Three-Dimensional Numerical Simulation of Vehicle Dynamic Load and Dynamic Response for Ballastless Track Subgrade: Fid-Bau Portal

Three-Dimensional Numerical Simulation of Vehicle Dynamic Load and Dynamic Response for Ballastless Track Subgrade

Wang, Xuan / Cheng, Hao / Zhang, Biao / Zhang, Jiasheng / Wang, Qiyun

With the development of the high-speed railway, the ballastless track is widely applied and the dynamic characteristics of subgrade are the bases of the design, construction, and maintenance of the ballastless track/subgrade system. In a sense, the distribution rule of dynamic response under the action of train loads and the influence of subgrade parameters lags far behind the construction of the high-speed railway in engineering because of their complication. Dynamic system which was composed of rail, track, and roadbed is so complex that it cannot be solved depending on available theory. In this paper, the numerical simulation method was introduced to describe the dynamic action of roadbed which beard high-speed rail loads. Therefore, a 3-d finite element model of the track/subgrade system was established with the aid of ANSYS for the dynamic response of ballastless track subgrade which bears vehicle dynamic loads and loads input behavior. At the same time, the choice method and basis of a unit-type, constitutive model of subgrade and material parameters were established. According to distributed mode and behaviors of vehicle dynamic load and load input characteristics, a 2-car and 8-wheelset vehicle model was introduced to get contact pressure time-history curves of fastening when two bogies pass between neighboring cars through Fourier transform. Furthermore, the rationality and applicability of model were verified depending on the data which came from the test in situ. Vertical dynamic stresses, dynamic displacement, and dynamic acceleration were calculated for CRTSII-type slab ballastless track and double-block ballastless track when train passes which its speed was 300 km/h and axle load was 170 kN. In addition, the relationship between all those response laws and rail/subgrade construction was analyzed. Interrelated analyses conclude that vertical dynamic stresses, dynamic displacement, and dynamic acceleration decay as roadbed deepens, and dynamic acceleration decays faster. In addition, the type of track which influenced dynamic response only focuses on the top of the roadbed.