Coal mining method for controlling ground surface settlement by blasting, fracturing and dilatation of floor rock stratum

Abstract

The invention relates to the field of mining area subsidence reduction, in particular to a coal mining method for controlling ground subsidence through blasting, fracturing and dilatation of a floor rock stratum. Comprising the following steps: arranging a stoping working face and stoping; blasting drill holes are constructed in roadways on the two sides of the advance working face towards a coal seam bottom plate, and the blasting drill holes are inclined in the open-off cut direction on the plane; blasting work of the pair of blasting drill holes is carried out before the working face is stoped to orifices of the pair of blasting drill holes closest to the working face; and working face stoping and bottom plate blasting work are continuously conducted till working face stoping is completed. The invention creatively provides a coal mining method for controlling ground surface settlement by blasting, fracturing and dilatation of a floor rock stratum, when a coal seam roof is not fully collapsed in the coal seam mining process, a rock mass of a coal seam floor is blasted, and the blasted floor rock mass expands under the breaking and expanding action and continuously bulges under the side pressure of solid coal, so that the coal seam floor is exploded; therefore, the fracture and sinking amplitude of the coal seam roof is reduced, and finally the surface subsidence is reduced.

Description

Technical Field

[0001] The invention relates to the field of mining area subsidence reduction, and in particular to a coal mining method for controlling surface subsidence by blasting and fracturing and expanding a bottom rock layer. Background Art

[0002] The "three-under" coal-pressing area contains extremely rich coal resources. In the context of the current deepening of coal resource development, how to efficiently and safely mine the "three-under" coal has become an urgent problem to be solved in the coal industry. Against this background, backfill coal mining technology came into being, providing an effective technical means to solve the "three-under" mining problems such as coal pressure under buildings. Compared with traditional coal mining technology, backfill coal mining can play a significant role in reducing surface subsidence and supporting the stability of overburden by filling various materials in the goaf. Specifically, backfill coal mining technology uses solid waste, paste materials or high-water solidification materials to fill the goaf to form a stable support structure, thereby effectively reducing the geological environmental problems caused by coal mining. In addition, this technology can make full use of mine waste resources, realize waste resource utilization, and further improve the comprehensive utilization efficiency of resources.

[0003] Although the existing backfill coal mining technology has significant advantages in alleviating the problem of coal pressure under buildings, there are still many technical and economic challenges in its practical application, which require further optimization and breakthroughs.

[0004] First, the interference of backfill mining on the recovery of the working face is more prominent. During the implementation process, the injection and solidification of the backfill material requires a large number of construction equipment and processes, which not only increases the complexity of the operation, but also directly affects the recovery progress of the working face. For example, in order to ensure a safe distance between the backfill body and the coal mining face, it is usually necessary to set an isolation zone, which limits the speed of coal mining. In addition, the backfill material takes a long time to solidify, which further delays the mining efficiency and causes the operation cycle to be extended.

[0005] Secondly, backfill mining technology has a certain restriction on the recovery rate of coal seams. Since backfilling will occupy the space of the goaf, in order to ensure its stability and carrying capacity, it is often necessary to retain some coal pillars or coal seams without mining, thereby reducing the recovery rate of coal resources. This decline in resource utilization has an adverse impact on the overall economic benefits of the mine, especially when coal prices fluctuate or resource reserves are limited. This problem is more significant.

[0006] In addition, the cost of filling materials and process complexity also pose challenges to the economic feasibility of the technology. Paste filling and high-water material filling usually require a large amount of high-quality materials and chemical additives, which significantly increases the mining cost per ton of coal compared to traditional methods. At the same time, the purchase, operation and maintenance of filling equipment require additional investment, and the training of technicians and professional operation requirements further increase labor costs. Summary of the invention

[0007] In view of the problems existing in the prior art, the present invention proposes a coal mining method for controlling surface subsidence by blasting and fracturing the bottom rock layer, which comprises the following steps:

[0008] S1: Design and arrange the mining face in the mining area and carry out normal mining operations;

[0009] S2: A blasting drill hole is constructed in the lanes on both sides of the working face toward the coal seam floor in the working face at the advanced working face mining position. The blasting drill hole is inclined toward the eye cutting direction on the plane. The blasting drill holes are constructed in pairs in the lanes on both sides of the working face at a certain distance from the eye cutting along the advancing direction of the working face, and the blasting range of the next pair of blasting drill holes is connected to the blasting range of the previous pair of blasting drill holes.

