Research on dynamic response and fatigue life of tunnel bottom structure under coupled action of train load and groundwater

Abstract

In this paper, based on a heavy-duty railway tunnel, the vibration characteristics and fatigue life of tunnel basement structure under the coupled action of train load and groundwater were studied by field tests and numerical simulation. The results showed that the field measurement and numerical simulation results were in good agreement, and the vertical dynamic stresses of the grade-IV and -V surrounding rock were attenuated significantly along the tunnel base. The attenuation rate to the bottom of the inverted arch were 88.6% and 87.0%, respectively. Thus, the inverted arch and the filling layer were the main carriers of the train dynamic load. When water damage occurred in the basement, the vertical displacement and vertical acceleration of the basement structure decreased due to the pore water pressure, but the principal stress increased significantly. Under conditions where the surrounding rocks of grade-IV and -V have water compared with no water, the lifespan of the inverted arch decreases by 21.07% and 29.28%, respectively. The worse the quality of the surrounding rock was, the greater the dynamic response and the shorter the life of the basement structure became.