About the author:

China Railway 18th Bureau Group Third Engineering Co., Ltd., Zhuozhou, Hebei 072750, China

Abstract:

With the rapid development of urban rail transit, railway tunnel structures are subjected tolong⁃term high⁃frequency reciprocating dynamic loads induced by train operations. The variability inconcrete material properties directly influences the structural dynamic response and service life. Based onABAQUS software, a three⁃dimensional dynamic coupling model of train⁃track⁃tunnel is established. Thedynamic response characteristics, damage evolution law and stiffness degradation mechanism of concretewith low strength and high toughness, standard strength and high strength and high modulus under movingtrain load were systematically studied. The results show that the elastic modulus of the material has areverse regulation effect on the dynamic displacement and dynamic stress. Although the high modulus caneffectively suppress the deformation, it will attract more dynamic internal forces and amplify the fatigueload base due to the stiffness absorption effect. The damage evolution mode shows a significant materialdependence. Low⁃strength materials show early wide⁃area network cracking, while high⁃strength materialsshow local brittle penetration characteristics. The stiffness evolution of the whole life cycle shows that thehigh⁃strength material has obvious advantages in the early stage, but it is prone to sudden instability inthe later stage due to the lack of plastic energy dissipation mechanism.