Abstract:

In order to find out a calculation method for bending stiffness value of segment joint which is easy for engineering application, a bending analysis mechanical model for segment joint of shield tunnel with large crosssection that considering complex structure form of segment joint, nonlinear characteristics of concrete and complex contact force characteristics of joint face is adopted to calculate the bending stiffness Kθ for the segment joints of two typical large crosssection tunnels，i.e. Shiziyang Tunnel on GuangzhouShenzhenHong Kong Highspeed Railway and Nanjing Yangtze River Tunnel. Based on nonlinear change rule of bending stiffness Kθ and data analysis method, an empirical formula for bending stiffness values is established. Meanwhile, fullscale tests of segment joint are carried out to verify the results of empirical formula. The study results show that: (1) When the axial force of joint is constant, the bending stiffness appears obviously with the increase of bending moment, which composes three phases, i.e. contact rising phase, linear decline phase and nonlinear decline phase. (2) The curve of relationship between bending stiffness and axial compression ratio is approximately linear. （3）The relationship between bending stiffness and eccentricity of joint surface can be divided into small deformation zone under normal service condition and large deformation zone with characteristics of concrete crushing and bolt yielding，which the relationship curves between bending stiffness and eccentricity can be approximate to straight line and parabola respectively. （4）The calculation results of empirical formula coincide with that of fullscale test of joint bending，which proves that the abovementioned bending stiffness value method is feasible and with high accuracy.

Key words: shield tunnel, segment joint, mechanical model, bending stiffness, fullscale test of segment joint