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

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

technical field [0001] 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 [0002] 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 co...

AI Technical Summary

Problems solved by technology

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 It is also impossible to realize the purpose of protecting ground buildings (structures)

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

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