Research On Real-time Measurement Of Compactness Of Vibration Compacted Asphalt Road

With the development of traffic road construction,the highway operation time is prolonged,the traffic volume is increasingly heavy,the vehicle load is also increasing,and the quality problem of highway construction has attracted more and more attention.Compaction degree as an important index to measure the quality of asphalt pavement,poor compaction will cause a variety of pavement diseases,so that the pavement can not reach the service life.However,the traditional compaction testing method has lag and randomness,so it can not detect the pavement compaction in a comprehensive way in time,so it is an important means to improve the pavement construction quality and has important practical significance to adopt the effective compaction real-time detection method.Based on the traffic science and technology project of yunnan province((A)15),this paper makes an in-depth study on the mechanism of vibration compaction,the influencing factors of compaction degree,the system model of "vibratory roller-pitch pavement ",the relationship between vibration acceleration and compaction degree,and the development of real-time measuring system for compaction degree.The main research results are as follows:(1)The mechanism of the vibratory roller is analyzed.According to the rheological properties of asphalt mixture,the elastic-plastic deformation characteristics of the mixture are analyzed.It is concluded that the maximum deformation of the mixture is located at the bottom of the vibratory wheel,and the distance from the vibratory wheel is smaller.(2)Based on the vibration compaction mechanism and Newton’s second law,the vibration compaction system is simplified,and the mathematical model of two degrees of freedom of the "vibratory roller-pitch pavement" system is established;the mathematical solution of the system model is carried out,and the expression of the relationship between vibration acceleration and pavement stiffness is obtained.At the same time,the Matlab simulation results show that the road compaction degree and vibration acceleration have positive correlation.(3)The DH5902 dynamic acquisition system is selected to determine the type and installation position of the acceleration sensor,and the vibration acceleration is collected.Through the processing of the collected vibration acceleration signal,the measured maximum value of each vibration period is determined as the effective value,and the principle of outputting an effective value with 20 vibration periods,i.e.0.4 s is taken as the principle.The rationality of the system model of "vibratory roller-pitch pavement" is determined based on the simulation results and the measured results.(4)based on Lab VIEW software,combined with GPS global positioning technology and 5 G wireless transmission technology,a real-time detection system for asphalt pavement compaction with the functions of rolling track positioning,data wireless transmission,compaction degree,vibration acceleration,rolling times and real-time display of rolling time is built.Combined with the test,the traditional compaction testing method and real-time compaction testing method are compared and analyzed,and the accuracy and applicability of the real-time measurement system of asphalt pavement compaction degree are verified.The results show that the new compaction measurement method solves the problem that the pavement compaction can not be detected in time and comprehensively,and overcomes the deficiency of the traditional compaction measurement method.