The Engineering Geological Characteristics And Evalution Of Stability Of The Roof Of13-1Coal Seam’s In The Deep Of Panji Mining Area

Roof accidents are major safety accident in China coal mine,threatting efficient and safe production,and research about coal seam roof stability practice is need in the production.This paper studys the roof’s engineering geologic characteristics which bases on rock mechanical property,mechanical properties,lithology combination and distribution,then using fuzzy comprehensive evaluation method to quantitative the roof stability from fractal dimension values, plane deformation coefficient,compressive strength and lithologic combination value.Using FLAC3D numerical simulation to analyze mining effect which compared with shallow mining situation.It is constituted by immediate and main roof.and its lithology is constituted by the region of siltstone-mudstone and mudstone.The RQD and leakage of sandstone is more bigger than siltstone, mudstone’s is the most small, but the RQD is small and leakage is big in the fracture development zone.The compressive strength of the rock has good correlation with logging characteristics,and which can be used for qualitative evaluation. The type of rock mass structure are given priority to the block structure and cataclastic structurethe,the distribution of loose structure is minimum. The more development is the main type of fold development, the mild development is second and the pole development is minimum. The partition of the compressive strength is given priority to with low intensity area, higher strength area rank second, the highest intensity zone is minimum.It is divided into four stability partitions by using the grey fuzzy comprehensive evaluation, which are given priority to unstable roof and medium stable roof,the extremely unstable roof and stable roof are less distribution.And the use of FALC3D numerical simulation technology to simulate characteristics of different roof types of mining effect, the results show:the main roof and immediate roof of maximum principal stress difference is lesser, and stress concentration coefficient is smaller than shallow in deep mining conditions; the roof displacement is bigger than the shallow and the displacement of the old than is less of the direct. It also suggests that:the development height of two belts is not only concerned lithology and mining height, but also associated with the mining depth.It can provide certain scientific basis for build well and coal seam mining based on its roof engineering geological characteristic and stability study.