Abstract

In recent years, serious accidents due to sand and water gushing around shield tunnel happen from time to time. Sand and water gushing could lead to large soil displacement, change soil stress field around tunnels, and then threaten the safety of tunnel structures. To date, there is a lack of theoretical research on the evolution of sand and water gushing, and the numerical simulation of the process is challenging because soil-water interaction, soil-structure interaction and large deformations have to be accounted for. In this paper, the Material Point Method (MPM) is used to deal with large deformation and various simulation cases considering different gushing locations at tunnels are carried out to investigate the development of soil displacement and stress around tunnels due to water and soil gushing. The results show that position of the gushing point greatly affect the damage scope. The sand gushing rate, the soil displacement and stress field, the ground settlement trough, and the earth pressure on the tunnel linings develop completely differently due to the varying position of the gushing point, which are analyzed to suggest reasonable guidance and countermeasures for preventing future sand and water gushing accidents.

Abstract

This study utilizes ABAQUS finite element software to analyze embankment deformation during shield tunneling. Results reveal that shield tunneling effects are manageable.The left tunnel line successfully tunnels beneath the embankment, causing a maximum settlement of 8.7 mm, meeting regulations. The ground surface exhibits a "V"-shaped lateral settlement trough, approximately five times the tunnel centerline width. Conversely, the right tunnel line induces a more extensive impact, with a 12.2 mm maximum settlement.Different lateral settlement patterns emerge in soil at varying depths. The left tunnel creates a "V" shape, with slightly increasing settlement above the tunnel axis as depth increases, accompanied by narrower troughs. The right tunnel line results in a pronounced "W" shape, especially at the grouting layer depth.Horizontal displacement forms an "S" shape, with maximum displacement at positions ±i from the tunnel axis. The right tunnel line induces greater maximum horizontal displacement than the left.In summary, this numerical analysis provides insights into embankment deformation during shield tunneling, aiding in assessing the impact and guiding safe tunneling beneath embankments.