Overlying strata isolation grouting filling method for overlying underlying coal seam of old goaf

Abstract

The invention belongs to the field of coal mine filling mining, and particularly relates to an overlying strata isolation grouting filling method for an overlying underlying coal seam of an old goaf. In order to solve the problem of overlying strata isolation grouting filling of the overlying and underlying coal seam of the old goaf, the overlying strata isolation grouting filling of the overlying and underlying coal seam of the old goaf is divided into different types according to the position relation between a coal seam to be mined and the old goaf by fully considering factors of a water flowing fissure zone and a floor fissure; and a method for determining the grouting filling layer position of the coal seam to be mined is provided. And meanwhile, according to the distance between the grouting layer and the coal seam to be mined and the position of the old goaf, a reinforcing measure for improving the ground subsidence control effect by combining goaf grouting holes is provided. According to the method, safe and efficient coal mining of the overlying and underlying coal seam of the old goaf can be achieved, and the surface subsidence control effect under various working conditions is guaranteed.

Description

Technical Field

[0001] The invention belongs to the field of coal mine filling mining, and specifically relates to a method for isolating and grouting filling of overlying and underlying coal seams in old goaf areas. Background Art

[0002] Mining coal under buildings (structures) has always been a major problem that has troubled coal enterprises. This is particularly prominent in the eastern and central regions where the economy is developed, the population is dense, and the cost of relocation is high. Solving the problem of mining coal under buildings (structures) can promote the coordinated development of industry and agriculture in mining areas. In recent years, filling mining technology has been rapidly developed and applied in the mining of coal under buildings (structures) in my country. Commonly used technologies include filling of goafs (such as solid dense filling, paste filling, high water filling) and overburden isolation grouting filling coal mining technology. Patent ZL201210164929.9 discloses a method for mining overburden with grouting and filling isolation in zoning. The method divides the mining area into several coal mining faces, and leaves isolation coal pillars of a certain width between the coal mining faces. Several groups of grouting holes perpendicular to the coal seam are constructed from the surface above the coal mining faces. During the mining process of the working face, fly ash slurry is injected into the stratum above the coal mining face through the grouting holes, thereby effectively controlling surface subsidence and realizing coal mining without relocating villages.

[0003] However, in practice, some compressed coal is compressed coal under old goafs, that is, there are two coal seams in the stratum and one of the coal seams has been mined by the full collapse method in the early stage. After mining, the ground was reclaimed and buildings (structures) were built. When the other coal layer is mined, it is necessary to adopt the filling coal mining method to protect the ground buildings (structures). For this type of situation, it is impossible to directly perform overburden isolation grouting filling according to the technology disclosed in patent ZL201210164929.9. The drilling construction position, grouting layer, grouting filling amount, etc. need to consider the influence of the old goaf. Therefore, it is necessary to study the overburden isolation grouting filling method under the old goaf, so as to accurately determine the grouting drilling arrangement plan and the grouting filling plan, so as to improve the surface subsidence control effect, realize the overburden isolation grouting filling under the old goaf without relocating the village for coal mining, and expand the application scope of overburden isolation grouting filling technology. Summary of the invention

[0004] In view of the deficiencies in the above-mentioned prior art, the present invention proposes a method for isolating and grouting the overburden and underlying coal seams in an old goaf, wherein the overburden coal seam refers to a coal seam to be mined located in the upper part of the old goaf, and the underlying coal seam refers to a coal seam to be mined located in the lower part of the old goaf; the coal seam to be mined is located in the lower part of the old goaf, or is located in the upper part of the old goaf, or there is a coal seam to be mined in the upper part and the lower part of the old goaf, and the method specifically comprises the following steps:

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

[0006] b. When the coal seam to be mined is located above the old goaf, the height D2 of the water-conducting fracture zone after the coal seam to be mined is estimated, D1 and D2 are compared, the higher one is selected, and a certain thickness of isolation layer is added on this basis as the grouting layer, grouting holes are constructed to the grouting layer, and the coal seam to be mined is mined and the overburden grouting is performed at the same time;

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

[0008] When the distance between D2 and S1 is greater than the first threshold, a certain thickness of isolation layer is added on the basis of D2 as a grouting layer, grouting holes are constructed to the grouting layer, and the coal seam to be mined is mined and the overburden grouting is performed at the same time;

[0009] When the distance between D2 and S1 is not greater than the first threshold, a certain thickness of isolation layer is added on the basis of D1 as a grouting layer, grouting holes are constructed to the grouting layer, grouting holes in the goaf are constructed to the old goaf, the coal seam to be mined is mined, and the grouting holes are used for grouting filling of the overburden, and the grouting holes in the goaf are used for grouting in the old goaf;

[0010] When D2 and S1 are connected, and D2 is greater than D1, or D2 is less than D1 but the heights of the two are similar, the higher one of D1 and D2 is taken, and a certain thickness of isolation layer is added on this basis as the grouting layer, and the grouting hole is constructed to the grouting layer, and the coal seam to be mined is mined and the overburden grouting is performed;

