Abstract
Longitudinal tension and compression deformations of a tunnel are caused by longitudinal non-uniform displacement of surrounding rock under earthquakes, and the longitudinal equivalent rigidity is one of the most important mechanical performance index in the seismic response analysis of a TBM tunnel. The back analysis of a jointed TBM tunnel lining rigidity under earthquakes was conducted, in which segments and joints are simulated by finite elements. The results show that the rigidity ratio of segment element to joint element decreases exponentially with the increase of shear modulus of surrounding rock when subjected to small earthquake (0.1 g), but the rigidity ratio of segment element to joint element is almost unchanged with the increase of shear modulus of surrounding rock when subjected to strong earthquake (0.3 g). Therefore, when a jointed TBM tunnel lining is equivalent to a continuous beam, the resistance spring of surrounding rock in parallel with the joint spring is introduced to establish the evaluation model of the equivalent longitudinal rigidity of the jointed TBM tunnel lining under earthquakes.
Highlights
Recent earthquake events show that tunnels are vulnerable to unrecoverable damage in strong seismic areas, the anti-seismic issue of tunnels arouses much attention from earthquake engineers around the world [1]
It is very important to study the effect of rock resistance on equivalent stiffness of a jointed TBM tunnel lining
The rigidity ratio of segment element to joint element decreases exponentially with the increase of shear modulus of surrounding rock when subjected to small earthquake (0.1 g)
Summary
Recent earthquake events show that tunnels are vulnerable to unrecoverable damage in strong seismic areas, the anti-seismic issue of tunnels arouses much attention from earthquake engineers around the world [1]. One way to deal with this issue is to consider the tunnel lining as a continuous straight beam in the longitudinal direction, while considering the tunnel lining as a continuous ring beam in the transverse direction, with a discounted rigidity. It is very important to study the effect of rock resistance on equivalent stiffness of a jointed TBM tunnel lining. Lee and Ge [2] studied the effect of rock resistance on equivalent stiffness of ring beam. Based on field monitoring data during earthquakes and numerical simulation analysis, Suzuki [3] proposed an equivalent rigidity calculation model of straight beam, with consideration of rock resistance, but the non-linear mechanical behavior of interface between surrounding rock and tunnel lining was not considered. EFFECT OF ROCK RESISTANCE ON LONGITUDINAL EQUIVALENT RIGIDITY OF A JOINTED TBM TUNNEL LINING UNDER EARTHQUAKES.
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