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Abstract Based on in-situ stress measurement results in 5 mine areas of Huainan coal mine，Anhui province，by hydraulic fracturing method，the in-situ stress characteristics and the influence of lithology on it are revealed；the variation law of stress and plastic zone of surrounding rocks around tunnels after excavation are analyzed. The following preliminary results are obtained as follows：(1) The tectonic stress is dominant in these areas and the stress level is high. (2) The lithology has a great influence on the coefficient of lateral pressure. The obtained coefficients of sandstone are 1.52–1.87，and for mudstone，they are 1.08–1.18. (3) The lithology has a great influence on the plastic zone of surrounding rocks around tunnels. Because of the difference of lithology，the range of plastic zone in Panyi mine differs greatly from that of south part of Guqiao coal mine，though the maximum horizontal principal stresses of these two mines are close. In addition，the range of plastic zone in Liuzhuang coal mine which consists of calcilutyte is obviously greater than that of Panyi coal mine which consists of quartz-sandstone，though the maximum horizontal principal stresses at the measured depth in Liuzhuang coal mine is smaller than that of Panyi coal mine. The results can provide references for analysis of failure mechanism of surrounding rocks and reinforcement and support of tunnels of similar projects.
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Received: 14 February 2011
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2011, Vol. 30 
