Isolation grouting and filling method for overlying and underlying coal seams above old goaf

Abstract

The present application belongs to the field of coal mine filling mining, and particularly relates to a method for isolation grouting filling of overlying and underlying coal seam over an old goaf. The present application aims at the problem of isolation grouting filling of overlying and underlying coal seam over an old goaf, and according to the positional relationship between the coal seam to be mined and the old goaf, fully considers the water-conducting fractured zone and floor fracture factors, divides the isolation grouting filling of overlying and underlying coal seam over an old goaf into different types, and respectively provides a method for determining the grouting filling horizon of the coal seam to be mined. Meanwhile, according to the distance between the grouting horizon and the coal seam to be mined and the position of the old goaf, a reinforcing measure for improving the ground subsidence control effect in combination with the grouting hole of the goaf is provided. The present application can realize safe and efficient mining of overlying and underlying coal seam over an old goaf, and ensure the ground subsidence control effect under various working conditions.

Description

Technical Field

[0001] This invention belongs to the field of coal mine backfilling mining, specifically a method for grouting and backfilling the overlying coal seam in old goaf areas. Background Technology

[0002] Mining coal under buildings and structures has always been a major challenge for coal enterprises. Solving this problem can promote the coordinated development of industry and agriculture in mining areas. In recent years, backfilling mining technology has been rapidly developed and applied in mining coal under buildings and structures in my country. Commonly used technologies include goaf backfilling (such as solid compaction backfilling, paste backfilling, and high-water backfilling) and overburden isolation grouting backfilling mining technology. Patent ZL201210164929.9 discloses a mining-driven overburden zone isolation grouting backfilling mining method. This method divides the mining area into several mining faces and leaves a certain width of isolation coal pillars between the mining faces. Several sets of grouting boreholes perpendicular to the coal seam are drilled from the surface above the mining faces. During the mining process, fly ash slurry is injected into the delamination layer above the mining faces through the grouting boreholes, thereby effectively controlling surface subsidence and achieving mining without relocation of villages.

[0003] However, in practice, some coal seams are located beneath old goaf areas, meaning that two coal seams exist in the strata, one of which was previously mined using the caving method. After mining, the surface was reclaimed and buildings were constructed. When the other coal seam is mined, a backfilling method is required to protect the surface buildings. In such cases, the overburden isolation grouting backfilling technique disclosed in patent ZL201210164929.9 cannot be directly applied. The drilling location, grouting layer, and grouting volume must take into account the influence of the old goaf area. Therefore, it is necessary to study the overburden isolation grouting backfilling method under old goaf areas to accurately determine the grouting borehole layout and grouting backfilling scheme, thereby improving the surface subsidence control effect, achieving overburden isolation grouting backfilling under old goaf areas without relocating villages for mining, and expanding the application scope of overburden isolation grouting backfilling technology. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, this invention proposes a method for grouting and filling overlying and underlying coal seams in old goaf areas. The overlying coal seam refers to the coal seam to be mined located above the old goaf, and the underlying coal seam refers to the coal seam to be mined located below the old goaf. The coal seam to be mined can be located below the old goaf, above the old goaf, or there can be one coal seam to be mined above and one below the old goaf. The method specifically includes the following steps:

[0005] a. Determine the height D1 of the water-conducting fracture zone and the depth S1 of the floor fracture zone generated after the mining of the coal seam;

[0006] b. When the coal seam to be mined is located above the old goaf, the height of the water-conducting fracture zone D2 after the coal seam to be mined is estimated. Compare D1 and D2, take the higher one, and add an isolation layer of a certain thickness as the grouting layer on this basis. Construct grouting holes to the grouting layer, and carry out the mining of the coal seam to be mined while carrying out overburden grouting and filling.

[0007] c. When the coal seam to be mined is located below the old goaf, predict the height D2 of the water-conducting fracture zone after the coal seam is mined, and determine the relationship between D2 and S1 and D1.

[0008] When the distance between D2 and S1 is greater than the first threshold, an isolation layer of a certain thickness is added on the basis of D2 as the grouting layer. Grouting holes are constructed to the grouting layer, and the coal seam to be mined is mined while the overburden is grouted and filled.

