CN106593445A - Old goaf underlying close distance coal seam strata-overlying isolation grouting filling exploitation method - Google Patents

Abstract

The method discloses an old goaf underlying close distance coal seam strata-overlying isolation grouting filling exploitation method. The method comprises 1) dividing an underlying coal seam mining area into a plurality of coal mining work faces and arranging isolated coal pillars between the work faces, 2) orderly and vertically processing a number of groups of grouting drill holes above the coal mining work faces along a direction from the earth surface to the coal seam, 3) carrying out first stage grouting before recovery of the coal mining work faces, and 4) carrying out recovery on the coal mining work faces until a position with a distance 10 to 30m from the grouting drill holes, and carrying out second stage grouting. The method eliminates the residual cracks caused by upper coal seam mining and improves the drilling and grouting capacity and surface subsidence control effects.

Description

A mining method for isolated grouting and backfilling of the underlying coal seam overlying rock in the old mined-out area

technical field

The invention relates to the fields of controlling coal mining subsidence and "three-down" coal pressing mining, in particular to a mining method for isolated grouting and filling mining of close-distance coal seam overburden in an old mined-out area.

Background technique

Coal mining under construction (structure) has always been a major problem that plagues coal enterprises in my country. This is especially prominent in the eastern and central parts of China where the economy is developed, the population is dense, and the cost of expropriation is high. Coal mining 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 coal mining under buildings (structures) in my country. Commonly used are goaf filling (such as solid compact filling, paste filling, high water filling), overlying rock filling, etc. Isolated grouting and filling coal mining technology. Patent ZL201210164929.9 discloses a coal mining method of isolated grouting and backfilling in mining overlying rock. This method divides the mining area into several coal mining faces, and leaves a certain width of isolated coal between the coal mining faces. Construct several groups of grouting boreholes perpendicular to the coal seam from the surface above the coal mining face, and inject fly ash slurry into the separation layer above the coal mining face through the grouting boreholes during the mining process of the working face, thereby Effectively control surface subsidence and realize coal mining without moving villages. However, in practice, a large amount of pressed coal is buried in the old goaf at a short distance. Reclamation and construction of buildings (structures) structures, just need to use filling coal mining method to protect ground buildings (structures) structures when mining the lower layer of coal. For such cases, according to the technology disclosed in patent ZL201210164929.9, the drilling depth may enter the comprehensive water-conducting fracture zone, so that the injected slurry directly enters the lower coal seam mining face, which not only affects mine production safety Also can't realize the purpose of protecting the ground building (structure). In addition, after the mining of the upper coal seam, there will be residual separation layers in the overlying rock (especially above the goaf boundary), and there will also be a large number of residual cracks in the old goaf, which will be rapidly transmitted when the working face of the lower coal seam is mined. To the surface, due to the failure of timely grouting, the building cannot meet the protection requirements, and even damage. Therefore, it is necessary to form a mining method of isolation and grouting filling in the close-distance coal seam under the old goaf, so as to accurately determine the grouting drilling layout plan and the grouting filling plan, thereby improving the effect of surface subsidence control and realizing coal mining without moving villages .

Contents of the invention

The technical problem to be solved by the present invention is to provide a mining method for isolated grouting and backfilling of the overlying coal seam in the old mined-out area, so as to solve the above-mentioned multiple defects caused by the prior art.

In order to achieve the above object, the present invention provides the following technical solutions: a mining method for isolated grouting filling of overlying coal seams in an old mined-out area, which is characterized in that it comprises the following steps:

1) The lower coal seam mining area is divided into several coal mining faces, and isolated coal pillars are set between the working faces;

2) Several groups of grouting drilling holes are vertically constructed in the direction of the coal seam on the surface above several coal mining faces in sequence;

3) The first stage of grouting is carried out before the mining of the coal mining face;

4) The coal mining face is recovered. When the coal mining face is recovered to 10-30m away from the grouting borehole, the second stage of grouting filling is carried out.

Preferably, in the step 2), the grouting hole includes a main grouting hole and an auxiliary grouting hole.

Preferably, the auxiliary grouting borehole is arranged above the goaf of the upper coal seam and the distance from the goaf of the upper coal seam is 20-40m.

