Dynamic Response Of Highway Asphalt Pavement Structure And Vehicle Ride Comfort Analysis

Asphalt pavements are widely used in highways.When the vehicle is driving on the road,the dynamic load acting on the road surface is constantly changing.This not only affects the dynamic response of the road,but also affects the comfort of driving.Therefore,it has theoretical and practical significance for the dynamic response of the pavement structure and the analysis of vehicle ride comfort.After summarizing the relevant literature in recent years,a coupled vibration model of a large bus-human and asphalt layered road is established.The bus-human model is modeled as a seven-degree-of-freedom bus model and six degrees of freedom human biomechanical model of the front,middle,and rear rows.The pavement is an interlayer contact model and is a two-way six-lane.Based on the inverse fourier transform method,the road irregularity sample is simulated and used as the excitation source of bus-road vibration.Based on the coordinated condition of tire and road surface,the coupled vibration equation of human-bus-road is established.APDL iteration command is written on ANSYS platform to solve the equation.The research results can provide a basis for optimizing the design of asphalt pavement structure and improving vehicle ride comfort.The main content of the present thesis can be summarized as follows:(1)The standard of highway as the background,the bus model is combined with the human biomechanical model,the self-compiled iterative command flow is used to solve the coupled vibration system of human-bus-road.When the parameters change independently such as road roughness,road thickness,base elastic mode,interlayer contact state,bus weight,bus speed,bus braking force and the seating position,the change of dynamic response of pavement,fatigue life of pavement,bus dynamic response and the passenger comfort.(2)In the pavement analysis,the dynamic response of asphalt pavement under bus loads(including vertical displacement,vertical stress,longitudinal stress,transverse stress,horizontal shear stress and transverse shear stress)is analyzed,and the dynamic response of each structural layer of the road is discussed.Then use the latest road asphalt pavement design specification "JTG D50-2017" and Cebon method to estimate the fatigue life of the road surface,and compare the difference between the two.The main conclusions are as follows: the changes of bus weight and road roughness have a great influence on the vertical response of the road surface;the change of bus braking force will obviously affect the horizontal direction of the road surface;the change of bus speed,the thickness of the asphalt surface layer and the elastic modulus of the base layer on the road surface dynamics the response is less affected.Considering the factors affecting the fatigue life of asphalt pavement,bus weight,road roughness and bus braking force have a great influence on the fatigue life of the asphalt pavement.(3)In the bus-human response analysis,the change of road roughness,interlayer contact,bus weight and bus speed have a certain influence on the bus-human of the bus in three directions;the change of bus braking force mainly affects the pitching vibration of the bus;the change of the seating position affects the vertical vibration of the human.Then,the comfort level is analyzed by the annoyance rate evaluation method and the time-frequency domain evaluation method.In the time domain,the objective indicators(Specification ISO 2631)and subjective annoyance rates were used for evaluation.The road roughness changes have the greatest impact on human comfort.Changes in bus speed,bus weight,bus braking force and the interlayer contact have a relatively large impact on human comfort.The difference in seating position has a relatively small impact on human comfort.In the frequency domain,it is evaluated from the perspective of human resonance,the psychological and physiological aspects of human beings.Under different working conditions,the bus vibration frequency is different,there is no obvious law,but it can provide a certain reference for bus developers.