Correct Answer - Option 3 : Shear strength of sands
Explanation:
Standard Penetration Test (SPT):
It is specially used for cohesionless soils. It is used to determine the relative density and the angle of shearing resistance of cohesionless soils.
It can also be used to determine the unconfined compressive strength of cohesive soils.
The standard penetration number is equal to the number of blows required for 300 mm of penetration beyond a seating drive of 150 mm.
If the number of blows for 150 mm drive exceeds 50, it is taken as refusal and the test is discontinued.
Hence the standard penetration test is useful to measure the angle of shearing resistance of cohesionless soils, i.e Shear strength of sands.
Some of the other methods for in-situ site exploration are
1) Pressure Meter Test (PMT)
2) Static Cone Penetration Test (SCPT)
4) Vane Shear Test (VST)
