Research On Seismic Behavior Of Deteriorated Shield Tunnel In Chloride Environment

With the continuous development of urban traffic tunnel,more and more underwater traffic tunnel project is being carried out,Coastal areas of China sit on circum-Pacific seismic belt,underwater traffic tunnel will inevitably pass through these areas,In addition,the tunnel structures are affected by the complex environmental factors,like complicated geological conditions,high water pressure and erosion environment.Dynamic response of underwater shield tunnel cannot be estimated with structure degraded,so,it is necessary to evaluate the safety and stability of the tunnel structure under the common influence of deterioration and seismic load.Based on the engineering of Xiamen’s Metro Line NO.2,the seismic response of tunnel structure under load and deterioration is analyzed,and the main research results are as follows:(1)The influencing factors of tunnel structure durability are introduced,soil-water load and erosive environment are the most important factors.This passage had discussed on deteriorated mechanism of structure performace of underwater shield tunnel with soil-water load and erosive environment.(2)Based on the existing constitutive model of segmental deterioration under the soil-water load and chloride penetration,the seismic response of the degraded tunnel structure under earthquake is analyzed based on the Xiamen subway project,an underwater shield tunnel.(3)According to the existing performance level of tunnel structure,the quantitative index of performance level which suits the circular shield tunnel is proposed.Based on the existing calculation formula of steel corrosion ratio with shield tunnel segment,the interval steel corrosion ratio with shield tunnel segment is related to its seismic performance.(4)According to the allowable stress and damage degree of the structure,the quantitative index limit of performance level which suits the circular shield tunnel is proposed.And the performance level of tunnel structure corresponding to the interval steel corrosion ratio is determined.