Preferably, the depth of the main grouting borehole and the auxiliary grouting borehole is controlled above the water-resisting layer above the top boundary of the comprehensive water-guiding fracture zone.

The beneficial effects of adopting the above technical scheme are: for the method of isolated grouting filling of the overburden coal seam under the old mined-out area in the present invention, enough space is left between the grouting drilling end hole and the comprehensive water-conducting fissure zone. The thickness of the water-resisting layer prevents the injected slurry from entering the mining face of the lower coal seam, ensuring safe underground production. The auxiliary grouting drilling is located in the development area of the residual separation layer after the mining of the upper coal layer, and the pre-grouting amount of the residual separation layer is increased. The pre-grouting method (the first-stage grouting) before the lower coal seam is recovered can fill the remaining abscission layer in the overlying strata of the upper mined coal seam, and at the same time compact the cracks in the old goaf of the upper mined coal seam, which is The lower seam coal grouting backfill lays the foundation.

The first stage of grouting, i.e. pre-mining pre-grouting, aims to fill the residual detachment layer in the overlying rock above the old goaf and compact the cracks in the old goaf; When the working face is recovered to 10-30m away from the grouting borehole, the second stage of grouting filling is carried out, that is, the new separation space generated by the mining of the lower coal seam working face is filled.

Compared with the prior art coal mining method of mining overlying strata with separate grouting and filling, the residual cracks caused by upper coal seam mining are eliminated, and the drilling grouting ability and surface subsidence control effect are improved.

Description of drawings

Fig. 1 is a plan view of grouting drilling arrangement of the present invention

Fig. 2 is a sectional view of grouting drilling arrangement during the first stage grouting filling in the present invention

Fig. 3 is a sectional view of grouting drilling arrangement during the second stage of grouting filling in the present invention

In the figure: 1-working face; 2-isolated coal pillar; 3-goaf boundary; 4-main grouting drilling; 5-auxiliary grouting drilling; 6-surface; 7-rock formation; Detachment layer; 9-water-resisting layer; 10-top boundary of comprehensive water-conducting fracture zone; 11-upper seam coal; 12-old goaf; 13-lower coal seam; 14-lower coal seam detachment layer.

detailed description

Preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

An embodiment of the present invention is further described below in conjunction with accompanying drawing:

(1) Divide the mining area of the lower coal seam into several working faces 1, and leave isolated coal pillars 2 between the working faces, and construct several groups of injectors in the direction of the coal seam 13 on the ground surface 6 above several coal mining working faces 1 in sequence. Grouting holes, each group of drilling holes contains a main grouting hole 4 and an auxiliary grouting hole 5. The position of the auxiliary grouting borehole 5 of each group is adjusted according to the goaf boundary 3 of the upper coal seam (main grouting borehole 4 position is constant), and the auxiliary grouting borehole 5 is arranged in the goaf 12 of the upper coal seam and The distance from the goaf boundary 3 of the upper coal seam is 20-40m.

(2) Calculating the height of the comprehensive water-conducting fissure zone after two layers of coal mining, the grouting drilling passes through the rock formation 7, and the depth of the final hole of the grouting drilling is selected above the water-resisting layer 9 above the top boundary 10 of the comprehensive water-conducting fracture zone .

(3) The first stage of grouting is carried out before mining in the working face 1 of the lower coal seam, that is, the pre-mining grouting. The old mined-out area is located in the upper coal seam 11, and the purpose is to fill the residual separation layer 8 in the overlying rock above the old mined-out area 12 Fissures in the old goaf 12 are compacted.

(4) The working face 1 of the lower coal seam is mined according to the conventional method. When the working face 1 of the lower coal seam is recovered to 10-30m away from the grouting borehole, the second stage of grouting filling is carried out, that is, the production of the mining face 1 of the lower coal seam 13 is filled. The new separated layer 14 space.

(5) Cycle like this until the isolation, grouting and backfilling of the entire mining area is completed.

In conjunction with the embodiment of a certain mine II2 mining area, make a specific description:

(1) Divide the working face of the lower coal seam and leave isolated coal pillars. According to the geological information of the II2 mining area, it is determined that the working face width of the 9# coal in the lower coal seam is 150m, and the first mining face is the II923 working face.

