Summary The research and development (R & D) of maglev technology had made a great progress in China since the early 1980s. Especially, a 35 km-long Shanghai high-speed maglev railway employing the German Transrapid system began to be constructed on March 1, 2001. Based on the Transrapid system, the paper develops a 10-degree-of-freedom model of maglev vehicle running over three types of guideways with constant speed. Random guideway irregularities are discussed and taken into account for simulation of the vehicle response and for evaluation of the ride comfort. Using the direct time integration method and the discrete fast Fourier transform (DFFT), random responses of the maglev vehicle-guideway systems are obtained and analyzed. Numerical results show that the resonant frequency of car body acceleration response is 0.5–1 Hz, and there is a 2.2 Hz periodic vibration due to the periodic configuration of rigid piers when the maglev vehicle travels over the elevated-beam guideway. The car body acceleration ...

Experimental validation is a precondition for dynamic simulation of high-speed train–track–bridge interaction system to be applied to railway engineering in the field. The paper first presents an onsite experiment of the train–track–bridge interaction dynamics carried out on the Beijing–Tianjin high-speed railway, and then the experimental results are used to validate the train–track–bridge interaction simulation software (TTBSIM). There is a good correlation between the calculated results and the measured data. As a case study, the Yellow River Bridge in the Beijing–Shanghai high-speed railway is studied, from modelling of the bridge structure to evaluating the dynamic performance of the train–track–bridge interaction system under the CRH₃ EMU passing through at speeds of 250–375 km/h. The calculated and measured results are also compared in the case of such a large steel bridge under high-speed moving train, demonstrating the effectiveness of the TTBSIM simulation for dynamic evaluation of complex bridge structures in high-speed railways.

Considering the real irregular shapes of ballast particles and complete track skeleton, a two-dimensional discrete element model is built to investigate the dynamic behavior of high-speed railway (HSR) ballasted track. Taking the moving wheel loads obtained from railway vehicle-track coupled dynamics simulation as the excitation inputs, the dynamic behavior of ballast particles in terms of contact force, stress, and vibration response are simulated using the discrete element model. Numerical results show that the ballast particles within the depth of 200 mm under sleepers would be most likely to carry a higher stress level when a vehicle passes by. Vibration amplitudes of ballast particles increase with the increase of vehicle speed, and the acceleration amplitudes rise sharply when the vehicle speed is higher than 200 km/h. Spectrum analyses indicate that the dominant frequencies of particle displacement and velocity are lower than 100 Hz, whereas the acceleration responses contain not only low-f...

To simulate ballast performance accurately and efficiently, the input in discrete element models should be carefully selected, including the contact model and applied particle shape. To study the effects of the contact model and applied particle shape on the ballast performance (shear strength and deformation), the direct shear test (DST) model and the large-scale process simulation test (LPST) model were developed on the basis of two types of contact models, namely the rolling resistance linear (RRL) model and the linear contact (LC) model. Particle shapes are differentiated by clumps. A clump is a sphere assembly for one ballast particle. The results show that compared with the typical LC model, the RRL method is more efficient and realistic to predict shear strength results of ballast assemblies in DSTs. In addition, the RRL contact model can also provide accurate vertical and lateral ballast deformation under the cyclic loading in LPSTs.