Model Test and Numerical Simulation for Tunnel Leakage-Induced Seepage Erosion in Different Strata

Abstract

Leakage in underground structures, especially tunnels, may cause seepage erosion in the surrounding soil, which in turn leads to ground subsidence, posing a great threat to urban safety. The current literature mainly focuses on seepage erosion in the sand but lacks a systematic study on the development process of seepage erosion induced by tunnel leakage in different strata. To investigate the different seepage erosion modes induced by tunnel leakage in different stratum types, a series of reduced-scale model tests were carried out. A coupled fluid–solid numerical model was further established to analyze the fine-scale characteristics of different seepage erosion modes. The results show that (1) the soil seepage erosion modes can be divided into three categories: no soil cave, unstable soil cave, and stable soil cave; (2) the adopted coupled fluid–solid numerical model based on DEM, which takes into account the degradation of clay during seepage erosion, can effectively simulate the erosion process of soil with different seepage erosion modes; (3) the phenomena of the three erosion modes are different in the process of erosion development; and (4) the micro-mechanisms of the three seepage erosion modes are different, which are manifested in the erosion range, soil arching effect, and displacement.

Numerical Simulation Study on the Deformation Patterns of Surrounding Rock in Deeply Buried Roadways under Seepage Action

“…Wang, W. et al [10] conducted a study on the effects of underlying karst caves on shield tunnels passing through sand strata using threedimensional fluid-solid coupling numerical simulations. Sun, Q. et al [11] investigated the different seepage erosion modes induced by tunnel leakage in various stratum types and analyzed the microscale characteristics of these seepage erosion modes. Wang, F. [12], based on the SSA-LSTM (Sparrow Search Algorithm-Long Short-Term Memory) model, achieved accurate predictions of surrounding rock deformation during soft rock tunnel construction.…”