Optimization Analysis Of Pavement Via Dynamic Response

Vehicle random vibration is triggered by the pavement surface roughness,which destructs the pavement. And the damage of pavement makes the vehicle random vibration more serious.So the coupling vibration system of vehicle and pavement is established. Vehicle load is considered as a static load during the current design of pavement, although a safety coefficient is appllicated, the stress of the pavement can't be fully reflected. In this paper, the effects of pavement dynamic response under the vehicle random load is researched from time-domain and frequency-domain based on Hebei traffic science fund. The result of this study provides theoretical basis for the design and optimization of pavement structure, the specific work and achievements are as follow:1. After comparing the different simulation methods of pavement surface roughness.harmonic superposition method is selected to generate different grade of pavements.2. Considering the advantages and disadvantages of different vehicle models, a quarter of two degrees of freedom vehicle model was used to simulate the vehicle load. The differential equations of motion is integrated by Newmark-? method. A quarter vehicle model is built by ANSYS software to simulate the process of vehicle driving on uneven pavement surface,which simplify the solving process of vehicle random load, the effects of pavement surface level on the dynamic load coefficient is discussed at last.3. Rigid pavement is regarded as the research object, the 3D pavement finite element model is established through calculation and demonstration. in the research of time-domain,in order to discuss the influences of structural parameters on dynamic displacement and bottom tensile stress of the surface layer, the random vehicle load is applied on the built pavement model, then the optimal structure parameters combination is put forward by the analysis of calculation results.4. In order to get the optimal calculation method,Comparing the modal analysis with the method that applicating a impact load on the 3D finite element model of pavement and the fundamental frequency of pavement was obtained from the results of spectral analysis of acceleration signals. The result shows that: the modal analysis of calculation results depends on the size of the finite model, which can't reflect the vibration of the pavement, and spectrumanalysis is based on acceleration signal, it can reflect dynamic characteristics of the pavement,so the spectrum analysis is more realistic.5. The power spectral density of vehicle random load was calculated through MATLAB in order to get the main frequency, and the influence of different factors on the power spectral density was discussed. Calculating the fundamental frequency of pavement through the spectrum analysis, The influences of different structural parameters on the fundamental frequency were investigated. the dynamic response of the pavement with different working condition was also studied for optimal design of the pavement.