Estimation of the drained shear strength parameters of fine grained soil of southern Tehran using nonlinear regression model

Determining the precise shear strength parameters of the fine grained soils is always a difficult task. In order to conduct the shear strength tests and determine the mechanical parameters of the soil، achieving an untreated high quality sample is a problem with a high degree of importance. Therefore، many researchers have attempted during the recent decades to provide relations between strength parameters and soil''s physical characteristics in a specific structure and so to provide the possibility of estimating the strength parameters based on these characteristics. The aim of this research is to estimate the shear strength parameters of a wide region of fine grained alluvial soil located in southern Tehran، Iran. In this regard، the geotechnical data including physical and shear strength parameters of 294 bore holes were firstly collected from the site. Then، the gained data were statistically and independently analyzed. Based on the results of analyzes، the soil''s geotechnical parameters were presented for various depths with an acceptable level of reliability. Moreover، they were considered as a basis for providing a nonlinear regression model to estimate the soil''s shear strength parameters and based on the index physical characteristics of the fine grained soil (water content and plasticity index). The developed model is capable to predict the soil''s drained shear strength parameters، also، other similar soils'' properties with a very good accuracy.