Abstract: The creep slippage of active fault leads to shearing of rock mass along the tunnel axis, causing axis bending and even destruction of rock mass. The nonlinear distribution of creep slippage displacement in rock mass plays an important role in structural design and operation safety of tunnels. In deep buried area, the three-dimensional in-situ stress and the structure of fault strips are the key factors to be considered, which are evidently different from geological conditions in shallow buried tunnel or subway project. However, the existing physical simulation tests are mostly used to study faults in shallow buried tunnels, subways and other projects, and are not suitable for the simulation of deep tunnel conditions. In this paper, a new experimental setup for physical modelling of deep buried tunnel crossing active fault is developed and utilized to simulate fault creep slippage under three-dimensional in-situ stress. Based on the Fenghuangshan tunnel that crosses active fault, the axis displacement mode along the tunnel under different slippages is obtained through physical model test. The results show that the displacement mode along the tunnel axis is S-shaped. The shear deformation is continuously transmitted from slippage plane to crushed zone under small slippage, while the slippage occurs between slip plane and crushed zone under large slippage. The deformation curve within the crushed zone is ‘slope line’ shape, and the transmission width within the zone is around 20 m. This result could provide important knowledge for the structural design of fault crossing tunnels.

Key words: physical modelling, active fault, three-dimensional loading, flexible loading, creep slippage, displacement mode