Grouting repair and water conservation method for goaf area

Abstract

The present application provides a method for grouting repair and water conservation in goaf, comprising: determining mining information of goaf and coal seam; performing a first grouting operation on the side of the goaf close to the coal seam to form a barrier wall according to the mining information; performing a second grouting operation from outside to inside in the goaf to complete the repair according to the mining information, wherein the first grouting pressure of the first grouting operation is less than the second grouting pressure of the second grouting operation. The method for grouting repair and water conservation in goaf provided by the present application is simple and convenient, can effectively block post-mining fissures, ensure the stability of the working face, reduce maintenance costs, and reduce the loss of shallow water resources.

Description

Technical Field

[0001] The present application relates to the technical field of grouting repair, and in particular to a method for grouting repair and water conservation in goaf areas. Background Art

[0002] Coal is an important natural resource. With the innovation of coal mining technology, the scale and intensity of mining are constantly increasing, especially in areas with good endowment conditions, simple geological conditions and large coal reserves. As the mining time continues to accumulate, a large number of goafs are left behind. Groundwater continues to gather in the goafs along the mining cracks. As the amount of water in the goafs continues to accumulate, the seepage water pressure continues to increase, and it continues to weaken under the action of repeated disturbances of the mine pressure, causing the danger of water inrush at the working face, which not only causes a waste of groundwater, but also seriously threatens the lives and property of on-site workers.

[0003] At present, grouting treatment is the most commonly used technical method to maintain the stability of aquifers in goaf areas. The fluidity or pumpability of the slurry itself can be pumped to the water inrush area through drilling to effectively repair the aquifer. However, the existing grouting repair method ignores the impact on the coal pillars around the goaf. The coal seam is easily damaged during the grouting process, causing harm. In addition, the slurry consumption is also very large, accompanied by dynamic water loss. Therefore, a better method of grouting repair and water conservation in goaf areas is urgently needed. Summary of the invention

[0004] In view of this, the purpose of this application is to propose a grouting repair and water conservation method for goaf areas to solve the above-mentioned technical problems.

[0005] The present application provides a method for grouting repair and water conservation in goaf, comprising: determining mining information of the goaf and the coal seam; performing a first grouting operation on the side of the goaf close to the coal seam to form a barrier wall according to the mining information; performing a second grouting operation from the outside to the inside of the goaf to complete the repair according to the mining information, wherein a first grouting pressure of the first grouting operation is less than a second grouting pressure of the second grouting operation.

[0006] Furthermore, the mining information includes location information of the goaf and the coal seam, and distribution information of equal water level lines in the mining area.

[0007] Furthermore, the first grouting pressure is less than the hydrostatic pressure at the grouting location; and the second grouting pressure is 2 to 3 times the hydrostatic pressure at the grouting location.

[0008] Furthermore, the method of determining the mining information of the goaf and the coal seam then includes: selecting multiple points in the ground area corresponding to the goaf to drill test holes; grouting each of the test holes and measuring the slurry diffusion radius; and selecting the smallest slurry diffusion radius as the target grouting radius.

[0009] Furthermore, performing a first grouting operation on a side of the goaf close to the coal seam according to the mining information to form a barrier wall comprises: determining a first cross-sectional figure of the goaf according to the mining information; starting from a coal seam close to a corner of the first cross-sectional figure, and extending into the goaf along an edge of the first cross-sectional figure to form a first trajectory line; the first trajectory lines corresponding to each corner of the first cross-sectional figure are connected to each other to form a closed first grouting figure; and performing a first grouting operation according to the first grouting figure to form a barrier wall.

[0010] Furthermore, the distance between the first trajectory line and the edge adjacent to the first cross-sectional figure is less than or equal to the target grouting radius; the distance between the starting point of the first trajectory line and the edge adjacent to the first cross-sectional figure is greater than or equal to the target grouting radius.

[0011] Furthermore, performing a first grouting operation according to the first grouting pattern to form a barrier wall comprises: vertically drilling a first grouting hole in a ground area corresponding to a starting point of each first trajectory line of the first grouting pattern; horizontally drilling along the first trajectory line through the first grouting hole to obtain a first branch hole; and performing a first grouting operation on each of the first branch holes to form a barrier wall.

