Research On Progressive Damage Of Segment Linling Of Underwater Shield Tunnel

Currently, shield construction has become a main tunnel construction for city metro and large tunnel crossing river or sea, the stability of tunnel is more and more attention. In a large number of shield tunnel, especially in the segment lining of underwater shield tunnel was built after a period of time (or even just completed soon), the shield tunnel is in the work under a state of damage. The problem of segment lining is serious and it’s safety has become a challenge, the segment lining of underwater shield tunnel has become a research hotspot at home and abroad gradually. Though the background of the national science fund project and relying on shield tunnel engineering of Wuhan metro line 2 and Shiziyang shield tunnel engineering of Guangzhou Shenzhen Hong Kong passenger dedicated line and shield tunnel engineering of Wuhan Sanyang road. The mechanism and process and influence factors of progressive damage of segment lining of underwater shield tunnel are studied in the paper by similar model test and the finite element software of Abaqus. The main conclusions of this paper are as follows:1) Through the analysis on the displacement of segment lining structure and the acoustic emission, the progressive damage of segment lining of large shield tunnel is divided into four stages:the elastic stage, the local damage stage, the macro damage stage and the overall bucking stage.2) Through the analysis on the displacement and load curve of the key points on the segment lining, the buckling critical point of segment lining of shield tunnel has been found, and the buckling critical suggested value in the form of the ratio of displacement of key point and the tunnel radius has been proposed; According to the results of model test, the analysis of the influence of the assembling way, cap block’s position, formation lateral pressure, water pressure and formation defect position to the ratio has been carried out.3) According to the analysis of damage of segment lining of similar model test, the main factors that lead to the instability of segment lining are concluded.4) According to the results of model test, the analysis of the influence of formation lateral pressure, the assembling way, cap block’s position, water pressure and formation defect position to the mechanical characteristics and the damage pattern has been carried out.5) The studies on the distribution and extension of crack have been proposed though the finite element. In order to meet the requirements of the finite element, this paper puts forward the ways to simplify the management of joint, and discusses the gist of the stiffness reduction factor λ and reduction area of central angle joint cp.As well as the analysis of the stress and displacement of vault at the moment of segment lining cracks has been carried out.