Waveform distortion by 2-step modeling ground vibration from trains

2017 International Conference on Structural, Mechanical and Materials Engineering

材料科学;力学

Wang, F.^1 ; Chen, W.^1 ; Zhang, J.^1 ; Li, F.^1 ; Liu, H.^1 ; Chen, X.^2 ; Pan, Y.^1 ; Li, G.^1 ; Xiao, F.^1

School of Civil Engineering, Heilongjiang University, Harbin, Heilongjiang

150080, China^1

School of Civil Engineering, Central South University, Changsha, Hunan

410075, China^2

关键词: Ground vibration;    Ground-borne vibrations;    Higher frequencies;    Load frequency;    Numerical research;    Speed of trains;    Very low frequency;    Waveform distortions;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/248/1/012020/pdf
DOI  :  10.1088/1757-899X/248/1/012020

来源: IOP

【 摘 要 】

The 2-step procedure is widely used in numerical research on ground vibrations from trains. The ground is inconsistently represented by a simplified model in the first step and by a refined model in the second step, which may lead to distortions in the simulation results. In order to reveal this modeling error, time histories of ground-borne vibrations were computed based on the 2-step procedure and then compared with the results from a benchmark procedure of the whole system. All parameters involved were intentionally set as equal for the 2 methods, which ensures that differences in the results originated from the inconsistencies of the ground model. Excited by wheel loads of low speeds such as 60 km/h and low frequencies less than 8 Hz, the computed responses of the subgrade were quite close to the benchmarks. However, notable distortions were found in all loading cases at higher frequencies. Moreover, significant underestimation of intensity occurred when load frequencies equaled 16 Hz. This occurred not only at the subgrade but also at the points 10 m and 20 m away from the track. When the load speed was increased to 350 km/h, all computed waveforms were distorted, including the responses to the loads at very low frequencies. The modeling error found herein suggests that the ground models in the 2 steps should be calibrated in terms of frequency bands to be investigated, and the speed of train should be taken into account at the same time.