Method for weakening rock by hydraulic splitting machine to make fully mechanized caving face directly pass through fault

Abstract

This application discloses a method for using a hydraulic rock splitter to weaken rock, enabling a fully mechanized mining / caving face to directly cross a fault. It belongs to the field of coal mining, and its key technical points are as follows: The method is carried out according to the following steps: Step S1, conduct on-site investigation and research, especially the fault-related parameters of the working face; Step S2, when the working face is mined back to the vicinity of the fault, stop the machine for sidewall protection; Step S3, set the drilling parameters for the sidewall of the working face near the fault and drill holes; Step S4, set the number of rock splitter groups and cyclically insert the rock splitters into the drill holes; Step S5, set the rock splitting pressure, start the hydraulic pump to supply fluid, and perform grouped fracturing; Step S6, the coal mining machine runs, cutting the rock near the fault; Step S7, start the next cycle, repeating the above steps until the fault is crossed. Using this method greatly improves the efficiency of the working face directly crossing the fault, while also being safer, more reliable, and more environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of coal mining, specifically to a method for using a hydraulic rock splitter to weaken rocks so that fully mechanized mining / caving faces can directly pass through faults. Background Technology

[0002] my country's coal seam geological conditions are relatively complex, and faults are frequently encountered during the longwall mining process in underground mines. Whether a longwall mining face can directly pass through a fault depends on factors such as the fault's elevation difference, the coal seam thickness, the minimum operating height of the longwall mining equipment, and the rock hardness at the fault location. Generally, when the fault elevation difference is small, a direct hard pass is chosen on-site; when the fault elevation difference is large, skip mining is adopted. That is, when the working face is a strike fault, a new cut is made on the other side of the fault according to the actual situation, and a roadway is excavated around the fault, connecting with the original cut and the return roadway, thus avoiding the fault during return mining. However, skip mining has the problems of low mining efficiency, serious waste of coal resources, and restricts efficient and green coal mining. Therefore, choosing a method that allows the working face to directly pass through faults safely and efficiently is of great significance.

[0003] Currently, there are three main methods for directly crossing faults in the working face: 1. The flat-push hard-crossing method, also known as the coal mining machine forced cutting of the surrounding rock, involves using a coal mining machine to forcibly cut the rock, treating it as coal and cutting it along with it, without special treatment or operation. This method is mainly used when the fault is small and the roof and floor of the coal seam are composed of relatively soft rock. The advantage of this method is its simplicity and ease of operation, but the disadvantages are low work efficiency, severe wear and frequent replacement of the coal mining machine pick. 2. The loosening blasting method, specifically, involves first loosening and blasting the fault rock, followed by the coal mining machine slowly sweeping through the roof and floor. The advantages of this method are good weakening of the fault rock and a fast direct crossing speed, but the disadvantages are certain safety hazards, such as the difficulty in controlling the flying rocks generated during blasting, which can easily damage equipment; and the possibility of gas or coal dust explosions during blasting operations. 3. Static fracturing technology involves using a static fracturing agent that expands after hydration to apply radial pressure to the borehole wall, causing rock breakage. When the tensile stress caused by the radial pressure in the tangential direction of the borehole wall exceeds the tensile strength of the rock, the rock will break. This method has minimal safety risks and can break rocks without vibration, shock waves, or flying rocks. However, its disadvantages include insufficient splitting force and poor splitting effect.

[0004] Therefore, to solve the above problems, this invention proposes a method for weakening rock with a hydraulic rock splitter to enable fully mechanized mining / caving faces to directly cross faults. Specifically, when the working face crosses a fault, a hydraulic rock splitter is used to weaken the rock, destroying its integrity and reducing its mechanical strength, allowing the coal mining machine to cut the rock, thereby improving mining efficiency. The principle is to use high-pressure oil output from a pump station to drive a hydraulic cylinder, applying pressure to the borehole wall to fracture the rock. This method is relatively static, avoids rockfall, has relatively low noise, and offers higher safety. In recent years, although hydraulic rock splitters have been used in surface rock excavation, there is no precedent for using them to weaken rock to enable fully mechanized mining / caving faces to directly cross faults in underground coal mines. Summary of the Invention

[0005] This invention provides a method for using a hydraulic rock splitter to weaken rock, enabling fully mechanized mining / caving faces to directly pass through faults. The aim is to solve the problem of partial rock strata interfering with the coal mining process due to fault influence, thereby improving mining efficiency. Current methods for directly passing through faults suffer from low efficiency, poor effectiveness, and certain safety hazards.

