advancement from the bottom of the pit at the slope to the end side, achieving side-side mining. Through pre-embedded inclination and force measuring devices, the changes in vertical displacement and vertical stress of the slope are monitored at all times during side-side mining.

[0007] Furthermore, the inclinometer device includes a horizontally fixed inclinometer sensor and a connecting rod. The horizontally fixed inclinometer sensors are arranged at 10m intervals from the entrance to the end of the mining tunnel, and adjacent horizontally fixed inclinometer sensors are connected by a connecting rod.

[0008] Furthermore, the force measuring device includes a steel frame, a spring, a baffle, an earth pressure gauge, a limiting pin, and a traction wire. The steel frame is located at the top outside the longitudinal axis of the reinforcing cage. Inside the steel frame, the spring, the baffle, and the earth pressure gauge are arranged sequentially from bottom to top. The side wall of the steel frame and the inside of the baffle are provided with through holes for the limiting pin to pass through. In the initial state, the inner end of the limiting pin passes through the through holes in the side wall of the steel frame and the inside of the baffle, and the spring is compressed inside the steel frame by the baffle. The outer end of the limiting pin is connected to one end of the traction wire, and the other end of the traction wire extends to the entrance of the mining tunnel.

[0009] Furthermore, when the weak rock stratum is a dip-sloping stratum, a hole is drilled vertically from the top of the slope into the mining chamber, and filling pipes are arranged in the hole.

[0010] Furthermore, the mining chamber is mined using a double-cycle interval skip mining method, where the first mining chamber is filled while the second mining chamber is being mined.

[0011] Furthermore, before filling the mining chamber, filling pipelines and return gas pipelines are first laid, and then a retaining wall is set up inside the mining chamber at a distance of 5m from the entrance to block the entrance. The mining chamber is then filled after the entrance is blocked.

[0012] Furthermore, the dip angle of the weak rock layer ranges from 0° to ±15°.

[0013] Compared with existing technologies, this invention involves inserting a steel cage equipped with force measuring and inclination measuring devices after mining weak rock strata, and then filling it with liquid filling material to solidify it into in-situ filling piles. This replaces the weak rock strata in the slope with in-situ filling piles with higher physical and mechanical parameters. Through the coupling effect of the steel cage and the in-situ filling piles, the overall stability of the slope can be significantly improved. This also increases the recovery rate of coal resources under slope pressure, saves a significant amount of stripping costs and disposal space in the internal spoil heap. At the same time, it allows for continuous monitoring of changes in vertical displacement and vertical stress of the slope, ensuring safety while improving the recovery rate. This has important practical significance for achieving sustainable development of mining enterprises. Attached Figure Description

[0014] Figure 1 This is a structural cross-sectional view of the weak rock strata being mined according to the present invention;

[0015] Figure 2 This is a cross-sectional view of the structure of the present invention, which includes a steel cage and is filled with weak rock layers.

[0016] Figure 3This is a cross-sectional view of the structure of the infill pipeline arrangement for the dip-side rock strata of the present invention;

[0017] Figure 4 This is a schematic diagram of the structure and installation of the inclinometer device of the present invention;

[0018] Figure 5 This is a schematic diagram of the structure and installation of the force measuring device of the present invention;

[0019] Figure 6 This is a schematic diagram of the mining sequence in the mining tunnel of the present invention;

[0020] Figure 7 This is a schematic diagram of the structure of the coal seam backfilling after the present invention.

[0021] In the diagram: 1. Longitudinal auger drilling rig; 2. Soft rock strata; 3. Reinforcing cage; 4. Connecting rod; 5. Traction wire; 6. Horizontal fixed inclinometer sensor; 7. Filling station; 8. Filling pipeline; 9. Return gas pipeline; 10. Filled mining chamber; 11. Temporary isolation rock pillar; 12. Steel frame; 13. Retaining wall; 14. Underlying rock strata; 15. Coal seam; 16. Slope top; 17. Earth pressure gauge; 18. Limiting pin; 19. Baffle; 20. Spring; 21. In-situ filling pile; 22. Coal mining machine; 1-1. First mining chamber of the first cycle; 1-2. Second mining chamber of the first cycle; 1-n. Last mining chamber of the first cycle; 2-1. First mining chamber of the last cycle; 2-2. Second mining chamber of the last cycle; 2-n. Last mining chamber of the last cycle. Detailed Implementation

[0022] The invention will now be further described with reference to the accompanying drawings.

