Chemical modification, expansion and settlement reduction control method for floor rock stratum

Abstract

The invention relates to the field of coal mining subsidence control, in particular to a floor rock stratum chemical modification expansion subsidence reduction control method. Comprising the steps of determining the range of a floor failure zone below a coal seam, and selecting a rock stratum with a certain thickness below the floor failure zone as an isolation protection zone; the lower part of the isolation protection belt is a chemical modified expansion belt; selecting a chemical agent for expansion according to mineral components of the chemically modified expansion zone rock stratum; directional drilling is conducted in a working face roadway, a directional drilling horizontal section is constructed in a chemical modified expansion zone, and directional drilling is conducted in the advancing direction of a working face towards the open-off cut direction; the expansion band is chemically modified through directional drilling fracturing; and after the working face is pushed over the horizontal section of the directional drilling hole and before the working face reaches the hole opening of the directional drilling hole, a chemical agent is injected into the chemical modified expansion zone through the directional grouting drilling hole. According to the method, the base plate rock stratum is chemically modified to generate an expansion effect, so that the base plate rock stratum is lifted to support the goaf, the subsidence of the overlying rock stratum is reduced, and the surface subsidence is controlled.

Description

Technical Field

[0001] The invention relates to the field of coal mining subsidence control, and in particular to a method for controlling subsidence reduction by chemically modifying bottom rock strata through expansion. Background Art

[0002] With the continuous advancement of coal resource mining technology and equipment, the production efficiency and capacity of coal mines have been significantly improved, playing an important role in ensuring energy security and promoting rapid economic development. However, at the same time, the surface subsidence and ecological environmental damage caused by high-intensity coal resource mining have become more and more serious. As one of the direct consequences of coal mining, surface subsidence is not only limited to the destruction of land resources and groundwater resources in the mining area, affecting the normal operation of regional agricultural production and ecosystems, but also posing a major threat to local buildings, infrastructure and the lives of local residents. High-intensity mining activities are also accompanied by serious ecological damage, causing vegetation destruction, soil structure degradation, a sharp decline in regional biodiversity, and intensified soil erosion and desertification, posing severe challenges to the sustainable development of the regional ecological environment. Therefore, how to effectively control and manage surface subsidence and ecological environmental damage while improving the efficiency of coal resource mining has become an important problem that needs to be solved in the mining industry.

[0003] At present, in order to solve the problems of surface subsidence and ecological environment damage in mining areas, some mining areas adopt backfill mining technology. During the mining process, solid, paste or high-water materials are filled in the goaf behind the working face to form a backfill body to support the overlying rock layer, thereby effectively controlling surface subsidence and reducing ecological damage in mining areas. Especially in areas with scarce water resources or fragile ecology, backfill mining technology can balance the contradiction between resource development and environmental protection to a certain extent. However, this technology also has some limitations. For example, it is necessary to build an independent backfill pipeline system in the mining field or on the ground, which not only significantly increases equipment investment and operating costs, but also may cause mutual interference between mining and backfilling construction, affecting mining efficiency. In addition, due to the complex preparation, transportation and injection process of backfill materials, the performance of backfill materials and system supporting equipment are required to be high, which further increases the difficulty of technical implementation. Summary of the invention

[0004] In order to solve the problems of high cost and low efficiency of current subsidence control methods, the present invention proposes a method for controlling subsidence by chemically modifying the bottom rock strata, comprising the following steps:

[0005] S1: Determine the range of the floor damage zone below the coal seam, select a rock layer of a certain thickness below the floor damage zone as an isolation protection zone, the isolation protection zone will be arched after the chemical modification expansion zone expands, but no cracks will be generated to connect to the upper floor damage zone, or the generated cracks will not be connected to the cracks in the floor damage zone; the lower part of the isolation protection zone is a chemical modification expansion zone, and the rock layer in the chemical modification expansion zone can react chemically with the chemical agent to produce expansion;

[0006] S2: Select the chemical agent for expansion according to the mineral composition of the chemically modified expansion zone rock formation;

[0007] S3: construct directional drilling holes in the tunnels on one side or both sides of the working face, wherein the horizontal section of the directional drilling holes is constructed in the chemically modified expansion zone, the directional drilling holes are constructed in the direction of the opposite tunnel in the width direction of the working face, and the directional drilling holes are constructed in the direction of the cutting eye in the advancing direction of the working face; after the construction is completed, the chemically modified expansion zone is fractured through the directional drilling holes;

[0008] S4: After the working face passes through a certain horizontal section of a directional borehole and before reaching the orifice of the directional borehole, the chemical agent is injected into the chemically modified expansion zone through the directional grouting drilling.