[0006] The purpose of this invention is to provide a method for using a hydraulic rock splitter to weaken rock, enabling a fully mechanized mining / caving face to directly pass through a fault. This method involves drilling holes in the rock surface near the fault, inserting a hydraulic rock splitter, and then using the hydraulic rock splitter to weaken the rock, achieving three benefits: ① High-efficiency rock weakening; the process is simple, convenient, and reusable; ② The hydraulic rock splitter has a large splitting force and good splitting effect; ③ It reduces the possibility of accidents such as flying rocks damaging equipment and gas / coal dust explosions, resulting in better safety. The specific method of this invention for using a hydraulic rock splitter to weaken rock, enabling a fully mechanized mining / caving face to directly pass through a fault, is carried out according to the following steps:

[0007] I. On-site investigation and research on the engineering geological conditions of the working face, especially the fault-related parameters within the working face.

[0008] On-site collection of mine geological reports, borehole columnar sections, preliminary design specifications, tunnel excavation operation procedures, and working face mining operation procedures clarifies the lithology, thickness, and mechanical strength of the coal seam and its roof and floor strata being mined, as well as parameters such as fault extent, drop, dip, and dip angle within the working face, and mining techniques including mining methods, cutting advance, and number of cycles. Fault-related parameters can be determined through tunnel exploration and drilling during tunnel excavation and further refined based on specific exposure conditions during working face mining.

[0009] II. When the working face is mined back to the vicinity of the fault, stop the machine and provide side protection.

[0010] The coal mining machine operates normally until it encounters rock during cutting. Then, it stops and the support side plates are opened to prevent coal wall spalling near the fault and to prepare for weakening the rock.

[0011] III. Set parameters such as borehole diameter, depth, spacing between rows, and number of rows, and drill holes in the rock near the fault within the working face.

[0012] The aperture size is selected based on the diameter of the hydraulic rock splitter.

[0013] The drilling depth is consistent with the cutting depth of the coal mining machine, which is 0.6m, 0.8m, 1.0m, or 1.2m. If the hole depth is greater than the cutting depth, it is easy to cause spalling, posing a safety hazard; if the hole depth is less than the cutting depth, the efficiency of directly passing through the fault is low.

[0014] The borehole spacing is 500mm, and the row spacing is determined according to the mining height. Specifically: when the mining height is within 1.3m (thin coal seam mining), one row of boreholes is arranged, centrally located; when the mining height is 1.3m-3.5m (medium-thick coal seam mining), two rows of boreholes are arranged, with a row spacing of 600-1000mm; when the mining height is above 3.5m (thick coal seam mining), three rows of boreholes are arranged, with a row spacing of 1000-1300mm.

[0015] IV. Set the number of splitting rod groups and cyclically insert the splitting rods into the borehole.

[0016] Six splitting rods are grouped together, and a total of 3 to 10 groups are arranged. The specific number of groups depends on the coal cutting rate of the coal mining machine and the length of the fault cut in the working face. If the number of groups is too small, it will waste construction time and increase the workload of workers; if the number of groups is too large, it will lead to an increase in the number of splitting rods and hydraulic pumps, resulting in redundancy and increased costs.

[0017] When the rock splitting rod is inserted into the borehole, a group of six splitting rods in one row is used to weaken the rock when the mining height is below 1.3m; when the mining height is between 1.3m and 3.5m, a group of six splitting rods in two rows is used to weaken the rock, with three splitting rods in each row; when the mining height is above 3.5m, a group of six splitting rods in three rows is used to weaken the rock, with two splitting rods in each row.