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] like Figure 1 and Figure 2 As shown, this invention provides a technical solution where a longitudinal auger drill rig 1 is arranged at the bottom plate of the weak rock layer 2 to mine a pit. The mining depth of the pit ranges from 0 to 150 m, and the mining diameter is the diameter of the auger drill, ranging from 50 to 150 cm. A filling station 7 is arranged at the upper flat plate of the slope top 16. The filling station 7 is filled with liquid filling material, and a filling pipeline 8 is arranged from the bottom of the filling station 7 down the slope to the mining pit. Figure 3As shown, if the weak rock layer 2 is a dip-sloping rock layer, then a hole is drilled vertically from the top of the slope 16 into the mining chamber, and a filling pipe 8 is arranged in the hole. After the longitudinal axis auger 1 finishes mining a mining chamber, the reinforcing cage 3 is sent into the mining chamber. An inclination measuring device is set at the bottom of the inner diameter of the longitudinal axis of the reinforcing cage 3, and a force measuring device is set at the top of the outer diameter of the longitudinal axis of the reinforcing cage 3. Measured from the entrance of the mining chamber, the force measuring device is located at about 1 / 4 of the total length of the reinforcing cage. The inclination measuring device and the force measuring device are used to monitor the changes in vertical displacement and vertical stress of the slope, respectively, in order to understand the creep deformation inside the slope, predict the trend of future slope displacement changes, and provide early warning for possible landslide disasters. If the monitored changes are small and the rate of change is slow, the staff can carry out "clearing and load reduction" on the slope to continue to recover the coal pressed against the side walls. If the monitored changes are large and the rate of change is fast, personnel and equipment need to be evacuated from the danger zone as soon as possible to ensure the safety of personnel and equipment.

[0025] like Figure 4 As shown, the inclinometer device includes a horizontally fixed inclinometer sensor 6 and a connecting rod 4. The horizontally fixed inclinometer sensors 6 are arranged at 10m intervals from the entrance of the mining tunnel to the end of the mining tunnel. The two ends of the horizontally fixed inclinometer sensor 6 need to be treated with insulating tape to prevent seepage. Adjacent horizontally fixed inclinometer sensors 6 are connected by the connecting rod 4 to form a rigid sensor string.

[0026] like Figure 5 As shown, the force measuring device includes a steel frame 12, a spring 20, a baffle 19, an earth pressure gauge 17, a limiting pin 18, and a traction wire 5. The steel frame 12 is located on the top outside the longitudinal axis of the diameter of the reinforcing cage 3. The spring 20, the baffle 19, and the earth pressure gauge 17 are arranged sequentially from bottom to top inside the steel frame 12. The spring 20 and the baffle 19 are welded together. The side wall of the steel frame 12 and the inside of the baffle 19 are both provided with through holes for the limiting pin 18 to pass through. In the initial state, the inner end of the limiting pin 18 passes through the through holes in the side wall of the steel frame 12 and the inside of the baffle 19. The baffle 19 compresses the spring 20 inside the steel frame 12, and the spring 20 is in a state of compression storing elastic potential energy. The outer end of the limiting pin 18 is connected to one end of the traction wire 5, and the other end of the traction wire 5 extends to the entrance of the mining tunnel.

[0027] After the steel cage 3 is sent into the mining chamber, the limiting pin 18 is pulled out by pulling the traction wire 5 outside the mining chamber. After the external force of the limiting is lost, the elastic potential energy of the spring 20 is released, which pops out the earth pressure gauge 17 and pushes it to the side wall of the upper soil layer. Then the filling station 7 injects liquid filling material into the mining chamber through the filling pipeline 8. After the liquid filling material solidifies, it forms an in-situ filling pile 21.

[0028] like Figure 7As shown, before the weak rock layer 2 was replaced with in-situ filling piles 21, the slope was mined according to the slope angle α of the mining design. After replacing the weak rock layer 2 with in-situ filling piles 21, the overall stability coefficient of the slope was significantly improved. With the slope height unchanged, the final slope angle α was increased to β, and the slope was advanced from the bottom of the pit at the toe to the end side. An end-side coal mining machine 22 was set on the overlying rock layer 14 to fill and mine the lower coal seam 15 of the side side. More side-side coal can be recovered under the premise of slope safety.

[0029] like Figure 6 As shown, the mining chambers are mined using a double-cycle, intermittent skip-mining method. First, the first mining chamber 1-1 of the first cycle is mined. After mining is completed, a temporary isolation rock pillar 11 is reserved before mining the second mining chamber 1-2 of the first cycle. Simultaneously, the first mining chamber 1-1 of the first cycle is filled while mining the second mining chamber 1-2, forming a filled mining chamber 10. This process continues until the last mining chamber 1-n of the first cycle is mined and filled. The temporary isolation rock pillar 11 provides support during the mining of the first cycle. Once all the first cycle mining chambers are opened... After mining is completed, the reserved temporary isolation rock pillar 11 will be used as the mining chamber for the final cycle. The mining method is the same as that of the first cycle mining chamber. First, the first mining chamber 2-1 of the final cycle is mined. After mining is completed, the filled mining chamber 10 is skipped and the second mining chamber 2-2 of the final cycle is mined. While mining the second mining chamber 2-2 of the final cycle, the first mining chamber 2-1 of the final cycle is filled. This process continues until the last mining chamber 2-n of the final cycle is mined and filled. The filled mining chamber 10 plays a supporting role during the mining of the final cycle mining chamber.

