# Comprehension The unconfined compressive strength of a saturated clay sample is 54 kPa. If a square footing of size 4 m × 4 m is resting on the surfac

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If a square footing of size 4 m × 4 m is resting on the surface of a deposit of the above clay, the ultimate bearing capacity of the footing(as per Terzhagi's equation) is
1. 1600 kPa
2. 300 kPa
3. 200 kPa
4. 100 kPa

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Correct Answer - Option 3 : 200 kPa

Concept:

As per Terzaghi’s theory, The ultimate bearing capacity of square footing is given by,

Ultimate bearing capacity (qu) = 1.3× c× Nc + q × Nq + 0.4 × γ × B × Nγ ....(1)

C - Cohesion of clay

Nc, Nq, Nγ - Bearing capacity factors, γ = unit weight of soil

q = overburden pressure = γ × D

D = depth of the footing, B = width of square footing

Calculation:

Given:

c = 27 kPa, Size of footing = 4 m × 4 m

For saturated clay ϕ = 0°

For ϕ = 0°, Nc = 5.7, Nq = 1, Nγ =0

∴ qu = 1.3 × 27 × 5.7 + γ × D × 1

It is given that the footing rests on soil, D = 0

∴ qu = 1.3 × 27 × 5.7 = 200 kPa.