大断面盾构隧道管片接头抗弯刚度取值研究

为找到一种便于工程应用的管片接头抗弯刚度取值方法，采用考虑管片接头复杂结构形式、混凝土非线性材料特性以及接缝面复杂接触传力特点的大断面管片接头抗弯分析力学模型，对广深港狮子洋隧道和南京长江隧道2座典型大断面隧道的管片接头抗弯刚度Kθ进行计算； 基于所得到的抗弯刚度Kθ的非线性变化规律和数据分析方法建立抗弯刚度取值经验公式，并开展接头抗弯足尺试验对取值结果进行验证。结果表明： 1）当接缝轴力不变时，抗弯刚度随弯矩的增大表现出明显的非线性变化规律，由接触上升段、线性下降段以及非线性下降段组成； 2）抗弯刚度与轴压比的作用关系曲线近似为线性； 3）抗弯刚度与偏心距的作用关系中分为正常使用状态下的小变形区以及伴有混凝土压碎、螺栓屈服特征的大变形区，其抗弯刚度-偏心距关系曲线可分别近似为直线和抛物线； 4）抗弯刚度经验公式的计算结果与接头抗弯足尺试验结果的相符度较高，表明该取值方法合理且计算准确度较高。

Bending Stiffness Values for Segment Joint of Shield  Tunnel with Large Cross section

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.