Development of Mathematical Model for Pavement Surface Deflection Basin and Determination of Optimal Distance of FWD Geophones

This research aims to develop a mathematical model for continuous modeling of the pavement deflection basin based on the measured deflections using FWD device. Another purpose of this research is determining the optimal distance of the geophones for measurement of deflections. For this purpose, 10000 different flexible pavement sections were analyzed using multi-layered elastic theory and then a database containing deflection at nine different distances in case of each pavement section was established. The results show that the coefficient of determination for fitting the proposed equation to the pavement surface deflection basin in all cases is more than 0.99, which confirms the ability of proposed equation for mathematical modeling of pavement surface deflection basin. In order to determine the optimal radial distance of geophones, all scenarios with 4, 5, 6, and 7 geophone were examined and five best scenarios were selected in each case. The results of this study showed that the best radial distance for six geophones is 1830, 1220, 915, 457, 203, and 0 mm and the best radial distance for seven geophones is 1830,1220, 915, 457, 305, 203 and 0 mm.