[0009] Preferably, in step S2, the chemical agent includes an expansive mineral activator, a gas expansive agent and a gel forming agent; the expansive mineral activator adopts a sodium-based or calcium-based solution, the gas expansive agent adopts sodium bicarbonate and acid solution, and the gel forming agent adopts a sodium silicate and calcium chloride solution.

[0010] Preferably, in step S3, the directional drilling is parallel to the width direction of the working surface.

[0011] Preferably, in step S4, the hole is sealed when the working surface passes through the opening of the directional drilling hole.

[0012] The invention and beneficial effects of the present invention: The present invention chemically modifies the bottom rock layer to make it expand, thereby lifting the bottom rock layer to support the goaf, thereby reducing the sinking of the overlying rock layer and controlling the surface subsidence. The present invention realizes active expansion through chemical modification, and the chemical agent selection is flexible. The expansion scheme can be adjusted according to different rock layer conditions, the overall operating cost is low, and the expansion effect is controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a cross-sectional schematic diagram of the control mechanism of the chemically modified expansion zone of the bottom plate rock layer in the present invention;

[0014] Figure 2 It is a schematic plan view of the directional drilling construction of the chemically modified expansion zone of the bottom plate rock layer in the present invention;

[0015] In the figure: chemically modified expansion zone-1, isolation protection zone-2, bottom plate uniform rupture zone-3, bottom plate crushing expansion zone-4, fracture zone-5, chemical agent-6, fracturing fracture-7, directional drilling-8, collapse zone-9. DETAILED DESCRIPTION

[0016] 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.

[0017] In order to solve the problems of high cost and low efficiency of current subsidence control methods, such as Figure 1-2 As shown, the present invention proposes a method for controlling the chemical modification of floor rock strata expansion and subsidence reduction; the method is applicable to mining conditions where there are easily chemically modified expansion rock strata on the floor of the coal seam; the specific steps include:

[0018] S1: Based on the lithology and thickness of the bottom plate rock formation, the range 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 fractures, forming regular relatively large broken blocks, and the bottom plate damage zone can form a water channel; in the bottom plate A rock layer of a certain thickness (usually including multiple rock layers) is selected below the damage zone as the isolation protection zone 2. The isolation protection zone 2 is arched after the chemically modified expansion zone expands, but no cracks are generated to connect to the upper bottom plate damage zone, or the generated cracks are not connected to the cracks in the bottom plate damage zone; the lower part of the isolation protection zone 2 is the chemically modified expansion zone 1, and the rock layer in the chemically modified expansion zone 1 can react chemically with the chemical agent 6 to produce expansion, such as a rock layer containing mineral components such as bentonite, kaolin, montmorillonite, etc.;

[0019] S2: Select the chemical agent 6 for expansion according to the mineral composition of the chemically modified expansion zone 1, the chemical agent mainly includes an expansion mineral activator, a gas expansion agent and a gel forming agent; the expansion mineral activator adopts a sodium-based or calcium-based solution (NaCl, CaCl2) to provide exchangeable cations (Na + , Ca 2+) to promote the expansion of the expansive mineral; the gas expansion agent such as sodium bicarbonate and acid solution, the two are mixed and reacted to release carbon dioxide gas to produce gas expansion; the gel forming agent such as sodium silicate and calcium chloride solution, the two are mixed and reacted to form a gel to fill the cracks and accompanied by expansion;

