Abstract:

Applying new composite to reinforce the segments of shield tunnel is a new reinforcement method. This paper focuses on the mechanical behavior of the binder and the shear properties of the interface between C50 concrete cube and the new composite structure after exposure to high temperature (50~400 ℃). The experiment results indicate that： 1) The mechanical behavior of the binder improves in relatively low temperature condition, however, the mechanical behavior of the binder reduces in relatively high temperature condition when the temperature increases; The optimum temperature of the binder is 150 ℃; The binder completely fails after exposure to a temperature over 300 ℃; 2) The failure of the interface between the C50 concrete cube and the new composite structure can be divided into 3 types; The optimum temperature Tp of the interface is about 50 ℃ and the failure temperature Tf is between 300 ℃ and 400 ℃; The shearing stiffness of the interface reduces when the temperature increases; Major factors affecting the shear properties of the interface after exposure to relatively low temperature(15,50 ℃), relatively high temperature(100,200 ℃)and high temperature (250 ℃~Tf) include the shear strength of the concrete, the bond property between the CFRP and the steel tube, and the bond property between the binder and the concrete.

Key words: high temperature (fire), shield tunnel, new composite structure, interface, shear properties