The Traffic Characteristics And Pavement Performance Deterioration Model Of The Trunk Highway In Chongqing City

In order to improve the level of highway maintenance and maintenance quality,and further optimize the maintenance strategy,overall traffic distribution characteristics of trunk highway,service life prediction of heavy load traffic pavement and pavement decay model are studied based on 136 traffic station,80 overload and overrun detection station,136 section of road traffic detection data and 89 pavement maintenance design in Chongqing,from October 2013?2015 December.First of all,the characteristics and development of pavement diseases are analyzed form the natural environment,traffic load,the type of pavement structure and construction variability by Single-factor analysis according to the real data of 136 trunk highway in Chongqing.The results show that:The types and characteristics of pavement diseases are different due to different influencing factors:crack diseases is main diseases in light traffic section,accounting for about 60?70%;medium traffic and more sections of disease mainly are pouring,cracking and repair,accounting for about 90%.The main road surface thickness of is 9cm,10cm,and one of the main factors to reduce the pavement life is the whole thin pavement structure:a large area of the trunk highway was opened to traffic in the early 1?5 years when the layer thickness is less than or equal to 9cm;the pavement service life is generally maintained at 3?8 when the road surface layer thickness is greater than 9cm.Secondly,from the three aspects of parameters of vehicle spectrum,traffic distribution and axial load spectrum,study the overall distribution of traffic volume and heavy load of trunk highway,the regional distribution characteristics and the change rules with time.The results showed that the distribution coefficient of heavy truck is mainly concentrated in the 10%?50%,the models are mainly focus on 2 axis(single axis wheel)and 3 axis(double shaft wheel),4 axle vehicle(triple shaft wheel)and the distribution of models has regional differences:the truck of 2 axle U113 type and the 4 axle U12 type are mainly distributed in the I and IV area;the U12 truck is accounted for about 30%?60%? and ? area.The truck overrun rate is mainly concentrated in the 0?30%,about 40?80%of the sections of the problem of varying degrees of overload,and the single axial overload rate is mainly concentrated in the 30%-90%.The overload problem is common and serious.Furthermore,effect of heavy load on fatigue life of asphalt layer is analysised from two angles of numerical simulation and numerical calculation.Based on cumulative equivalent axle,the pavement service life is estimated.The results show that:the relationship between fatigue life and axial load is a significant negative power function with the increase of axle load;When the axial load is increased from 120KN to 160KN,the axle load for each 20KN increase is about 20%reduction of fatigue life;When the load increases to 300KN,fatigue life there is reduction of 97%.After reduction of heavy load traffic,the cumulative effect of the equivalent axle load which can bear in the design period of the trunk highway is about 2.0 X 107?4.5�107.By comparison,it is found that there are about 7%of the road is open to traffic less than one year,and the number of fatigue action is exceeded.The service life of trunk highway is mainly concentrated in 2?3,only about 15%of the road section can be over 5 years.Finally,based on the survey data of the road traffic conditions in Chongqing City,the degradation model of pavement performance is established,and the model parameters are calibrated.The results show that the decay rate increases gradually with the increase of ?or?.The initial decay is very slow,and this kind of situation is extremely rare in the actual project when ?<0.04 or?<0.1;When ?>2or?>1,the rate of decline is too fast.So,the parameters is 0.1?1.0,0.04?0.20 respectively.Decay curve and a three-dimensional array(a,?)are in one-to-one correspondence,parameter mathematical model has clear physical meaning.The model can be transplanted,the prediction precision is less than 8%,high fitting degree,to better fit the different regions,different traffic classes or base type pavement performance decay law,provide a reference for the decision of maintenance,the model parameters have clear mathematical physics meaning and strong portability.The model prediction accuracy is controlled within 8%,which can better simulate the law of pavement decay,which can provide reference for maintenance decision.