[0010] S3: The working face continuously mines coal forward, and blasts the pair of blasting holes before the working face mines to the openings of the pair of blasting holes closest to it, and the construction parameters of the blasting holes can ensure that the roof rock layer above the blasting holes does not collapse when the blasting holes are blasted, but the roof collapses in time after the working face pushes through the blasting holes that have just been blasted;

[0011] S4: Continue the mining work on the working face, and refer to step S3 to blast the subsequent blasting holes until the mining of the working face is completed.

[0012] Preferably, in step S2, the blasting drilling is performed by non-explosive blasting.

[0013] Preferably, in step S2, when the bottom plate is hard rock, the diameter of the drill hole is 100-130 mm, the drill hole depth is 2 times the mining height, and the drill hole spacing is 15-25 meters.

[0014] Preferably, in step S2, when the bottom plate is soft rock, the diameter of the drill hole is 60-90 mm, the depth of the drill hole is 2 times the mining height, and the spacing between the drill holes is 8-15 meters.

[0015] Preferably, in step S2, when the bottom plate is of medium hardness, the drilling diameter is 80-120 mm, the drilling depth is 2 times the mining height, and the drilling spacing is 10-20 meters.

[0016] Preferably, in step S3, the pair of blasting drill holes does not affect the production and safety of the working face during blasting.

[0017] Preferably, in step S3, the blasting range of the blasting borehole does not cover the entire length of the blasting borehole.

[0018] Preferably, alternatively, step S3 is that the working face continuously mines the coal body forward, and blasting the pair of blasting boreholes is performed before the working face mines to the openings of a pair of blasting boreholes closest to it, and the construction parameters of the blasting boreholes can ensure that the roof rock layer above the blasting boreholes does not fully collapse when the blasting boreholes are blasted.

[0019] The inventive point and beneficial effects of the present invention: The present invention creatively proposes a coal mining method for controlling surface subsidence by blasting the bottom rock strata to cause fracturing and expansion; during coal seam mining, when the coal seam roof has not fully collapsed, the rock mass of the coal seam bottom stratum is blasted; the bottom rock mass after blasting expands under the action of crushing and expansion, and continuously rises under the lateral pressure of the solid coal, and then contacts with the collapsed roof stratum and supports the top rock stratum, thereby reducing the breakage and subsidence of the coal seam roof, and ultimately reducing surface subsidence. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a cross-sectional schematic diagram of a coal mining method for controlling ground surface settlement by blasting and fracturing and expanding the bottom rock layer in the present invention;

[0021] Figure 2 It is a schematic plan view of the arrangement of blasting drilling holes in the present invention;

[0022] In the figure: coal pillar-1, blasting drill hole-2, tunnel-3, rock mass after blasting fracture and expansion-4, collapse zone-5, fracture zone-6. DETAILED DESCRIPTION

[0023] In order to better understand the technical content of the present invention, the specific implementation methods are 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. 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 implementation methods described in detail below, because the concepts and embodiments disclosed in the present invention are not limited to any implementation method. 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.

[0024] like Figure 1-2 As shown, the present invention provides a coal mining method for controlling surface subsidence by blasting and fracturing the bottom rock layer, comprising the following steps:

[0025] S1: Design and arrange the mining face in the mining area and carry out normal mining operations;

[0026] S2: A blasting borehole 2 is constructed in the lanes 3 on both sides of the working face toward the coal seam floor in the working face, that is, the blasting borehole 2 is constructed toward the floor in the vertical direction, and the blasting borehole 2 is inclined toward the eye cutting direction in the plane; the blasting borehole 2 is constructed in pairs in the lanes 3 on both sides of the working face at the same distance from the eye cutting along the advancing direction of the working face, and the vertical depth and angle and plane inclination of each pair of blasting boreholes 2 are the same, and the blasting range of the adjacent rear pair of blasting boreholes 3 is connected with the blasting range of the previous pair of blasting boreholes 3; the blasting borehole is preferably a non-explosive blasting method, such as carbon dioxide blasting;

[0027] S201: When the base plate is a hard rock base plate, such as granite or limestone;

[0028] Drilling diameter: Choose a larger drilling diameter, usually between 100-130mm;

[0029] Drilling depth: Determined by the mining height, the depth is about twice the mining height;

[0030] Drilling spacing: The spacing between drilling holes along the working face is relatively large, usually between 15-25 meters;

[0031] S202: When the floor is a soft rock floor, such as mudstone and shale;

[0032] Drilling diameter: Choose a smaller drilling diameter, usually between 60-90mm;

[0033] Drilling depth: Determined by the mining height, the depth is about twice the mining height;

[0034] Drilling spacing: the spacing of the boreholes along the advancing direction of the working face, usually between 8-15 meters;

