Research On The Property Of Rubber Gaskets In Shield Tunnel Lining Joints After High Temperature

Subway becomes the important part in country transportation system with the fast development of urbanization. Shield-driven tunnel is made up of concrete segments. As a result, gasket in the joint is the key part of tunnel waterproofing property. Relevant reports are scarce that what extent does high temperature caused by tunnel fire impact the waterproofing ability of rubber gasket. Thus initial tests and numerical analysis about the properties of rubber gasket after fire are presented in this paper, which contains:1. Waterproofing property tests about rubber gaskets after heated(at 70℃/2h、120℃/2h) in initial free state were performed. Then compared with tests about normal specimens to study the influence of heating temperature to waterproofing ability of gasket quantificationally. It showed that:(1) waterproofing ability of gasket after heated at temperature lower than 120℃ was comparable to the waterproofing ability of normal gasket;(2) the inflection point appeared at decrement about 11mm(in double gaskets) in the curve of water pressure of leakage-decrements.2. Loading and unloading compression tests of rubber gaskets after heated(at 70℃/2h、120℃/2h) in initial free state and gasket after heated in initial compression state were performed. Then compared with tests about normal specimens to study the influence of heating temperature and initial compression to compression property of rubber gasket. It showed that:(1) rheostriction was more obvious in the specimens heated with initial compression deformation than the specimens heated without initial compression deformation;(2) the ratio of compressive force in unloading process and compression force in loading process about specimens after heated(at 70℃/2h、120℃/2h) in initial free state was a little larger than the ratio of compressive force in unloading process and compressive force in loading process about normal specimens at the decrement of 4mm. but the ratio of specimens heated in compression state was obviously larger than the ratio of normal specimens.3. Uniaxial tension tests and uniaxial cyclic tension tests about rubber specimens heated(at 70℃/2h、120℃/2h) in initial free state were performed. Then compared with tests about normal specimens and confirmed the material parameters in rubber constitutive relation. Numerical analysis about the compression behavior of gasket was performed by ABAQUS to study the contact stress which was related to waterproofing property directly. It showed that:(1) average contact force on contact face of gaskets heated at lower than 120℃ was larger than the critical value of leakage;(2) decreasing amplitude of compressive force about specimen s-n and s-120 reached to 19.6% and 23.1%, respectively.