Dynamic response of the tunnel bottom structure considering groundwater influence under heavy-haul train loading

Abstract

In this research, by adopting numerical simulation method, the dynamic response characteristics of the tunnel bottom structure under a heavy-duty train load in a water-rich soft stratum were studied. Taking the pore water pressure and the vertical dynamic stress as evaluation indicators, the response law of the excess pore water pressure and dynamic soil stress at the bedrock with the action of 25 t, 27 t, and 30 t axle load train loads were analyzed. The horizontal distribution and vertical attenuation law of vertical dynamic stress on the base structure were revealed. The results showed that the influence range of the heavy train load on the bedrock of the water-rich tunnel was about 5 m below the tunnel. The vertical dynamic stress was attenuated vertically along the basement. When the stress was attenuated towards the surface of the surrounding rock, the maximum peak value was 21.4 kPa. The increase of the axle load of the train would cause a stress concentration in the bottom structure and the base rock for the heavy-duty line, and with the continuous action of hydro-mechanical coupling, the basement would be cracked or develop voids.