[0012] Furthermore, the repair is completed by performing a second grouting operation from the outside to the inside of the goaf according to the mining information, including: determining a second cross-sectional figure of the retaining wall and the lowest water level in the goaf according to the mining information; starting from any corner of the second cross-sectional figure, spirally extending along the edge of the second cross-sectional figure toward the lowest water level point to form a second grouting figure; and performing a second grouting operation according to the second grouting figure to complete the repair.

[0013] Furthermore, the second grouting pattern includes a plurality of second trajectory lines connected end to end, and the spacing between the second trajectory lines parallel to the same edge of the second cross-sectional pattern is less than or equal to 2 times of the target grouting radius; the spacing between the second trajectory line located at the outermost side of the second grouting pattern and the adjacent edge of the second cross-sectional pattern is less than or equal to the target grouting radius.

[0014] Furthermore, the repair is completed by performing a second grouting operation according to the second grouting pattern, including: vertically drilling a second grouting hole in a ground area corresponding to the corner of the second grouting pattern; horizontally drilling a second branch hole along at least one second trajectory line through the second grouting hole to obtain a second branch hole; and performing a second grouting operation on each of the second branch holes from the outside to the inside in the goaf to complete the repair.

[0015] As can be seen from the above, the present application provides a method for grouting repair and water conservation in goaf, including: determining the mining information of the goaf and the coal seam; performing a first grouting operation on the side of the goaf close to the coal seam according to the mining information to form a barrier wall. By forming a barrier wall between the goaf and the coal seam, the coal pillars can be protected to avoid damage to the coal pillars and induce water gushing accidents at the working face, thereby improving safety, and reducing slurry loss in the subsequent second grouting operation, thereby improving the grouting effect; performing a second grouting operation from the outside to the inside of the goaf according to the mining information to complete the repair, wherein the first grouting pressure of the first grouting operation is less than the second grouting pressure of the second grouting operation, and the first grouting operation The first grouting pressure is relatively small to avoid damaging the coal seam, while the second grouting pressure of the second grouting operation is relatively large, which has the effect of splitting and diffusion grouting, and can squeeze the gushing water flow. Through the second grouting operation from the outside to the inside, it plays a guiding role, and can gradually squeeze the gushing water in the goaf back to the aquifer to avoid diffusion outside the goaf, thereby reducing the amount of slurry used, improving the grouting effect, effectively blocking the cracks, effectively reducing the loss of shallow water resources, and maintaining the stability of the aquifer; the goaf grouting repair and water conservation method is simple and convenient, can effectively block post-mining cracks, ensure the stability of the working face, reduce maintenance costs, and reduce the loss of shallow water resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present application or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 This is a schematic flow chart of a method for grouting repair and water conservation in a goaf area in an embodiment of the present application;

[0018] Figure 2 A schematic diagram of the longitudinal section of grouting in the goaf;

[0019] Figure 3 A schematic cross-sectional view of a first grouting operation in a goaf;

[0020] Figure 4 Schematic diagram of the transverse section of the second grouting operation in the goaf.

[0021] Figure numerals: 1. grouting hole; 2. branch hole; 3. coal seam; 4. collapse zone; 5. goaf; 6. blocking wall; 7. first trajectory line; 8. first grouting hole; 9. second trajectory line; 10. second grouting hole. DETAILED DESCRIPTION

[0022] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0023] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should be the usual meanings understood by people with ordinary skills in the field to which the present application belongs. The "first", "second" and similar words used in the embodiments of the present application do not represent any order, quantity or importance, but are only used to distinguish different components. "Including" or "comprising" and similar words mean that the elements or objects appearing in front of the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0024] Coal is an important natural resource. With the innovation of coal mining technology, the scale and intensity of mining are constantly increasing, especially in areas with good endowment conditions, simple geological conditions and large coal reserves. As the mining time continues to accumulate, a large number of goafs are left behind. Groundwater continues to gather in the goafs along the mining cracks. As the amount of water in the goafs continues to accumulate, the seepage water pressure continues to increase, and it continues to weaken under the action of repeated disturbances of the mine pressure, causing the danger of water inrush at the working face, which not only causes a waste of groundwater, but also seriously threatens the lives and property of on-site workers.

[0025] At present, grouting treatment is the most commonly used technical method to maintain the stability of aquifers in goaf areas. The fluidity or pumpability of the slurry itself can be pumped to the water inrush area through drilling to effectively repair the aquifer. However, the existing grouting repair method ignores the impact on the coal pillars around the goaf. The coal seam is easily damaged during the grouting process, causing harm. In addition, the slurry consumption is also very large, accompanied by dynamic water loss. Therefore, a better method of grouting repair and water conservation in goaf areas is urgently needed.