[0011] When D2 and S1 are connected, and D2 is smaller than D1 but the height difference between the two is large, a certain thickness of isolation layer is added on the basis of D1 as the grouting layer, and grouting holes are constructed to the grouting layer, and grouting holes in the goaf area are constructed to the coal seam to be mined, and the diffusion radius R of the slurry in the goaf area during grouting in the goaf area grouting holes is determined, and the coal seam to be mined is mined and the overburden grouting is filled. When the mining position of the coal seam to be mined is greater than R, grouting is started from the grouting holes in the goaf area to the goaf area 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, first mine the coal seam to be mined below the old goaf according to the method in step c, determine the comprehensive conductivity D3 of the old goaf and the coal seam to be mined below it after mining, estimate the height D2 of the water-conducting fracture zone after mining the coal seam to be mined above the old goaf, compare D3 with D2, take the higher one, and on this basis add an isolation layer of a certain thickness as the grouting layer, construct grouting holes to the grouting layer, recover the coal seam to be mined in the old goaf and perform grouting filling of the overburden.

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

[0014] Beneficial effects: The present invention aims at the problem of grouting and isolation of overlying and underlying coal seams in old goafs. According to the positional relationship between the coal seam to be mined and the old goaf, the factors of water-conducting fracture zones and floor fractures are fully considered, and the grouting and isolation of overlying and underlying coal seams in old goafs are divided into different types, and methods for determining the grouting and filling layers of the coal seams to be mined are respectively given. At the same time, according to the distance between the grouting layer and the coal seam to be mined and the position of the old goaf, reinforcement measures are given to improve the control effect of ground subsidence in combination with the grouting holes in the goaf. The present invention can realize safe and efficient coal mining of overlying and underlying coal seams in old goafs, and ensure the control effect of surface subsidence under various working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overburden grouting filling method for overburden and underlying coal seams in an old goaf in the working condition of the present invention;

[0016] Figure 2 It is a schematic diagram of the overburden grouting filling method for overlying and underlying coal seams in the two old goafs of the present invention;

[0017] Figure 3 It is a schematic diagram of the overburden grouting filling method for isolating the overburden and underlying coal seams in the Sanlao goaf in the working condition of the present invention;

[0018] Figure 4 It is a schematic diagram of the overburden grouting filling method for overlying and underlying coal seams in the four old goafs of the present invention;

[0019] Figure 5 It is a schematic diagram of the overburden grouting filling method for overlying and underlying coal seams in Wulao goaf in the working condition of the present invention;

[0020] Figure 6 It is a schematic diagram of the overburden grouting filling method for isolating the overburden and underlying coal seams in the Liulao goaf in the working condition of the present invention;

[0021] In the figure: mined coal seam 1, coal seam to be mined 2, grouting layer 3, filling body 4, ground 5, grouting hole 6, old goaf 7, goaf grouting hole 8. DETAILED DESCRIPTION

[0022] In combination with the attached embodiment of the present invention, Figure 1-6 , the technical solution of the present invention is described in more detail.

[0023] The overburden rock isolation grouting filling method for the overlying and underlying coal seams in the old goaf is aimed at the working condition that the old goaf 7 is generated after the mining of the mined coal seam 1, and then the ground is reclaimed and buildings (structures) are built. Now the coal seams above and / or below the old goaf 7 are mined by the overburden rock isolation grouting filling method to protect the ground buildings (structures); specifically, the following steps are included:

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

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

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

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

[0028] like Figure 3 As shown in the figure, when the distance between D2 and S1 is between 0 and 30 m (D2 and S1 are not connected), an isolation layer with a thickness of 30 m to 50 m is added on the basis of D1 as the grouting layer 3, a grouting hole 6 is constructed from the ground 5 to the grouting layer 3, and a goaf grouting hole 8 is constructed from the ground 5 to the old goaf 7, the coal seam 2 to be mined is mined and the overburden isolation grouting filling is performed using the grouting hole 6 (a separation filling body 4 is formed at the bottom of the grouting layer 3), and the goaf grouting hole 8 is used for Grouting in the old goaf 7; under this working condition, the grouting layer 3 is far away from the coal seam 2 to be mined, and the pressure transmitted from the separation grouting pressure to the goaf of the coal seam 2 to be mined is difficult to compact the broken rock mass therein. Grouting in the old goaf 7 using the goaf grouting holes 8 can compress the broken rock mass in the goaf produced after the mining of the coal seam to be mined. Due to the existence of the isolation layer, the slurry produced by grouting in the old goaf 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 to be mined.

