Estimation of Residual Longitudinal Axial Force in Segmental Tunnel Linings Caused by TBM Thrust Jacks

Lining of tunnels constructed using full-face tunnel boring machine consist of set of concrete segments which form a ring at each step of construction. In order to move forward, TBM inserts a great force through thrust jacks resting on segments. Installing a new ring requires decrease or elimination of jacking force. Therefore, the magnitude of force alternates as the construction continues which a part of this force remains as residual through the lining. This residual force may influence longitudinal flexural stiffness of the lining. On the other hand, time-dependent behavior of injected grout has a significant effect on the residual force. In this study first the time-dependent behavior of cement-based grout considering confining condition is investigated using the oedometer test and then modeling of staged tunnel construction and alternate loading of thrust jacks considering time-dependent grout setting is proposed using an analytical approach. In the end, residual force of lining after construction could be calculated. This approach is used to estimate the longitudinal residual force in No.1 line of Tabriz Subway Lining.