Analysis of a tunnel failure caused by leakage of the shield tail seal system

Abstract

This paper presents an analysis of a tunnel failure accident during shield tunnel construction on Foshan Metro Line 2 in China. The failure is caused by the leakage of the multilayer seal system, which consists of several brush seals at the tail of the shield. Four different failure modes for the multilayer seal system are discussed. A simple structural analysis of the brush seals is then conducted, and failure mode 4 (failure due to brush seal deformation) is identified as a major reason for the Foshan tunnel accident. A finite element method (FEM) analysis is employed to validate the conclusions drawn from the simple structural analysis of the brush seals.