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

[0030] like Figure 5 As shown, when D2 is connected with S1, and D2 is smaller than D1 but the height difference between the two is large, such as the difference between the two 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, a grouting hole 6 is constructed from the ground 5 to the grouting layer 3, a goaf grouting hole 8 is constructed from the ground 5 to the coal seam 2 to be mined, the diffusion radius R of the slurry in the goaf during grouting of the goaf grouting hole 8 is determined, the coal seam 2 to be mined is mined and the overburden isolation grouting filling is performed, a separation filling body 4 is formed at the lower part of the grouting layer 3, and grouting is started from the goaf grouting hole 8 to the goaf generated by mining the coal seam 2 to be mined when the mining position of the coal seam 2 to be mined is delayed by 1.2R;

[0031] d. Figure 6 As shown, when there is a coal seam 2 to be mined on the upper part of the old goaf 7 and there is another coal seam 2 to be mined under the old goaf 7, the coal seam 2 to be mined in the lower part of the old goaf is first mined according to the method of step c, and the comprehensive conductivity D3 of the old goaf 7 and the coal seam 2 to be mined below it after mining (the final highest water-conducting fracture zone height position after mining the old goaf 7 and the coal seam 2 to be mined below it) is determined, and the water-conducting fracture zone height D2 of the coal seam 2 to be mined on the upper part of the old goaf 7 after mining is estimated, and D3 is compared with D2 to take the higher one, and on this basis, an isolation layer with a thickness of 30m to 80m is added as a grouting layer 3, and grouting holes 6 are constructed from the ground 5 to the grouting layer 3, and the coal seam 2 to be mined in the old goaf is mined and the overburden isolation grouting filling is carried out to form a delamination filling body 4 at the lower part of the grouting layer 3.

[0032] In the overburden and underlying coal seam grouting filling method for old goaf of the present invention, the number of grouting holes 6 and goaf grouting holes 8 is determined based on needs, and the attached drawings are only for illustration and do not represent the specific number. The grouting material is selected from a slurry of coal gangue ground into powder and mixed with water, or a slurry of fly ash and water, or a slurry of coal gangue ground into powder, fly ash and water.

[0033] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. The overburden grouting filling method for the overburden and underlying coal seams in the old goaf, the overburden coal seam refers to the coal seam to be mined located in the upper part of the old goaf, and the underlying coal seam refers to the coal seam to be mined located in the lower part of the old goaf; The coal seam to be mined is located at the lower part of the old goaf, or at the upper part of the old goaf, or there is one coal seam to be mined at the upper part and the lower part of the old goaf respectively; it is characterized by comprising the following steps: a. Determine the height D1 of the water-conducting fracture zone and the depth S1 of the floor fracture generated after the mining of the mined coal seam; b. When the coal seam to be mined is located above the old goaf, the height D2 of the water-conducting fracture zone after the coal seam to be mined is estimated, D1 and D2 are compared, the higher one is selected, and a certain thickness of isolation layer is added on this basis as the grouting layer, grouting holes are constructed to the grouting layer, and the coal seam to be mined is mined and the overburden grouting is performed at the same time; c. When the coal seam to be mined is located below the old goaf, the height D2 of the water-conducting fracture zone after the coal seam to be mined is estimated, and the relationship between D2 and S1 and D1 is determined; When the distance between D2 and S1 is greater than the first threshold, a certain thickness of isolation layer is added on the basis of D2 as a grouting layer, grouting holes are constructed to the grouting layer, and the coal seam to be mined is mined and the overburden grouting is performed at the same time; When the distance between D2 and S1 is not greater than the first threshold, a certain thickness of isolation layer is added on the basis of D1 as a grouting layer, grouting holes are constructed to the grouting layer, grouting holes in the goaf are constructed to the old goaf, the coal seam to be mined is mined, and the grouting holes are used for grouting filling of the overburden, and the grouting holes in the goaf are used for grouting in the old goaf; When D2 and S1 are connected, and D2 is greater than D1, or D2 is less than D1 but the heights of the two are similar, the higher one of D1 and D2 is taken, and a certain thickness of isolation layer is added on this basis as the grouting layer, and the grouting hole is constructed to the grouting layer, and the coal seam to be mined is mined and the overburden grouting is performed; When D2 and S1 are connected, and D2 is smaller than D1 but the height difference between the two is large, a certain thickness of isolation layer is added on the basis of D1 as the grouting layer, and grouting holes are constructed to the grouting layer, and grouting holes in the goaf area are constructed to the coal seam to be mined, and the diffusion radius R of the slurry in the goaf area during grouting in the goaf area grouting holes is determined, and the coal seam to be mined is mined and the overburden grouting is filled. When the mining position of the coal seam to be mined is greater than R, grouting is started from the grouting holes in the goaf area to the goaf area 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, first mine the coal seam to be mined below the old goaf according to the method in step c, determine the comprehensive conductivity D3 of the old goaf and the coal seam to be mined below it after mining, estimate the height D2 of the water-conducting fracture zone above the coal seam to be mined in the old goaf after mining, compare D3 with D2, take the higher one, and on this basis add an isolation layer of a certain thickness as the grouting layer, construct grouting holes to the grouting layer, recover the coal seam to be mined in the old goaf and perform grouting filling of the overburden.

2. The overburden isolation grouting filling method according to claim 1 is characterized in that: The grouting material is selected to be a slurry obtained by mixing coal gangue into powder and water, or a slurry obtained by mixing fly ash and water, or a slurry obtained by mixing coal gangue into powder and adding fly ash and water.

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