Research On Crack State Identification Device Of Ballastless Ballast By Falling Weight Method

Ballastless track has become an important infrastructure in railway transportation because of its unique advantages.However,due to the long-term impact of the complex environment and the reciprocating loads of trains,cracks and other damages will inevitably occur.The damage will directly affect the service performance of the track.If the damage state can not be grasped and the using performance of the track structure can not be evaluated in time,even the railway operation safety will be threatened.In order to improve the accuracy of crack state identification of ballastless track bed,a set of falling weight method crack state identification device of ballastless track bed is designed,and the parameters of the device are optimized.(1)On the basis of previous studies,frequency band energy,energy ratio,correlation coefficient,Euclidean distance and vibration transmission rate were extracted as the characteristic indexes to characterize the damage state of cracks by using wavelet packet decomposition,correlation degree and transmissibility analysis methods,and the identification method of the ballastless track-bed crack state by falling weight method was determined.(2)Combined with the structural characteristics of ballastless track bed,a set of identification device for crack damage state of ballastless track bed by falling weight method was designed to realize the accuracy control of impact height of falling weight,which greatly reduced the dependence on operators,so that the impact energy was more concentrated and the impact was more stable.(3)In order to improve the identification accuracy of the ballastless track bed crack state identification device by falling weight method,the calculation model of cushion impact response was established to study the cushion material and parameters under the load transfer parts.Four kinds of materials,steel(St),aluminum(Al),rubber(rigid,Ru)and PVC,were analyzed and processed from three aspects: time domain,transmissibility and equipment performance requirements,and Ru material with a thickness of 10 mm was determined as the cushion for crack recognition of ballastless track bed.(4)By using the control variable method and simulation calculation,the combination schemes of falling weight and impact height were optimized.The variation of the crack state characteristic index under different combinations was analyzed,and the accuracy of four combinations in identifying the same crack damage state under the same conditions was analyzed through the ballastless track bed crack state identification method by falling weight method.The best crack-detection parameter of the crack damage state identification device by falling weight method was determined as the falling weight was 10 kg and the impact height was 50 cm,which further improved the accuracy of the device in identifying the crack state.(5)The crack damage state of the track bed slab in the training base was identified,and the crack state identification method of the ballastless track bed by the falling weight method effectively identified the crack damage state,which verified the applicability of the ballastless track crack state identification device by falling weight method and the accuracy of the identification result.