Research On Pavement Modulus Backcalculation Based On Finite Element

Pavement performance evaluation and prediction is the basis for formulating road maintenance strategy.Back calculation of pavement modulus based on deflection basin can provide the required modulus parameters for pavement performance evaluation and prediction,which is of great significance for guiding pavement maintenance.In order to consider the dynamic load and interlayer contact state in the process of back calculation,and considering the application prospect,this paper intends to carry out the modulus back calculation based on the large-scale general finite element software ABAQUS.Therefore,the finite element software ABAQUS and the analytical solution software BISAR and EPADS are used to calculate the 9-point deflection value of the road surface.The analysis and comparison show that finite element method is feasible to calculate the road deflection when the finite element road model depth is 14 m,and its root mean square error with BISAR calculation results is only about 4%.Based on this,how to simulate the interlayer contact state in ABAQUS and the effect of friction coefficient are discussed.Considering both FWD dynamic load and interlayer contact state,ABAQUS is re-developed based on Python language to realize the automatic construction of pavement model and deflection basin database,which greatly improves the efficiency and accuracy of modeling and database construction.The secondary development of ABAQUS making it possible to construct a large-scale,high-density "pavement structure parameter-theoretical deflection basin" database using finite element,providing the basis for the exhaustive method to calculate the road surface modulus.The narrowest range of the most unfavorable verification and the large-scale random verification show that it is feasible to use the exhaustive method to carry out the modulus back calculation based on the large-scale and high-density database.The algorithm is simple and reliable,and there are no problems such as initial value and convergence,also the calculation speed and accuracy meet the engineering needs,which make it a powerful means of modulus back calculation.Through the analysis of the results of the FWD deflection basin data measured by the STR 19 of the full-scale pavement test loop of the Ministry of Communications,the rationality of the back calculation results is illustrated.