[0026] Below, through specific embodiments and combined Figures 1 to 4 To describe the technical solution of this application in detail.

[0027] Some embodiments of the present application provide a method for grouting repair and water conservation in goaf areas, such as Figure 1 As shown, the following steps are included:

[0028] S1. Determine the mining information of the goaf 5 and the coal seam 3.

[0029] The mining information of the goaf 5 and the coal seam 3 can be determined based on the hydrological historical data and on-site investigation. The mining information includes, for example, the location information of the goaf 5 and the coal seam 3 and the distribution information of the equal water level lines in the mining area.

[0030] S2. Perform a first grouting operation on the side of the goaf 5 close to the coal seam 3 to form a barrier wall 6 according to the mining information.

[0031] After determining the position information of the goaf 5 and the coal seam 3, the interface between the goaf 5 and the coal seam 3 can be determined, and a first grouting operation is performed on the side of the goaf 5 close to the coal seam 3 to form a barrier wall 6, such as Figure 4 As shown, by forming a barrier wall 6 between the goaf 5 and the coal seam 3, the coal pillars can be protected, and the damage of the coal pillars to induce water inrush accidents at the working face can be avoided, thereby improving safety, reducing slurry loss in the subsequent second grouting operation, and improving the grouting effect.

[0032] During conventional ground grouting, the pressure is generally high, which can easily damage the water-proof coal pillar at the edge of the goaf 5. By grouting the edge of the goaf 5, a barrier wall 6 is formed on one side of the goaf 5. The barrier wall 6 is used to resist the pressure formed by subsequent large-scale grouting, thereby reducing damage to the coal pillar. Compared with traditional grouting methods, grouting is more reliable and avoids water seepage accidents on the working face caused by coal pillar damage caused by grouting.

[0033] S3. Perform a second grouting operation from outside to inside in the goaf 5 according to the mining information to complete the repair, wherein a first grouting pressure of the first grouting operation is less than a second grouting pressure of the second grouting operation.

[0034] After determining the equal water level distribution information of goaf 5, the second grouting operation can be gradually carried out in goaf 5 from the high water level area to the low water level area, that is, the grouting operation can be carried out from the outside to the inside, which plays a guiding role and can gradually squeeze the gushing water in goaf 5 to flow inward and return to the aquifer, avoiding diffusion outside goaf 5, thereby reducing the amount of slurry used, improving the grouting effect, effectively blocking the cracks, effectively reducing the loss of shallow water resources, and maintaining the stability of the aquifer; it also avoids squeezing and damaging the coal pillar and improves safety.

[0035] The first grouting pressure of the first grouting operation is less than the second grouting pressure of the second grouting operation. The first grouting pressure of the first grouting operation is relatively small. For example, the first grouting pressure is less than the hydrostatic pressure at the grouting location, so as to avoid damaging the coal seam 3. Because the rock gaps are large there, the effect of infiltration grouting can be achieved by a lower grouting pressure. The second grouting pressure of the second grouting operation is relatively large. For example, the second grouting pressure is 2 to 3 times the hydrostatic pressure at the grouting location, so as to achieve the effect of splitting diffusion grouting and squeeze the water flow.

[0036] The grouting repair and water conservation method for the goaf 5 is simple and convenient, can effectively seal post-mining cracks, ensure the stability of the working face, reduce maintenance costs, and reduce the loss of shallow water resources. This method is mainly aimed at the goaf 5 with a large amount of water accumulation and a fast water accumulation speed, which poses a great threat to the subsequent working face production. It can reduce the water hazard risk of the goaf 5, protect groundwater resources, reduce the loss and waste of water resources overlying the coal seam 3, and reduce resource waste and environmental pollution.

[0037] In some embodiments, step S1 includes:

[0038] S201, selecting a plurality of points in the ground area corresponding to the goaf 5 and drilling to obtain test holes.

[0039] At least three points are selected at equal intervals or randomly in the ground area corresponding to the edge of the goaf 5 to drill test holes.

[0040] S202, grouting is performed on each of the test holes and the slurry diffusion radius is measured.