[0009] When the distance between D2 and S1 is not greater than the first threshold, an isolation layer of a certain thickness is added on the basis of D1 as the grouting layer. Grouting holes are constructed to the grouting layer, and grouting holes in the goaf are constructed to the old goaf. The coal seam to be mined is recycled and the overburden is filled by grouting holes. At the same time, grouting holes in the goaf are used to grout the old goaf.

[0010] When D2 and S1 are connected, and D2 is greater than D1, or D2 is less than D1 but their heights are similar, take the higher of D1 and D2, and add an isolation layer of a certain thickness as the grouting layer. Construct grouting holes to the grouting layer, carry out the mining of the coal seam to be mined, and carry out overburden grouting and filling.

[0011] When D2 and S1 are connected, and D2 is less than D1 but their heights differ significantly, an isolation layer of a certain thickness is added on the basis of D1 as the grouting layer. Grouting holes are constructed to the grouting layer, and goaf grouting holes are constructed to the coal seam to be mined. The diffusion radius R of the grout in the goaf is determined when the grouting holes are used for grouting. The coal seam to be mined is then mined and the overburden is filled with grout. When the position of the coal seam to be mined is greater than R, grouting is started from the goaf grouting holes into the goaf generated by the mining of the coal seam to be mined.

[0012] d. When there is a coal seam to be mined above the old goaf and another coal seam to be mined below the old goaf, the coal seam to be mined below the old goaf should be mined first according to the method in step c. The combined conductivity D3 after the old goaf and the coal seam to be mined below it should be determined. The height of the water-conducting fracture zone D2 after the coal seam to be mined above the old goaf should be estimated. Compare D3 and D2, and take the higher one. On this basis, an isolation layer of a certain thickness should be added as the grouting layer. Grouting holes should be constructed to the grouting layer. The coal seam to be mined in the old goaf should be back-mined and the overburden grouting should be carried out.

[0013] Preferably, the grouting material is a slurry made by grinding coal gangue into powder and mixing it with water, or a slurry made by mixing fly ash with water, or a slurry made by grinding coal gangue into powder, mixing it with fly ash and water.

[0014] Beneficial Effects: This invention addresses the challenge of grouting and filling the overlying coal seams in old goaf areas. Based on the positional relationship between the coal seam to be mined and the old goaf, and fully considering factors such as water-conducting fracture zones and floor fractures, it categorizes the grouting and filling of the overlying coal seams in old goaf areas into different types, and provides methods for determining the grouting and filling layer position for each type. Furthermore, based on the distance between the grouting layer and the coal seam to be mined, and the location of the old goaf, it provides reinforcement measures to improve the surface subsidence control effect by combining grouting holes in the goaf. This invention enables safe and efficient mining of overlying coal seams in old goaf areas, while ensuring effective surface subsidence control under various working conditions. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the grouting and filling method for isolating the overlying coal seam in an old goaf area, according to the present invention.

[0016] Figure 2 This is a schematic diagram of the grouting and filling method for isolating the overlying coal seam in the old goaf area under the working conditions of this invention;

[0017] Figure 3 This is a schematic diagram of the grouting and filling method for isolating the overlying coal seam in the Sanlao goaf under the working conditions of this invention;

[0018] Figure 4 This is a schematic diagram of the grouting and filling method for isolating the overlying coal seam in the Si Lao goaf area under the working conditions of this invention;

[0019] Figure 5 This is a schematic diagram of the grouting and filling method for isolating the overlying coal seam in the Wulao goaf under the working conditions of this invention;

[0020] Figure 6 This is a schematic diagram of the grouting and filling method for isolating the overlying coal seam in the six-old goaf area of ​​the present invention.

[0021] In the diagram: 1. Mined coal seam; 2. Coal seam to be mined; 3. Grouting layer; 4. Filling body; 5. Ground surface; 6. Grouting hole; 7. Old goaf; 8. Goaf grouting hole. Detailed Implementation

[0022] The following is an illustration of an embodiment of the present invention. Figure 1-6 The technical solution of the present invention will be described in more detail below.

