Study On Overburden Failure Characteristics And Mechanisms Due To High-intensity Mining

China's western region is rich in coal resources,and many coalfields have stable and thin overburden strata,thick coal seam,shallow depth;easy mining large scale,high efficiency,high-intensity mining,etc.;It is very necessary to study the characteristics and mechanism of overburden strata failure due to high-intensity mining because of special natural environment,such as sparse vegetation,serious desertification,and fragile ecological environment.Based on the geological conditions,technical characteristics,and negative externalities due to high-intensity mining,the key issues of dissertation as follows:(1)The definition and index system of high-intensity mining were put forward that contain geological features,technical indexes and negative externalities based on the concept of coordinated development of resources and environment and green mining.(2)Based on a large number survey data of “two-zone” height that come form high-intensity mining panel.The computational formula of “two-zone” height and the relationship between mining thickness and overburden strata failure height and the influence of lithology on the failure height of “Two-Zone” height were given also.(3)The overburden strata failure characteristics due to high-intensity mining were researched and the overburden failure models were put forwarded by way of analyzing the magnetotelluric sounding data during the mining of typical high-intensity mining panel in Shendong mining area.(4)The characteristics of stress evolution and overburden failure were researched by way of similar simulation and numerical simulation.The simulation results show that the caving step was basically synchronous in “Two-Zone”,water flowing fracture zone get to the surface,at the same location,the horizontal movement decreases with the increase of buried depth,and the horizontal movement curve fluctuate like ‘steps'.The stress of high-intensity mining show discontinuous distribution,and have a rapid accumulation and release rate.(5)The joint model that consists of ‘thin elastic plate' and ‘stress parallel arch' were put forwarded,and the overburden strata failure formula,forming conditions and calculation formulas of overburden separation,evolutionary features and morphological parameters of stress arch were given based on plate theory also.These research results providing a kind of effective method for judging overburden strata failure by way of rock mass physical parameters due to high-intensity mining.