A coal mining method for controlling surface subsidence by blasting cracking and expansion of bottom rock layers

Abstract

The present invention relates to the field of mining area subsidence reduction, specifically a coal mining method for controlling surface subsidence by blasting the bottom rock stratum to cause cracking and expansion; the method comprises arranging a mining face and performing mining; constructing blasting drill holes in the roadways on both sides of the leading working face toward the coal seam bottom stratum, with the blasting drill holes inclined in the plane toward the cutting eye direction; blasting the pair of blasting drill holes before the working face is mined to the openings of the pair of blasting drill holes closest to it; and continuously performing mining of the working face and blasting of the bottom stratum until the working face is mined. The present invention creatively proposes a coal mining method for controlling surface subsidence by blasting the bottom rock stratum to cause cracking and expansion. During the coal seam mining process, when the coal seam roof has not fully collapsed, the rock mass of the coal seam bottom stratum is blasted. The bottom stratum 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 the collapsed roof stratum and supports the roof stratum, thereby reducing the fracture and subsidence of the coal seam roof and ultimately reducing surface subsidence.

Description

Technical Field

[0001] The present invention relates to the field of mining area subsidence reduction, and in particular to a coal mining method for controlling surface subsidence by blasting bottom rock layers to cause cracking and expansion. Background Art

[0002] The "three-under" coal-pressing areas are extremely rich in coal resources. As coal resource development continues to deepen, how to efficiently and safely mine the "three-under" coal has become a pressing issue for the coal industry. Against this backdrop, backfill mining technology has emerged, providing an effective technical means to address the "three-under" mining challenges, such as coal pressure beneath buildings. Compared with traditional coal mining techniques, backfill mining, by filling the goaf with various materials, can significantly reduce surface subsidence and support the stability of overburden. Specifically, backfill mining technology uses solid waste, paste materials, or high-water-solidifying materials to fill the goaf, forming a stable support structure, thereby effectively reducing geological environmental problems caused by coal mining. Furthermore, this technology can fully utilize mine waste resources, realize waste resource utilization, and further improve the efficiency of comprehensive resource utilization.

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

[0004] First, backfill mining poses a significant risk of interference with face recovery. The injection and curing of backfill materials requires extensive equipment and processes, increasing operational complexity and directly impacting the recovery progress of the face. For example, to ensure a safe distance between the backfill and the mining face, a barrier is often required, limiting the speed of mining. Furthermore, the backfill material takes a long time to cure, further slowing mining efficiency and extending the operating cycle.

[0005] Secondly, backfill mining technology imposes certain restrictions on coal seam recovery rates. Because backfilling occupies space in the goaf, it is often necessary to leave some coal pillars or seams unmined to ensure stability and bearing capacity, thereby reducing coal resource recovery rates. This decline in resource utilization negatively impacts the overall economic benefits of the mine, a problem that is particularly pronounced when coal prices fluctuate or reserves are limited.

[0006] Furthermore, the cost of backfill materials and the complexity of the process also pose challenges to the economic viability of the technology. Paste backfill and high-water-density backfill typically require large quantities of high-quality materials and chemical additives, significantly increasing the cost per ton of coal mined compared to traditional methods. Furthermore, the purchase, operation, and maintenance of backfill equipment require additional investment, while the training and specialized operation requirements of technicians further increase labor costs. Summary of the Invention

[0007] In response to the problems existing in the prior art, the present invention proposes a coal mining method for controlling surface subsidence by blasting the floor rock layer to cause cracking and expansion, comprising the following steps:

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

[0009] S2: At the advanced working face mining position, blasting drill holes are constructed in the roadways on both sides of the working face towards the coal seam floor within the working face, with the blasting drill holes inclined in the plane towards the eye cutting direction; the blasting drill holes are constructed in pairs in the roadways on both sides of the working face at a certain interval from the eye cutting direction, and the blasting range of the adjacent 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 the coal body forward, and blasts the pair of blasting holes closest to it before the working face mines to the openings of the pair of blasting holes, 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 drill holes until the mining of the working face is completed.

