Research On Relationship Between Traffic Volume And Dynamic Load Based On Time Domain Model

Currently,the research of vehicle dynamic load is one of the hot issues in road design,pavement maintenance and so on.It is able to calculate pavement load more accurate,according to the research and application of vehicle dynamic load,thus enhance the prediction accuracy of pavement damage rate,reduce the cost of pavement maintenance,and increase service life,etc.However,static load is widely adopted to design instead of dynamic load in the present road design specification.Consequently,it is still actual meaningful and engineering valuable to research vehicle dynamic load.Speed as an important factor plays an essential role in calculating load.However,it's likely to cause barriers in practical application when accurate overall speed data is obtained difficultly because of limit of acquisition equipment.So to solve this problem,traffic volume which can do mathematical derivation to overall speed and still be more accurate and easier to obtain than speed data,was adopted to replace overall speed to research effects of traffic volume on vehicle dynamic load in urban road.Based on the actual data of main road,secondary road and urban expressway in Tangshan,Hebei,the Greenshields model,S model and BPR model were recalibrated.Finally,the recalibrated BPR model was selected as basic model according to analysis result.The function between volume and road roughness was established with timedomain model based on the sum of sinusoids.To verify achievement,typical time domain spectrums were given.Based on established vehicle dynamics equation with 2DOF,function between traffic volume and dynamic load was established.The dynamics equations were solved with the mode-superposition and Newmark-? respectively,and load spectrums of dynamic coefficient were given in different conditions.The results show that traffic volume has great influence on vehicle dynamic load.In the same level road,the heavier traffic is,the lower speed will be.And so will the smaller coefficient be.Dynamic load changes are small under the condition of lower and higher traffic volume.Reference to research data,this interval that changes larger is 500-1000 pcu/h/lane.The results solved by mode-superposition method and Newmark-? method are all in accordance with the actual change law,and thus the validity and feasibility of the traffic volume as the parameter to calculate vehicle dynamic load are proven.