Correlation of Pressuremeter Test Results with SPT N Values and Liquidity Index for Cohesive Soil of Normal Calcutta Deposit

Economical geotechnical design requires proper sub-soil characterization by means of its consistency, compressibility and strength. In this respect, conventional borehole (BH) accompanied by standard penetration test (SPT) and laboratory tests is commonly conducted in the geotechnical investigation. Pressuremeter test (PMT) may be used to characterize the sub-soil profile by two parameters, i.e., limit pressure (P_L) and pressuremeter modulus (E_PMT). It is necessary to predict a standard range of these parameters of the sub-soil formation. In the present study, correlation between P_L, E_PMT with standard penetration value (SPT N) and E_PMT/P_L with the liquidity index (LI) for the cohesive (silty clay/clayey silt) sub-soil of Kolkata, India, are proposed. Further, a reference range of P_L, E_PMT and E_PMT/P_L is predicted for the same type of soil. Forty-eight numbers of PMT tests are carried out adjacent to the conventional boreholes, at three different sites, located in and around Kolkata city. The comparison of P_L and E_PMT with SPT N and E_PMT/P_L with the liquidity index (LI) is made for each site. Finally, a typical range of P_L and E_PMT for different SPT N values along with the range of E_PMT/P_L for different value of LI is established.