Question

A 5 m wall retains a dry sand backfill with a unit weight of 18.5 kN/m³, an angle of internal friction of 36° and a porosity of 31%. The backfill is fully drained through weep holes.

What is the magnitude of the backfill force on a 1 m wide slice of wall and its location from its heel, if it is not allowed to deflect?

Answer 1

The magnitude of the backfill force on a 1 m wide slice of wall is 47.28 kN, and its location from the heel of the wall is 2.74 m.

Step-by-step explanation:

The magnitude of the backfill force on a 1 m wide slice of wall can be calculated using the equation:

Backfill_force = unit_weight * width * height * cos(angle_of_internal_friction)

Substituting the given values: unit_weight = 18.5 kN/m³, width = 1 m, height = 5 m, angle_of_internal_friction = 36°

Backfill_force = 18.5 * 1 * 5 * cos(36°) = 47.28 kN

The location of the backfill force from the heel of the wall can be calculated using the equation:

Location = height * (1 - sin(angle_of_internal_friction))

Substituting the given values: height = 5 m, angle_of_internal_friction = 36°

Location = 5 * (1 - sin(36°)) = 2.74 m