STUDY ON LONGITUDINAL CRACK OF SHIELD TUNNEL SEGMENT JOINT DUE TO ASYMMETRIC SETTLEMENT IN SOFT SOIL

After the metro was put into operation,there has been increasing longitudinal nonuniform settlements of shield tunnel due to various causes including the vibration load of train,leakage of tunnel,different soil properties,etc..This kind of nonuniform settlement will greatly endanger the safety of the train.Based on the measured data for longitudinal settlements of a tunnel in soft soil,the security of the tunnel caused by settlements is studied.Firstly,the longitudinal settlement was simulated by polynomial part by part and the relative longitudinal curvature was gained.Secondly,the equivalent axial stiffness model of shield tunnel initiated by a Japanese scholar is introduced.Finally,the relationship between longitudinal curvature and crack of shield tunnel segment joint was found based on the equivalent axial stiffness model of shield tunnel.The results not only can help us to learn the current situation of the longitudinal settlement of shield tunnel and the longitudinal crack of shield tunnel segment joint,but also provide the guidance for tunnel protection,waterproof design and construction technique of shield tunnel.