Long-term behavior of earth pressure around a high-filled cut-and-cover tunnel

Abstract

The Northwest Loess Plateau in China is mountainous and contains deep valleys which consist mostly of loess. Tunnels constructed in such deep valley and backfilled with soil are called high-filled cut-and-cover tunnels (HFCCT). Several studies have been conducted on HFCCT, but the creep behavior of loess backfill has not been fully explored. Post-construction settlement in loess is large, and it is difficult for stability to be reached in a short time. Therefore, it is necessary to predict long-term behavior of earth pressure around an HFCCT to ensure long-term safety. The primary purpose of this paper is to investigate changes in earth pressure and displacement of soil with time after the completion of the backfill process. This is achieved using FLAC3D software (finite difference method). The results show that discrepancies in soil settlement and surface settlement will gradually increase and eventually reach stability. The distribution and value of earth pressure also becomes redistributed. Meanwhile, influencing factors such as slope angle and valley width gradually weaken with time, and only affect the time needed to reach stability.