Study On Continuous Detecting Technology Of Construction Temperature And Compaction Quality Of Asphalt Surface Course

In recent years,due to the increase in high-speed and heavy-load traffic and the climatic environment becoming more complex,higher requirements have been put forward on the quality of highway construction.However,serious early damage and insufficient durability of asphalt pavement are still major problems in highway infrastructure.One of the main reasons for undurability is that the quality control of the pavement cannot be guaranteed during the construction process.Especially,the surface construction temperature and compaction quality have an important impact on durability.However,the control of construction temperature and compaction quality during the construction of asphalt pavement has the problems of ‘replace the surface with points,passive and low efficiency’,and cannot achieve continuous and high-precision detection.Therefore,a method that can achieve high-precision and continuous detection of construction temperature and compaction quality is proposed to improve the construction quality,to ensure the pavement’s durability.It is of great significance to solve the problem of weak links in the current construction process control,and promote the high-quality development of highway construction,and realize long-life or durable asphalt pavement.Firstly,in view of the problem that the non-contact temperature measurement method can only achieve continuous detection of the surface temperature about the asphalt mixture,but the surface and internal temperatures are inconsistent under the action of external factors.Therefore,a non-contact high-precision temperature measurement device considering external factors has been developed.Clarified the influence of single external factor on the internal and surface temperature between AC-16 and SMA-16 asphalt mixtures,and the type of asphalt mixture has no significant effect on the temperature difference.Based on the orthogonal experiment,the order of the influence of external factors on the temperature between internal and surface is determined: solar radiation>environmental temperature>wind speed>humidity(standard temperature at 150℃),and solar radiation>wind speed>environmental temperature>humidity(other standard temperature).Choose solar radiation,wind speed and ambient temperature as the main external factors.By comparing and analyzing the prediction effects of internal temperature prediction models based on multiple regression and support vector machines,the prediction model based on support vector machines with an average relative error of the prediction results of 1.7% was selected as the highprecision prediction model of internal temperature during the construction process.Secondly,the dynamic analysis of the interaction between the vibratory roller and the compressed asphalt mixture during the vibratory compaction of the asphalt surface is carried out.Combined with the numerical simulation analysis,the vibration acceleration amplitude in the vertical direction of the vibrating wheel is selected as the continuous inspection index of the compaction quality.It is clear that the greater the degree of compaction and the lower the temperature,the more significant the effect of compaction temperature on the relationship between the degree of compaction and the amplitude of vibration acceleration.Thirdly,based on the finite element analysis method,the vibration compaction process of the asphalt pavement was simulated and analyzed.The vertical stress distribution in the pavement structure under the action of vibration compaction was clarified.It is proposed to determine the impact depth of the vibrating wheel by the amplitude of vertical stress with depth attenuation.It is clarified that the impact depth is about 0.6～0.7m and 0.5m on the flexible or semi-rigid base asphalt pavement.It is clarified that both the semi-rigid and flexible base modulus have a significant impact on the vibration acceleration,and the amplitude caused by the change of the flexible base modulus is smaller than that of the semi-rigid base.Based on the support vector machine,two types of base asphalt surface compaction prediction models were constructed,and the average relative errors of the prediction models were 1.04% and 1.49%.Finally,based on the indoor vibration compaction test,it is clear that the asphalt surface compaction degree,compaction temperature and semi-rigid base modulus affect the acceleration amplitude,which verifies the correctness of the conclusions obtained by numerical simulation and simulation analysis.The average relative error of the prediction results obtained after training the compaction prediction model with experimental data is only 0.44%,and the prediction effect is good.