Analysis And Evaluation Of Structural Parameters Of Composite Pavement

With more and more airport cement concrete pavement approaching or reaching its design life and carrying out renovation measures such as reinforcing cover,the application of cement concrete paving asphalt pavement will be more and more extensive.As for the above composite pavement,it is generally equivalent to one of the two structural forms of cement concrete or asphalt pavement at present,lacking the theory and method to analyze the structural parameters of composite pavement based on the results of deflection test,and directly affecting the rationality of the analysis results of the bearing strength index PCN value of composite pavement.Based on the above background,the main research contents and achievements of this paper are as follows:Firstly,the slope index analysis model of asphalt overlay is studied.According to the composite pavement structure of airfield,the influence of the parameters of each structural layer of composite pavement on the bended basin was studied by using the theory of elastic layered system.On this basis,a parameter describing the shape of the basin,slope index K_D12,was proposed according to the characteristics of the basin.Through the calculation of pavement deflection under the combination of different modulus and thickness,the elastic modulus analysis model of asphalt overlay based on slope index K_D12 was established,and the difference between the calculated value and the actual value was found to be within 3%through verification.Secondly,the research on the Sigmoid function restoration of the dissimilated sinkbasin of composite pavement surface.By comparing the deflection data of composite pavement with the theoretical analysis results,it is found that the analysis error caused by the alienation of deflection basin caused by asphalt material characteristics cannot be ignored,especially the difference between the deflection value of load plate center and the theoretical value is up to 90%.The Sigmoid function was selected to modify the deflection value of composite track surface based on the analysis of various types of basins and curve characteristics,and the error of the corrected deflection value could be controlled within 3%by this method.At the same time,based on the calculated asphalt layer modulus,the method of directly calculating the elastic modulus of cement concrete layer of composite pavement surface is put forward.Thirdly,the evaluation process of PCN value of single paving composite pavement surface is proposed based on the previous two research results.The process is as follows:?1?accurately analyze asphalt overlay modulus,original cement pavement panel modulus and interlayer bonding state parameters based on deflection data;?2?Take the shear stress inside the asphalt layer?_k,the original cement pavement panel bottom bending tensile stress?_e as the limit index,the trial calculation evaluation model meets the corresponding fatigue equation,the maximum allowable weight of cumulative damage factor G_max;?3?calculate the ACN value corresponding to the evaluation model G_max,and the obtained ACN value is the final PCN value of the composite pavement surface.Fourthly,the research in this paper was applied to the calculation and analysis of pavement structure parameters in the HWD structural performance test of asphalt composite pavement surface of a domestic airport.The PCN value of pavement surface obtained according to the research results in this paper was compared with the traditional method to verify the feasibility of the research content in this paper.