A method for protecting mine groundwater resources

Abstract

The application discloses a protection method of underground water resources in a mining area, and comprises the following steps: detecting fissure development zones in bedrock layers of the mining area before mining, obtaining development states of the fissure development zones in each region, and performing different operation modes according to different development degrees of the fissure development zones. The protection method improves a protection scheme of underground water in the mining area, can more effectively protect the underground water resources, and is beneficial to maintaining the ecological balance of water resources in the mining area.

Description

Technical Field

[0001] This invention relates to the field of water resource protection technology in mining areas, and in particular to a method for protecting groundwater resources in mining areas. Background Technology

[0002] In coal mining operations, it is necessary to protect both surface water and groundwater resources. Surface water protection typically involves transporting surface water resources from the mining area to other regions for storage and utilization. Groundwater resources are generally located in Quaternary aquifers, or simply aquifers. Under normal circumstances, underground structural layers are divided into surface layers (topsoil + topsoil-rock layers), aquifers, bedrock layers, coal seams, etc. Bedrock layers contain fracture zones with numerous fissures that conduct water. If these fissure zones are close to or connected to the aquifer, water in the aquifer will flow downwards along the fissures. Under normal circumstances, this water flow does not affect the surrounding environment. However, when the coal face is mined, a goaf is formed, and rock from the overlying bedrock layers falls into the goaf. If, at this time, a large number of fissures in the fissure development zone are connected to the goaf, a large amount of water in the aquifer will flow into the goaf, causing the surface water level to drop and affecting the water ecological balance of the surrounding environment.

[0003] Current technologies often employ the method of constructing underground reservoirs in mined-out areas to store mine water, which is then filtered and transported to the surface for reuse. However, this does not solve the technical problem of declining surface water levels.

[0004] Another existing technology involves constructing a barrier layer beneath the aquifer throughout the mining area to prevent water seepage and maintain surface balance. This method requires a large construction area and is costly. Furthermore, the barrier layer is a grout-formed concrete layer, forming a monolithic structure. When the coal face passes through and forms a goaf, rocks from the overlying bedrock layer will fall into the goaf. If the fall is significant and the vibration is intense, the barrier layer may fracture, or even fall into the goaf along with the rocks, thus failing to function as a barrier. Water from the aquifer will then flow into the goaf, causing a drop in the surface water level. In some areas, the fracture zone is highly developed, essentially connecting the aquifer and the coal seam. Constructing a barrier layer in these areas is less meaningful. Because the lower end of the fracture zone in these areas essentially reaches the coal seam, the borehole for the barrier layer can only penetrate the fracture zone. Due to the numerous and irregular fractures, grout leakage is severe, making it difficult to ensure the grout fills the borehole, thus hindering the formation of an effective barrier layer. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a new method for protecting groundwater resources in mining areas. Before mining, the fracture development zones in the bedrock of the mining area are detected to obtain the development status of the fracture development zones in each area. Different operation methods are carried out according to the different development degrees of the fracture development zones, which improves the protection scheme for groundwater in mining areas, can more effectively protect groundwater resources, and is conducive to maintaining the ecological balance of water resources in mining areas.

[0006] The present invention provides a method for protecting groundwater resources in mining areas, comprising the following steps:

[0007] S1: Multiple exploratory boreholes are drilled in the surface layer along a predetermined direction, with the lower end of the exploratory boreholes reaching the coal seam;

[0008] S2: Deploy detection equipment on the surface layer. The detection equipment includes a detection probe, which includes an integrated acoustic detection unit and a camera detection unit.

[0009] S3: Before mining, the detection probes are placed into each detection borehole in a preset order to detect the development status of the fracture development zone in the bedrock layer between the aquifer and the coal seam.

[0010] S4: Set the safe distance between the fracture development zone and the aquifer as L1, and the safe distance between the fracture development zone and the coal seam as L2;

[0011] If the distance between the fracture development zone and the aquifer is L3 > L1 and the distance between the fracture development zone and the coal seam is L4 > L2, then normal coal mining operations shall be carried out.

