Characteristics and causes of cracking and damage of shield tunnel segmented lining in construction stage - a case study in Shanghai soft soil

The study investigates the cracking and damage of shield tunnel segmented lining via the field observations and measurements of a case in Shanghai metro system. The observations are carried out on local damage of segment, segment cracking and joint dislocation, respectively. Notable deformation can be observed on several lining rings. Two parameters, proportion of damaged rings and radius ovality (O-R), are introduced to describe to what extent the lining rings are damaged in a tunnel section and how large the transverse deformation of the lining ring is. The construction-relevant data, such as attitude of shield machine and assembled lining rings, are collected and analysed to explore the exact causes for tunnel sections with different characteristics of cracking and damage. Surrounding environment was checked and numerical results are also presented to validate our speculation.