Discontinuous mechanical behaviors of existing shield tunnel with stiffness reduction at longitudinal joints  

作　　者：Xiang LIU Qian FANG Annan JIANG Dingli ZHANG Jianye LI 

机构地区：[1]Liaoning Key Laboratory of Marine Environmental Bridge and Tunnel Engineering,Dalian Maritime University,Dalian 116026,China [2]Key Laboratory for Urban Underground Engineering of Ministry of Education,Beijing Jiaotong University,Beijing 100044,China

出　　处：《Frontiers of Structural and Civil Engineering》2023年第1期37-52,共16页结构与土木工程前沿（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant No.52108363);Postdoctoral Science Foundation of China(No.2021M700654);Fundamental Research Funds for the Central Universities(No.3132022175);Key Laboratory of Urban Underground Engineering of Ministry of Education,Beijing Jiaotong University(No.TUL2022-01);Liaoning Revitalization Talents Program(No.XLYC1905015).

摘　　要：An analytical model is proposed to estimate the discontinuous mechanical behavior of an existing shield tunnel above a new tunnel. The existing shield tunnel is regarded as a Timoshenko beam with longitudinal joints. The opening and relative dislocation of the longitudinal joints can be calculated using Dirac delta functions. Compared with other approaches, our method yields results that are consistent with centrifugation test data. The effects of the stiffness reduction at the longitudinal joints (α and β), the shearing stiffness of the Timoshenko beam GA, and different additional pressure profiles on the responses of the shield tunnel are investigated. The results indicate that our proposed method is suitable for simulating the discontinuous mechanical behaviors of existing shield tunnels with longitudinal joints. The deformation and internal forces decrease as α, β, and GA increase. The bending moment and shear force are discontinuous despite slight discontinuities in the deflection, opening, and dislocation. The deflection curve is consistent with the additional pressure profile. Extensive opening, dislocation, and internal forces are induced at the location of mutation pressures. In addition, the joints allow rigid structures to behave flexibly in general, as well as allow flexible structures to exhibit locally rigid characteristics. Owing to the discontinuous characteristics, the internal forces and their abrupt changes at vulnerable sections must be monitored to ensure the structural safety of existing shield tunnels.

关 键 词：tunnel–soil interaction discontinuous analysis longitudinal joints existing shield tunnel Timoshenko beam Dirac delta function 

分 类 号：TU[建筑科学]