[0012] If the distance between the fracture development zone of the first region in the mining area and the aquifer is L3≤L1, and the distance between the fracture development zone and the coal seam is L4>L2, then a fracture barrier layer is constructed below the fracture development zone of the first region to prevent water from seeping downwards, and a fracturing borehole is constructed at a predetermined distance below the fracture barrier layer to fracture the surrounding bedrock layer, so as to prevent the fracture barrier layer from being pulled down by the bedrock layer below during coal mining operations;

[0013] If the distance between the fracture development zone and the coal seam in the second area of ​​the mining area is detected to be L3≤L1 and L4≤L2, then an underground reservoir shall be built directly below the second area during coal mining operations.

[0014] In one of the alternative technical solutions, the construction method of the partition layer is as follows:

[0015] Multiple first grouting boreholes are drilled downwards from the ground surface at intervals. The vertical section of the first grouting borehole is located around the first region, and the horizontal section of the first grouting borehole extends below the fracture development zone of the first region.

[0016] Grout is injected into the first grouting borehole to form the partition layer below and around the fracture development zone of the first regional crack.

[0017] In one of the alternative technical solutions, the fracturing borehole is constructed as follows:

[0018] After the first grouting borehole is completed and before grouting is injected into the first grouting borehole, multiple fracturing boreholes are drilled downwards from the ground surface at intervals. The vertical section of the fracturing borehole is located outside the vertical section of the first grouting borehole, and the horizontal section of the fracturing borehole is located at a predetermined distance below the horizontal section of the first grouting borehole.

[0019] After fracturing the horizontal section of the fracturing borehole using fracturing equipment, grout is injected into the first grouting borehole to form the partition layer.

[0020] In one of the alternative technical solutions, the roof of the coal seam below the first area and / or the second area is reinforced before the coal mining face passes below the first area and / or the second area.

[0021] In one of the alternative technical solutions, the method for protecting groundwater resources in the mining area also includes:

[0022] Step S5: During and / or after mining, the state of the partition layer is detected by the detection probe. If a fracture gap is found in the partition layer, isolation and sealing operations are carried out.

[0023] In one of the alternative technical solutions, the isolation and sealing operation includes the following steps:

[0024] Multiple second grouting boreholes are drilled downwards from the ground surface, and the multiple second grouting boreholes are arranged at intervals around the fracture gap, with the lower end of the second grouting boreholes drilled into the partition layer;

[0025] Grout is injected into the second grouting borehole to form an isolation layer around the fracture gap.

[0026] In one of the alternative technical solutions, a water pool is formed by excavating a trench from the ground surface in the middle of the isolation layer, and water in the water pool is pumped out for storage and / or utilization.

[0027] In one of the alternative technical solutions, the water resources situation in the mining area needs to be assessed before drilling exploratory boreholes.

[0028] If there are surface lakes and / or reservoirs in the mining area, the water in the surface lakes and / or reservoirs in the mining area must be transferred to outside the mining area for storage and / or utilization before exploration to avoid water inrush during coal mining.

[0029] In one of the alternative technical solutions, if there are above-ground lakes and / or reservoirs around the mining area, the water in the above-ground lakes and / or reservoirs within the mining area is transferred to the above-ground lakes and / or reservoirs surrounding the mining area.

[0030] In one of the alternative technical solutions, a waterproof layer is constructed on the bottom slab and side walls of the above-ground lakes and / or reservoirs in the mining area after mining;

[0031] Part of the water in the above-ground lakes and / or reservoirs surrounding the mining area will be diverted back to the above-ground lakes and / or reservoirs in the mining area.

[0032] The above technical solution has the following beneficial effects:

[0033] The method for protecting groundwater resources in mining areas provided by this invention involves detecting fracture zones in the bedrock strata of the mining area before mining to obtain the development status of fracture zones in each area. Different operational methods are then implemented according to the different development levels of the fracture zones.

[0034] If the fracture development zone in a certain area is found to be of low development level, and the fracture development zone is within a safe range from the aquifer and coal seam, then normal mining operations can be carried out directly.

[0035] If a fracture development zone is detected to be of moderate development in a certain area, and the fracture development zone is close to or connected to the aquifer, and the fracture development zone is within a safe range from the coal seam, then a fault layer is constructed below the fracture development zone, and a fracturing borehole is constructed below the fault layer to prevent the fault layer from fracturing and collapsing.