[0041] For grouting each test hole, the parameter setting of the first grouting operation or the parameter setting of the second grouting operation may be selected. After grouting, the slurry diffusion radius of each test hole is measured by sampling.

[0042] S203, selecting the smallest slurry diffusion radius as the target grouting radius.

[0043] The smallest slurry diffusion radius is selected as the target grouting radius to facilitate the subsequent grouting trajectory design based on the target grouting radius and ensure the grouting effect.

[0044] In some embodiments, step S2 includes:

[0045] S211. Determine a first cross-sectional diagram of the goaf 5 according to the mining information.

[0046] According to the position information of the coal seam 3 and the goaf 5, the first cross-sectional figure of the goaf 5 can be determined, such as Figure 3 As shown, the cross-sectional shape of the goaf 5 is a rectangle.

[0047] S212, starting from the coal seam 3 near the corner of the first cross-sectional figure, extending along the edge of the first cross-sectional figure into the goaf 5 to form a first trajectory line 7; the first trajectory lines 7 corresponding to each corner of the first cross-sectional figure are connected to each other to form a closed first grouting figure.

[0048] Starting from the coal seam 3 near the corner of the first cross-sectional figure, a first trajectory line 7 is formed along the edge of the first cross-sectional figure and extending into the goaf 5. Figure 3As shown in the figure, the circle positions at the four corners of the goaf 5 are the starting points, and starting from a starting point, along the edge of the first cross-sectional figure, that is, along the long side or short side of the rectangle, it extends until it connects with another first trajectory line 7 in the goaf 5; Figure 3 As shown, a total of four first track lines 7 are formed, and the four first track lines 7 are connected end to end to form a first grouting pattern, and the first grouting pattern is a rectangle with extended edges at the four corners.

[0049] S213, performing a first grouting operation according to the first grouting pattern to form a barrier wall 6.

[0050] The first grouting operation is performed according to the first grouting pattern, that is, grouting is performed along each first trajectory line 7, so that the corners of the first cross-sectional pattern can be grouted densely to form a Figure 4 The closed barrier wall 6 shown ensures protection of the coal pillars around the goaf 5.

[0051] The first grouting operation, for example, uses 0.8 times the hydrostatic pressure for grouting. When the grouting pressure stabilizes and lasts for 3 hours, the grouting is stopped and a 12-hour waiting period is performed to stabilize the slurry solidification skeleton, and then the subsequent second grouting operation is performed.

[0052] In some embodiments, the distance between the first trajectory line 7 and the edge adjacent to the first cross-sectional figure is less than or equal to the target grouting radius; the distance between the starting point of the first trajectory line 7 and the edge adjacent to the first cross-sectional figure is greater than or equal to the target grouting radius.

[0053] The target grouting radius is the aforementioned minimum slurry diffusion radius. The distance between the first trajectory line 7 and the edge adjacent to the first cross-sectional figure is less than or equal to the target grouting radius. Figure 3 As shown, for example, the first trajectory line 7 is arranged horizontally below, and the distance between the first trajectory line 7 and the long side below the first cross-sectional figure is smaller than the target grouting radius. In this way, after the first grouting operation, it can be ensured that the slurry covers the space between the first trajectory line 7 and the long side to form a complete barrier wall 6, thereby ensuring the stability of the working surface and the subsequent grouting effect.

[0054] The distance between the starting point of the first trajectory line 7 and the edge adjacent to the first cross-sectional figure is greater than or equal to the target grouting radius. Figure 3 As shown, for example, the starting point of the first trajectory line 7 set horizontally below is the circle position in the lower left corner of the figure, and the distance between the starting point and the short side on the left side of the first cross-sectional figure is greater than the target grouting radius, so drilling and grouting at the starting point can reduce damage to the edge of the coal seam 3.

[0055] In some embodiments, step S213 includes:

[0056] S2131. Drill vertical holes at equal intervals in the ground area corresponding to each first trajectory line 7 of the first grouting pattern to obtain first grouting holes 8, and the distance between two adjacent first grouting holes 8 is less than 2 times the target grouting radius.

[0057] S2132. Perform a first grouting operation on each of the first grouting holes 8 to form a barrier wall 6.

[0058] like Figure 3 As shown, for example, a plurality of first grouting holes 8 are arranged at equal intervals along the ground area corresponding to the first trajectory line 7 below the first grouting pattern, and the interval between two first grouting holes 8 is set to 1.5 times the target grouting radius, so that after grouting each first grouting hole 8, a continuous barrier wall 6 can be formed along the first trajectory line 7; and a closed barrier wall 6 is formed after grouting along each first trajectory line 7.