[0018] V. Set the fracturing pressure, turn on the pressure pump to supply fluid, and perform group fracturing. Simultaneously operate 3 to 10 hydraulic pumps, that is, 3 to 10 groups of rock splitters working at the same time to weaken the rock.

[0019] VI. The coal mining machine operates, cutting through the rock near the fault.

[0020] VII. Start the next cycle and repeat the above steps until the fault is passed.

[0021] A method for using a hydraulic rock splitter to weaken rock so that a fully mechanized mining / caving face can directly pass through a fault, the method being carried out according to the following steps:

[0022] Step S1: Conduct on-site investigation and research, especially the fault-related parameters of the working face;

[0023] Step S2: When the working face is mined back to the vicinity of the fault, stop the machine to protect the sidewalls;

[0024] Step S3: Set the drilling parameters for the side of the working face near the backfilling side when crossing the fault, and then drill.

[0025] Step S4: Set the number of splitting rod groups and insert the splitting rods into the borehole in a cyclical manner.

[0026] Step S5: Set the fracturing pressure, start the hydraulic pump to supply fluid, and perform group fracturing;

[0027] Step S6: The coal mining machine operates, cutting the rock near the fault.

[0028] Step S7: Start the next cycle and repeat the above steps until the fault is passed.

[0029] Furthermore, the drilling parameters include: borehole diameter, depth, spacing, row spacing, and arrangement.

[0030] Furthermore, the aperture size is selected based on the diameter of the hydraulic rock splitter;

[0031] The drilling depth is consistent with the cutting depth of the coal mining machine, which is 0.6m, 0.8m, 1.0m or 1.2m;

[0032] Drilling spacing 500mm;

[0033] The spacing between rows is selected based on the mining height, and its range is 600~1300mm;

[0034] The arrangement is a three-color pattern.

[0035] Furthermore, when the mining height of the fully mechanized mining / longwall mining face is within 1.3m, a row of boreholes should be arranged, centered on the center.

[0036] When the mining height is 1.3m-3.5m, two rows of boreholes are arranged with a row spacing of 600-1000mm.

[0037] When the mining height is above 3.5m, arrange 3 rows of boreholes with a row spacing of 1000-1300mm.

[0038] Furthermore, step S4 also includes: grouping 6 splitting rods into a group, arranging a total of 3 to 10 groups, and grouping the splitting rods into three categories according to different mining heights: a group of 1 row of 6 columns of holes, a group of 2 rows of 3 columns of holes, and a group of 3 rows of 2 columns of holes.

[0039] Furthermore, step S5 also includes: operating 3 to 10 hydraulic pumps, i.e., 3 to 10 sets of rock splitters working simultaneously to weaken the rock; opening the reversing valve to begin splitting the rock.

[0040] Furthermore, step S4 also includes: the placement method of the splitting rods: when the mining height is below 1.3m, a group of 6 splitting rods in one row is used to weaken the rock; when the mining height is between 1.3m and 3.5m, a group of 6 splitting rods in two rows is used to weaken the rock, with 3 splitting rods arranged in each row; when the mining height is above 3.5m, a group of 6 splitting rods in three rows is used to weaken the rock, with 2 splitting rods arranged in each row.

[0041] Furthermore, for rocks with a uniaxial compressive strength of 60~100MPa, the splitting pressure is set to 60~80MPa; for rocks with a uniaxial compressive strength of 40~60MPa, the splitting pressure is set to 40~60MPa; and for rocks with a uniaxial compressive strength of 20~40MPa, the splitting pressure is set to 20~40MPa.

[0042] The method provided above by the present invention for weakening rock with a hydraulic rock splitter to enable fully mechanized mining / caving faces to directly pass through faults, compared with existing methods:

[0043] 1) This application is the first to use a hydraulic rock splitter in a fully mechanized mining / caving face with weakened rock. Several key challenges are encountered in this process:

[0044] First, how to determine the drilling parameters; second, how to determine the splitting force.

[0045] 1.1 Regarding the first question, the drilling parameters include: borehole diameter, depth, spacing, row spacing, and arrangement. Among these, row spacing is the most challenging to determine; this application presents a method for determining row spacing in conjunction with the fully mechanized mining height.

