Study On The Dynamic Force Of Large Trucks Acting On The Ascent

With the implementation of the present national highway network, the focus of highwayconstruction is shifted to the mountain area from the large and medium urban area. Because ofthe limitation of the some factors,such as the terrain,geological conditions and the difficultiesof the environment protection, the mountains area have larger and longer slope. It bringsgreater impact on the respond of the asphalt pavement because the speed of vehicle driving upis much lower and the time of the horizental force to the asphalt pavement is much longer.This paper focused on the speed of the vehicle on assent and the horizental force to the asphaltpavement. It relied on the technology project of Communications Department of ShaanxiProv. which was “dynamic response of the asphalt pavement on the uphill and the study of thedesign specifications.” Based on the full investigation, a speed prediction model and ahorizontal force calculation model were bulit.Firstly,based on the automobile dynamic and driving theory, a speed prediction modelfor vehicles on uphill road is set up by the dynamic performance of vehicles and investigatedshift behavior. The field tests show that the speed change trends by the prediction model andexperiment test are the same, the maximum relative error is only1.56%when vehicles don’tshift, and if vehicles shift, the maximum relative error raised to3.68%, which validate thecorrectness of the vehicle speed prediction model. Taking the truck of Dong FengEQ1108G6D13and Dong Feng EQ1290W for example, the author gets the regularity ofvehicle’s speed with the length of slope, slope value, load and the speed of going into slope.Secondly,based on the principle of the vehicle dynamics and the predicting vehicle speedon the uphill road, a modal for calculating the horizontal forces of heavy vehicles at ascent isformed, which is based on the velocity iterative modal and the force balance equations ofvehicles. Taking Dong Feng EQ1108G6D13and Dong Feng EQ1290W truck for example, thehorizontal forces of the wheels, which are variation with the slope length, gradient, load andspeed, are calculated as the vehicle on the uphill road. The results showed that, for theexisting longest slope of the highway, increasing the starting uphill speed appropriately can reduce the times of the driver’s shift and is beneficial to prolong the service life of thepavement, and the overloaded vehicles not only reduce the uphill speed greatly, but alsodeteriorate the vehicle dynamics, which would affect the traffic safety and accelerate thedamage of the uphill pavement. The result in the paper can provide a reference for the designand conservation of the uphill road.