[0059] In some embodiments, step S213 includes:

[0060] S2131. Vertically drill a hole in the ground area corresponding to the starting point of each first trajectory line 7 of the first grouting pattern to obtain a first grouting hole 8.

[0061] S2132. Horizontally drill a hole along the first trajectory line 7 through the first grouting hole 8 to obtain a first branch hole.

[0062] S2133, performing a first grouting operation on each of the first branch holes to form a barrier wall 6.

[0063] like Figure 3 As shown, for example, a first grouting hole 8 is obtained by vertically drilling a hole at the starting point of the first trajectory line 7 below the first grouting pattern corresponding to the ground area, and then a first branch hole is obtained by horizontally drilling along the first trajectory line 7 through the first grouting hole 8. Figure 2 As shown, a first grouting operation is performed through the first branch hole to form a continuous barrier wall 6 along the first trajectory line 7; and a closed barrier wall 6 is formed after grouting along each first trajectory line 7.

[0064] Compared with the aforementioned method of setting multiple first grouting holes 8 on the same first trajectory 7, this method can reduce the number of drilling holes, greatly improve the grouting efficiency, cause less damage to the formation, and ensure the grouting quality.

[0065] In some embodiments, performing a second grouting operation from outside to inside in the goaf 5 to complete the repair according to the mining information includes:

[0066] S311, determining the second cross-sectional figure of the retaining wall 6 and the lowest point of the water level in the goaf 5 according to the mining information.

[0067] According to the position information of the coal seam 3 and the goaf 5, as well as the first trajectory line 7 and the slurry diffusion radius, the second cross-sectional figure of the barrier wall 6 can be determined, such as Figure 4 As shown, the cross-sectional shape of the barrier wall 6 is a rectangle; the lowest water level point in the goaf 5 can be determined according to the iso-water level line diagram, such as Figure 4 Middle triangle position.

[0068] S312, starting from any corner of the second cross-sectional figure, spirally extending along the edge of the second cross-sectional figure toward the lowest point of the water level to form a second grouting figure.

[0069] Starting from any corner of the second cross-sectional figure, a second grouting figure is formed by spirally extending along the edge of the second cross-sectional figure toward the lowest point of the water level, such as Figure 4 As shown in the figure, the circle position in the lower left corner is the corner of the second cross-sectional figure, that is, the starting point. Starting from the starting point, along the edge of the second cross-sectional figure, it extends inward in a spiral until the lowest point of the water level, forming a second grouting figure in the shape of a circle; Figure 4 As shown, the second grouting pattern includes a plurality of second trajectory lines 9 connected end to end, and each second trajectory line 9 is parallel to the corresponding edge of the second cross-sectional pattern.

[0070] S313, performing a second grouting operation according to the second grouting pattern to complete the repair.

[0071] The second grouting operation is carried out according to the second grouting pattern, that is, grouting is carried out from the outside to the inside along each second trajectory line 9, which plays a guiding role and can gradually squeeze the gushing water in the goaf 5 to flow inward and return to the aquifer, avoiding diffusion outside the goaf 5, thereby reducing the amount of slurry used, improving the grouting effect, effectively blocking the cracks, effectively reducing the loss of shallow water resources, and maintaining the stability of the aquifer.

[0072] The second grouting operation, for example, uses 3 times the hydrostatic pressure for grouting. When the grouting pressure is stable and lasts for 3 hours, the grouting is stopped and a 12-hour waiting period is performed to stabilize the slurry solidification skeleton.

[0073] In some embodiments, the spacing between the second trajectory lines 9 parallel to the same edge of the second cross-sectional figure is less than or equal to 2 times the target grouting radius; the spacing between the second trajectory line 9 located at the outermost side of the second grouting figure and the adjacent edge of the second cross-sectional figure is less than or equal to the target grouting radius.

[0074] The target grouting radius is the aforementioned minimum slurry diffusion radius, and the spacing between the second trajectory lines 9 parallel to the same edge of the second cross-sectional figure is less than or equal to 2 times the target grouting radius. Figure 4As shown, for example, a plurality of second track lines 9 are arranged transversely with a spacing of 1.5 times the target grouting radius, so that after the second grouting operation, the slurries of adjacent second track lines 9 overlap with each other, effectively filling the cracks and forming a stable skeleton structure.

