Experimental Study on Mechanical Properties of a New Longitudinal Joint for Large-Diameter Shield Tunnels

Longitudinal joint is the weak part of shield tunnel mechanical performance, the form of segment joint directly affects the mechanical properties of shield tunnel. At present, bolts are mainly used for the connectors of the longitudinal joint of shield tunnel in China, a new connector is used in the new longitudinal joint, which is the slide-in connector, mechanical properties of this joint in large-diameter shield tunnel needs to be studied. The research object of this paper is a new longitudinal joint, which has two different types of slide-in connectors. The mechanical properties of the new longitudinal joint of large-diameter shield tunnel are researched by means of model test, and the ultimate bearing capacity of the new longitudinal joint is calculated by theoretical analysis. The mechanical properties of the traditional bolt longitudinal joint and the new longitudinal joint are compared and analyzed. The conclusions are as follows: the weak part of the new joint lining segment is in the concrete area around the joint; the type of slide-in joint directly affects the mechanical properties of the new longitudinal joint; the Angle stiffness of the larger connector increases by 7.2 ~ 169.5% and the ultimate bearing capacity increases by 69.9% compared with that of the smaller connector; compared with the bolt joint, the new longitudinal joint has higher bending rigidity and better mechanical properties, which is suitable for large-diameter shield tunnel.