Numerical on design of a Retaining wall
Q. Determine suitable dimensions of a cantilever retaining wall, which is required to support a bank of earth 4.0 m high above the ground level on the toe side of the wall. Consider the backfill surface to be inclined at an angle of 15o with the horizontal. Assume good soil for foundation at a depth of 1.25 m below the ground level with a safe bearing capacity of 160 kN/m2. Further assume the backfill to comprise granular soil with a unit weight of 16 kN/m3 and an angle of shearing resistance of 30o. Assume the coefficient of friction between soil and concrete to be 0.5.
2. Preliminary proportions
• Thickness of footing base slab ≈ 0.08h = 0.08 × 5.25 = 0.42 m
Assume a thickness of 420 mm.
• Assume a stem thickness of 450 mm at the base of the stem, tapering to a value of 150 mm at the top of the wall.
• For an economical proportioning of the length L of the base slab, it will be assumed that the vertical reaction R at the footing base is in line with the front face of the stem. For such a condition, (assuming the height above top of wall to be about 0.4 m), the length of the heel slab (inclusive of stem thickness)
• Assuming a triangular base pressure distribution,
L = 1.5X = 3.0 m
3. Stability against overturning
= 5250 2000 tan 15o = 5786 mm