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Undrained shear strength of a soil from water content around the liquid limit to water content around the plastic limit can be determined by the fall cone test. Determination of liquid limit by the fall cone test is based on the premise that soil assumes a unique state at the liquid limit yielding a unique shear strength. Many research workers have attempted to show that this unique shear strength at the liquid limit bears a definite relationship with that at the plastic limit [2, 8, 13, 16, 25, 26]. If undrained shear strength at liquid and at the plastic limit are related then it is brought out that the liquid limit and the plastic limit could also be uniquely related. According to several researchers ([10, 12, 15, 23, 26] to name a few), undrained shear strength at the liquid limit water content can be considered to be unique (without much loss of accuracy) for all soils. These researchers have shown that shearing strength of fine grained soils at the liquid limit falls within a narrow range of about 1.7-2.0 kPa. Mitchell [11], has reported equal undrained shear strength of about 1.7 to 2.0 kPa at liquid limit water content and has mainly attributed this to the same average adsorbed water layer thickness on all particle surfaces at the liquid limit of the soil. Skempton and Northey

Guwahati, the major city in the North Eastern region of India is growing rapidly in every aspect with major infrastructures like sports complex, educational institutions, hospitals, flyovers, multiplex halls, etc. Knowledge of the subsurface soil condition is necessary to ensure the structural safety and serviceability of the above mentioned structures before any construction. Therefore, contour maps of Standard penetration test N value, ground water table and shear wave velocity map using Geographical Information System (GIS) platform will be of great help to the foundation designers at the initial stage for site selection and preliminary foundation design under static and seismic condition. Contour maps of Standard penetration test N value at different depth and average contour map of N value of Guwahati city have been prepared. Standard penetration Test N values and depth of water table were taken from a data base of 200 boreholes up to 30 meter depth to prepare N value contour map of Guwahati city. A regression equation between shear wave velocity Vs and Standard penetration test N value based on twenty seven previous similar correlations was also developed. This regression equation was used to determine shear wave velocity of Guwahati city. The average shear wave velocities for 30 m depth for all locations had been determined and used to generate map on (GIS) platform. Other subsurface geotechnical information of Guwahati city like soil classification and depth to water level from ground surface is also presented in the form of GIS based maps in order to form a data base.

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