Correlation Between Shear Strength of Soils and Water Content Ratio as a Substitute for Liquidity Index

Abstract

Undrained shear strength of saturated clays is a vital property in geotechnical engineering practice. If any relationship between shear strength of soil and index properties of soil is developed, it would be exceptionally alluring. A few endeavors have been made in the past to associate shear strength with Liquidity Index. The Liquidity Index requires the estimation of plastic limit calculated by Casagrande [1] thread rolling method which does not provide the correct assurance of plastic limit of the soil particularly in less plastic soils. Shear strength variation with water content does not follow a regular trend, which makes the analysis difficult. It has been observed in the past researches that shear strength of soil correlates very well with the consistency limits of soils. The present paper develops the correlation between shear strength and Water Content Ratio (w_X) and between shear strength and Liquidity Index, to find out the better parameter to evaluate shear strength between Water Content Ratio (w_X) and Liquidity Index. The experimental results on three different highly compressible soils having water content ranging from 5% to 25% showed that the regression coefficient value of relation between undrained shear strength with Water Content Ratio came out to be closer to one compared with Regression coefficient value of relation between undrained shear strength with Liquidity Index, for the soils of same geological origin. Liquidity Index variation with Water Content Ratio suggests that there is a definite relation between Liquidity Index and Water Content Ratio and Liquidity Index can be substituted by Water Content Ratio. However, the results obtained from both are more or less same for the soils irrespective of their origin.