[0035] S203: Medium hardness rock base (such as sandstone, siltstone)

[0036] Drilling diameter: Choose a drilling diameter between hard rock and soft rock, usually between 80-120mm;

[0037] Drilling depth: Determined by the mining height, the depth is about twice the mining height;

[0038] Drilling spacing: The drilling spacing is moderate, usually between 10-20 meters;

[0039] S3: Blasting of the base rock layer by blasting drilling

[0040] The working face continuously mines the coal body forward, and before the working face mines to the opening of the pair of blasting boreholes 2 closest to it, the blasting work of the pair of blasting boreholes 2 is carried out. For example, the blasting position of each pair of blasting boreholes is located at Figure 2The blasting range of the blasting borehole 2 does not cover the entire blasting borehole length, the blasting range of the blasting borehole 2 is lagging behind the working face mining position. Figure 2 The middle dotted line is at a certain distance, such as about 5m, to avoid affecting the production and safety of the working face; and the construction parameters of the blasting borehole 2 can ensure that the roof rock layer above the blasting borehole 2 does not collapse when the blasting borehole 2 is blasted, but the roof collapses in time after the working face pushes through the blasting borehole 2 that has just been blasted, and the roof collapses at least when the working face is fully advanced to the hole position of the blasting borehole 2 that has just been blasted; or the construction parameters of the blasting borehole can ensure that the roof rock layer above the blasting borehole does not fully collapse when the blasting borehole is blasted;

[0041] After the blasting of the blasting borehole 2, the cracks in the bottom plate rock layer will expand and the rocks will be broken. The volume of the broken bottom plate rock layer 4 will expand and bulge due to the crushing and expansion characteristics. Under the lateral pressure of the solid coal 1 and its own expansion, the broken bottom plate rock mass 4 gradually rises and contacts with the top plate rock layer (including the collapse zone 5 and the fracture zone 6) that has lagged behind its collapse, thereby forming a control effect on the top plate rock layer to reduce its sinking and damage. Since the explosion and expansion of the bottom plate rock layer offsets part of the space generated by the mining of the coal seam, the equivalent mining height of the coal seam is reduced (the actual mining height minus the mining height offset by the explosion and expansion of the bottom plate rock layer), thereby reducing the surface subsidence and achieving subsidence control.

[0042] S4: Continue the mining work on the working face, and refer to step S3 to blast the subsequent blasting boreholes 2 until the mining of the working face is completed.

[0043] 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 coal mining method for controlling surface subsidence by blasting and fracturing the bottom rock layer, characterized in that: The steps include: S1: Design and arrange the mining face in the mining area and carry out normal mining operations; S2: A blasting drill hole is constructed in the lanes on both sides of the working face toward the coal seam floor in the working face at the advanced working face mining position. The blasting drill hole is inclined toward the eye cutting direction on the plane. The blasting drill holes are constructed in pairs in the lanes on both sides of the working face at a certain distance from the eye cutting along the advancing direction of the working face, and the blasting range of the next pair of blasting drill holes is connected to the blasting range of the previous pair of blasting drill holes. S3: The working face continuously mines coal forward, and blasts the pair of blasting holes before the working face mines to the openings of the pair of blasting holes closest to it, and the construction parameters of the blasting holes can ensure that the roof rock layer above the blasting holes does not collapse when the blasting holes are blasted, but the roof collapses in time after the working face pushes through the blasting holes that have just been blasted; S4: Continue the mining work on the working face, and refer to step S3 to blast the subsequent blasting holes until the mining of the working face is completed.

2. The coal mining method according to claim 1, characterized in that: In step S2, the blasting drilling is performed by non-explosive blasting.

3. The coal mining method according to claim 1, characterized in that: In step S2, when the bottom plate is hard rock, the diameter of the drill hole is 100-130 mm, the drilling depth is twice the mining height, and the drilling spacing is 15-25 meters.

4. The coal mining method according to claim 1, characterized in that: In step S2, when the bottom plate is soft rock, the diameter of the drill hole is 60-90 mm, the drilling depth is twice the mining height, and the drilling spacing is 8-15 meters.

5. The coal mining method according to claim 1, characterized in that: In step S2, when the bottom plate is of medium hardness, the drilling diameter is 80-120 mm, the drilling depth is twice the mining height, and the drilling spacing is 10-20 meters.

6. The coal mining method according to any one of claims 1 to 5, characterized in that: In step S3, the pair of blasting drill holes does not affect the production and safety of the working face during blasting.

7. The coal mining method according to any one of claims 1 to 5, characterized in that: In step S3, the blasting range of the blasting borehole does not cover the entire blasting borehole length.

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