[0020] S3: constructing a directional drill hole 8 in the tunnels on one side or both sides of the working face, wherein the horizontal section of the directional drill hole 8 is constructed in the chemically modified expansion zone 1, and the directional drill hole 8 is constructed in the direction of the opposite tunnel in the width direction of the working face, and the directional drill hole is preferably parallel to the width direction of the working face, and the directional drill hole 8 is constructed in the direction of the eye cut in the advancing direction of the working face (i.e., the length direction of the working face); after the construction is completed, the chemically modified expansion zone 1 is fractured by the directional drill hole 8 to form a fracture 7 in the chemically modified expansion zone 1, and the fracturing means include carbon dioxide blasting, hydraulic fracturing and other means;

[0021] S4: After the working face passes through a horizontal section of a directional borehole 8 and before reaching the opening of the directional borehole 8 (e.g. Figure 2 The solid line position in the middle working face), the chemical agent 6 is injected into the chemically modified expansion zone 1 through the directional grouting drilling 8, and the grouting pressure is controlled to ensure that the chemical agent 6 can be evenly distributed and penetrate into the rock layer in the chemically modified expansion zone 1; the chemical agent 6 reacts with the rock layer in the chemically modified expansion zone 1, the volume of the chemically modified expansion zone 1 expands, and the isolation protection zone 2, the bottom plate uniform fracture zone 3 and the bottom plate damage zone 4 are lifted; among them, the bottom plate uniform fracture zone 3 and the bottom plate crushing expansion zone 4 will increase the damage range under the action of the volume expansion of the chemically modified expansion zone 1, and the looseness of the irregular rock blocks in the bottom plate crushing expansion zone 4, that is, the degree of crushing and expansion, will also increase, further enriching the goaf space, and together with the volume expansion of the chemically modified expansion zone 1, offset the space formed by part of the coal seam mining, thereby reducing the equivalent mining height of the coal seam, reducing the height of the collapse zone 9 and the fracture zone 5, and controlling the sinking of the overlying rock layer, thereby reducing the surface subsidence.

[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 controlling the expansion and subsidence of a bottom rock layer by chemical modification, characterized in that: The steps include: S1: Determine the range of the floor damage zone below the coal seam, select a rock layer of a certain thickness below the floor damage zone as an isolation protection zone, the isolation protection zone will be arched after the chemical modification expansion zone expands, but no cracks will be generated to connect to the upper floor damage zone, or the generated cracks will not be connected to the cracks in the floor damage zone; the lower part of the isolation protection zone is a chemical modification expansion zone, and the rock layer in the chemical modification expansion zone can react chemically with the chemical agent to produce expansion; S2: Select the chemical agent for expansion according to the mineral composition of the chemically modified expansion zone rock formation; S3: construct directional drilling holes in the tunnels on one side or both sides of the working face, wherein the horizontal section of the directional drilling holes is constructed in the chemically modified expansion zone, the directional drilling holes are constructed in the direction of the opposite tunnel in the width direction of the working face, and the directional drilling holes are constructed in the direction of the cutting eye in the advancing direction of the working face; after the construction is completed, the chemically modified expansion zone is fractured through the directional drilling holes; S4: After the working face passes through a certain horizontal section of a directional borehole and before reaching the orifice of the directional borehole, the chemical agent is injected into the chemically modified expansion zone through the directional grouting drilling.

2. The method for controlling the expansion and subsidence reduction of the bottom rock layer by chemical modification according to claim 1, characterized in that: In step S2, the chemical agent includes an expansive mineral activator, a gas expansive agent and a gel forming agent; the expansive mineral activator adopts a sodium-based or calcium-based solution, the gas expansive agent adopts sodium bicarbonate and acid solution, and the gel forming agent adopts a sodium silicate and calcium chloride solution.

3. The method for controlling the expansion and subsidence reduction of the bottom rock layer by chemical modification according to claim 1, characterized in that: In step S3, the directional drilling is parallel to the width direction of the working surface.

4. The method for controlling the expansion and subsidence reduction of the bottom rock layer by chemical modification according to claim 1, characterized in that: In step S4, the hole is sealed when the working face passes through the directional drilling hole.

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