| CRTS Ⅱ slab ballastless track is one of the main structural forms of high-speed railway tracks in China.During operation,various diseases are difficult to avoid due to long-term coupling effects of train dynamic loads and environmental loads.Among them,the disease caused by the arch on the slab and the CA mortar void,resulting in the under-slab gap,is particularly prominent.Local unsmoothness is formed in the line,and the interaction between wheel and rail will be intensified when the train passes by,and the traffic safety will be threatened in serious cases.Therefore,it is of great practical significance to study the influence of upper arch gap and CA mortar void gap on the dynamic characteristics of vehicle and track structures.In this paper,common diseases of CRTS Ⅱ slab ballastless track on the subgrade are summarized first,and the formation reasons of upper arch gap and CA mortar void gap are analyzed.Then,based on the vehicle-track coupling dynamic theory and finite element method,a dynamic finite element analysis model of CRTS Ⅱ slab ballastless track containing gap diseases is established.Finally,the impact of upper arch gap and CA mortar void gap on the dynamic response of the vehicle-track system is studied respectively.The main research content and results are as follows.(1)A finely coupled dynamic model of vehicle-CRTS Ⅱ slab ballastless track-roadbed was established using ABAQUS finite element software.The setting methods of upper arch gap on the track plate and CA mortar void gap separation were accurately simulated in the model.Finally,the reliability of the model was verified by comparing it with existing literature calculation results.(2)Based on the dynamic model of CRTS Ⅱ track with upper arch gap,the influence of different arching separation conditions and running speed on the dynamic characteristics of the vehicle-track system was analyzed.The results show that the system dynamic response increases with the increase of gap amplitude,and first increases and then decreases with the increase of gap length.The vertical acceleration of vehicle body and the reduction rate of wheel load are more sensitive to gap amplitude than separation gap.Under the same amplitude condition,the vertical acceleration of vehicle body and the reduction rate of wheel load reach the maximum value when the separation length is 6.5m.In the conditions of 10mm/6.5m(upper arch gap amplitude/upper arch gap length),the dynamic response of the vehicle and track structure increases linearly with the increase of running speed.When the running speed is400km/h,the reduction rate of wheel load will exceed the limit value,seriously threatening the safety of train operation.(3)The effects of lateral unconnected gap,laterally connected gap and running speed on the dynamic characteristics of the vehicle-track system were analyzed when the high-speed train passes through the CA mortar void section.The results show that when the CA mortar is not completely connected laterally along the slab,the gap mainly affects the dynamic response of the track structure,and has little effect on the dynamic response of the vehicle.When the CA mortar is completely connected laterally along the slab,the dynamic responses of the vehicle,rail and slab increase with the length of the gap,while the dynamic response of the support layer decreases with the length of the gap.When the gap length exceeds 1.3 meters,the change in vehicle dynamic response will significantly increase.When the gap length reaches 1.6 meters,the vertical displacement of the rail exceeds the limit value.After the occurrence of CA mortar viod gap disease in the line,the dynamic response of the vehicle-track system will significantly increase with the increase of running speed. |
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