Question

The standard penetration resistance N of a granular deposit is found to be 20. The soil can be classified approximately in terms of $\varphi$ and density index respectively as

• A. 20° and 10% for very loose condition
• B. 32° and 50% for medium condition
• C. 32° and 30% for loose condition
• D. 38° and 65% for dense condition

Answer 1

The correct option is B 32° and 50% for medium condition

N -Value	Density Index	Condition	$\varphi$
0 - 4 4 -10 10-30 30-50 >50	0 - 15% 15-35% 35-65% 65-85% > 85%	very loose Loose Mediumdense Dense Very Dense	$<{28}^{\circ }$ ${28}^{\circ }-{30}^{\circ }$ ${30}^{\circ }-{36}^{\circ }$ ${36}^{\circ }-{42}^{\circ }$ $>{42}^{\circ }$
N = 20 means medium condition soild with $\varphi ={32}^{\circ }$ $D_r=50\%$