Abstract:

To overcome the challenges involved in the application of mountain tunnel engineering in regions with active faults and highintensity seismic activity, a structural solution of filling a novel rubber seismic isolation layer between the primary support and secondary lining is proposed. Three isolation layer structure schemes, including a microcellularfoamed rubbercompositeporous rubber structure, a microcellularfoamed rubbercompositestiffened skeleton structure, and a pointband supportdamping structure, are designed. In addition, a highdamping rubber material, tailored for speedrelated applications, is developed. Cyclic loading test is performed to evaluate the energy dissipation effect of these materials. The laboratory static loading test and numerical calculation reveal that the stiffness of the bandshaped supportdamping structure increases with increasing deformation. This variable stiffness of the seismic isolation structure allows for enhanced resistance to rapid external loads during earthquakes and accommodating the gradual shearing associated with fault activity. The bandshaped supportrubber isolation layer structure is implemented in the seismic damage repair project of the LanzhouXinjiang highspeed railway, and the structural solution for the tunnel seismic damage rehabilitation is designed. The application results reveal that the rehabilitation of the tunnel employing the proposed structure ensures the safe operation of vehicles.

Key words: mountain tunnel, rubber seismic isolation layer, seismic isolation structure, active fault zone, resilience