Study Of Surrounding Rock Movement Of Steep Seam Under Pore-water Pressure

China is one of the countries which have the world's most abundant coal resources. With the strength of the coal mining increased,steep seam mining are attracting increasing attention. The study of surrounding rock movement and deformation of the steep seam mining is a major issue of the Western coal mining,Especially for the steep seams which are under the rivers,karst water,old kiln water and impacted by the surface water infiltration in the rainy season. Mine safety production has serious hidden danger. This paper studies YunNan guishan steep seam,on the basis of participation tutor's subject of research on complex coal mining, and tentatively study the movement of surrounding rock of the steep seam mining under pore water pressure affected.First, the basic mechanical properties of sandstone aquifer of the coal seam roof were tested in diffent water content.The weakening equation of sandstone in diffent water content have been given. Using F-RFPA2D numerical simulation software,we can reproduce pore-water pressure on the sandstone destruction process,rock damage feature under different confining pressure and pore-water pressure combinations,rock stress-strain and permeability during the whole evolution of the destruction process and analysis the four factors influence of pore pressure.Secondly, with elastic mechanics and fracture mechanics,the principle of the pore-water pressure were analyzed.The mechanical properties of sandstone (strength and modulus of deformation) under the pore-water pressure were discussed.According to the elas-plastic theory,from the start of deformation of sandstone,elas--plastic constitutive equation and elas-plastic model of sandstone were obtained.Finally, using the results of these studies,the forthcoming mining working face were analyzed with a numerical simulation soft of FLAC3D.Research suggests roof rock strength and deformation modulus has been changed as impact of pore-water pressure.These changes caused different damage and movement of surrounding rock,compared with no pore pressure and change tends to complex phenomena. The consistency of the conclusion of this essay and field has been vertified.