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

With the increase of traffic volume and traffic load,a large number of road surfaces have different degrees of damage before reaching the design service life,resulting in economic losses and bringing many potential safety hazards.The main reason for this early damage is that the construction equipment,construction technology or construction materials are not strictly controlled during the construction process,resulting in insufficient pavement compaction and unevenness,and the traditional compaction detection method is time-consuming and laborious,and its sampling detection method determines that it can not achieve continuous real-time detection of the compacted pavement,so in order to better improve the quality of pavement compaction,it is of practical significance to develop a continuous real-time detection system that can timely and accurately evaluate the compaction of the entire construction road.The thesis relies on the science and technology project of Yunnan Communications Department and the science and technology project of Zhengzhou Road and Bridge Group of Henan Province,and establishes a dynamic model of "vibrating wheel-asphalt mixture" from the theoretical aspect according to the vibration compaction process,studies the mathematical relationship between vibration acceleration and stiffness,optimizes the algorithm of data processing method in the compaction process,studies the relationship between vibration acceleration and compaction degree under different influencing factors through model simulation and on-site measured signals,designs a continuous real-time detection system for asphalt pavement compaction and carries out engineering verification.The following main conclusions are drawn:(1)According to the working principle of vibrating compaction and the analysis of vibrating compaction process,the dynamic model of "vibrating wheel-asphalt mixture" is established,and a numerical simulation model is established on the MATLAB/simulink platform according to the dynamic equation,and the relationship between asphalt pavement stiffness and vibration acceleration under different models is simulated and analyzed,and it is found that the two are positively correlated and have a strong linear correlation.(2)The relationship between pavement stiffness and vibration acceleration under different damping and different follow-up masses of different models is studied,and the three-dimensional surface diagram of damping-stiffness-vibration acceleration and the three-dimensional surface diagram of follower mass-stiffness-vibration acceleration are obtained.It is clear that under the condition of certain stiffness,damping is negatively correlated with vibration acceleration,and follow-up mass and vibration acceleration are positively correlated,and vibration acceleration can be used to characterize the compaction degree of pavement.(3)The sensor type and its installation method are determined,and the data collector is selected and the acquired acceleration signal is filtered.Based on the measured data,the standard deviation of the rms value of vibration acceleration by the mean method is analyzed,and then a step iterative fitting algorithm is proposed,and a comparative analysis is carried out from the aspects of data utilization,accuracy and accuracy,and the results show that the data utilization rate of the iterative method can reach more than 9 times that of the mean method using the second-order fitting formula.The maximum accuracy is 0.485 in the period T=20,which is 43.7% higher than that,and the minimum value is 0.4218 at T=12,which is 38.8% higher than that.Using the chi-square goodness-of-fit test,when the original data are the same and the total sample size is the same,the proportion of residual results of the step iterative method that conform to the null hypothesis is 88.3%,which is higher than that obtained by the mean method.The real-time operation and continuity of the program structure operation are verified by the built-in profiler timing function and breakpoint test function of MATLAB,and the results show that the processing time is about 1/3 of the total construction time,the data processing rate is significantly faster than the construction data generation rate,and the real-time continuity of data processing can be guaranteed and realized.(4)The mathematical relationship between the collected acceleration effective value and the measured corresponding compaction degree is obtained,and the trend is consistent,indicating that the vibration acceleration have a good positive linear relationship with the compaction degree.Based on the measured acceleration and compaction degree data on site,the compaction degree and acceleration data under different surface layers of different thicknesses and different models are fitted,and the vibration acceleration-compaction relationship curve and the thickness-vibration acceleration-compaction degree three-dimensional relationship surface under different thicknesses,different models and different surface layers are obtained,and then the vibration acceleration-compaction fitting relationship corrected after considering the influence of thickness parameters was obtained.Based on the measured acceleration and compaction data,the compaction degree and acceleration data under different surface layers of different temperatures and different models were fitted,and the vibration acceleration-compaction relationship curve and the temperature-vibration accelerationcompaction degree three-dimensional relationship surface under different temperatures,different models and different surface layers are obtained,and the vibration acceleration-compaction fitting relationship modified after considering the influence of temperature parameters is further obtained.(5)The GPS acquisition hardware is determined,and the conversion of WGS84 geodetic coordinate system based on GPS positioning technology from latitude and longitude to the coordinate system of the construction site is programmed,and the development of the system positioning module is completed,which realized the continuous real-time display of the roller’s rolling trajectory and the continuous realtime detection of compaction.Based on the Lab VIEW development platform,a continuous real-time detection system for asphalt pavement compaction is designed with compaction as the ultimate control goal.Relying on the Yunnan scientific research project,the engineering measurement is carried out in the Guangna test section,and the results show that the compaction detection system can realize the real-time collection and processing of compaction process data,the automatic detection of the rolling trajectory and the number of rolling passes,and the real-time display of the change of pavement compaction,and verify the reliability of the continuous real-time testing system of compaction by comparing the system test results with the on-site test results.