Numerical Simulation Of Acoustic Emission Characteristics Of AC Pavement

Low temperature cracks of Asphalt concrete(referred to AC)pavement is a common phenomenon in cold areas.Assess life of the road and detect the development of low temperature cracks and test the development of low-temperature cracks as to alleviate the appearance of low-temperature cracks is become a studied topic in highway construction.Usually AC pavement structure will produce many signals in the process of deformation and failure.Among them the acoustic emission activity(characteristics)is closely related to the evolution mechanism of micro-cracks.Today,the characteristics of solid acoustic emission have been used as acoustic emission detection techniques as a dynamic non-destructive monitoring method to measure the extent of damage.Due to the high acoustic emission characteristics、the ability to evaluate the state of defects in the entire structure has been widely used in structural damage detection and material property evaluation of concrete material、AC materials、concrete beams and the like.However,there are few attempts to study the acoustic emission characteristics of AC pavement structures.The structure of AC pavement itself is larger,the indoor and outdoor test conditions is difficult to achieve the integrity of the structural damage behavior,so the research results are less.Therefore,based on the RFPA analysis system,based on the measured temperature data and structural conditions of the engineering example,the numerical simulation method is used to explore the acoustic emission characteristics of AC pavement structure.This is an attempt to use acoustic emission characteristics of pavement structure in the field of acoustic emission detection,Exploration and research results can provide reference for better application of acoustic emission detection technology in reconstruction of highway projects and have certain engineering application value.The main research contents are as follows:On the one hand,considering the nonuniformity of AC pavement,the double-layer model of non-uniform AC pavement structure is established by numerical experiment.The internal acoustic emission of AC pavement structure is superimposed on each other at different temperature drop rates,combined to form an acoustic emission rupture zone,the final acoustic emission rupture zone continues to expand until the process of structural failure damage process.The numerical results show that the faster the cooling rate,the more serious the damage inside the AC pavement structure.Moreover,the process of acoustic emission reveals that AC road surface cracks are produced in two cases,one is with the temperature changes that extended from the table,the other from the surface of the surface layer of the middle layer gradually developed.On the basis of this,this paper further analyzes the relationship between temperature-stress-acoustic emission and discusses the effects of different cooling rate on the "embrittlement temperature" and the peak time of AC emission.On the other hand,on the basis of the two-layer model of AC pavement structure,the different intermittent cracks with different explorations are added in the surface layer,retrieved the acoustic evolution process of AC pavement process with equidistant crack.It is found that the internal acoustic emission characteristics of AC pavement structures with different crack spacing are different.The larger the interval of the crack is few the number of acoustic emission,and the more the number of acoustic emission is the small interval of the crack.In addition,comparison the acoustic failure of the pavement between among larger and small cracks.The depth of the acoustic emission rupture zone is relatively deep and the acoustic emission is mainly observed in the grassroots,and the small spacing cracks is equally disturbed more serious is mainly the surface layer.This shows that different intervals of cracks on the road surface and the grassroots damage degree are different.So the default spacing of cracks to prevent low-temperature environment on the pavement structure of the grassroots damage,can save the cost of engineering renovation.