Sedimentary environment and stability evaluation of seam roof of No.2 seam in LYL Coal mine of Yonglong coal field

In order to make reasonable evaluation on the stability of coal seam roof, thus for mine design, equipment selection, the roof maintenance management to provide scientific basis and to ensure the safety of mine high-efficient exploitation, research from the coal seam roof depositional environment through the roof strata classification and correlation, core fine description, samples of rock mechanics analysis of the sampling and testing system combining with the geophysical well logging technology (including hydrological logging), pumping test technology, mine production data analysis technology, and so on. The coal seam roof depositional environment and the relationship between engineering geological and hydrogeological are studied. The main research area extracting seam roof belongs to the meandering river sedimentary environments, the main development sedimentary microfacies in the flood plain, the growth of sporadic crevasse splay sedimentary microfacies, point bar sedimentary microfacies, flood plain sedimentary formation of roof rock stability belongs to the poor. The point bar, crevasse splay sedimentary formation of roof rock stability belongs to the medium, the aquifer of roof mainly formed in the crevasse splay, point bar sedimentary environment, mainly for the lenticular, small range to thick bedded sandstone, J₂z aquifer formed in multiphase vertical superimposed channel sand body formed by the thick layer of sand body. Sedimentary environment not only affects the engineering geological characteristics but also impacts coal seam roof aquifer distribution, water content, the height of water flowing fracture belt and so on hydrogeological characteristics.