(2) grouting drilling arrangement. Two sets of grouting boreholes were constructed directly above the II923 working face before recovery. Each set of grouting boreholes consisted of a main grouting borehole and an auxiliary grouting borehole. The auxiliary grouting boreholes were located at the 7# It is directly above the old goaf of the coal seam and 20m away from the boundary of the old goaf of the 7# coal seam. The height of the comprehensive water-conducting fissure zone after the 7# and 9# two-layer coal mining is located 45m above the 7# coal seam, that is, 85m above the 9# coal seam (the 7# coal seam is located 40m above the 9# coal seam). A 20m-thick water-resisting layer is left above, and the final depth of the final grouting drilling is located 105m above the 9# coal seam.

(3) Implement the first stage of grouting filling. Before the recovery of the II923 working face, grouting is used to fill the remaining 7# coal separation layer cracks in the overlying rock through grouting drilling, and at the same time compact the cracks in the 7# coal old goaf, and stop grouting when the grouting pressure is greater than 3MPa filling.

(4) Implement the second stage of grouting filling. The II923 working face was mined using comprehensive mechanized coal mining technology. When the working face was mined to 20m away from the grouting borehole, the grouting borehole was used to fill the new separation layer space generated by the mining of 9# coal.

(5) Repeat steps (1), (2), (3), and (4), and continue to take over the operation of the working face in turn.

For the mining method of isolated grouting filling of the overlying coal seam in the old mined-out area, a sufficient thickness of the water-resisting layer is left between the grouting drilling end hole and the comprehensive water-conducting fissure zone, and the injected slurry It will not enter the working face of the lower coal seam to ensure safe production underground. After the auxiliary grouting drilling position is adjusted, it can be located in the development area of the residual separation layer after the upper coal mining, and the pre-grouting amount of the residual separation layer can be increased. The pre-grouting scheme (the first-stage grouting) before the lower coal seam is recovered can fill the remaining detached layer in the overlying rock of the upper mined coal seam, and at the same time produce a compaction effect on the cracks in the old goaf of the upper mined coal seam. Coal grouting backfill lays the foundation.

The first stage of grouting, i.e. pre-mining pre-grouting, aims to fill the residual detachment layer in the overlying rock above the old goaf and compact the cracks in the old goaf; When the working face is recovered to 10-30m away from the grouting borehole, the second stage of grouting filling is carried out, that is, the new separation space generated by the mining of the lower coal seam working face is filled.

Compared with the prior art mining overlying strata isolation grouting filling coal mining method, the remaining cracks caused by upper coal seam mining are eliminated, and the drilling grouting ability and surface subsidence control effect are improved.

The above is only the preferred embodiment of the present invention, it should be pointed out that for those skilled in the art, without departing from the inventive concept of the present invention, some modifications and improvements can also be made, and these all belong to the present invention. protection scope of the invention.

Claims (4)

1. a kind of old goaf underlie contiguous seams overlying strata isolation grouting filling recovery method, it is characterised in that including following Step：

1) coal seam exploiting field is divided into several coal-faces under, and is provided with to stay between working face and sets isolated coal pillar；

2) earth's surface successively above several coal-faces is to some groups of inlet wells of coal seam direction vertical construction；

3) first stage slip casting was carried out before coal-face back production；

4) coal-face carries out back production, when back production is to away from 10～30m of inlet well, carries out second stage grouting filling.

2. old goaf according to claim 1 is underlied contiguous seams overlying strata isolation grouting filling recovery method, and it is special Levy and be, the step 2) in, inlet well includes a main inlet well and an auxiliary inlet well.

3. old goaf according to claim 2 is underlied contiguous seams overlying strata isolation grouting filling recovery method, and it is special Levy and be, the auxiliary inlet well be arranged in coal seam goaf top and with the distance on upper coal seam goaf border be 20～ 40m。

4. old goaf according to claim 1 is underlied contiguous seams overlying strata isolation grouting filling recovery method, and it is special Levy and be, the main inlet well and water barrier of the auxiliary inlet well severity control above the circle of comprehensive water flowing fractured zone top with On.