[0036] If a fracture development zone is detected to be highly developed in a certain area, or if the fracture development zone is close to or connected to an aquifer, or if the fracture development zone is close to or connected to a coal seam, then an underground reservoir can be built directly in the goaf area below that area to store groundwater resources. After filtration, the groundwater can be returned to the surface for use.

[0037] The method for protecting groundwater resources in mining areas provided by this invention improves the protection scheme for groundwater in mining areas, can more effectively protect groundwater resources, and is conducive to maintaining the ecological balance of water resources in mining areas. Attached Figure Description

[0038] The disclosure of this invention will become more readily understood by referring to the accompanying drawings. It should be understood that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings:

[0039] Figure 1 This is a schematic diagram illustrating a method for protecting groundwater resources in a mining area according to an embodiment of the present invention, when using detection equipment for detection.

[0040] Figure 2 for Figure 1 A magnified view of a portion of the image;

[0041] Figure 3 This is a schematic diagram showing that the distance between the fracture development zone in the bedrock layer and the aquifer and coal seam is within a safe range;

[0042] Figure 4 This is a schematic diagram showing that the fractured zone in the bedrock is close to or connected to the aquifer, while the distance from the coal seam is within a safe range;

[0043] Figure 5 A schematic diagram of the first grouting borehole and fracturing borehole for construction;

[0044] Figure 6 This is a schematic diagram showing the horizontal end of the fracturing borehole after fracturing.

[0045] Figure 7 A schematic diagram showing the formation of a partition layer by injecting grout into the first grouting borehole;

[0046] Figure 8 A schematic diagram of the goaf formed after the coal mining face has passed through;

[0047] Figure 9 This is a schematic diagram showing a highly developed fracture zone in the bedrock layer, which is close to the aquifer and coal seam.

[0048] Figure 10 Cross-sectional view of multiple second grouting boreholes to be drilled around the fracture gap;

[0049] Figure 11 A top view of the construction of multiple second grouting boreholes around the fracture gap;

[0050] Figure 12 A cross-sectional view showing the formation of an isolation layer around the fracture gap;

[0051] Figure 13 A schematic diagram showing above-ground lakes and / or reservoirs both inside and outside the mining area;

[0052] Figure 14 Cross-sectional views of above-ground lakes and / or reservoirs in the mining area;

[0053] Figure 15 A schematic diagram showing that waterproof layers are installed on the bottom slab and side walls of lakes and / or reservoirs on land;

[0054] Figure 16 This is a schematic diagram illustrating the post-mining pumping of water back into surface lakes and / or reservoirs within the mining area. Detailed Implementation

[0055] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. Identical components are indicated by the same reference numerals. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, while the terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0056] The accompanying drawings of this invention only show the general shape or state of each layer and fracture, and refer to their actual shape or state. The terms "pre-mining," "during mining," and "post-mining" in this invention refer to before coal seam mining, during coal seam mining, and after coal seam mining is completed, respectively.

[0057] like Figure 1-9 As shown, an embodiment of the present invention provides a method for protecting groundwater resources in mining areas, comprising the following steps:

[0058] S1: Construct multiple exploratory boreholes 5 along a predetermined direction in the surface layer 1, with the lower end of the exploratory boreholes 5 reaching the coal seam 4.

[0059] S2: A detection device 6 is arranged on the surface layer 1. The detection device 6 includes a detection probe 63, which includes an integrated acoustic detection unit 631 and a camera detection unit 632.

[0060] S3: Before mining, the probe 63 is inserted into each probe borehole 5 in a preset order to obtain the development status of the fracture development zone 31 in the bedrock layer 3 between the aquifer 2 and the coal seam 4.

[0061] S4: Set the safe distance between fracture development zone 31 and aquifer 2 as L1, and the safe distance between fracture development zone 31 and coal seam 4 as L2.

[0062] If the distance L3 between the fractured zone 31 and the aquifer 2 is found to be greater than L1, and the distance L4 between the fractured zone 31 and the coal seam 4 is found to be greater than L2, then normal coal mining operations can proceed.

