Abstract
To probe into the time-dependent behaviour of the ballastless track–bridge structural system under train load, based on the import of the static and fatigue damage constitutive model of materials to simulate damage deterioration of the structural system and interface cohesive zone model to the interface layer, a three-dimensional nonlinear finite element model of the China Railway Track System Type II (CRTS II) ballastless track–bridge structural system was established using the equivalent static method. Then, using this model, we developed the numerical simulation analysis of the influence law of material damage deterioration on structural system performance under train load and revealed the fatigue evolution of the structural system. The results show that the beam remains in compressed status for the whole process, the track is in compression in the midspan and in tension at the beam end, and the tensile stress is larger near the shear groove under the double-track static load. Under the fatigue load, stiffness degradation of the structural system is not obvious, and integral rigidity of the structural system is dependent on the rigidity of the beam. Strength reduction of the materials caused stress redistribution of the structural system and had a larger effect on the stress of each layer of track structure than on the stress on the beam. The fatigue degradation of the cement-emulsified asphalt (CA) mortar layer material has a significant impact on the structural system, which directly affects structural layer stress variation with the fatigue loading cycle.
Highlights
The China Railway Track System Type II (CRTS II) ballastless slab track is widely used in China’s national high-speed railway system due to its various advantages such as running comfort and high structural stability [1,2]
As the ballastless track–bridge structural system composed of CRTS II slab track is a vertical multilayer spatial structure, the randomness and time-dependent material properties of structural layers, the interlayer connection nonlinearity and the boundary condition complexity are a series of factors that inevitably impact the mechanical fatigue properties of the structural system under train load, affecting the running comfort and safety of the high-speed trains and increasing the difficulty of maintenance
The results show that the cement-emulsified asphalt (CA) mortar layer fatigue life decreases with the increase in train loads, and the position of CA mortar layer that experiences the most unfavourable fatigue life is at the end of the track
Summary
The China Railway Track System Type II (CRTS II) ballastless slab track is widely used in China’s national high-speed railway system due to its various advantages such as running comfort and high structural stability [1,2]. Liu [9] studied the effects of different temperature gradients and Combined loads on the mechanical properties of the CRTS II ballastless slab track. Zhu [14] used the cohesive zone model for an interface to establish the vehicle-track coupling model, analysed the damage fracture and delamination between the slab layer and the CA mortar layer under the coupled action of temperature and train load. Based on the existing research results on static and the fatigue constitutive law of concrete and CA mortar layer [24,25,26] and introducing a cohesive zone model, this paper establishes a three-dimensional finite element model of the CRTS II ballastless slab track–bridge structural system and uses an equivalent static method to analyse the mechanical fatigue properties of the structural system under double-track train load
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