Study On The Durability Analysis And Evaluation System For River Shield Tunnel

River shield tunnels are usually key projects with high standards within their service lives, therefore, traditional strength design methods can not meet these requirements any more and concrete durability design, analysis and evaluation must be considered. Current concrete durability research mainly focuses on aboveground structures or habor and coastal works; seldom have the underground structures, especially river shield tunnels been involved, mainly due to short serveice life with less unfavorable durability problems of underground structures. Consequently, relavant research is inadequate and comprehensive and integrated durability design, analysis and evaluation system for river shield tunnels has not been founded yet.Basing on the research project of 'Durability and Service Life of Linings of Underground Structures' that sponsered by Natural Science Foundation (Grant No.50678135) as well as the under construction project of Shanghai shield tunnel under Yangtze esturary, this paper analized and concluded the durability influencing factors of river shield tunnel by considering its environmental and structural properties. Then it studied the migration properties of chloride ions in muddy clay above typical section of shield tunnel under Yangtze estuary, as well as the stress relaxation properties of waterproof materials through laboratory experiments, and basing on which, this paper further devoted a great part to try to establish the durability analysis and evaluation system for river shield tunnel. The main research contants and achievements of this paper are as follows:(1) Concluded and classified the durability influencing factors of river shield tunnel by considering its environmental and structural properties, and established the corresponding tree digram.(2) Derived the migration parameters of chloride ions in muddy clay above typical section of Shanghai shield tunnel under Yangtze estuary through laboratory soil column experiments, and concluded its dispersion-convection migration governing equation. (3) Carried out the hot-oxygen ageing experiments of EPBM that used in Shanghai shield tunnel under Yangtze esturary to study its stress relaxation properties under different displacements of joints. Established the ageing model of EPBM and numerically simulated the experiments.(4) Established the multi-factor fuzzy carbonation model by using fuzzy theory; and analized the relationships among the considering factors, which gave out a new way for multi-factor durability analysis of concrete structures.(5) Analised the advantages and disadvantages of existing durability evaluation methods; Established multi-layer and multi-index evaluation model for evaluating the durability of river shield tunnel at service by considering its unique structural and environmental durability properties.