[0030] To prevent the liquid filling material from flowing out of the mining chamber before solidification during filling, thus affecting the filling effect, a filling pipeline 8 and a return gas pipeline 9 are installed before filling. Then, a retaining wall 13 is installed 5m away from the entrance inside the mining chamber to block the entrance. The mining chamber is filled after the entrance is blocked. The installation of the retaining wall 13 can improve the utilization rate and filling rate of the liquid filling material. At the same time, the installation of the return gas pipeline 9 can discharge the air "squeezed out" by the liquid filling material in the mining chamber, avoid the formation of a closed gas in the mining chamber, reduce the pressure in the mining chamber, and help improve the filling efficiency of the filling pipeline 8.

[0031] 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 in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, 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.

[0032] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any minor modifications, equivalent substitutions, and improvements made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for recovering coal trapped in the side walls of an open-pit mine with monitored stress displacement, characterized in that, A longitudinal auger drill (1) is set up at the bottom plate of the weak rock layer (2) to mine the cave; a filling station (7) is set up at the uppermost flat plate of the slope top (16). The filling station (7) is filled with liquid filling material. A filling pipeline (8) is set up from the bottom of the filling station (7) down the slope to the cave; after the longitudinal auger drill (1) has finished mining a cave, a steel cage (3) is sent into the cave. A tilt measuring device is set at the bottom of the longitudinal axis of the steel cage (3) and a force measuring device is set at the top of the longitudinal axis of the steel cage (3). After the steel cage (3) is sent into the mining pit, the filling station (7) injects liquid filling material into the mining pit through the filling pipeline (8). After the liquid filling material solidifies, it forms an in-situ filling pile (21). In-situ filling piles (21) replace the weak rock layer (2), and with the slope height unchanged, the final slope angle is increased, and the slope is advanced from the bottom of the pit at the toe of the slope to the end side to achieve side mining; By pre-installing inclination and force measuring devices, the changes in vertical displacement and vertical stress of the slope are monitored at all times during the mining process. The inclinometer device includes a horizontal fixed inclinometer sensor (6) and a connecting rod (4). The horizontal fixed inclinometer sensor (6) is arranged at a spacing of 10m from the entrance of the mining tunnel to the end of the mining tunnel. Adjacent horizontal fixed inclinometer sensors (6) are connected by the connecting rod (4). The force measuring device includes a steel frame (12), a spring (20), a baffle (19), a soil pressure gauge (17), a limiting pin (18), and a traction wire (5). The steel frame (12) is set on the top outside the longitudinal axis of the steel cage (3). The steel frame (12) is arranged from bottom to top with the spring (20), the baffle (19), and the soil pressure gauge (17). The side wall of the steel frame (12) and the inside of the baffle (19) are provided with through holes for the limiting pin (18) to pass through. In the initial state, the inner end of the limiting pin (18) passes through the through holes in the side wall of the steel frame (12) and the inside of the baffle (19) in turn. The spring (20) is compressed inside the steel frame (12) by the baffle (19). The outer end of the limiting pin (18) is connected to one end of the traction wire (5). The other end of the traction wire (5) extends to the entrance of the mining tunnel.

2. The method for recovering coal from sidewall compression in open-pit mines with monitored stress displacement according to claim 1, characterized in that, When the weak rock layer (2) is a dip-sloping rock layer, a hole is drilled vertically from the top of the slope (16) into the mining chamber, and a filling pipe (8) is arranged in the hole.

3. The method for recovering coal from sidewall compression in open-pit mines with monitored stress displacement according to claim 1, characterized in that, The mining chamber is mined using a double-cycle interval skip mining method, where the first mining chamber is filled while the second mining chamber is being mined.

4. A method for recovering coal from sidewall compression in open-pit mines with monitored stress displacement, as described in claim 3, is characterized in that... Before filling the mining chamber, a filling pipeline (8) and a return gas pipeline (9) are first laid. Then, a retaining wall (13) is set up inside the mining chamber at a distance of 5m from the entrance to block the entrance. The mining chamber is then filled after the entrance is blocked.

5. A method for recovering coal from sidewall compression in open-pit mines with monitored stress displacement, as described in claim 1, is characterized in that... The dip angle of the weak rock layer (2) is in the range of 0° to ±15°.

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