[0075] The distance between the second track line 9 located at the outermost side of the second grouting pattern and the adjacent edge of the second cross-sectional pattern is less than or equal to the target grouting radius. Figure 4 As shown, for example, the distance between the lowermost horizontal second trajectory line 9 and the long side of the second cross-sectional figure is smaller than the target grouting radius, so that the slurry can fill the area between the second trajectory line 9 and the barrier wall 6 to ensure the grouting effect.

[0076] In some embodiments, step S313 includes:

[0077] S3131. Drill vertical holes at equal intervals in the ground area corresponding to each second trajectory line 9 of the second grouting pattern to obtain second grouting holes 10, and the distance between two adjacent second grouting holes 10 is less than 2 times the target grouting radius.

[0078] S3132, performing a second grouting operation on each of the second grouting holes 10 to form a barrier wall 6.

[0079] like Figure 4 As shown, for example, a plurality of second grouting holes 10 are arranged at equal intervals along the ground area corresponding to the second trajectory line 9 below the second grouting pattern, and the interval between two second grouting holes 10 is set to 1.5 times the target grouting radius, so that after grouting each second grouting hole 10, the second trajectory line 9 and the surrounding cracks can be blocked.

[0080] In some embodiments, step S313 includes:

[0081] S3131. Drill vertically in the ground area corresponding to the corners of the second grouting pattern to obtain a second grouting hole 10.

[0082] S3132. Horizontally drill a second branch hole through the second grouting hole 10 along at least one second trajectory line 9 to obtain a second branch hole.

[0083] S3133, performing a second grouting operation on the second branch holes one by one from the outside to the inside in the goaf area 5 to complete the repair.

[0084] like Figure 4 As shown, for example, vertical drilling is performed at each corner of the second grouting pattern corresponding to the ground area to obtain a second grouting hole 10, and then the second grouting hole 10 is inclined and horizontal drilling is performed along a second trajectory line 9 to obtain a second branch hole, and a second grouting operation is performed from the outside to the inside through the second branch hole to achieve repair.

[0085] Or Figure 4 As shown, vertical drilling is performed only at some corners of the second grouting pattern corresponding to the ground area to obtain the second grouting hole 10, and there is a corner between the adjacent second grouting holes 10 along the second grouting pattern, and then the second grouting holes 10 are inclined and horizontal drilling is performed along two vertical second trajectory lines 9 to obtain second branch holes, and the second grouting operation is performed from the outside to the inside through the second branch holes to achieve repair. Compared with the aforementioned setting that one second grouting hole 10 only corresponds to one second trajectory line 9, the number of drilling holes can be further reduced and the grouting efficiency can be greatly improved.

[0086] Compared with the aforementioned method of setting multiple second grouting holes 10 on the same second trajectory line 9, this method can reduce the number of drilling holes, greatly improve the grouting efficiency, cause less damage to the formation, and ensure the grouting quality.

[0087] In some embodiments, the method of grouting repair and water conservation in goaf is applied to the goaf of Shaanxi Coal Caojiatan Coal Mine. First, the collapse zone morphology and aquifer water level are explored. The collapse zone morphology is determined by theoretical calculation and drilling exploration. The collapse zone height is determined according to the formula Calculation, where ΣM is the cumulative mining height of the coal seam. The exploration holes are arranged just above the goaf of the working face, and the number of holes is calculated every 10,000 m 2 The frequency of arranging one borehole shall be set, and the number of boreholes at the edge of the goaf shall not be less than 50% of the total number of boreholes. The height of the collapse zone shall be comprehensively analyzed through core sampling, leakage of drilling flushing fluid, and drilling television. The core sampling results shall be inverted, and the void and porosity of the core samples shall be analyzed. The water level of the aquifer shall be observed in the long observation hole. According to the number of main aquifers on the roof, each aquifer shall be measured at every 10,000 m 2 Arrange a frequency of 1, draw exploration lines, and cross construction at the intersections of the exploration lines. For example, at a certain intersection, a long observation hole is constructed to the Quaternary system, and its adjacent long observation hole is constructed to the weathered bedrock, and so on. Try to arrange the long observation holes of each aquifer evenly in the construction area, thereby determining the mining information of the goaf and coal seam.