[0063] If the distance L3≤L1 between the fracture development zone 31 in the first region of the mining area and the aquifer 2, and the distance L4>L2 between the fracture development zone and the coal seam 4, then a fracture barrier 9 is constructed below the fracture development zone 31 in the first region to prevent water from seeping downwards. A fracturing borehole 8 is constructed at a predetermined distance below the fracture barrier 9 to fracture the surrounding bedrock layer 3, preventing the fracture barrier 9 from being dragged down by the bedrock layer 3 below during coal mining operations.

[0064] If the distance between the fracture development zone 31 and the coal seam 4 in the second area of ​​the mining area is detected to be L3≤L1 and L4≤L2, then an underground reservoir shall be built directly below the second area during coal mining operations.

[0065] The method for protecting groundwater resources in mining areas provided by this invention involves detecting the fracture development zones 31 in the bedrock layer 3 of the mining area before mining to obtain the development status of the fracture development zones 31 in each area. Different operating methods are carried out according to the different development degrees of the fracture development zones 31.

[0066] Specifically, the first step involves constructing multiple or rows of exploratory boreholes 5 along a predetermined direction (the direction of advance of the coal face during mining) in the surface layer 1 of the mining area. The lower ends of the exploratory boreholes 5 reach the coal seam 4. The distance between adjacent exploratory boreholes 5 can be set as needed. Based on preliminary geological surveys and data analysis, key exploration areas and general exploration areas can be determined in advance. The distance between exploratory boreholes 5 in key exploration areas is relatively dense, for example, about 5 to 10 meters, while the distance between exploratory boreholes 5 in general exploration areas is relatively sparse, for example, about 20 to 30 meters. The diameter of the exploratory boreholes 5 is about 88 to 97 mm, and the depth depends on the actual burial depth of the specific coal seam 4.

[0067] Step 2: Deploy corresponding detection equipment 6 on the surface layer 1 of the mining area to detect the development status of the fracture development zone 31 in the bedrock layer 3.

[0068] The detection device 6 includes a computer system 61, a winch 62, a detection probe 63, and a bracket 64. The detection probe 63 is connected to the computer system 61 via a cable, which is wound up by the winch 62. The bracket 64 has a fixed pulley. When the detection probe 63 needs to be lowered into the detection borehole 5 for detection, the bracket 64 is placed at the opening of the borehole 5, and the cable is redirected via the fixed pulley on the bracket 64. The detection probe 63 includes an acoustic wave detection unit 631 and a camera detection unit 632, which are integrated together. Their relative positions can be set as needed. The acoustic wave detection unit 631 emits ultrasonic waves towards the well wall, which are received by a transducer. Then, through AD conversion, the received signal amplitude and other characteristics are converted into a geological image of the rock formation, allowing the acquisition of information such as formation wave velocity, porosity, and internal defects of the rock formation. The camera detection unit 632 has a high-definition camera and a light source. Under the illumination of the light source, the high-definition camera collects signals, and the data acquisition card performs photoelectric conversion on the signals to display the condition of the borehole wall on the monitor. The acoustic detection unit 631 can detect the development state of the fracture development zone 31 in the bedrock layer 3 surrounding the detection borehole 5. The camera detection unit 632 can detect the condition of the borehole wall of the detection borehole 5 to determine whether the detection borehole 5 passes through the fracture development zone 31 of the bedrock layer 3.

[0069] The development status of fracture development zone 31 generally refers to the development height of fracture development zone 31 in bedrock layer 3, that is, its length in the vertical direction. Since fracture development zone 31 includes many irregular fractures, the height or length of fracture development zone 31 in the vertical direction is selected from the height or length of most fractures or fracture concentration areas.

[0070] The relatively low / small development state of fracture development zone 31 means that it is located approximately midway between aquifer 2 and coal seam 4. The distance between fracture development zone 31 and aquifer 2 is relatively large, making it less likely that water from aquifer 2 will seep downwards through fracture development zone 31, and thus will not significantly affect the water level of aquifer 2. Similarly, the relatively large distance between fracture development zone 31 and coal seam 4 also makes it less likely that water from fracture development zone 31 will seep downwards into the coal face, and thus will not affect normal mining operations.

