Study On Movement And Deformation Law Of Rock And Soil Mass Mined Under Thick Loose Layer With High Groundwater Table

As the most important basic energy in China,coal resources have always accounted for more than half of China’s total energy consumption.The occurrence state of coal resources in China has certain regional characteristics.Among them,the eastern mining areas generally have deep coal seam burial,thick loose layer and high underground phreatic water level.The surface movement and deformation has the characteristics of large subsidence coefficient,wide movement range and long movement time.In addition,there are certain particularity in the destruction of rock and soil mass,which is easy to form a large-scale coal mining ponding subsidence area,It poses a threat to the surface ecological environment and people’s production and life in the mining area.This paper taken the Juye mining area as the research object.Based on the surface moving deformation measured data,the dynamic deformation characteristics of rock and soil movement and the variation law of surface movement parameters under mining thick loose layer with high groundwater table were studied,using FLAC^3Dnumerical simulation technology,the dynamic law of seepage of thick water bearing loose layer with high phreatic level were analyzed,the influence laws of different geological and mining conditions on the movement and deformation of rock and soil mass are revealed.Through the study:（1）The analysis of measured data of surface movement in a mining area of Juye mining area shows that the dynamic deformation of Juye mining area mining surface under thick loose layer with high groundwater table mainly presents the characteristics of short initial period,short starting distance,large surface movement and deformation in active period and long settling time;The surface movement parameters have the characteristics of large subsidence coefficient,small boundary angle and advance influence angle and large movement angle.（2）The effects of geological mining conditions such as coal seam inclination,mining depth,mining thickness and face width depth ratio on surface movement parameters are revealed.The parameters of probability integral method are mainly affected by the dip angle of coal seamα;The surface movement angle parameter is mainly affected by the coal seam dip angleα、Influence of mining depth H,mining thickness M and working face width depth ratio D/H.（3）Based on FLAC^3Dnumerical simulation,the influence of hydrophobic consolidation settlement of water bearing loose layer on rock and soil movement and deformation is studied.The seepage consolidation settlement in the loose rock and soil mass further increases the surface deformation and influence range,accounting for about 8.5%of the total surface subsidence,mainly in the upper aquifer and the bottom aquifer in the loose layer;According to the changes of excavation deformation settlement increment and seepage consolidation settlement increment,the surface deformation can be divided into three stages:synchronous growth period,dynamic change period and synchronous slowdown period.（4）The numerical calculation model of the position of the aquifer in the loose layer and the thickness ratio of the bedrock in the loose layer is established,and the influencing factors of the movement and deformation of the rock and soil mass mined under the thick loose layer with high groundwater table are analyzed.With the upward movement of the position of the aquifer in the loose layer,the surface subsidence coefficient increases linearly,and the seepage consolidation settlement also gradually transfers to the upper part of the loose layer;With the increase of the thickness ratio of loose bed rock,the surface subsidence coefficient increases first and then decreases.The study on the movement and deformation law of rock and soil mass mined under thick loose layer with high groundwater table will further improve the law of overburden damage and mining subsidence,and provide theoretical basis and technical reference for coal mine safety production,surface subsidence control and ecological environment protection.