Stress Simulation Analysis Of "White-to-Black" Pavement With Stress Absorbing Layer

During the years of use,the cement concrete pavement constructed in China has been subjected to various external factors,which eventually led to various damages,which seriously affected the safety and comfort of use.Many aspects make up for the lack of cement concrete pavement.Therefore,the“white to black”pavement has become a common solution for the renovation of old cement concrete pavements.There are many measures for adding asphalt overlays,and different transformation schemes can be selected for different old road conditions.In a functional overlay,the stress absorbing layer is provided for the stress concentration at the joint of the rigid base layer of the dispersed overlay structure layer and the generation of the reflection crack is alleviated.The extension has a good effect.Based on the previous studies,this paper further analyzes the internal stress of the "white-black" pavement structure with stress absorption layer.Study from the individual effects of each factor to the interaction between factors.It is mainly divided into the following three parts:The first part of the research is based on the theoretical results,through the design of the finite element analysis model of the pavement structUre,the stress concentration of the old cement concrete pavement at the bottom of the overlay structure and the stress absorption layer have reduced stress.The effect of the concentration is explained.The results show that the maximum principal stress,the Mises equivalent stress and the maximum shear stress appear in the joint of the old cement concrete pavement at the bottom of the stress absorbing layer of the overlay structure,both under vehicle load and temperature.That is to say,the pavement overlay structure has stress concentration at the joint of the old road panel,and therefore,the damage is most likely to occur here.The second part of the research is the stress analysis of the overlay structure under the action of a single external force.Through the calculation of the corresponding finite element analysis model,the individual effects of load stress and temperature stress in the overlay structure caused by the thickness and modulus of each structural layer are analyzed respectively,so as to analyze the stress under the axial load-temperature coupling.At the same time,it is verified that the stress absorbing layer can effectively reduce the stress value concentrated on the bottom surface of the overlay structure.The results show that the stress absorption layer has a significant effect on the load stress and temperature stress when the thickness of the stress absorption layer is between 2cm and 4cm.The greater the thickness,the smaller the stress value at the bottom joint of the layer;When the compressive elastic modulus of the stress absorbing layer is 200MPa-600MPa,the stress absorption effect is obvious,and the influence of load stress is greater than the influence of temperature stress;Heavy load and large temperature drop have a great influence on the load stress and temperature stress in the pavement structure,and the temperature decrease will also weaken the effect of the stress absorption layer dispersion stress.The third part of the research is the axial load-temperature coupled stress analysis of the stress absorption layer.According to the results of the specific analysis of the load stress and temperature stress of the "white-black" pavement structure with stress absorbing layer in the second part,the thickness of the stress absorbing layer(2cm?4cm),the compressive rebound modulus(200MPa?600MPa),and the axle load size(100kN?220kN)are selected.The three factors are the main influencing factors.Through the response surface test design,the stress states of the pavement structure under the axial load-temperature coupling are further studied,and the effects of interaction of different factors on each stress are analyzed,and the scheme is optimized.Finally,the data is fitted to obtain the regression formula of each stress value,and the optimization result of the stress absorption layer overlaying scheme is obtained based on the obtained regression formula.