Work

Investigating tunnel seepage erosion and induced structural mechanical response using CFD-DEM-FEM method

Year: 2026

Type: article

Abstract: Seepage erosion, induced by groundwater infiltrating surrounding soils through cracks between tunnel segments, poses a significant threat to the long-term stability of underground tunnels. However, the evolution of erosion and its influence on tunnel mechanical behavior remain insufficiently understood. This study presents a macro–micro numerical investigation of tunnel erosion using a coupled CFD‑DEM-FEM (computational fluid dynamics-discrete element method- finite element method) framework. The CFD‑DEM model is used to capture soil particle migration, seepage flow, and microscopic force-chain evolution, while the resulting particle-structure interaction forces are transferred to an FEM model to evaluate the mechanical response of the tunnel lining. Parametric analyses are conducted to examine the effects of crack width, crack position, tunnel burial depth, and groundwater level on soil mass loss, surface displacement, particle migration trajectories, and micro-scale force chains. The results show that three distinct erosion modes can be identified according to crack width. Variations in crack position significantly modify the spatial extent of the erosion zone, while increased burial depth and groundwater level intensify soil loss. Structural analysis further indicates that when the crack location shifts from the tunnel crown toward the invert, the ability of the surrounding soil to transfer overburden pressure gradually decreases, leading to higher tensile stresses and a greater potential for structural damage. Overall, the study provides a qualitative understanding of the coupled evolution of seepage erosion and tunnel mechanical response, offering insights into the mechanisms of tunnel deterioration in sandy soils and potential strategies for mitigating erosion‑induced tunnel failures.

Source: Tunnelling and Underground Space Technology

DOI: 10.1016/j.tust.2026.108129

Authors: Chuang Zhou, Zhen-yu Yin, Jian-gu Qian, Zi-bo Du, Wei-qi Gong