Dynamic Response of a Heavy-Haul Railway Tunnel’s Bottom Structures in Hard Rock

Abstract

A train–tunnel–surrounding rock numerical model was established by using ABAQUS to analyze the dynamic response of a heavy-haul railway tunnel in hard rock, quantify the influence of the train axle load on the tunnel dynamic response and determine its potential vulnerable position. The results suggested that: Under the 30 t train load and surrounding rock pressure coupling, the maximum principal stress caused by rock pressure was 1.27 MPa, located at the bottom of the structure below the side drain; the maximum dynamic response of the tunnel structure and base rock was located directly below the rail. The lower part of the side drain and rail was the vulnerable position in the tunnel bottom structure, and the probability of base disease under the rail may be higher than that in soft-rock tunnels, for it has a greater dynamic response and thinner structure compared to a soft-rock tunnel. The maximum principal stress amplitude of the tunnel structure and base rock were 129.3 kPa and 43.0 kPa, respectively. When the axle load increased by 1 t, the dynamic amplitude of the structure’s maximum principal stress increased by about 4.14 kPa, and the base rock’s maximum principal stress increased by about 1.33 kPa. The rock pressure was not negligible in the dynamic analysis of the railway tunnel, and the dynamic response of the tunnel bottom structure and base rock will decrease, obviously, when the rock pressure is ignored.