Q. A retaining wall of height H with smooth vertical backface supports a backfill inclined at an angle b with the horizontal. The backfill consists of cohesionless soil having angle of internal friction f. If the active lateral thrust acting on the wall is Pa, which one of the following statements is TRUE?
(A) Pa acts at a height H/2 from the base of the wall and at an angle b with the horizontal
(B) Pa acts at a height H/2 from the base of the wall and at an angle f with the horizontal
(C) Pa acts at a height H/3 from the base of the wall and at an angle b with the horizontal
(D) Pa acts at a height H/3 from the base of the wall and at an angle f with the horizontal
Ans: Pa acts at a height H/3 from the base of the wall and at an angle f with the horizontal
Solution:
Active thrust act at a height H/3 from the base of the wall and at an angle equal to backfill inclination.