Study On The Interaction Of The Pavement And Soft Clay Ground Under Generalized Load

The soft clay, which its natural strength is very slow, should be disposed to satisfy the design requirements of the highway and ensure the road running before it is covered by the semi-rigid asphalt pavement. The reflective cracking and the surface cracking in the semi-rigid pavement are common under the sudden temperature changed and continuous low temperature for its sharp contraction characters produced by the change of temperature and humidity. The computed model should be simplified according to the practical engineering when studying the served highway.The present status of research and application is reviewed to the undamaged and damaged pavement from the theory study, the indoor experiments and numerical simulation. The numerical simulation method on the interaction of pavement and soft clay ground is presented. The generalized load simplified, the determination of properties and structure pavements of all the layers, the reasonable size of the computed model are introduced.The temperature stress is analyzed by formula and numerical method respectively; and the fit temperature step is obtained. The interactions of undamaged pavement and soft clay ground, damaged pavements and soft clay ground are studied under the conditions of temperature change. The influence of temperature change, reference temperature, the surface cracking length and the reflective cracking length on the working properties of road structure is discussed.Drucker-Prager plastic criteria is used to simulate the characters of composite foundation and soft clay ground. The vehicle load is simplified as static load. The influence of asphalt concrete temperature, the resilient modulus of the semi-rigid base and the composite foundation on the maximum deflection of the road surface, retained deflections, the radial stress of the base bottom and sub-base bottom is discussed.The working properties are analyzed by FEM based on elasto-plastic dynamic mechanics. It is discussed that the load period, the damp ratio of pavement, thetemperature of asphalt concrete, the resilient modulus of semi-rigid base, the material parameters and thickness of the composite foundation have influence on the vertical displacement, the radial stress of the base bottom and the sub-base bottom.The dynamic stress intensity factors are obtained based on node displacement extrapolation near the crack tip singular element using the elasto-plastic dynamic FEM. It is discussed that the load period, the damp ratio of pavement, the temperature of asphalt concrete, the resilient modulus of semi-rigid base, the material parameters and thickness of the composite foundation have influence on the dynamic stress intensity factor and the vertical displacement.Finally, the distribution discipline of the cyclic changing temperature damage factor under the conditions of low temperature through the equivalent assumption and energy equivalent model based on damage mechanics theory. The fatigue life of the 4cm depth sawed cracking road is obtained under the conditions of -15℃ based on the Shenyang-Dalian highway.In this paper, the inhomogeniety of asphalt concrete resulting from temperature change is considered, when the influence of the temperature change on the semi-rigid asphalt pavement concrete is analyzed. Linear elastic dynamic fracture mechanics are adopted to analyze the working characters of the semi-rigid asphalt pavement with the reflective cracking. It is successful to simulate the crack expansion process based on elastic damage theory, at the same time the fatigue life is forecast. The research findings are valuable for the pavement engineering practice on the soft clay ground.