Abstract
This study presents an improved constitutive model for concrete under uniaxial cyclic loading which considers the fatigue stiffness degradation, fatigue strength degradation, and fatigue residual strain increment of concrete fatigue damage. According to the constitutive model, the dynamic response and cumulative damage of the tunnel cross structure under various train operation years were analyzed. The results show that the vibration in the middle of the main tunnel is most violent. With the increase of train operation period, the acceleration in the middle of the transverse passage floor, both sides of the wall corner and the vault increase significantly, and the maximum principal stress increases significantly only in both sides of the wall corner. The compressive damage is mainly distributed at both sides of the wall corner, while tensile damage is distributed in both sides of the inner wall corner. The accumulative damage of the cross structure exhibits a two-stage profile. The size and range of accumulative tensile damage of the connecting transverse passage are greater than those of accumulative compressive damage.
Highlights
For long and large tunnels, a certain number of connecting transverse passages are normally set up to meet the needs of the operating ventilation, accident evacuation, fire rescue, and other functions
There is a lack of research on dynamic responses of the tunnel structure under the high cyclic loads and lack of the fatigue damage analysis of the cross tunnel structure, formed by the main tunnel and the transverse passage
The dynamic response and cumulative damage characteristics of cross tunnel structure of Shiziyang railway shield tunnel at various operation years were analyzed, which meet the requirements of the designed life of 100 years according to the Chinese standard
Summary
For long and large tunnels, a certain number of connecting transverse passages are normally set up to meet the needs of the operating ventilation, accident evacuation, fire rescue, and other functions. It is very important to study the dynamic response and fatigue cumulative damage law of the special structure of the cross tunnel under long-term train which caused loads for the safety of long and large tunnels. There is a lack of research on dynamic responses of the tunnel structure under the high cyclic loads and lack of the fatigue damage analysis of the cross tunnel structure, formed by the main tunnel and the transverse passage. Based on the actual situation of the Shiziyang tunnel project of Guangzhou-ShenzhenHongkong Railway Passenger Dedicated Line, numerical analysis models were established, and the dynamic response and cumulative damage characteristics of the tunnel cross structures under train vibration load were analyzed
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