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Abstract Peripheral rock large deformation，shotcrete crack，steel frame distortion and other phenomenon of destruction often appear in the tunnels with soft rock and high geostress due to the high pressure on the primary lining. The safety of tunnel during construction and long-term operation will be affected. Taking Baozheng tunnel along Yiwan Railway as engineering background，based on statistical analysis of in-situ monitoring data，mechanical characteristics of surrounding rock pressure，stress of shotcrete and steel arch，axial force of bolts and deformation distribution of deep seated rock have been analyzed. Development law over time and spatial distribution along the tunnel ring of the above test items are discussed. During the excavation in the tunnel，rock pressure，steel arch stress and shotcrete stress change rapidly，and sensitivity decreases in turn with the character “upper larger，lower smaller” along the tunnel cross section. The analytical method and results can provide references to accurately understand the support-surrounding rock interaction and their mechanical characters.
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Received: 14 June 2012
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2013, Vol. 32 
