Study On Three-dimensional Array Scanning Method In High-speed Railway Under-track Structure

In recent years,China has witnessed a huge development in the construction of high-speed railway,which greatly promoted the achievement of national strategic plan “One Belt One Road”.However,with the growth of operation time and the increase of operation distance of high-speed railway,there have been injuries under the high-speed structure such as through cracks,layer alienation gap and pulping,due to various reasons including environment,design and construction.The most common injuries in the CRTS II slab type unballasted track is CA mortar layer void.Due to the construction and negative pressure of high-speed rail,there are common layer alienation gaps as well as local seams and damages,which might cause the increases of train vibration and security danger when the train at high speed.Considering the characteristics of high-speed railway line construction and CA mortar layer gap,we analyzed the characteristics and main problems of detection of high-speed railway line construction.Based on the theory of elastic wave propagation in 3 d medium,and combined the maneuverability and speed detection requirements,this paper proposes a rapid detection method which combined three-dimensional array.The detection principle,mode of execution and analytical approach of this method were introduced in detail.Firstly,by means of finite element analysis,established a defect model of three-dimensional high-speed railway to simulate the response of changes in wave field.Based on the amplitude characteristics,the spectral characteristics of the response waveform and the like,analyzing the sensitivity of the method parameters.Secondly,based on the specific disease of high-speed railway,we proposed the pattern matching method.Established a pattern matching database,and verify the database by the conditions of different distribution of CA mortar layer gap disease.High-speed rail operators for the actual line clearance from CA mortar layer provides necessary basis for the disease to carry out non-destructive testing and a further high-speed rail operators elastic wave nondestructive testing pattern matching method.Finally,according to the operating high-speed railway detection problem,developed a three-dimensional array scanning system,actualize fast three-dimensional scanning method in nighttime detection.Using the established pattern matching database,evaluated the distribution of CA mortar layer disease for a section of the Shanghai-Hangzhou high-speed railway,and verified the repairing effects.The results show that this method can effectively detect CA mortar layer delamination gaps and its distribution,and have the advantages of convenient data acquisition,testing speed,high precision.