Research On Performance Evaluation And Overlay Design Of Old Cement Concrete Pavement

Using the basic theory and method of the finite element analysis, fracture mechanics etc, and combining with the real project, this paper mainly focuses on the study of the following aspects: the old cement concrete pavement comprehensive performance evaculation, the old cement concrete pavement impact crushing technology, structure of asphalt overlay on old cement concrete pavement based on stress absorption interlayer mechanics analysis and structure design. The main achievements of this paper are as below:Firstly, based on MATLAB toolbox, the model of BP artificial neural network which can make a comprehensive evaluation to the cement concrete pavement performance is established. After applying it to the assess of the real pavement performance,its results coincides with the actual road conditions, and the network's training error and output error is small, which can be used to guide the old cement road reconstruction program development.Secondly,using ANSYS finite element analysis software, the static and dynamic analysis on the mechanism of action of the impact roller cracking and seating the cement concrete board is carried out. We can get the bottom of deformation and stress distribution of concrete board, the cracks produce and expand mode, the impact depth for the subgrade under the effect of the impact roller.Thirdly, A systematic analysis is made on the effects of the thickness and modulus of asphalt overlay, the modulus of foundation,the thickness and modulus of stress absorption layer on the cracked plates overlayer structure of the load stress, thermal stress, deflection and deflection difference, summarizing the change regularity of the stress and deformation with the change of its parameters. In addition, using the indirect coupling method, it analyzes the overlay structure load-thermal coupling stress.Fourthly, on the basis of the previous step, this paper uses the numerical simulation to compute the fatigue life of cracked plates asphalt concrete overlay structure under the thermal-load couple. The calculation results show that the life of the overlay structure setting the stress absorption layer of the asphalt concrete is far longer than that of the overlay structure not setting stress absorption layer,which indicates that the stress absorption layer can effectively prevent reflective cracking to extend the life of the road, worthy of popularity.