A cylindrical specimen of saturated soil failed under an axial vertical stress of 100 kN/m2 when it was laterally un-confmed. The failure plane was inclined to the horizontal plane at an angle of 45°. The values of cohesion and angle of internal friction for the soil are respectively
A. 0.5 N/mm2 and 30°
B. 0.05 N/mm2 and 0°
C. 0.2 N/mm2 and 0°
D. 0.05 N/mm2 and 45°
Answer: Option B
This Question Belongs to Civil Engineering >> Soil Mechanics And Foundation
σ1=σ3tan²θ+2ctanθ
σ1=2ctanθ [since, unconfined test,so σ3=0]
100=2c*1[θ=45°]
c=.05N/mm²
θ=45°+Φ/2
45°=45°+Φ/2
Φ=0°
use unconfined compression test formula for C-Fi soil.
c=Qu/2=(100*10^3)/ (2*10^6)= .05N/mm2
explain plz