[0071] Assuming the safe distance between fracture development zone 31 and aquifer 2 is L1, and the safe distance between fracture development zone 31 and coal seam 4 is L2, the specific distances can be set according to actual needs, for example, L1 = 10-20m, L2 = 30-50m. If the distance L3 between the upper part of the fracture concentration area or most of the fractures in fracture development zone 31 and aquifer 2 is greater than L1, and the distance L4 between the lower part of the fracture concentration area or most of the fractures in fracture development zone 31 and coal seam 4 is greater than L2, it indicates that the fracture development zone 31 in this area is in a relatively low / small development state, and normal coal mining operations can be carried out.

[0072] The term "moderate development" for fracture development zone 31 refers to a region where fracture development zone 31 is relatively close to or connected to aquifer 2, with L3 ≤ L1, while the distance between fracture development zone 31 and coal seam 4 is within a safe range, with L4 > L2. Therefore, a fault layer 9 can be constructed below fracture development zone 31 to achieve water isolation.

[0073] A high degree of development of fracture development zone 31 means that a certain fracture development zone 31 is close to or connected to the aquifer 2, L3≤L1, and the fracture development zone 31 is close to or connected to the coal seam 4, L4≤L2. This indicates that the area is no longer suitable for borehole grouting for water isolation. In the first scenario, if the fracture development zone 31 is close to the coal seam 4, there is no space below the fracture development zone 31 to construct a grouting barrier 9. Even if a barrier 9 is constructed, it will collapse when a goaf is formed due to its proximity to the coal seam 4. In the second scenario, if the fracture development zone 31 is connected to the coal seam 4, the grouting borehole constructed below the fracture development zone 31 will be located within the fracture development zone 31. Due to the numerous and irregular fractures, grout leakage is severe, making it difficult to ensure that the grout fills the borehole, thus hindering the formation of an effective barrier. Therefore, if the fracture development zone 31 in a certain area is highly developed, an artificial dam will be built between the coal pillar dams on both sides after the coal mining face has passed, and an underground reservoir will be built directly in the goaf below the area to store groundwater resources, which will then be filtered and returned to the surface for use.

[0074] Step 3: Before mining, obtain the development status of fracture development zones 31 in the bedrock layer 3 of the entire mining area. Specifically, probes 63 are inserted into each probe borehole 5 in a preset order for detection. The computer system 61 can be placed on a transport vehicle and moved together with the winch 62.

[0075] The fourth step involves implementing different operational methods based on the development status of fracture development zone 31 in a specific area. Specifically:

[0076] If the distance L3 between the fractured zone 31 and the aquifer 2 is found to be greater than L1, and the distance L4 between the fractured zone 31 and the coal seam 4 is found to be greater than L2, then normal coal mining operations can proceed.

[0077] If the distance L3 ≤ L1 between the fracture development zone 31 in the first region of the mining area and the aquifer 2, and the distance L4 > L2 between the fracture development zone and the coal seam 4, then a fracture barrier 9 is constructed below the fracture development zone 31 in the first region to prevent water from seeping downwards. Simultaneously, to prevent the fracture barrier 9 from being dragged down by the underlying bedrock 3 during coal mining operations, a fracturing borehole 8 is constructed at a predetermined distance below the fracture barrier 9 to fracture the surrounding bedrock 3. When rock collapses in the bedrock 3 of the goaf, the portion of the bedrock 3 below the fracture barrier 9 is fractured and will automatically collapse, minimizing its impact on the fracture barrier 9 and maintaining its integrity. The predetermined distance between the fracturing borehole 8 and the fracture barrier 9 is generally more than twice the fracturing radius to avoid affecting the fracture barrier 9 during fracturing.

[0078] If the distance between the fracture development zone 31 and the coal seam 4 in the second area of ​​the mining area is detected to be L3≤L1 and L4≤L2, then an underground reservoir shall be built directly below the second area during coal mining operations.

