Abstract
As a newly appeared defect under slab tracks in high-speed railways, mud pumping weakens the support ability of the subgrade to slab track, bringing about deviations on the vibration responses of the vehicle, slab track, and subgrade. Therefore, this paper proposes a vehicle-slab track-subgrade coupled model based on the multibody simulation principle and the finite element theory to highlight the influences of mud pumping defect. As an external excitation to this model, random track irregularity is considered. In order to simulate the mud pumping defect, the contact between the concrete base and subgrade is described as a spring-damper system. This model is validated by field test results and other simulation results, and a very good agreement is found. The vibration responses of the vehicle, slab track, and subgrade under different mud pumping lengths and train speeds are studied firstly. The deviations of vibration responses in high-speed railways induced by mud pumping are then obtained, and the limited mud pumping length is put forward finally to provide a recommendation for maintenance works of high-speed railways in practice.
Highlights
Slab tracks are widely used in high-speed railways because they have many advantages such as high stability, low deformation, and easy maintenance [1, 2]
Several scholars have studied the main parameters that induced the defect of mud pumping under slab tracks [9,10,11]. eir studies show that when the sealing material of slab tracks has some cracks, the rainwater could penetrate into the subgrade surface . e dynamic train load could arouse excess pore water pressure at the subgrade surface when the train runs upon the railway substructures. en, the fine particles of subgrade can be taken out by the rainwater under dynamic load, leading to mud pumping defect in high-speed railways
Zhang et al and Liu et al carried out a field test to study the vibration responses of slab tracks, and the results show that mud pumping will increase the vibration responses obviously [6, 7]. erefore, previous studies have mainly focused on the occurrence of mud pumping and vibration responses of slab track under certain mud pumping lengths
Summary
Slab tracks are widely used in high-speed railways because they have many advantages such as high stability, low deformation, and easy maintenance [1, 2]. Huang et al carried out a model test to analyze the long-term dynamic responses of slab track-subgrade system under mud pumping defect. It is crucial to study the vibration responses of the whole dynamic system in high-speed railways where there is mud pumping defect. Liu et al developed a train-slab track-saturated subgrade coupled model to study the dynamic responses of the railway under saturated subgrade [26]. Cai et al analyzed the mud pumping mechanism and built a finite element model to study the contact force between subgrade and slab track under mud pumping defect [27]. E vibration responses of the vehicle, slab track, and subgrade are analyzed under different mud pumping lengths and train speeds. The mud pumping of the railway is assessed on the basis of the calculated vibration responses
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