Standard Penetration Test is a powerful tool for measuring the penetration resistance of the ground and for relating it to the degree of compactness of cohesionless soil and consistency of cohesive soil. The results can be used for design of foundations. SPT is widely used for measuring the undisturbed strength of the soil and for assessing its resistance to liquefaction due to ground vibrations caused by earthquakes or other dynamic forces. The Standard Penetration Resistance is measured as the number of blows ‘N’ required to drive a split spoon sampler to a depth of 300 mm using a 63.5 kg weight falling freely through a height of 750 mm.
Ref. Standards IS:2131 , IS:9640