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Abstract The following preliminary results are obtained based on the study of in-situ stress measurements using hydraulic fracturing(HF) method and distributing characteristics of stress in surrounding rock masses in the region of Panyi Mine：(1) The dominative stress of the tunnel for Gangue adhesive tape machine at elevation －790 m is tectonic stress and the maximum horizontal principal stress is larger than 28.33 MPa. The ratio of saturated uniaxial compressive stress to maximum horizontal principal stress is 5.82，which means that the stress level in this region belongs to high stress are. (2) The plastic zone of surrounding rock to the ratio of maximum horizontal principal stress for the tunnel extends from the periphery to depth；at the same time，the stress of surrounding rock gradually increases and reaches the maximum value at a location of about 2 times of tunnel diameter，then gradually decreases and is finally equal to in-situ stress in some location. (3) The influence range of the floor track tunnel on the stress of surrounding rock of the top tunnel is greater than 6 times of tunnel diameter，which far exceeds the influence range of 3 times of that obtained by traditional elastic mechanics. The above results indicate that the distributing characteristics of stress in surrounding rock masses for deep-buried tunnels are different from that for shallow-buried tunnels，and it can provide references for similar projects.
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Received: 20 January 2010
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