Grouting and filling water-preserved coal mining method for goaf bottom plate

Abstract

The invention relates to the field of coal mine water-preserved mining and filling mining, in particular to a goaf bottom plate grouting and filling water-preserved coal mining method. The method is particularly suitable for the working conditions that a coal seam roof has multiple pressure-bearing water-rich rock stratums and the water inflow of top water coal mining is large, and comprises the steps that a stope face is arranged in a mining area, the range of a bottom plate failure zone below a coal seam is determined, and a rock stratum with a certain thickness is selected below the bottom plate failure zone to serve as a bottom plate grouting pressure-bearing layer; directional grouting drill holes are constructed outside the working face open-off cut from the ground, the horizontal sections of the directional grouting drill holes are tightly attached to the bottom interface of the bottom plate pressure-bearing protection layer for construction, and construction is at least conducted within a certain range within the working face; after the working face is pushed over the open-off cut by a certain distance, high-pressure grouting filling is conducted through the directional grouting drill holes; slurry injected into the bottom plate and breaking and expanding of the bottom plate caused by grouting offset part of space generated by coal seam mining, the equivalent mining height of the coal seam is reduced, then the height of a water flowing fissure zone is reduced, and water-preserved coal mining is achieved.

Description

Technical Field

[0001] The invention relates to the field of water-retaining mining and filling mining in coal mines, and in particular to a method for water-retaining coal mining by grouting and filling a bottom plate of a goaf area. Background Art

[0002] When there are multiple layers of pressurized aquifers above the coal seam roof, especially when the aquifers are located in or near the water-conducting fracture zone, water-conserving coal mining technology is particularly important and becomes a core element in the green coal mining strategy. Mining activities reveal that even if the water-conducting fracture zone caused by mining is separated from the aquifer by a certain distance, water will still penetrate into the mining area through the developed rock fractures. This increased permeability caused by mining and the lack of aquicludes put water resources at risk of loss. Without effective water conservation measures, long-term and intensive mining will lead to the gradual depletion of water resources in the aquifer, seriously threatening the regional ecological environment. Therefore, water-conserving coal mining technology plays a vital role in ensuring water resources and ecological balance in mining areas. Summary of the invention

[0003] In view of the above technical problems, the present invention proposes a method for water-retaining coal mining by grouting and filling the bottom plate of the goaf, comprising the following steps:

[0004] S1: The mining face is arranged in the mining area, with coal pillars on both sides of the mining face;

[0005] S2: Based on the lithology and thickness of the floor rock layer, the scope of the floor damage zone below the coal seam is determined, and the floor damage zone can form a water channel; a rock layer of a certain thickness is selected below the floor damage zone as the floor grouting pressure-bearing layer, and the floor grouting pressure-bearing layer arches up under the grouting pressure, but does not generate cracks that conduct to the upper floor damage zone, or the generated cracks are not connected to the cracks in the floor damage zone;

[0006] S3: constructing a directional grouting drill hole from the ground outside the cut-out of the working face, wherein the horizontal section of the directional grouting drill hole is constructed close to the bottom interface of the bottom plate pressure-bearing protective layer, and is constructed at least to a certain range within the working face;

[0007] S4: After the working face has been pushed past the cut hole for a certain distance, high-pressure grouting is performed through directional grouting drilling;

[0008] S5: The working face is continuously mined forward, and grouting is continuously injected into the self-directional grouting drilling hole. The grouting is stopped when the slurry cannot be injected after the working face is mined.

[0009] Preferably, the method is particularly suitable for working conditions where there are multiple layers of pressurized water-rich rock layers on the coal seam roof and the amount of water gushing from top water mining is large.

[0010] The inventive point and beneficial effects of the present invention: In view of the working conditions where there are multiple layers of pressurized water-rich rock layers on the roof of a coal seam and a large amount of water gushing during top-water coal mining, the present invention creatively proposes a method for water-preserving coal mining by grouting the bottom plate of the goaf. The slurry injected into the bottom plate and the expansion of the bottom plate caused by grouting together offset part of the space created by coal seam mining, thereby reducing the equivalent mining height of the coal seam (the actual mining height minus the mining height offset by filling and expansion), thereby reducing the height of the collapse zone, fracture zone and water-conducting fracture zone, so that the water-conducting fracture zone does not communicate with the upper aquifer, thereby achieving water-preserving coal mining. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of water-bearing rock formation leakage when the conventional caving method is used for mining in the prior art;

[0012] Figure 2 It is a schematic diagram of the principle of the method for water-retaining coal mining by grouting and filling the bottom plate of the goaf in the present invention;

[0013] In the figure: bottom plate grouting bearing layer-1, loose layer-2, bottom plate uniform fracture zone-3, bottom plate crushing and expansion zone-4, coal pillar-5, collapse zone-6, fracture zone-7, bedrock aquifer-8, directional grouting borehole-9, grouting slurry-10, water-conducting fracture zone-11. DETAILED DESCRIPTION

[0014] In order to better understand the technical content of the present invention, specific embodiments are cited and described as follows in conjunction with the accompanying drawings. In the present invention, various aspects of the present invention are described with reference to the accompanying drawings, in which many illustrative embodiments are shown. The embodiments of the present invention are not limited to those described in the accompanying drawings. It should be understood that the present invention is implemented by any of the various concepts and embodiments introduced above, as well as the concepts and implementations described in detail below, because the concepts and embodiments disclosed in the present invention are not limited to any implementation. In addition, some aspects disclosed in the present invention can be used alone or in any appropriate combination with other aspects disclosed in the present invention.

