Backcalculation of layer moduli from nondestructive pavement deflection data using the expert system approach : Nondestructive Testing of Pavements and Backcalculation of Moduli, ASTM STP 1026. Bush, A.J. and Baladi, G.Y. (Ed.) pp. 341–354. American Society for Testing and Materials. (1989)

Abstract

None of the existing backcalculation procedures is guaranteed to give a reasonable, effective elastic layer modulus for every deflection basin measured. The differences of results among various backcalculation programs are magnified by the differences if distinct analysts using the same program but applying different input parameters. A more experienced analyst often obtain better results. Some of the difficulties, such as the deviation of pavement material properties from the linear elastic, isotropic, and homogenous assumptions, the uncertainty of input parameters (for example, the deflection measurement), and the limitation of basin matching techniques, may only be dealt with by informed engineering judgment. A knowledge-based expert system approach as described in this paper may be used to generate more consistent and better estimations of in situ pavement material properties by combining numerical computations with a pavement experts knowledge and judgment. A knowledge base which serves as an intelligent pre- and postprocessor to the backcalculation program is developed. The knowledge base may be revised easily as better understanding emerges.