Research And Evaluation Of Asphalt Pavement Crack Detection Method

Asphalt concrete pavement is easy to produce surface cracks and internal cracks under the action of load and temperature.In the maintenance of asphalt pavement cracks,whether the surface crack and internal crack can be detected timely and accurately is very important.At present,the detection and identification of cracks are mainly focused on the surface crack,but the detection of internal cracks is insufficient,which makes the internal crack cannot be found and treated in time,thus affecting the overall structure and performance of the pavement,and making appropriate maintenance decisions and effective maintenance measures.Based on this,this paper carried out the research of crack detection methods and internal crack prediction based on surface crack detection.Firstly,in the research of surface crack detection methods,two-dimensional image detection method,three-dimensional image detection method,UAV detection method and infrared thermal imaging method are used to detect the surface crack,and the practical method of asphalt pavement surface crack detection is proposed by comprehensively comparing and analyzing the factors of accuracy,convenience,economy and efficiency.In addition,in order to have a more accurate judgment of the pavement cracking condition,based on a large number of research and field coring on the pavement cracks,this paper summarizes the manifestation of the reflection crack on the pavement surface,and obtains the number of reflection cracks on the pavement surface.The GPR method is used to detect the internal cracks.Based on the radar image of the surface crack,the image form of the cracks is judged,and the location of the internal crack is found.Core verification is carried out for the internal cracks found,and then the feasibility of the method is evaluated.Secondly,in order to predict the time of the internal crack development to the surface,the finite element simulation of the internal crack propagation process is carried out.The pavement temperature model is established,the thermal properties of pavement materials are set,and the temperature field of pavement is obtained.Paris formula is used to establish the damage model,which is combined with XFEM in ABAQUS software to establish the pavement finite element model with internal cracks.The temperature field of pavement is introduced into the model,and the corresponding vehicle load is applied to realize the simulation of the whole process of pavement crack propagation under thermal mechanical coupling.The relationship between internal crack propagation depth and time is obtained,and the time of internal crack development to the surface at different depths is predicted.Finally,the number of internal cracks and their propagation time are predicted based on the surface cracks,and the propagation process of multiple internal cracks to the surface is simulated and analyzed.Through theoretical calculation,the minimum spacing of base cracks is obtained,and on this basis,the spacing of cracks is changed many times to simulate the propagation law of internal cracks of pavement under different spacing.Through the comprehensive analysis of the process of multiple cracks extending to the surface under different spacing,the minimum spacing of internal cracks is further determined,and the general spacing between cracks which can be ignored is obtained.Based on the number of surface reflection cracks,the prediction model of internal cracks is established,and the probability of internal cracks is calculated.The applicability of the model is verified by comparing the prediction of internal cracks and the actual number of internal cracks in specific road sections,and the residual propagation time of internal cracks is estimated combined with the crack propagation rate under different crack spacing.