Correlation between undrained shear strength and liquidity index of soils in Malaysia

Accuracy of soil undrained shear strength measurement is often governed by the quality of undisturbed soil sampling. Numerous previous attempts have been made to establish correlations between the undrained shear strength and various soil physical parameters. This paper aims to determine a correlation between the undrained shear strength (cu) and liquidity index (IL) based on 34 soil samples collected from selected sites in Peninsular Malaysia. Sieving, hydrometer analysis and Atterberg limit tests were performed to determine physical properties of the soils. The undrained shear strengths were determined using the Unconsolidated Undrained (UU) triaxial test. An attempt was made to correlate the undrained shear strength with liquidity index of all the soil specimens. However, the correlation was found to be considerably weak (r2 = 0.47). The correlation was improved significantly (r2 = 0.82) by limiting the data to soils with fines content of more than 65% only. The proposed equation was in the form cu = a exp(-bIL) where the values of constants a and b were determined empirically as 72.9 and 1.95, respectively