Research On Influence Of CRTSII Track Slab Void And Crack On Modal Parameters Of Track System

CRTSⅡ slab ballastless track is widely used in China.However,due to the high-speed railway operation characteristics of high speed,high traffic density and complex service environment,a series of track diseases have occurred in CRTSⅡ slab ballastless track in recent years.Among them,the track slab void disease has great harm to the service performance of the structure,and the track slab crack disease is particularly common in CRTSII ballastless track,so it needs to be focused on.Considering that the structural modal parameters are the inherent vibration characteristics of the structure,when the CRTSⅡ slab ballastless track is damaged,the constraint conditions of the track will have different degrees of reduction,and then affect the changes of structural modal parameters.The damage state of ballastless track is closely related to the modal parameters of the track.By studying the change law of modal parameters of ballastless track under the condition of track slab void and crack,and mastering the modal parameters characteristics of ctrsii slab ballastless track under the condition of track slab void and crack,the service state of track structure can be evaluated from the perspective of modal.At the same time,based on the specific modal characteristic parameters,it can also identify and locate the internal damage of ballastless track,and guide the track maintenance.Therefore,it is necessary to study the influence of CRTSII track slab void and crack on track system modal parameters.This article relies on the National Natural Science Foundation of China(high speed rail joint fund)(U1734206).The model of CRTSII slab ballastless track is established.Based on the model,the modal characteristics of CRTSII slab ballastless track under undamaged condition are analyzed,and the influencing factors of modal parameters are studied;The influence of void and crack on modal parameters of ballastless track is studied;Finally,combined with the above research results,the modal characteristic parameters are applied to locate and identify the track diseases,and the suggestions for track maintenance and repair are provided based on the modal repair performance of materials.The specific research contents and results are as follows:(1)The model of CRTSII slab ballastless track is established,and the void and crack of track slab are accurately simulated.Finally,the model is verified from multiple angles.The finite element model of CRTSII slab ballastless track is established by using finite element software;The setting method of track slab void and crack disease in the model is determined,and the track slab void and crack disease are accurately simulated in the model;The modal test of CRTSII slab ballastless track is carried out and the modal parameters of track structure are obtained.The simulation results are compared with the modal test results to verify the accuracy and reliability of the finite element model of CRTSII slab ballastless track.The accuracy and reliability of the disease model are verified by comparing with the calculation results in the existing literature.(2)Based on the modal analysis theory,the modal analysis of CRTSII slab ballastless track is carried out by using the finite element model,and the influence factors of modal parameters of ballastless track are further studied.Combined with structural dynamics and modal superposition method,the theoretical modal frequencies and modes of rail and track slab are analyzed.The modal analysis of CRTSII slab ballastless track is carried out by using the established finite element model.The modal parameters of CRTSII slab ballastless track under undamaged condition are obtained,and the modal shapes of rail and slab are summarized and described systematically.Furthermore,the influence of structural material parameters and structural constraints on modal parameters of CRTSII slab ballastless track is studied.(3)The change law of modal parameters of CRTSⅡ slab ballastless track is studied under the conditions of slab void disease,slab crack disease and composite disease of slab void crack.The model of CRTSII slab ballastless track can be used to simulate the slab void and crack accurately,and the change law of modal parameters is analyzed under the condition of slab void and crack disease.Aiming at the defect of track slab void,the variation of modal parameters under different void length,void width and void position is studied;Aiming at the crack disease of track slab,the change law of modal parameters under different crack width,crack degree,crack length and crack position is studied;Aiming at the composite diseases of void and crack in track slab,the variation of modal parameters under the conditions of multiple void diseases,multiple crack diseases,void and crack diseases existing at the same time are studied.(4)Based on the modal characteristic parameters,the location and identification of track slab void and crack diseases are studied,and the modal repair performance of disease repair materials is analyzed,which provides suggestions for track maintenance.Taking full account of the changes of modal parameters of CRTSII slab ballastless track before and after the occurrence of diseases,two modal characteristic parameters,displacement modal mode change rate and strain modal mode change amount,are used to locate and identify the defects of slab voids and cracks,and a method of disease identification based on the area coverage rate of disease identification is proposed.The modal repair performance of different elastic modulus of repair materials for track slab voids and cracks is compared and analyzed.Through the analysis of track modal frequency growth and track modal frequency offset after repair with different elastic modulus materials,the range of elastic modulus of repair materials for track slab voids and cracks is proposed.