Abstract
Cement asphalt mortar (CA) disengagement of a ballastless track will induce changes of dynamic response of a passing vehicle, which can accordingly be used to estimate the disengagement degree. In this paper, a novel method called CA mortar disengagement degree estimation algorithm (CMDEA) is proposed through an analysis of wheel acceleration of a passing vehicle. The disengagement degree estimation is transformed into an optimization problem by regarding the CA mortar disengagement degree as a parameter of a vehicle-track coupling model. An improved genetic algorithm with a shifting window is employed for the parameter optimization, which is split into a number of phases and whose initial values are given in terms of a priori probabilities. The accuracy and robustness of the estimation are discussed, and the results are compared with regular genetic algorithm. The simulation results show that CMDEA can estimate CA mortar degrees with an acceptable accuracy. Meanwhile, the proposed algorithm has the advantages of a lower error value and much shorter computation time. Moreover, the robustness of the algorithm under different vehicle speeds, track irregularities, and signal noise levels is also verified.
Highlights
With the commissioning of the Beijing-Tianjin intercity railway in 2008, the running mileage of China’s high-speed railways has exceeded 20,000 kilometers
A vehicle travels over a track at a constant speed of 300 km/h. e scanning frequency used for all simulations is 10 kHz. e simulated acceleration signal of the front wheel when a vehicle crosses a track model including the hypothetical cement-emulsified asphalt (CA) mortar disengagement condition is taken as the “measured” signal, shown in Figure 4. en, the simulated response (“measured” signal) is input into CA mortar disengagement degree estimation algorithm (CMDEA), which was used to estimate the CA disengagement degrees
A CA mortar disengagement degree estimation algorithm is described based on an adapted genetic optimization algorithm. e disengagement degree estimation is transformed into an optimization problem by regarding
Summary
With the commissioning of the Beijing-Tianjin intercity railway in 2008, the running mileage of China’s high-speed railways has exceeded 20,000 kilometers. When the entire CA mortar layer is separated from the interface of the track slab, it will give rise to a complete loss of cohesion, a phenomenon known as CA mortar disengagement If it is not repaired in time, it will accelerate the structural damage of track and even have adverse effects on traffic safety. On-board methods using vehicle dynamic responses have the potential to be used as a monitoring tool to estimate track infrastructure conditions Most of these indirect methods utilize low-speed vehicles and involve disturbing normal rail traffic. The research on the estimation of CA mortar disengagement degree based on dynamic responses of passing vehicles is still a blank field.
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