Research On Void Detection Method Of CRTS Ⅱ Slab Track Based On Transient Impulse Response

The CA mortar layer void is one of the most serious diseases of CRTS Ⅱ slab track at present.It is difficult to detect voids effectively by existing methods.To solve this problem,this paper studied the dynamic response characteristics of ballastless track before and after the impact load,a set of methods for identifying voids of ballastless track based on transient shock response was proposed.By analyzing the vibration response of the track board under the impact load,the damage characteristic index was extracted to identify the void,which provides a new idea and method for the CA mortars.The main research contents are as follows:(1)According to the vibration response characteristics of ballastless track,the loading scheme and the measurement point layout scheme were optimized and selected.According to the difference of the vibration response of the track board with different structural states,the feasibility of the detection method of the ballastless track based on the transient impact response was carried out.(2)The finite element model of ballastless track structure was established,and different working conditions was set.The vibration response acceleration data of ballastless track under the impact load was extracted,and the signal characteristics were preliminarily analyzed.(3)Using wavelet packet frequency band energy,singular value,information entropy,and pearson correlation coefficient and vibration transfer rate damage feature extraction method,the void characteristic index of simulation acceleration signal was analyzed and optimized from many angles,and the high sensitivity index of void characteristic of ballastless track was finally selected.(4)Through principal component analysis,this paper decreased dimensions for the feature index of pre-selected ballastless voids and a new identification index was formed.The identification model of damage detection for void categories was established by using support vector machine.After the principal component analysis and calculation,the sample data was input to support vector.The identification of void type was realized,the detection accuracy was improved,and the calculation quantity was reduced.(5)The verification test was carried out for CRTS Ⅱ slab track with defect.According to the measured test data,the damage feature was extractred.The method of principal component analysis combined with support vector machine was used to effectively identify the voids,and verified the applicability of the method of void identify for ballastless track based on transient impulse response.