SCIENCE CHINA Technological Sciences © Science China Press and Springer-Verlag Berlin Heidelberg 2014 tech.scichina.com link.springer.com *Corresponding author (email: cbcai@home.swjtu.edu.cn) Special Topic: High-speed Railway Infrastructure October 2014 Vol.57 No.10: 1883–1894  Article  doi: 10.1007/s11431-014-5636-8 Damage evolution and dynamic response of cement asphalt mortar layer of slab track under vehicle dynamic load ZHU ShengYang 1 , FU Qiang 2 , CAI ChengBiao 1* & SPANOS Pol D 3 1 State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, China; 2 School of Civil Engineering, Central South University, Changsha 410075, China; 3 Ryon Chair in Engineering, Rice University, Houston 77005, USA Received March 28, 2014; accepted June 23, 2014 The damage evolution and dynamic performance of a cement asphalt (CA) mortar layer of slab track subjected to vehicle dy- namic load is investigated in this paper. Initially, a statistical damage constitutive model for the CA mortar layer is developed using continuous damage mechanics and probability theory. In this model, the strength of the CA mortar elements is treated as a random variable, which follows the Weibull distribution. The inclusion of strain rate dependence affords considering its in- fluence on the damage development and the transition between viscosity and elasticity. Comparisons with experimental data support the reliability of the model. A three-dimensional finite element (FE) model of a slab track is then created with the commercial software ABAQUS, where the devised model for the CA mortar is implemented as a user-defined material subrou- tine. Finally, a vertical vehicle model is coupled with the FE model of the slab track, through the wheel-rail contact forces, based on the nonlinear Hertzian contact theory. The evolution of the damage and of the dynamic performance of the CA mortar layer with various initial damage is investigated under the train and track interaction. The analysis indicates that the proposed model is capable of predicting the damage evolution of the CA mortar layer exposed to vehicle dynamic load. The dynamic compressive strain, the strain rate, and the induced damage increase significantly with an increase in the initial damage, whereas the dynamic compressive stress exhibits a sharp decrease with the increasing initial damage. Also, it is found that the strain rate dependence significantly influences the damage evolution and the dynamic behavior of the CA mortar layer. cement asphalt mortar, slab track, statistical damage constitutive model, vehicle-track coupled dynamics, damage evolution Citation: Zhu S Y, Fu Q, Cai C B, et al. Damage evolution and dynamic response of cement asphalt mortar layer of slab track under vehicle dynamic load. Sci China Tech Sci, 2014, 57: 18831894, doi: 10.1007/s11431-014-5636-8 1 Introduction High-speed railway lines in the form of slab tracks in Eu- rope, China and Japan have been widely constructed. This is because of the fact that this construction offers better stiff- ness uniformity, higher running stability, and lower mainte- nance cost [1–3]. In the slab tracks, the CA mortar layer is placed between the slab and the concrete base to ensure desirable elevation and high smoothness of the slab tracks. It is critical as it not only enhances the structural integrity through its bonding constraints to the slab and the concrete base, but also improves the riding comfort of high-speed vehicles by absorbing a certain amount of vibrations. Although the slab tracks have experienced improvements in their applications in high-speed railway lines compared with traditional ballasted tracks, the slab tracks still exhibit certain disadvantages. Premature structural damage has oc- curred in nearly all kinds of the slab tracks caused by a va- riety of factors. On the Chinese high-speed railway lines, the damage or deterioration of the CA mortar layer are rec-