Mechanical And Deformation Characteristics Of Composite Segment Rings For Shield Tunnel

Construction of the subway,underground highway,underground tunnels and underground regulation pool(reservoir)and other major infrastructure can effectively solve the social problems in cities of our country such as the ground traffic congestion,vehicle exhaust pollution and urban floods.These deep buried tunnels can also avoid the complex and shallow underground pipelines,and is conducive to the rational use of underground space.But the earth and water pressure in the process of shield tunnel construction is very high,and the traditional lining structure can not satisfy the required performance of stiffness and strength.The need exists for developing new type segment as composite segment.And has been used in the deep,long large,and multi-cross-section shield tunnels of the subway,underground road,underground pedestrian passage and underground reservoir,etc.However,the mechanical behavior of the composite segment is not clarified,because the structural type is complicated.Meanwhile,the selected structure model and parameters are not reasonable.Therefore,the designed composite segment lining of a shield tunnel has the disadvantages of safety and economy.The stress and deformation characteristics of tunnel linings under high water pressure and earth pressure should be clarified for the design of shield tunnel.At the same time,as a common disaster,the tunnel fire will cause serious damage to the lining structure.The joint between the composite segment and steel wrapped outside the concrete and other metal components of the segment are the weak parts of lining structure.How to evaluate the performance of the composite segment ring and the joint part under high temperature is the basis on the fire resistance design.Therefore,a precise model of the composite segment ring is established by ABAQUS software,and the mechanical mechanism of the composite segment ring under complex conditions is studied.The main research is the mechanical and deformation characteristics of composite segment ring and segment joints under high hydraulic pressure and earth pressure with different inner pressure by static load model and under different covering thickness by thermo mechanical coupling model on high temperature condition.The spring stiffness coefficient of the beam-spring model are given for the composite segmeng ring under different inner pressure and under high temperature condition.At last,the influence of high temperature on the mechanical and deformation of the composite segment ring is analyzed.This study will provide a theoretical basis for the design of composite segment ring.