Soil model determination using asymptotic approximations to Sunde's curves

This paper derives a pair of simple analytical formulas for the Sunde curves, which are then used to determine a two-layer soil model through numerical optimization. Sunde's curves were effectively generated from an infinite series of multiple images in two-layer soil, but in this paper are replaced by their asymptotes. Simplicity provides confidence in the soil model constructed, which will lead to better ground grid design, and the possibility in the future of extending the soil model into 3 or even more layers. The simplicity of the formulas is also found to make the optimization process of the soil determination much faster than previous methods, and yet the accuracy is found to be equal or even slightly better.