Study On Control Of Large Sudden Surface Collapse By Grouting Backfill Into Isolated Areas Under The Giant Thick Igneous Rock

The huge thick rock strata are distributed in many mining areas in our country. Because of the different characteristics of the surface subsidence caused by the coal mining under the huge thick rock strata, in recent years, the problem of surface subsidence caused by the special geological condition has attracted the attention of researchers. II102 mining area of Hai Zi coal mine is a typical area, The characteristics of Hai Zi coal mine surface subsidence have the specific performance: The surface subsidence after two mining face in the West Wing of II102 is far less than the surface area of the same sinking experience. Studies have shown that Hai Zi the special characteristics of subsidence in coal mine are mainly due to the thick fire seam over the coal is without breaking, alleviating the surface subsidence. However, with the increase of the size of coal mining, the vertical load of giant thick igneous rock will increase gradually. Once the vertical load is over its ultimate bearing, the igneous rock may break rapidly, which will cause the mining area surface sinking fast. It will bring fatal disaster to the area and building surface environment.In view of this, this paper uses the surface subsidence problems of long-wall mining under giant thick igneous rock in II102 mining area of Hai Zi coal mine as the background. With comprehensive utilization of the research method of theoretical analysis and numerical simulation, combining with the engineering detection, I research the large surface area collapse of long-wall mining under the giant thick igneous rock and the means of controlling the problem by grouting. The main research results of this paper are as follows:(1) Based on the theory of elastic mechanics, the load bearing characteristics, the limit breaking distance and the breaking position of the giant thick igneous rock under vertical load are analyzed.(2) Simulate the surface subsidence after mining in II102 mining area without protective measures by using UDEC. Numerical simulations show that:Under the conditions of II1022 and II1024 without any filling, the risk of large sudden surface collapse will happen after mining of II1026.(3) We study the surface subsidence after mining in II1026 area under the condition of grouting in II1022、II1024、II1026., The numerical simulation shows that the separation grouting can effectively control the stability of the giant thick igneous rock and reduce the surface subsidence.