An energy-based crack-growth model was developed in this study to simulate the propagation of top-down cracking in asphalt pavements. A viscoelastic fracture mechanics approach, the generalized J-integral, was employed to model the crack growth of asphalt concrete. Laboratory fatigue crack propagation tests for three asphalt mixtures were performed at various load levels, frequencies, and temperatures. Disk-shaped specimens with a proper loading fixture and crack growth monitoring system were selected for the tests. It was observed from the tests that the crack-propagation model based on the generalized J-integral was independent of load levels and frequencies, while the traditional Paris law model based on stress intensity factor was dependent on loading frequencies. However, both models were unable to deal with the temperature dependence of the mixtures. The fatigue crack propagation model proposed in this study had a good agreement between experimental and predicted crack-growth lives, an indicator that the energy-based J-integral could be a better parameter to describe fatigue crack propagation of viscoelastic materials such as asphalt mixtures.
To verify the foamed warm mix asphalt mixture road property, the article formed foaming warm mix asphalt mixture, Sasobi-LM warm mix asphalt mixture, ordinary hot mix asphalt mixture test piece, comparative analysis of different asphalt mixture The resistance of high temperature to rutting, shear resistance, resistance of low temperature crack, water stability and fatigue properties, and comparative economic analysis. The results show that the resistance of low temperature crack, water stability and shear resistance of foamed warm asphalt mixture surpass Sasobi-LM warm asphalt mixture, but slightly lower than ordinary asphalt mixture; The resistance of high temperature rutting and fatigue resistance of the mixture is lower than that of Sasobi-LM warm mix asphalt mixture; through economic analysis, the economical efficiency of foamed warm mix asphalt mixture surpasses the economical efficiency of the Sasobi-LM warm mix asphalt mixture, lower than the ordinary hot mix asphalt mixture, it is recommended to choose construction in special areas.
Abstract-Several typical existing calculation methods of earth pressure considering displacement are introduced and compared; Typical methods are used to calculate the condition of laboratory tests and the result is compared with that from Rankine earth pressure results to explain which is more reasonable. Based on the experimental model and data of Fang, it shows that the Lu's and Mei's calculation methods are still operational, and Mei's method is more close to the test data, which reflects the change of the earth pressure with the displacement of retaining wall better.
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