#Pavement backcalculation software software#

(7,9) The MODCOMP В© software package was used in the first round of backcalculation for all pavements. Many backcalculation packages use this method, especially those that are used for production and research purposes.Д®VERCALC В© and MODCOMP В© are two programs that fall within this category. The assumed modulus values are adjusted, and the process is repeated until the calculated deflections match the measured deflections within a specified tolerance. These modulus values are used to compute surface deflections, which are compared to the measured deflections. (15,16) The iterative search method involves selecting an initial set of layer modulus values. Lytton and Anderson provided a detailed description of two algorithms included in this category of programs. The user sets the tolerance and maximum number of iterations. The iteration process stops when the measured and calculated deflections are within a tolerance level or when the maximum number of iterations is reached.

The iterative search method is based on the backcalculation program making repeated calls to an elastic layer subroutine to match the measured to calculated deflections for program-selected or derived layer moduli. The types of backcalculation methods can be grouped into five generalized categories, which are summarized in the following sections. Many backcalculation software programs use this general approach, matching measured deflections to deflections calculated with multilayer elastic theory. (13) HouвЂ™s approach is to search for the set of layer modulus values that minimize the sum of the squared differences between the calculated and measured deflections. Hou developed one of the first solutions for backcalculation of elastic layer modulus values of more than two layers. There are many programs and methods that can be used to estimate the in-place elastic modulus values of pavement structural layers from deflection basins. (13) It describes how specific backcalculation packages were selected as candidates to determine the elastic layer modulus values for all test sections included in the LTPP program. This chapter summarizes the activities completed in phase I of this project.

Long-Term Pavement Performance Program Determination of In-Place Elastic Layer Modulus: Backcalculation Methodology and ProceduresД¬hapter 2.

Pavement backcalculation software