MODIFICATION OF THE CASAGRANDE'S EQUATION OF PHREATIC LINE

The purpose of the present paper is to carry out the seepage analysis for a model to derive the equation of the phreatic line experimentally and thereafter proposing the best solution to trace the line. Sandy silt is used as a base material for this case. Phreatic Line for the model is plotted by carrying out 3 iterations each for two cases, that is, earthen dam without filter and with filter. Their corresponding phreatic line curves are traced on the butter paper on one of the longer side of the model. Plastic channel sections are used to contain the model sealing it air tight with the use of mseal and rubber stoppers. Further, the traced curves are compared with the Analytical solution of Casagrande[2]. Thereafter, a detailed analysis that is using regression modeling, a more accurate solution to obtain an equation of phreatic line in case of sandy silt earthen dam is proposed. The equation can be used for both the cases to determine the phreatic line more accurately than suggested by Casagrande.