Abstract: To investigate the structural failure mechanism and longitudinal joint′s outboard deformation of shield tunnel, two groups of fullscale experiments on staggered joint assembled shield tunnel are conducted based on a shield tunnel with many defects and complex load conditions.  The key points of structural failure in the whole process of shield tunneling are excavated, the correlation between convergence deformation and longitudinal joint deformation is summarized, and the key indexes are obtained. The results show the following: (1) When the convergence deformation of shield tunnel reaches 20~30 mm, segment cracks along the longitudinal direction of the tunnel occur. (2) The structural failure of shield tunnel can be divided into three stages, i.e., elastic, elastoplastic, and ultimate stages, and when it reaches the ultimate state, some segments and longitudinal joints are damaged by compression. (3) The outboard deformation of waist longitudinal joint is highly correlated with the convergence deformation and assembly angle.

Key words:  , shield tunnel, full-scale test, failure mechanism, convergence deformation, longitudinal joint deformation