[0079] In summary, the method for protecting groundwater resources in mining areas provided by this invention improves the protection scheme for groundwater in mining areas, can more effectively protect groundwater resources, and is conducive to maintaining the ecological balance of water resources in mining areas.

[0080] In one embodiment, such as Figure 5-7 As shown, the construction method of partition layer 9 is as follows:

[0081] Multiple first grouting boreholes 7 are drilled downwards from the ground surface at intervals. The vertical section 71 of the first grouting borehole 7 is located around the first region, and the horizontal section 72 of the first grouting borehole 7 extends below the fracture development zone 31 of the first region.

[0082] Grout is injected into the first grouting borehole 7 to form a partition layer 9 below and around the fracture development zone 31 of the first regional fracture.

[0083] In this embodiment, multiple first grouting boreholes 7 are drilled downwards from the ground surface around the first region. These first grouting boreholes 7 are arranged at intervals and surround the first region. The distance between two adjacent first grouting boreholes 7 can be set as needed, preferably twice the diameter of the first grouting borehole 7. This is because drilling the first grouting boreholes 7 will also create fissures around them, allowing grout to seep into these fissures and increase the partition area. The first grouting boreholes 7 first extend downwards, and then extend horizontally after reaching below the fissure development zone 31 of the region. That is, the first grouting borehole 7 includes a vertical section 71 and a horizontal section 72. The vertical section 71 is located around the first region, and the horizontal section 72 extends below the fissure development zone 31 of the first region. Then, grout is injected into the first grouting boreholes 7 using grouting equipment. The grout is concrete grout, which will seep into the surrounding area through the first grouting boreholes 7 and solidify to form a partition layer 9. The partition layer 9 is roughly funnel-shaped. Part of the partition layer 9 will block the fracture development zone 31 of the first regional fracture, and another part of the partition layer 9 will block the fracture development zone 31 of the first regional fracture. This can effectively prevent the fracture development zone 31 of the first regional fracture from conducting water into the bedrock layer 3, so as to maintain the water level of the aquifer 2.

[0084] In one embodiment, such as Figure 5-7 As shown, the construction method of fracturing borehole 8 is as follows:

[0085] After the first grouting borehole 7 is completed and before grouting is injected into the first grouting borehole 7, multiple fracturing boreholes 8 are drilled downwards from the ground surface at intervals. The vertical section 81 of the fracturing borehole 8 is located outside the vertical section 71 of the first grouting borehole 7, and the horizontal section 82 of the fracturing borehole 8 is located at a predetermined distance below the horizontal section 72 of the first grouting borehole 7.

[0086] After fracturing the horizontal section 82 of the fracturing borehole 8 using fracturing equipment, grout is injected into the first grouting borehole 7 to form a partition layer 9.

[0087] In this embodiment, after the first grouting borehole 7 is formed, the fracturing borehole 8 is drilled directly. After the fracturing borehole 8 is fracturing, grout is injected into the first grouting borehole 7 to form a partition layer 9. This can effectively prevent the partition layer 9 from being affected when the fracturing borehole 8 is fracturing.

[0088] Specifically, the drilling method of the fracturing borehole 8 is roughly the same as that of the first grouting borehole 7. The fracturing borehole 8 is located around the first grouting borehole 7, the vertical section 81 of the fracturing borehole 8 is located outside the vertical section 71 of the first grouting borehole 7, and the horizontal section 82 of the fracturing borehole 8 is located below the horizontal section 72 of the first grouting borehole 7.

[0089] The horizontal section 82 of the fracturing borehole 8 is fracturing using existing fracturing equipment. Even if the fracturing affects the horizontal section 72 of the first grouting borehole 7, it will only cause cracks to form around the horizontal section 72. When grouting the first grouting borehole 7 is performed later, the grout can seep into the cracks around the horizontal section 72 and solidify to form part of the isolation layer 9.

[0090] Using this method, the integrity of the isolation layer 9 will not be affected at all when fracturing the fracturing borehole 8.

[0091] In one embodiment, before the coal mining face passes below the first and / or second zones, the roof of the coal seam below the first and / or second zones is reinforced with support in advance, for example, by means of anchor bolts, anchor cables, metal mesh, etc., to avoid roof collapse accidents.

