Mechanical Behavior And Predicted Performance Of Inverted Asphalt Pavement Structure

As a new type of asphalt pavement structure,inverted pavement structure consists of many kinds of construction materials,including asphalt concrete(AC),granular materials,fine-grained soil,which have complex mechanical properties.Moreover,the stiffness distribution of inverted pavement structure is different from the traditional pavement structures,such as semi-rigid base pavement structure and flexible base pavement structure.However,the practical engineering experience of this pavement structure is inadequate in China.Therefore,the further research focused on inverted pavement structure needs to be implemented.Based on the review of previous studies,this paper performed the comprehensive numerical simulation of inverted pavement structure considering the nonlinear and viscoelastic properties of materials,and the finished main work is shown below:(1)In this paper,the modulus distribution of the representative base materials was sorted out,and the research range of base modulus was selected.Furthermore,the modulus ratio of AC layer and base was introduced as the control variable,then the distribution of critical strain along depth,the difference between the bottom and maximum strain of AC layer,and the tensile and compressive zone of AC layer under different modulus ratios were analyzed.And,the proposed modulus ratio of AC layer and base was presented.The result could provide the basis for the following overall discussion of the inverted pavement structure performance,and for the study focused on the mechanical behavior of the new pavement structure like the inverted pavement structure;(2)Two representative special-purpose software,MICH-PAVE and KENLAYER were selected to compare the key aspects of their nonlinear analysis algorithms,which based on the finite element method and layered system theory,respectively.Furthermore,by conducting a case study of flexible base asphalt pavement,the impact of using different analysis methods on the calculation results was presented.In addition,the feasibility of the equivalent resilient modulus obtained by the finite element method was validated.The result could provide the theoretical foundation for the following comprehensive numerical simulation of inverted pavement structure;(3)Considering the viscoelasticity and nonlinearity of materials,a comprehensive numerical simulation was performed based on KENLAYER program for inverted pavement structure and two conventional pavement structures,including flexible base pavement structure and semi-rigid base pavement structure.Moreover,the critical mechanical responses of three pavement structures were compared,and the predicated functions of MEPDG(Mechanistic-Empirical Pavement Design Guide)was introduced to evaluate the fatigue life and rutting depth.Additionally,an overall discussion was presented based on the modulus ratio of AC layer and base,and the preliminary suggestions were provided for optimizing the design of inverted pavement structure.This paper has certain guiding significance and practical value for further theoretical research and design optimization of inverted asphalt pavement structure.