Question

For two infinite slopes (one in dry condition and other in submerged condition) in
a sand deposit having the angle of shearing resistance 30° , factor of safety was
determined as 1.5 (for both slopes). The slope angles would have been
a)
18.4° for dry slope and 21.05° for submerged slope
b)
19.47° for dry slope and 18.4° for submerged slope
©)
21.05° for dry slope and 21.05° for submerged slope
d
22.6° for dry slope and 19 47° for submerged slope

Answer 1

c. 21.05° for dry slope and 21.05° for submerged
slope

Answer 2

Solution:

The factor of safety for the stability of an infinite slope in completely dry cohesion less soil is given by FS = tan theta / tan alpha.

Therefore, tan alpha = tan 30 / 1.5 = 21.05 degrees for both dry and submerged slope.

Hence the correct answer would be option C.