[0023] The overlying coal seam isolation grouting method for old goaf areas is designed for situations where old goaf area 7 was created after the mining of coal seam 1, followed by surface reclamation and construction of buildings and structures. The method involves mining the coal seams above and / or below old goaf area 7 using overlying coal seam isolation grouting to protect the surface buildings and structures. The specific steps include:

[0024] a. Determine the height D1 of the water-conducting fracture zone and the depth S1 of the floor fracture zone generated after the mining of coal seam 1;

[0025] b. Figure 1 As shown, when the coal seam to be mined 2 is located above the old goaf 7, the height of the water-conducting fracture zone D2 after the coal seam to be mined 2 is expected to be D2. Comparing D1 and D2, the higher one is selected, and an isolation layer with a thickness of 30m to 80m is added on this basis as the grouting layer 3. The grouting hole 6 is constructed from the ground 5 to the grouting layer 3. At the same time as the mining of the coal seam to be mined 2, the overburden isolation grouting is carried out. A delamination filling body 4 is formed in the lower part of the grouting layer 3.

[0026] c. When the coal seam to be mined 2 is located below the old goaf 7, predict the height D2 of the water-conducting fracture zone after the coal seam to be mined 2, and determine the relationship between D2 and S1 and D1.

[0027] like Figure 2 As shown, when the distance between D2 and S1 is greater than 30-80m (D2 and S1 are not connected), the grouting layer 3 is set at the lower part of the old goaf 7. An isolation layer with a thickness of 30m-80m is added on the basis of D2 as the grouting layer 3. The grouting hole 6 is constructed from the ground 5 to the grouting layer 3. The mining of the coal seam 2 is carried out at the same time as the overburden isolation grouting and filling. A delamination filling body 4 is formed at the lower part of the grouting layer 3.

[0028] like Figure 3 As shown, when the distance between D2 and S1 is between 0 and 30m (D2 and S1 are not connected), a 30m to 50m thick isolation layer is added on the basis of D1 as grouting layer 3. Grouting holes 6 are constructed from the ground surface 5 to grouting layer 3, and goaf grouting holes 8 are constructed from the ground surface 5 to the old goaf 7. The coal seam 2 to be mined is then mined, and overburden isolation grouting is carried out using grouting holes 6 (forming a delamination filling body 4 in the lower part of grouting layer 3). At the same time, goaf grouting is carried out using grouting holes 8. Grouting of the old goaf 7: Under this working condition, the distance between the grouting layer 3 and the coal seam 2 to be mined is far. The pressure transmitted from the grouting layer to the goaf of the coal seam 2 to be mined is difficult to compact the broken rock mass inside. Grouting of the old goaf 7 using the goaf grouting hole 8 can compress the broken rock mass in the goaf generated after the coal seam to be mined is mined. Due to the existence of the isolation layer, the grout generated by the old goaf grouting will not enter the working face of the coal seam 2 to be mined, and will not affect the safe production during the mining of the coal seam 2.

[0029] like Figure 4 As shown, when D2 and S1 are connected, and D2 is greater than D1, or D2 is less than D1 but their heights are similar, such as when the difference between the two is less than 30m, the higher of D1 and D2 is taken, and an isolation layer with a thickness of 30m to 50m is added on this basis as the grouting layer 3. The grouting hole 6 is constructed from the ground 5 to the grouting layer 3, and the coal seam 2 to be mined is back-mined and the overburden is isolated by grouting and filling. A delamination filling body 4 is formed in the lower part of the grouting layer 3.

[0030] like Figure 5 As shown, when D2 and S1 are connected, and D2 is less than D1 but the height difference between the two is large, such as when the difference is greater than 30m, an isolation layer with a thickness of 30m to 50m is added on the basis of D1 as the grouting layer 3. Grouting holes 6 are constructed from the ground 5 to the grouting layer 3, and goaf grouting holes 8 are constructed from the ground 5 to the coal seam to be mined 2. The diffusion radius R of the grout in the goaf is determined when grouting holes 8 are used. The coal seam to be mined 2 is mined and the overburden isolation grouting is filled. A delamination filling body 4 is formed at the lower part of the grouting layer 3. Grouting is started from the goaf grouting hole 8 into the goaf generated by the mining of the coal seam to be mined 2 when the goaf position is 1.2R behind the mining position of the coal seam to be mined.

[0031] d. such as Figure 6 As shown, when there is a coal seam 2 to be mined above the old goaf 7 and another coal seam 2 to be mined below the old goaf 7, the coal seam 2 to be mined below the old goaf 7 is mined first according to step c. The comprehensive guide height D3 after the old goaf 7 and the coal seam 2 to be mined below it are determined (the final highest water-conducting fracture zone height after the old goaf 7 and the coal seam 2 to be mined below it are determined). The height D2 of the water-conducting fracture zone after the coal seam 2 to be mined above the old goaf 7 is estimated. D3 and D2 are compared, and the higher one is selected. On this basis, an isolation layer with a thickness of 30m to 80m is added as the grouting layer 3. The grouting hole 6 is constructed from the ground 5 to the grouting layer 3. The old goaf coal seam 2 to be mined is then mined and the overburden is isolated by grouting. A delamination filling body 4 is formed below the grouting layer 3.

