Crack Propagation Law of Segment Tendon under Jacking Forces

To explore the cracking and local damage of tenon segment that easily occurs during the construction of shield-driven tunnels, a model of standard tenon segment was built using the extend finite element method (XFEM) with ABAQUS. The initiation location, propagation direction and distribution of segment cracks were analyzed in a dozen of working conditions including non-uniform jacking forces, asynchronous jacking and eccentric jacking loads. Numerical results indicate that bad construction load is the main cause of cracks. Areas burden with large loads and that the jacks first contact are liable to crack. Cracks are easier to initiate and propagate at the central area of the top surface of segment than at both ends, and at the intrados than at outer surface. Three factors, if sorted in a descending order by their damage severity to a tenon segment, are eccentric jacking loads, asynchronous jacking and non-uniform jacking forces.