Distribution of underground pressure for Working face under different lithological characters of coal roof

The underground pressures of longwall face with different lithological characters of coal roof and its phenomenon are studied by using the numerical simulation technique and strata control observation.The research results show that in the progress of coal mining,there is certain difference in maximal abutment stress of longwall face with different lithological characters of coal roof.The sandstone roof with higher strength has a longer distance of initial weighting and periodic weighting,the abutment stress ahead of the working face is bigger,the distance between the peak position of the abutment stress and working face is smaller and the phenomenon of underground pressure is intense.It is on the contrary in case of the mudstone roof with lower strength.The distance of initial weighting and periodic weighting is shorter;the abutment stress on the working face is smaller,the peak position of abutment stress transfers to the inter of rock mass ahead of working face and the phenomenon of underground pressure is not obvious.