[0088] According to the development morphology of the goaf collapse zone that has been exposed and the design plan of the first construction barrier wall, the starting point of the first trajectory is determined. This point should be on one side of the coal pillar goaf, no less than 10 meters away from the coal pillar (target grouting radius 10 meters), and less than 1 meter away from the top of the collapse zone. According to the local topography, landform, rock formation lithology, etc., the construction difficulty and economic cost are evaluated, and the appropriate trajectory starting point is selected.

[0089] Because the coal pillar needs to be protected during the establishment of the barrier wall to avoid excessive grouting pressure from damaging the water-proof coal pillar, a short-distance, large-curvature directional drilling process is used. The grouting pressure is less than the water pressure at the grouting point, and cumulative grouting is performed until a barrier wall is formed at the edge of the goaf. After determining the location of the first grouting hole, drilling begins from the ground. The hole opening position is located on the designed directional drilling axis, more than 20 meters away from the edge of the collapse zone. The first opening is 311mm, and the drilling is carried out until 10m into the intact bedrock, and a 273×10mm casing is lowered (the outer ring gap of the casing is sealed with 0.6:1 cement single-liquid slurry); the second opening is 133mm, and the inclination is started 20 meters above the top of the collapse zone. Directional drilling is carried out to the starting point of the first trajectory, and a 177.8mm steel pipe is lowered for cementing. If a large amount of drilling fluid is lost during the early drilling process (more than 10m away from the collapse zone), quantitative grouting and accelerated setting agent are used to protect the wall. When the borehole approaches the collapse zone (less than 10m from the collapse zone), a large amount of drilling fluid leakage occurs, and the filling operation is immediately started. The elastic wave equipment is carried with the drill to detect the distance between the drill bit and the coal pillar and the collapse zone in real time, and to make real-time dynamic corrections.

[0090] The purpose of forming a retaining wall is to protect the water-proof coal pillar at the edge of the goaf. Therefore, the grouting pressure in this section is lower than the water pressure at the grouting point. The grouting quality is checked using underground water exploration and drainage holes. When the stone rate of the water-cement mixture collected by the underground water exploration and drainage holes is greater than 80%, the water exploration and drainage holes are closed and the pressure is maintained for 1 to 2 hours. Then the retaining wall is completed.

[0091] Then, according to the water level observed in the exploration hole, the sufer interpolation method is used to draw the isowater level line, find the drop funnel of each aquifer, and then superimpose the isowater level lines of each aquifer to find the groundwater drop channel and skylight (the lowest point of the water level). According to the determined groundwater descending skylight, it is set as the final grouting area, and gradually converges from its surroundings to the skylight until the entire area is filled.

[0092] Because a protective wall has been formed at the edge of the coal wall, the second grouting operation adopts a high-pressure splitting grouting scheme to split the cracks within the grouting range as much as possible. The grouting pressure is the driving force for the slurry to overcome various resistances and fill and diffuse in the rock cracks. The grouting pressure is also affected by many factors during the grouting process. During the construction process, necessary and reasonable adjustments should be made according to the actual situation to meet the requirements of grouting quality. The grouting pressure is related to factors such as groundwater pressure, rock fracture rate and fracture opening, grouting section height, slurry ratio and performance. The grouting pressure is generally taken as the orifice pressure. When the distance between the grouting pump and the orifice is not far and the resistance is not large, the pump pressure can be used instead. The final grouting pressure is designed based on the rock properties, hydrogeological characteristics and empirical values. It is generally 2 to 3 times the hydrostatic pressure and can be calculated by the formula Calculation, where H is the burial depth; γ is the cumulative density of the overlying rock strata. It can be adjusted according to actual conditions during construction. The selection and drilling method of the second grouting hole can refer to the first grouting hole.

[0093] By performing the second grouting operation on the second grouting hole, a guiding role is played from the outside to the inside, which can gradually squeeze the water gushing out of the goaf to flow inward and return to the aquifer, avoiding diffusion outside the goaf, thereby reducing the amount of slurry used and improving the grouting effect. After the second grouting operation, a 12-hour waiting period is carried out. After the water pressure test, the water pressure rises rapidly and the curve is steep and straight, which meets the grouting end standard and continues to wait for setting.

