Differential Settlement Control Criterion Of Bridge-Approach And People-Vehicle-Road Interaction

In recent years, the bump on bridge-approach has been an urgent worldwide problem on highways and bridges, caused by differential settlement between the bridge abutment and approaching pavement. It has a direct effect on the vehicle velocity, the vehicle's safety and ride comfort, and it is a general problem in our country. But the current differential settlement control criterion of bridge-approach, the existing calculation models and methods of bridge-approach pavements could not describe and explain the mechanism of bump under vehicle dynamic load appropriately. So this paper will establish the differential settlement control criterion of bridge-approach on ride comfort, and will analyze the vehicle dynamic load of the bridge-approach pavement and the dynamic response of pavement under dynamic load.Firstly, through the contrast between the investigation results in the field and the calculation results from theory, the exponential curve was chosen as road unevenness curve of bridge-approach pavement, and the road unevenness model of bridge-approach pavement in time domain was established to analyze the interaction between people, vehicle and bridge-approach pavement, and to provide the basis on the differential settlement control criterion of bridge-approach.Secondly, based on the analysis on the evaluation method of human exposure to whole body vibration and the evaluation index of ride comfort, the human weighed acceleration RMS (Root Mean Square) was considered as the evaluation index of ride comfort when the vehicle was passing through bridge-approach, and the index could be used to estimate the abutment bump.Thirdly, the whole vehicle was simplified as the 5-freedom degree system when the vehicle was passing the bridge-approach pavement, and the interaction of people-vehicle-pavement was analyzed from vehicle dynamics and road dynamics, and the people-vehicle-pavement system model was established. Through the harmony superposition method, the vibration equations were solved to calculate the human weighed acceleration RMS, and the correlative program was established to analyze the key effect factors on ride comfort, Based on the important effect results, the differential settlement control criterion of bridge-approach was proposed, and it was proved feasible.Fourthly, the key factors on the vehicle dynamic load were analyzed to solve the existing problems of the current calculation index of vehicle load on the bridge-approach pavement. The procedure was proposed to calculate the vehicle dynamic load and dynamic load constant, and the maximum dynamic load constant index was brought forward.Finally, the calculation model of the bridge-approach pavement under the moveable vehicle dynamic load was constructed, and the dynamic response of bridge-approach pavement under vehicle dynamic load was calculated accurately through the transformed field domain analysis method and ABAQUS finite element method, then the sensitivity analysis of the parameters such as the vehicle velocity, vehicle load and damping ratio was implemented. Based on the calculated results and analyzed conclusions, the mechanism of the bridge-approach pavement under the vehicle dynamic load was explained, and some suggestions were proposed.