A raft of 6 m × 9 m is found at a depth of 3 m in a cohesive soil...
Given Data:
- Dimensions of the raft: 6 m x 9 m
- Depth of the raft: 3 m
- Cohesive soil properties: c = 120 kN/m3
To determine the ultimate net bearing capacity of the soil using Terzaghi's theory, we can follow the below steps:
1. Determine the effective overburden pressure (σ') at the depth of the raft using the formula:
σ' = γ × D
Where γ is the unit weight of soil and D is the depth of the raft.
Given γ = 120 kN/m3 and D = 3 m, we have:
σ' = 120 kN/m3 × 3 m = 360 kN/m2
2. Calculate the ultimate bearing capacity of the soil using the formula:
qult = cNc + σ'Nq + 0.5γBNγ
Where qult is the ultimate bearing capacity, c is the cohesion of the soil, γ is the unit weight of soil, and Nc, Nq, and Nγ are the bearing capacity factors.
3. Determine the bearing capacity factors Nc, Nq, and Nγ based on the shape and dimensions of the raft. For a rectangular raft, the factors can be obtained from Terzaghi's bearing capacity factors table.
4. Substitute the values of c, σ', γ, Nc, Nq, and Nγ into the ultimate bearing capacity formula and calculate the result.
Since the question does not provide the values of the bearing capacity factors Nc, Nq, and Nγ, we cannot directly calculate the ultimate bearing capacity using Terzaghi's theory. Therefore, we cannot determine the correct option without additional information.
It is important to note that the ultimate bearing capacity is influenced by various factors such as the shape and dimensions of the raft, soil properties, and the load applied to the raft. Therefore, without knowing the bearing capacity factors, it is not possible to accurately determine the ultimate bearing capacity of the soil.
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