[0092] In one embodiment, such as Figure 10 As shown, the methods for protecting groundwater resources in this mining area also include:

[0093] Step S5: During and / or after mining, the state of the partition layer 9 is detected by the probe 63. If a fracture gap 91 is found in the partition layer 9, isolation and plugging operations are carried out.

[0094] In this embodiment, the state of the partition layer 9 is detected by the detection borehole 5 and the detection equipment 6 during and after mining.

[0095] If a fracture gap 91 is found in the partition layer 9, the water leakage at that point is severe, and it is necessary to isolate and seal the area of ​​the fracture gap 91 to reduce the downward seepage of water in the aquifer 2.

[0096] In one embodiment, such as Figure 10-12 As shown, the leak isolation and sealing operation includes the following steps:

[0097] Multiple second grouting boreholes 10 are drilled downwards from the ground surface. The multiple second grouting boreholes 10 are arranged at intervals around the fracture gap 91, and the lower end of the second grouting boreholes 10 is drilled into the partition layer 9.

[0098] Grout is injected into the second grouting borehole 10 to form an isolation layer 11 around the fracture gap 91.

[0099] In this embodiment, during the isolation and sealing operation, the approximate outline of the fracture gap 91 is marked on the ground surface. Then, multiple second grouting holes 10 are drilled downwards around the outline. These second grouting holes 10 are arranged at intervals, the interval of which can be set as needed. Generally, the distance between two second grouting holes 10 is less than or equal to the diameter of the second grouting hole 10, which facilitates the grout from adjacent holes 10 to converge and solidify. Because part of the second grouting holes 10 is located within the aquifer 2, the distance between two holes 10 is set relatively close to facilitate the grout's convergence and solidification within the aquifer 2. A fast-setting agent can be added to the concrete grout to increase the setting speed.

[0100] In one embodiment, such as Figure 12 As shown, a water tank 12 is formed by excavating a trench from the ground surface downwards in the middle of the isolation layer 11. Water is pumped out of the water tank 12 for storage and / or utilization, thereby reducing the loss of water resources in the space surrounded by the isolation layer 11.

[0101] In one embodiment, such as Figure 13-14 As shown, before drilling exploratory borehole 5, it is necessary to assess the water resources situation in the mining area.

[0102] If there are surface lakes and / or reservoirs 13 in the mining area, the water in the surface lakes and / or reservoirs 13 in the mining area must be transported to outside the mining area for storage and / or utilization before exploration, so as to avoid water inrush during coal mining and improve the safety of coal mining.

[0103] In one embodiment, such as Figure 13 As shown, if there are above-ground lakes and / or reservoirs 14 around the mining area, the water in the above-ground lakes and / or reservoirs 13 within the mining area will be transferred to the above-ground lakes and / or reservoirs 14 around the mining area.

[0104] If there are no above-ground lakes and / or reservoirs 14 around the mining area, above-ground reservoirs can be constructed and utilized based on the terrain, pits formed by previous coal mining, etc.

[0105] In one embodiment, such as Figure 14-16 As shown, after mining, a waterproof layer 15 is constructed on the bottom plate 131 and side wall 132 of the above-ground lakes and / or reservoirs 13 in the mining area to reduce the downward leakage of water in the above-ground lakes and / or reservoirs 13.

[0106] Then, some of the water in the above-ground lakes and / or reservoirs 14 surrounding the mining area is diverted back to the above-ground lakes and / or reservoirs 13 in the mining area to maintain the ecological balance of water resources in the mining area.

[0107] As needed, the above technical solutions can be combined to achieve the best technical effect.

