The Multiclass Inverse Analysis Of The Multiphase Volume Ratio Of Asphalt Mixtures Based On Dielectric Modeling And Its Engineering Applications

Asphalt mixture is the building material of the asphalt pavement surface layer,and its material performance index detection is an important part of the non-destructive testing of asphalt pavement.Ground penetrating radar,as a broad-spectrum electromagnetic technology used to determine the distribution of underground media,has the characteristics of high efficiency,fast,continuous,non-destructive,and high resolution,and represents the development direction of non-destructive testing of road structural layers.The differences in dielectric properties of asphalt mixtures are the basis for their non-destructive testing using ground penetrating radars.The dielectric model characterizes the functional relationship between the dielectric properties of the mixture and the dielectric properties and volume ratio of each single-phase dielectric.Multiphase volume ratio is an important parameter for calculating technical indicators such as compaction,porosity,and Asphalt content.Therefore,the determination of multiphase volume ratio is the key to revealing the intrinsic relationship between the dielectric properties of asphalt mixtures and indicators such as compactness,porosity,and Asphalt content,as well as the nondestructive testing of asphalt mixtures using ground penetrating radar.In the current research,there is a lack of systematic research on the influence of multiphase volume ratio of asphalt mixtures on dielectric properties.Most of the existing classical dielectric models are proposed for two-phase media or based on certain assumptions.Whether it is suitable for the interpretation of the dielectric properties of asphalt mixtures still remains to be tested.Radar electromagnetic wave propagation simulations mostly focus on the dielectric properties of asphalt mixtures,without deeply considering the effect of multiphase volume ratio on electromagnetic wave propagation.How to build a radar electromagnetic wave propagation model based on the dielectric model is the basis for studying the multiphase volume ratio inversion and also a difficult problem to be solved.At present,the inversion methods of dielectric properties are mostly single algorithms,and their application range has certain limitations.Whether the existing inversion methods can be applied to multiphase volume ratio inversion remains to be verified.The current research situation has caused the application of ground penetrating radar to fast and non-destructive testing of asphalt pavement to some extent.Aiming at the problems of ground penetrating radar in the non-destructive testing of asphalt pavement surface,this research carried out a multiphase volume ratio inversion study of asphalt mixture.Based on the study of the dielectric properties of the composite dielectric and the theory of electromagnetic wave propagation,we conducted an experimental study on the effect of the multiphase volume ratio of the asphalt mixture on the dielectric properties.Based on China's national conditions,we built dielectric models of various types of asphalt mixtures,and built forward models of ground penetrating radar electromagnetic waves based on dielectric models.We also used multi-class inversion methods to perform inversion studies on the multiphase volume ratio of asphalt mixtures.The relevant research results and conclusions are as follows:(1)Experimental research on the influence of multiphase volume ratio of asphalt mixture on dielectric properties was carried out.Considering the heterogeneous characteristics of the asphalt mixture,we systematically study the effect of the heterogeneous volume ratio of the mixture on the dielectric property.The experimental results show that,for the same type of asphalt mixture,the volume ratio of the aggregate has the greatest influence on the dielectric properties of the mixture,and the dielectric constant of the asphalt mixture increases with the increase of the volume ratio of the aggregate.The effect of porosity on the dielectric properties of the mixture is minimal,and changes in volume ratio of aggregate and asphalt will offset the effect of changes in porosity.The effect of asphalt content on the dielectric properties of asphalt mixture is between aggregate and air.The experimental results provide basis for the establishment of the dielectric model of commonly used asphalt mixtures.(2)Based on the experiments on the dielectric properties of asphalt mixtures,we examined the rationality and applicability of existing classic dielectric models in explaining the dielectric properties of asphalt mixtures.The test results show that the existing classical dielectric model is not suitable for explaining the dielectric properties of commonly used asphalt mixtures.We established the dielectric models of AC-13,AC-16,SMA-13,and SMA-16 four commonly used asphalt mixtures,and tested the new models.The test results show that the dielectric properties of the four commonly used asphalt mixtures can be explained using the new dielectric model.The research results provide data support for the establishment of the pavement material dielectric model library,and lay a theoretical foundation for revealing the correlation between the mixture dielectric constant of the asphalt mixture and the volume ratio of each component and the determination of the multiphase volume ratio.(3)A forward model of electromagnetic wave propagation of ground penetrating radar based on asphalt mixture dielectric model was established.Through forward modeling,we study the effect of changes in asphalt mixture multiphase volume ratio on radar electromagnetic wave echo signals,and revealed the response characteristics of radar electromagnetic wave echo signals to multiphase volume ratio.Through model tests,we compared the measured waveforms with forward modeling waveforms,and evaluated the rationality and applicability of the established forward model of radar electromagnetic wave propagation based on the dielectric model.The results show that considering the dielectric model in the radar electromagnetic forward model,the inversion calculation of multiphase volume ratio becomes possible,which provides a theoretical basis and an accurate calculation model for the inversion of multiphase volume ratio of asphalt mixture.(4)Based on the dielectric model of the asphalt mixture and the forward model of radar electromagnetic wave propagation,we conducted multi-class inversion studies of the multiphase volume ratio of the asphalt mixture.By establishing five types of inversion methods including particle swarm(PSO),genetic(GA),PSO-GA hybrid,BP neural network and PSO,and BP-GA inversion for multiphase volume ratio inversion,we achieved multiphase volume ratio of multi-class inversion calculations.We verified the calculation accuracy and efficiency of multi-class inversion methods through evaluation.We study the intelligent selection of multi-class inversion methods,construct pre-judgment logic,and achieve intelligent inversion of multiphase volume ratio.We carry out engineering applications of multiphase volume ratio and multi-class inversion methods.Engineering application results have proved the feasibility and effectiveness of multiphase volume ratio inversion,and provide a new analysis method for the non-destructive testing of key indicators such as Asphalt content and compactness.In this research,a multiphase volume ratio inversion study of asphalt mixtures based on dielectric models was conducted,and a new approach for non-destructive testing of key indicators of asphalt mixtures was explored by ground penetrating radar.The research results of this study have important academic value for enriching and developing the application research of ground penetrating radar,and have broad application prospects in road nondestructive testing and construction process control.