Non-linear Stiffness Behavior and Analysis of Tunnel Lining with Reinforcing Bars

This paper describes research which focused on comparing the mechanical behavior of reinforced concrete (RC) linings with that of plain concrete linings. RC lining models assuming a double track tunnel with concrete having two layered reinforcing bar and plain concrete lining models were made. Tests were conducted using a tunnel lining loading test unit, and results showed that with appropriate stress redistribution, the RC lining achieved a satisfactory and stabilized structure, even though cracks in the lining impaired the durability of the overall structural system. The research also established a modeling methodology for appropriately expressing the mechanical behavior of an RC lining model. This was achieved through numerical simulation with finite element method (FEM) analysis, involving examining the bond strength between mortar and stainless steel wire, and the tensile softening characteristics of mortar associated with cracking.