Analytical Algorithm of Longitudinal Bending Stiffness of Shield Tunnel Considering the Longitudinal Residual Jacking Force
Longitudinal bending stiffness is the basic longitudinal mechanical property of a tunneling shield,as well as an important parameter for analyzing the longitudinal response of the shield tunnel.However,the tensile stiffness of the circumferential joint and the longitudinal residual jacking force are not considered in longitudinal bending stiffness calculations for a shield tunnel.Thus,an analytical algorithm for the longitudinal bending stiffness of a shield tunnel considering the longitudinal residual jacking force is proposed herein.First,two parts of the longitudinal deflection deformation of a shield tunnel under external load were determined through theoretical analysis,namely,the longitudinal deflection deformation of homogeneous circular pipe and the longitudinal deflection deformation caused by the opening of segment ring seam.Subsequently,the analytical algorithm for the longitudinal bending stiffness of shield tunnel could be obtained,regarding the elastic modulus of material,shield tunnel diameter,segment width,number of circumferential joints,tensile stiffness of the circumferential joint,and longitudinal residual jacking force.Then,a scaled shield tunnel model considering the tensile stiffness of the circumferential joint and the longitudinal residual jacking force was designed.Accordingly,tests were conducted on the longitudinal bending stiffness model,specifically for the longitudinal deflection deformation and the opening of the circumferential joint.Finally,the analytical algorithm for the longitudinal bending stiffness was verified through the experimental data.The results show that:the measured longitudinal bending stiffness from the shield tunnel model is basically consistent with that obtained from the theoretical algorithm;when the longitudinal residual jacking force is not applied,the longitudinal bending stiffness of the shield tunnel does not change much with increased loading,but when the longitudinal residual jacking force is applied,for the same longitudinal residual jacking force,the longitudinal bending stiffness of the shield tunnel decreases with an increase in loading and tends to stabilize gradually.In the longitudinal response analysis of a shield tunnel,it is necessary to reduce the longitudinal deflection deformation caused by the longitudinal residual jacking force as the safety reserve of the shield tunnel.
NETL
NSTL
万方数据
维普
