The backcalculation of pavement layer moduli is a very complex problem. Therefore, the backcalculation of pavement layer moduli has become a research hotspot in pavement engineering. In order to determine the rigidity and the strength of pavements, the resilient moduli of pavement layers must be backcalculated and analyzed from the deflection basins on pavement surface measured with FWD. At present there are about 30 FWDs in various kinds in China. It was introduced into China in the late of the 1980s. Since the application of Falling Weight Deflectometer (FWD) in the 1970s for pavement evaluations, FWD has been regarded as a non-destructive testing device in a wider range of application for its accuracy, fast speed, safety, labor saving, convenience, non-destruction to pavement layers and other advantages. Homotopy method Backcalculation of moduli Pavement Deflection Falling weight deflectometer (FWD) This shows that the homotopy method for backcalculation of pavement layer moduli has effectively solved the problems of initial value and local convergence in traditional optimization algorithms, so the method is high in precision, fast in speed, great in efficiency, stable in result and wide in convergent range. In the meantime, the property of a wide range of convergence and the stability of backcalculation results with the homotopy method are checked through comparing to the results of different initial values. The precision and the reliability of backcalculation results with the homotopy method are verified by backcalculating seven kinds of pavement layer moduli according to the deflection basins measured with Falling Weight Deflectometer (FWD) and comparing to other common backcalculation programs. A relevant program HMBPLM is developed for the backcalculation of moduli. Then Li-Yorke algorithm is applied in solving initial value problems for differential equations to trace homotopy curves. A backcalculation model based on homotopy method is established by using a numerical differential method to solve the first and the second partial derivatives of deflections with respect to moduli. In accordance with the extreme value condition for optimization, the backcalculation of pavement layer moduli is converted into the solution of a zero point problem for nonlinear mapping. Homotopy method for backcalculation of pavement layer moduli*Ĭhangsha Communications University, Changsha City, Hunan Province, P. Start > Contributions > Lectures > Pavement: Print International Symposium (NDT-CE 2003)Non-Destructive Testing in Civil Engineering 2003 Homotopy method for backcalculation of pavement layer moduli

Backcalculation modulus