[0032] The present invention relates to a method for isolating and filling the overlying coal seam in old goaf areas using grouting. The number of grouting holes 6 and 8 in the goaf area is determined based on requirements; the attached drawings are for illustrative purposes only and do not represent specific quantities. The grouting material can be a slurry made by grinding coal gangue into powder and mixing it with water, or a slurry made by mixing fly ash with water, or a slurry made by grinding coal gangue into powder, mixing it with fly ash and water.

[0033] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. Grouting and filling method for isolating overlying and underlying coal seams in old goaf areas. The overlying coal seam refers to the coal seam to be mined located above the old goaf area, and the underlying coal seam refers to the coal seam to be mined located below the old goaf area; among which, The coal seam to be mined is located in the lower part of the old goaf, or in the upper part of the old goaf, or there is one coal seam to be mined in both the upper and lower parts of the old goaf; its characteristic is that it includes the following steps: a. Determine the height D1 of the water-conducting fracture zone and the depth S1 of the floor fracture zone generated after the mining of the coal seam; b. When the coal seam to be mined is located above the old goaf, the height of the water-conducting fracture zone D2 after the coal seam to be mined is estimated. Compare D1 and D2, take the higher one, and add an isolation layer of a certain thickness as the grouting layer on this basis. Construct grouting holes to the grouting layer, and carry out the mining of the coal seam to be mined while carrying out overburden grouting and filling. c. When the coal seam to be mined is located below the old goaf, predict the height D2 of the water-conducting fracture zone after the coal seam is mined, and determine the relationship between D2 and S1 and D1. When the distance between D2 and S1 is greater than the first threshold, an isolation layer of a certain thickness is added on the basis of D2 as the grouting layer. Grouting holes are constructed to the grouting layer, and the coal seam to be mined is mined while the overburden is grouted and filled. When the distance between D2 and S1 is not greater than the first threshold, an isolation layer of a certain thickness is added on the basis of D1 as the grouting layer. Grouting holes are constructed to the grouting layer, and grouting holes in the goaf are constructed to the old goaf. The coal seam to be mined is recycled and the overburden is filled by grouting holes. At the same time, grouting holes in the goaf are used to grout the old goaf. When D2 and S1 are connected, and D2 is greater than D1, or D2 is less than D1 but their heights are similar, take the higher of D1 and D2, and add an isolation layer of a certain thickness as the grouting layer. Construct grouting holes to the grouting layer, carry out the mining of the coal seam to be mined, and carry out overburden grouting and filling. When D2 and S1 are connected, and D2 is less than D1 but their heights differ significantly, an isolation layer of a certain thickness is added on the basis of D1 as the grouting layer. Grouting holes are constructed to the grouting layer, and goaf grouting holes are constructed to the coal seam to be mined. The diffusion radius R of the grout in the goaf is determined when the grouting holes are used for grouting. The coal seam to be mined is then mined and the overburden is filled with grout. When the position of the coal seam to be mined is greater than R, grouting is started from the goaf grouting holes into the goaf generated by the mining of the coal seam to be mined. d. When there is a coal seam to be mined above the old goaf and another coal seam to be mined below the old goaf, the coal seam to be mined below the old goaf should be mined first according to the method in step c. The combined conductivity D3 after the old goaf and the coal seam to be mined below it should be determined. The height of the water-conducting fracture zone D2 after the coal seam to be mined above the old goaf should be estimated. Compare D3 and D2, and take the higher one. On this basis, an isolation layer of a certain thickness should be added as the grouting layer. Grouting holes should be constructed to the grouting layer. The coal seam to be mined in the old goaf should be back-mined and the overburden grouting should be carried out.

2. The overburden isolation grouting and filling method according to claim 1, characterized in that, The grouting material can be a slurry made by grinding coal gangue into powder and mixing it with water, or a slurry made by mixing fly ash with water, or a slurry made by grinding coal gangue into powder, mixing it with fly ash and water.

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