[0046] When the mining height of the fully mechanized mining / longwall mining face is within 1.3m, arrange one row of boreholes, with the middle one arranged in the middle;

[0047] When the mining height is 1.3m-3.5m, two rows of boreholes are arranged with a row spacing of 600-1000mm;

[0048] When the mining height is above 3.5m, arrange 3 rows of boreholes with a row spacing of 1000-1300mm.

[0049] Depending on the mining height, the splitting rods are placed in three groups: one group consists of 6 rows of holes, another group consists of 3 rows of holes, and yet another group consists of 2 rows of holes.

[0050] 1.2 Regarding the second question, this application provides a method for determining the splitting force:

[0051] For rocks with a uniaxial compressive strength of 60~100MPa, the splitting pressure is set to 60~80MPa; for rocks with a uniaxial compressive strength of 40~60MPa, the splitting pressure is set to 40~60MPa; for rocks with a uniaxial compressive strength of 20~40MPa, the splitting pressure is set to 20~40MPa.

[0052] 2) This method allows for safer, more effective, and faster weakening of the rock surface. It offers greater flexibility in use, lower maintenance costs, and better economic benefits. The rock splitter operates in a static, hydraulically controlled environment, eliminating safety hazards such as flying rocks and shock waves, and requiring no complex safety measures. Matching the drilling depth with the coal mining machine's cutting depth significantly improves mining efficiency. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of a working face in a mine crossing a fault, according to the present invention.

[0054] Figure 2 This is a schematic diagram of a cross-section of a working face in a mine, based on the present invention.

[0055] Figure 3 This is a schematic diagram of a drilling operation on a rock near a fault in a mine working face according to the present invention.

[0056] Figure 4 This is a schematic diagram of the group splitting of a fault in a mining face according to the present invention.

[0057] Figure 1-4 The accompanying diagrams are described below:

[0058] 1. Goaf; 2. Rock near fault; 3. Transport roadway; 4. Fault; 5. Return air roadway; 6. Coal seam in working face; 7. Limestone; 8. Mining face; 9. Coal seam; 10. Mudstone; 11. Drill hole or split hole; 12. Hydraulic pump; 13. Splitting rod; Detailed Implementation

[0059] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and specific examples.

[0060] Example 1

[0061] The method for weakening rock surfaces provided by this invention for fully mechanized mining / longwall mining faces to directly cross faults is carried out according to the following steps:

[0062] Step 1: As Figure 1 and Figure 2 According to the above, through on-site investigation and research, the single tensile strength of the rock near the fault was determined to be 47.8 MPa, and the coal seam thickness was 6.5 m.

[0063] Step 2: Stop the machine and open the support side plates to prepare for weakening the rock.

[0064] Step 3: As Figure 3 Drilling was carried out as shown. For a coal seam height of 6.5m, three rows of boreholes were arranged, positioned at rock depths of 1.7m, 3.2m, and 4.7m from the bottom, respectively. The borehole spacing was 0.5m. The drilling depth was consistent with the cutting depth of the coal mining machine, which was 0.8m.

[0065] Step 4: Place the splitting rods in groups into the borehole in a cyclical manner. When placing the splitting rods, use three rows of six splitting rods as a group, connected to the hydraulic pump, for a total of 5 groups.

[0066] Step 5: Turn on the pressure pump to supply fluid, insert the rock splitting rod into the hole, and begin weakening the rock. Depending on the number of groups, operate 5 hydraulic pumps simultaneously, meaning 5 groups of rock splitters will be operating to split the rock. Figure 4 As shown, each cycle can advance 4.5m. The splitting pressure is set at 50MPa.

[0067] Step Six: The coal mining machine operates, cutting the rock near the fault.

[0068] Step 7: Repeat the above cycle until all the rock has been cut.

[0069] Example 2:

[0070] Step 1: As Figure 1 and Figure 2 According to the above, through on-site investigation and research, the single tensile strength of the rock near the fault was determined to be 78.4 MPa, and the coal seam thickness was 2.4 m.