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

[0013] Preferably, in step S2, when the bottom plate is hard rock, the diameter of the drill hole is 100-130 mm, the drilling depth is 2 times the mining height, and the drilling 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 drilling depth is 2 times the mining height, and the drilling spacing 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 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 fully collapse when the blasting holes 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 layer to cause cracking and expansion. During the coal seam mining process, when the coal seam roof has not fully collapsed, the rock mass of the coal seam bottom plate is blasted. The bottom plate 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 the collapsed roof plate and supports the roof plate rock layer, 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 the coal mining method of the present invention in which the bottom rock layer is cracked and expanded by blasting to control surface subsidence;

[0021] Figure 2 It is a schematic plan view of the blasting drilling arrangement 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, specific implementation methods are described below 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 the bottom rock layer to cause cracking and expansion, comprising the following steps:

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

[0026] S2: Ahead of the working face mining position, blasting drill holes 2 are constructed in the roadways 3 on both sides of the working face toward the coal seam floor within the working face, i.e., the blasting drill holes 2 are constructed vertically toward the floor, and the blasting drill holes 2 are inclined in the plane toward the eye cutting direction; the blasting drill holes 2 are constructed in pairs in the roadways 3 on both sides of the working face at equal intervals from the eye cutting direction along the working face advancement direction, the vertical depth and angle and plane inclination of each pair of blasting drill holes 2 are all the same, and the blasting range of the adjacent pair of blasting drill holes 3 is connected to the blasting range of the previous pair of blasting drill holes 3; the blasting drill holes are preferably non-explosive blasting, 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] Drill hole spacing: The spacing between drill 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 or 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] Drill hole spacing: the spacing between drill holes along the working face advancement direction, 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 drill hole 2 does not cover the entire blasting drill hole length, the blasting range of the blasting drill hole 2 is lagging from 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 drill hole 2 can ensure that the roof rock layer above the blasting drill hole 2 does not collapse when the blasting drill hole 2 is blasted, but the roof collapses in time after the working face pushes through the blasting drill hole 2 that has just been blasted, and the roof collapses at least when the working face is fully advanced to the hole mouth position of the blasting drill hole 2 that has just been blasted; or the construction parameters of the blasting drill hole can ensure that the roof rock layer above the blasting drill hole does not fully collapse when the blasting drill hole is blasted;

[0041] After the blasting of the blasting borehole 2, the bottom rock layer will experience crack expansion and rock fragmentation. The volume of the broken bottom rock layer 4 will expand and bulge due to its crushing and expansion characteristics. Under the lateral pressure of the solid coal 1 and its own expansion, the broken bottom rock mass 4 gradually rises and contacts the roof rock layer (including the collapse zone 5 and the fracture zone 6) that has lagged behind it in collapse, thereby forming a control effect on the roof rock layer and reducing its sinking and damage. Since the blasting and expansion of the bottom rock layer offsets part of the space created by coal seam mining, the equivalent mining height of the coal seam is reduced (the actual mining height minus the mining height offset by the blasting and expansion of the bottom 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. However, any technical solution that is the same or similar to that of the present application falls within the scope of protection of the present invention.

Claims

1. A coal mining method for controlling surface subsidence by blasting the floor rock layer to cause cracking and expansion, characterized in that: The steps include: S1: Design and arrange the mining face in the mining area and carry out normal mining operations; S2: At the advanced working face mining position, blasting drill holes are constructed in the roadways on both sides of the working face towards the coal seam floor within the working face, with the blasting drill holes inclined in the plane towards the eye cutting direction; the blasting drill holes are constructed in pairs in the roadways on both sides of the working face at a certain interval from the eye cutting direction, and the blasting range of the adjacent 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 the coal body forward, and blasts the pair of blasting holes closest to the working face before the working face mines to the openings of the pair of blasting holes, 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 drill 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 a non-explosive blasting method.

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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