[0015] like Figure 1 As shown, when the existing technology (such as the caving method) is used to mine coal seams, the water-conducting fracture zone 11 may develop to the bedrock aquifer 8, or the aquifer in the loose layer 2; causing the water in the bedrock aquifer 8 or the water in the loose layer 2 to infiltrate into the working face through the water-conducting fracture zone 11 (including the caving zone 6 and the fracture zone 7), thereby exposing water resources to a serious risk of loss, threatening the ecological and environmental stability of the region.

[0016] like Figure 2 To solve the above problems, the present invention proposes a method for water-retaining coal mining by grouting and filling the bottom plate of the goaf, which is particularly suitable for working conditions where there are multiple pressurized water-rich rock formations and a large amount of water inflow in top water mining. The water-retaining coal mining method specifically includes the following steps:

[0017] S1: a mining face is arranged in the mining area, and coal pillars 5 are formed on both sides of the mining face;

[0018] S2: Based on the lithology and thickness of the bottom plate rock formation, the scope of the bottom plate damage zone below the coal seam is determined. The bottom plate damage zone includes a bottom plate crushing and expansion zone 4 and a bottom plate uniform fracture zone 3. The bottom plate rock formation in the bottom plate crushing and expansion zone 4 is broken in an irregular network, and the broken blocks are relatively small. Since there are gaps between the broken blocks, there are certain expansion characteristics; the bottom plate rock formation in the bottom plate uniform fracture zone 3 is broken in regular vertical and horizontal cracks, forming regular relatively large broken blocks, and the bottom plate damage zone can form a water channel; a certain thickness of rock formation (usually including multiple layers of rock formation) is selected below the bottom plate damage zone as the bottom plate pressure-bearing protective layer 1, and the bottom plate pressure-bearing protective layer 1 is arched under the grouting pressure, but no cracks are generated to conduct to the upper bottom plate damage zone, or the generated cracks are not connected to the cracks in the bottom plate damage zone;

[0019] S3: constructing a directional grouting borehole 9 from the ground outside the cut-out of the working face, wherein the horizontal section of the directional grouting borehole 9 is constructed close to the bottom interface of the bottom plate pressure-bearing protective layer 1, and is constructed at least to a certain range within the working face;

[0020] S4: After the working face is pushed past the cut hole for a certain distance, high-pressure grouting is performed through the directional grouting drilling hole 9. The injected high-pressure grout 10 gradually lifts the bottom plate pressure-bearing protective layer 1 and the bottom plate uniform fracture zone 3 and the bottom plate crushing expansion zone 4 thereon; the bottom plate uniform fracture zone 3 and the bottom plate crushing expansion zone 4 will increase the damage range under the action of grouting (compared with the prior art without bottom plate grouting, such as Figure 1 As shown in the figure), the looseness of the irregular rock blocks in the floor crushing and expansion zone 4, i.e., the crushing and expansion degree, will also increase, further enriching the space of the goaf, and together with the injected slurry 10, offset the space formed by part of the coal seam mining, thereby reducing the equivalent mining height of the coal seam, and the height of the collapse zone 6, the fracture zone 7, and the water-conducting fracture zone 11 will also be reduced (compared to the prior art without floor grouting, such as Figure 1 As shown), no channel for the aquifer to seep downward is formed, water loss in the bedrock aquifer 8 and the loose layer 2 is avoided, and the water conservation effect is finally achieved;

[0021] S5: The working face is continuously mined forward, and grouting is continuously injected from the directional grouting borehole 9. When the grouting of the working face is completed and the grouting 10 cannot be injected, the grouting is stopped.

[0022] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of methods under the inspiration of the present invention. Any technical solution that is the same or similar to that of the present application falls within the protection scope of the present invention.

Claims

1. A method for water-retaining coal mining by grouting and filling the bottom plate of the goaf, characterized in that: The following steps are involved: S1: The mining face is arranged in the mining area, with coal pillars on both sides of the mining face; S2: Based on the lithology and thickness of the floor rock layer, the scope of the floor damage zone below the coal seam is determined, and the floor damage zone can form a water channel; a rock layer of a certain thickness is selected below the floor damage zone as the floor grouting pressure-bearing layer, and the floor grouting pressure-bearing layer arches up under the grouting pressure, but does not generate cracks that conduct to the upper floor damage zone, or the generated cracks are not connected to the cracks in the floor damage zone; S3: constructing a directional grouting drill hole from the ground outside the cut-out of the working face, wherein the horizontal section of the directional grouting drill hole is constructed close to the bottom interface of the bottom plate pressure-bearing protective layer, and is constructed at least to a certain range within the working face; S4: After the working face has been pushed past the cut hole for a certain distance, high-pressure grouting is performed through directional grouting drilling; S5: The working face is continuously mined forward, and grouting is continuously injected into the self-directional grouting drilling hole. The grouting is stopped when the slurry cannot be injected after the working face is mined.

2. The method for water-retaining coal mining by grouting and filling the goaf floor according to claim 1, characterized in that: This method is particularly suitable for working conditions where there are multiple layers of pressurized water-rich rock layers in the coal seam roof and the amount of water gushing from top water mining is large.

Images