(1. Key Laboratory of Road and Traffic Engineering of Ministry of Education，Tongji University，Shanghai 201804，China；2. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education，Tongji University，Shanghai 200092，China；3. School of Mechanics and Civil Engineering，China University of Mining and Technology，Xuzhou，Jiangsu 221116，China；
4. Shenzhen City Traffic Infrastructure Construction Center，Shenzhen，Guangdong 518040，China)
Abstract：Faults and fractured zones are common unfavorable geological phenomena encountered in the process of tunnel excavation. It is also the place where the surrounding rock is unstable and prone to accidents. In this paper，the weak rock mass of grade IV commonly found in mountain tunnels was selected as the reference object，and geomechanical model test and numerical simulation were carried out to study the progressive failure process as well as the stress and deformation characteristics of the surrounding rock of fault-crossing tunnel. After tunnel excavation，the rock mass of fault footwall located above tunnel arch was in the cantilevered state，and tensile cracks were found near the fault region. Tunnel excavation made the overburden load be transferred to the two sides of tunnel，which often led to the shear failure of rock mass below tunnel waist，especially for the rock mass close to fault footwall. Tunnel excavation caused stress redistribution around surrounding rock. Once the redistributed stress exceeded the ultimate strength of rock，the surrounding rock collapsed into the arch shape. At the same time，the tangential stress in rock mass located within the collapse scope dropped sharply. This feature can be used to determine the range of collapsed rock mass. When tunnel was excavated，due to the barrier effect of fault，the rock mass stress within the hanging wall and footwall of fault presented the characteristics of discontinuous and nonlinear distribution.
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2016, Vol. 35 
