Zhai Wanming

PSD of ballastless track irregularities of high-speed railway

The calculation method, fitting function and fitting spectrum of power spectral density (PSD) of track irregularity were proposed in the paper. To improve the calculation accuracy of PSD of track irregularity, a linear interpolation method and a wavelet analysis method are given and used to eliminate the outliers and trends in the track irregularities. The paper describes the window function, window length and PSD estimation method to calculate track irregularity PSD. For comparison the track irregularity power spectral densities (PSDs) calculated with different window functions, window lengths and PSD estimation methods. Combing the above mentioned results and the data from the high speed comprehensive inspection train, the paper determines the track irregularity PSD fitting equation and introduces the frequency multiplication energy table to reflect the impact of track periodical structure of High Speed Railway. PSD of ballastless track irregularities of high-speed railway includes fitting spectrum and frequency multiplication energy table, which provides basis for maintenance and optimization design for High Speed Railway.

Basic scientific issues on dynamic performance evolution of the high-speed railway infrastructure and its service safety

The development of Chinese high-speed railway has entered the new stage of long-term safe and stable operations from the stage of large-scale constructions. How to scientifically maintain the large-scale operating lines, with the aim of holding a high operation quality of the high-speed railway characterized with a high safety, a high stability, and a high reliability during its long-term operation, is a key research task currently faced by China. Based on the summary and analysis of construction characteristics and operation environments of Chinese high-speed railway infrastructures, this paper proposes three key scientific issues on dynamic performance evolution of the high-speed railway infrastructure and its service safety. They include dynamic performance evolution of the critical materials and structures of the high-speed railway infrastructures subjected to repeated train and environment loads, the mapping relationship between the cumulative deformation of the high-speed railway infrastructures and the rail surface geometry, and the interaction and evolution mechanism between the infrastructure deteriorations and dynamic performances of the coupled high-speed train-infrastructure system. Then this paper reviews the current research status and the latest progress on the above three scientific issues, and points out the developing trends and the fundamental research works that need to be focused on and strengthened in the future.

Mapping relationship between uneven settlement of subgrade and rail deformation in subgrade-bridge transition section and its dynamic application

The uneven settlement of subgrade-bridge transition section has a great influence on the driving safety and comfort of high-speed vehicles. This paper studies the mapping relationship between uneven settlement of subgrade and rail deformation in this section and it has been used to analyze the dynamic characteristics of the high-speed train when it is passing through the transition section. After the mechanism analysis of rail deformation, the subgrade-bridge transition section with CRTS-III slab ballastless track is built by finite element method (FEM). Mapping relationship between uneven settlement of subgrade and rail deformation can be obtained by large amounts of calculation. Based on the rail deformation curves from FEM model, the functional expression of the mapping relationship is given using least squares polynomial method. Finally, based on train-track coupled dynamics, the dynamic behaviors of the high speed train are analyzed on different conditions. The results show that there is a mapping relationship between settlement of subgrade and rail deformation, which can be given by a function. The function can describe the rail deformation accurately and reliably in transition section. The uneven settlement amplitude will not influence the wheel and rail force. However, the acceleration of carbody will increase with greater amplitude of settlement. The results of this paper can be the reference to the construction and maintenance of subgrade-bridge transition section.

Experimental Study on Vibration Of Slab Track on Subgrade under the dynamic loads

Slab track on subgrade was paved for the first time on Sui-Yu railway line in China. The dynamic performance of track structure was tested under train load, with the passenger train and the freight train at variable speeds, in order to analyse its vibration and deformation characteristics. The displacement of track structure was obtained from a self-assembly displacement meter with half bridge converter on a cantilever beam of uniform strength. Vibration measurements have been performed in the test. The signals were preamplified, then data acquisition system Wavebook512, combined with software platform Lab View, were used to sample and process the signals in real-time.