[0071] Step 2: Stop the machine and open the support side plates to prepare for weakening the rock.

[0072] Step 3: As Figure 3 Drilling was carried out as shown. Two rows of boreholes were arranged at a coal seam height of 2.4m, one at 0.8m and the other at 1.6m from the bottom of the rock. The borehole spacing was 0.5m. The drilling depth was consistent with the cutting depth of the coal mining machine, which was 0.6m.

[0073] Step 4: Place the splitting rods into the borehole in groups in a cyclical manner. When placing the splitting rods, use two rows of six splitting rods as a group to connect to the hydraulic pump, and arrange a total of 3 groups.

[0074] Step 5: Turn on the pressure pump to supply fluid, insert the rock splitting rod into the hole, and begin weakening the rock. Depending on the number of sets, operate 3 hydraulic pumps simultaneously, meaning 3 sets of rock splitters will operate to split the rock. Figure 4 As shown, each cycle can advance 4m. The splitting pressure is set to 80MPa.

[0075] Step Six: The coal mining machine operates, cutting the rock near the fault.

[0076] Step 7: Repeat the above cycle until all the rock has been cut.

[0077] The above-described embodiments are preferred embodiments of the present invention and are only used to facilitate the illustration of the present invention. They are not intended to limit the present invention in any way. Any person skilled in the art who makes local modifications or alterations to the technical content disclosed in the present invention without departing from the scope of the technical features of the present invention shall still fall within the scope of the technical features of the present invention.

Claims

1. A method for weakening rock by hydraulic fracturing machine to make fully mechanized / fully mechanized caving face directly pass through fault, characterized in that, The method is performed by the following steps: Step S1, on-site investigation and research are conducted to obtain the fault-related parameters of the working face; Step S2, when the working face is close to the fault, stop and support the side; Step S3, set the drilling parameters of the working face on the side of the drilling near the mining side when passing through the fault, and drill; the drilling parameters include: drilling diameter, depth, spacing, row spacing, arrangement; the diameter is selected according to the diameter of the hydraulic splitting machine; the drilling depth is consistent with the cutting depth of the coal mining machine, which is 0.6m, 0.8m, 1.0m or 1.2m; the drilling spacing is 500mm; the row spacing is selected according to the mining height, which ranges from 600 to 1300mm; the arrangement is three flower eyes; When the mining height of the fully mechanized / fully mechanized caving face is less than 1.3m, one row of drilling is arranged, which is arranged in the middle; when the mining height is 1.3m to 3.5m, two rows of drilling are arranged, and the row spacing is 600-1000mm; when the mining height is more than 3.5m, three rows of drilling are arranged, and the row spacing is 1000-1300mm; According to the different mining heights, the splitting rods are placed in three groups: one group of 1 row and 6 columns, one group of 2 rows and 3 columns, and one group of 3 rows and 2 columns; The placement method of the splitting rod: when the mining height is less than 1.3m, one row of 6 splitting rods is used as a group to weaken the rock; when the mining height is 1.3m to 3.5m, two rows of 6 splitting rods are used as a group to weaken the rock, and 3 splitting rods are arranged in each row; when the mining height is more than 3.5m, three rows of 6 splitting rods are used as a group to weaken the rock, and 2 splitting rods are arranged in each row; Step S4, set the number of splitting rod groups, and put the splitting rods into the drilling in groups; 3-10 hydraulic pumps work at the same time to weaken the rock; open the reversing valve to start splitting the rock; Step S5, set the splitting pressure, open the hydraulic pump to supply liquid, and perform group fracturing; the determination method of the splitting pressure of the splitting rod is: for the rock with uniaxial compressive strength of 60-100MPa, the splitting pressure is set to 60-80MPa; for the rock with uniaxial compressive strength of 40-60MPa, the splitting pressure is set to 40-60MPa; for the rock with uniaxial compressive strength of 20-40MPa, the splitting pressure is set to 20-40MPa; Step S6, the coal mining machine runs and cuts the rock near the fault; Step S7, open the next cycle and repeat the above steps until the fault is passed.

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