Question

In standard penetration test, the split spoon sampler is penetrated into the soil stratum by giving blows from a drop weight whose weight (in kg) and free fall (in cm) are, respectively

• A. 30 and 60
• B. 60 and 30
• C. 65 and 75
• D. 75 and 65

Answer 1

The correct option is C 65 and 75

A standard split spoon sampler consists of a thick wall tube having outer diameter of 50.8 mm and internal diameter of 35 mm and a length of 600 mm. The tube has a drive shoe attached to its bottom and coupling head at top to accommodate the drill rod, used for testing. The drill rod is coupled to sampler head and the sampler is lowered into the clean hole, made in the ground in advance. The sampler is driven into the undisturbed soil at the bottom of the hole, with the help of a driving weight assembly consisting of a driving head and a 650 N weight with 750 mm free fall. The blows from the driving weight fall on the drill rod which drives the sampler into the soil. The sampler is first driven through 150 mm in the hole. This is known as seating drive. The sampler is then driven further through 300 mm and the number of blows required for 300mm penetration are recorded. This number of blows is termed as penetration resistance of soil and is represented by symbol N.