PROTOTYPE TEST OF A NEW TYPE SEGMENT STRUCTURE WITH DISTRIBUTED MORTISES AND TENONS FOR SHIELD TUNNEL

Abstract

Reinforcement measures are often employed to control dislocation and joint opening between rings of shield tunnels with large diameters. A full-scale test is conducted on staggered assembled segmental linings of Shiziyang Tunnel with four distributed mortises and tenons. The study aims to explore the mechanical properties and failure mechanism of the new type of segment with mortises and tenons. Variations and characteristics of structural deformation, dislocation and joint opening are discussed, and the failure mechanism and crack development of the structure are analyzed. The results show that the structural deformation of the new type of segment experiences a slow linear increase when the reinforcement of the centre ring is elastic, and a nonlinear increase when it is plastic; The deformation between rings is first manifested as dislocation, and the inter-ring interaction is provided by the friction of the contact surface. After the mortise and tenon contact, the inter-ring deformation is manifested as rotational opening. The longitudinal bolt bears bending moments while the mortise and tenon bear shear forces, and the inter-ring action is a combination of bending and shear; The initial crack of segmental linings occurs at the edge of the centre ring arch, and its failure mechanism is summarized as follows: concrete cracks cause the reinforcement to bear tension, and the cracks develop more deeply and widely, and then the reinforcement enters plasticity, and the structure finally loses stability and fails. The research results can provide reference for theoretical analysis and design of shield tunnels with large diameters.