[0108] The above are merely the principles and preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several other modifications can be made based on the principles of the present invention, and these modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for protecting groundwater resources in mining areas, characterized in that, Includes the following steps: S1: Multiple exploratory boreholes are drilled in the surface layer along a predetermined direction, with the lower end of the exploratory boreholes reaching the coal seam; S2: Deploy detection equipment on the surface layer. The detection equipment includes a detection probe, which includes an integrated acoustic detection unit and a camera detection unit. S3: Before mining, the detection probes are placed into each detection borehole in a preset order to detect the development status of the fracture development zone in the bedrock layer between the aquifer and the coal seam. S4: Set the safe distance between the fracture development zone and the aquifer as L1, and the safe distance between the fracture development zone and the coal seam as L2; If the distance between the fracture development zone and the aquifer is L3 > L1 and the distance between the fracture development zone and the coal seam is L4 > L2, then normal coal mining operations shall be carried out. If the distance between the fracture development zone of the first region in the mining area and the aquifer is L3≤L1, and the distance between the fracture development zone and the coal seam is L4>L2, then a fracture barrier layer is constructed below the fracture development zone of the first region to prevent water from seeping downwards, and a fracturing borehole is constructed at a predetermined distance below the fracture barrier layer to fracture the surrounding bedrock layer, so as to prevent the fracture barrier layer from being pulled down by the bedrock layer below during coal mining operations; If the distance between the fracture development zone and the coal seam in the second area of ​​the mining area is detected to be L3≤L1 and L4≤L2, then an underground reservoir shall be built directly below the second area during coal mining operations.

2. The method for protecting groundwater resources in mining areas according to claim 1, characterized in that, The construction method for the partition layer is as follows: Multiple first grouting boreholes are drilled downwards from the ground surface at intervals. The vertical section of the first grouting borehole is located around the first region, and the horizontal section of the first grouting borehole extends below the fracture development zone of the first region. Grout is injected into the first grouting borehole to form the partition layer below and around the fracture development zone of the first regional crack.

3. The method for protecting groundwater resources in mining areas according to claim 2, characterized in that, The construction method for the fracturing borehole is as follows: After the first grouting borehole is completed and before grouting is injected into the first grouting borehole, multiple fracturing boreholes are drilled downwards from the ground surface at intervals. The vertical section of the fracturing borehole is located outside the vertical section of the first grouting borehole, and the horizontal section of the fracturing borehole is located at a predetermined distance below the horizontal section of the first grouting borehole. After fracturing the horizontal section of the fracturing borehole using fracturing equipment, grout is injected into the first grouting borehole to form the partition layer.

4. The method for protecting groundwater resources in mining areas according to claim 1, characterized in that, Before the coal mining face passes below the first area and / or the second area, the roof of the coal seam below the first area and / or the second area shall be reinforced with support.

5. The method for protecting groundwater resources in mining areas according to claim 1, characterized in that, include: Step S5: During and / or after mining, the state of the partition layer is detected by the detection probe. If a fracture gap is found in the partition layer, isolation and sealing operations are carried out.

6. The method for protecting groundwater resources in mining areas according to claim 5, characterized in that, The isolation and sealing operation includes the following steps: Multiple second grouting boreholes are drilled downwards from the ground surface, and the multiple second grouting boreholes are arranged at intervals around the fracture gap, with the lower end of the second grouting boreholes drilled into the partition layer; Grout is injected into the second grouting borehole to form an isolation layer around the fracture gap.

7. The method for protecting groundwater resources in mining areas according to claim 6, characterized in that, In the middle of the isolation layer, a trench is dug downwards from the ground to form a water pool, and water in the pool is pumped out for storage and / or use by a water pump.

8. The method for protecting groundwater resources in mining areas according to claim 1, characterized in that, Before drilling exploratory boreholes, it is necessary to assess the water resources situation in the mining area. If there are surface lakes and / or reservoirs in the mining area, the water in the surface lakes and / or reservoirs in the mining area must be transferred to outside the mining area for storage and / or utilization before exploration to avoid water inrush during coal mining.

9. The method for protecting groundwater resources in mining areas according to claim 8, characterized in that, If there are surface lakes and / or reservoirs around the mining area, the water in the surface lakes and / or reservoirs within the mining area will be transferred to the surface lakes and / or reservoirs surrounding the mining area.

10. The method for protecting groundwater resources in mining areas according to claim 9, characterized in that, After mining, waterproof layers are constructed on the bottom slab and side walls of above-ground lakes and / or reservoirs in the mining area; Part of the water in the above-ground lakes and / or reservoirs surrounding the mining area will be diverted back to the above-ground lakes and / or reservoirs in the mining area.

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