Research On Ground Movement Laws Of Full-mechanized Caving Mining Under Thick Collapsible Loess

It is the underground mining of coal resources that makes the balance between environment and buildings (structures) in mining area destroyed. Thus it is of important significance to achieve accurate prediction and control of surface subsidence, mine coal under "three body" safely and reduce the mining-induced damages by studying the law of the strata and surface movement caused by mined.The surface of Zhaijiazhai coal mine is covered by thick collapsible loess. In this paper, with the first work face Zhaojiazhai as the research object, measured the surface subsidence caused by full-mechanized caving mining under thick collapsible loess through establishing observation station of surface movement. According to the observatory data, analyzed the dynamic surface movement characteristics and related parameters cased by mining under thick collapsible loess, researched the characteristics of surface cracks, put forward conception of advancing crack angle and crack distance and crack group, and gave the corresponding size of the value; calculated and analyzed prediction parameters of the probability integration method with combining the theoretical analysis of feature points and least squares curve fitting. And at the same time, the relationship of characteristics of the surface cracks and the periodic weighting of the main roof in working face of full-mechanized caving mining under thick collapsible loess was analyzed. The results show that the surface movement tempestuous, surface subsidence rate large, subsidence factor large, the level of movement factor large, the surface damagement severe, starting distance small and so on, are the traits of the mining under the thick collapsible loess, and also prove that the surface step crack's development is concerned with the periodic fracture on roof by mining under thick collapsible loess.On the basis of the field observation and reseach, this paper, taking the geological and mining conditions of Zhaojiazhai coal mine as the prototype, established a numerical simulation models by using numerical simulation software UDEC, studied on mining height, mining depth for the influent laws of surface movement and deformation caused by mined under thick collapsible loess, and analyzed the sameness and differences of laws of strata and ground movement between thick collapsible loess mining and non-collapsible loess mining. The results of this paper can provide some theoretical value and significance for Zhaojiazhai mining area and similar mining area to predict and control surface subsidence and mined under the"three body"and estabilish the size of pillar.