[0094] It should be noted that the above describes some embodiments of the present application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the above embodiments and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0095] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present application (including the claims) is limited to these examples. In line with the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0096] In addition, to simplify the description and discussion, and in order not to make the embodiment of the present application difficult to understand, the known power supply / ground connection with other components may or may not be shown in the provided drawings. In addition, the device can be shown in the form of a block diagram to avoid making the embodiment of the present application difficult to understand, and this also takes into account the following fact, that is, the details of the implementation method of these block diagram devices are highly dependent on the platform to be implemented in the embodiment of the present application (that is, these details should be completely within the scope of understanding of those skilled in the art). In the case of elaborating specific details to describe the exemplary embodiments of the present application, it is obvious to those skilled in the art that the embodiment of the present application can be implemented without these specific details or when these specific details are changed. Therefore, these descriptions should be considered to be illustrative rather than restrictive.

[0097] Although the present application has been described in conjunction with the specific embodiments of the present application, many replacements, modifications and variations of these embodiments will be apparent to those of ordinary skill in the art based on the foregoing description. The present application embodiments are intended to encompass all such replacements, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application embodiments should be included in the protection scope of the present application.

Claims

1. A method for grouting repair and water conservation in goaf, characterized in that: include: Determine mining information of goafs and coal seams; According to the mining information, a first grouting operation is performed on the side of the goaf near the coal seam to form a barrier wall, including: determining a first cross-sectional figure of the goaf according to the mining information; starting from the coal seam near the corner of the first cross-sectional figure, extending into the goaf along the edge of the first cross-sectional figure to form a first trajectory line; the first trajectory lines corresponding to each corner of the first cross-sectional figure are connected to each other to form a closed first grouting figure; a first grouting operation is performed according to the first grouting figure to form a barrier wall; wherein the spacing between the first trajectory line and the edge adjacent to the first cross-sectional figure is less than or equal to the target grouting radius; the spacing between the starting point of the first trajectory line and the edge adjacent to the first cross-sectional figure is greater than or equal to the target grouting radius; A second grouting operation is performed from the outside to the inside of the goaf according to the mining information to complete the repair, including: determining a second cross-sectional figure of the retaining wall and the lowest water level in the goaf according to the mining information; starting from any corner of the second cross-sectional figure, spirally extending along the edge of the second cross-sectional figure to the lowest water level point to form a second grouting figure; performing a second grouting operation according to the second grouting figure to complete the repair; wherein a first grouting pressure of the first grouting operation is less than a second grouting pressure of the second grouting operation; the second grouting figure includes a plurality of second trajectory lines connected end to end, and a spacing between the second trajectory lines parallel to the same edge of the second cross-sectional figure is less than or equal to 2 times of the target grouting radius; a spacing between the second trajectory line located at the outermost side of the second grouting figure and the adjacent edge of the second cross-sectional figure is less than or equal to the target grouting radius.

2. The method for grouting repair and water conservation in goaf according to claim 1, characterized in that: The mining information includes location information of the goaf and the coal seam, and distribution information of equal water level lines of the goaf.

3. The method for grouting repair and water conservation in goaf according to claim 1, characterized in that: The first grouting pressure is less than the hydrostatic pressure at the grouting location; the second grouting pressure is 2 to 3 times the hydrostatic pressure at the grouting location.

4. The method for grouting repair and water conservation in goaf according to claim 1, characterized in that: The mining information of the determined goaf and coal seam then includes: Select multiple points in the ground area corresponding to the goaf to drill test holes; Performing grouting on each of the test holes and measuring the grout diffusion radius; The smallest slurry diffusion radius is selected as the target grouting radius.

5. The method for grouting repair and water conservation in goaf according to claim 1, characterized in that: The step of performing a first grouting operation according to the first grouting pattern to form a barrier wall comprises: Vertically drilling a first grouting hole in a ground area corresponding to a starting point of each first trajectory line of the first grouting pattern; A first branch hole is obtained by horizontally drilling along a first trajectory through the first grouting hole; A first grouting operation is performed on each of the first branch holes to form a barrier wall.

6. The method for grouting repair and water conservation in goaf according to claim 1, characterized in that: The step of performing a second grouting operation according to the second grouting pattern to complete the repair comprises: Vertically drilling holes in the ground area corresponding to the corners of the second grouting pattern to obtain second grouting holes; Horizontally drilling a second branch hole along at least one second trajectory line through the second grouting hole to obtain a second branch hole; The repair is completed by performing a second grouting operation on the second branch holes one by one from the outside to the inside of the goaf.

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