👉Ultimate bearing capacity means the maximum load per unit area that the soil can support before it fails or collapses.

📜In simple terms:

💫It is the highest pressure the ground can take from the foundation without the soil shearing or giving way.

💡 Example:

⏺If a foundation rests on soil, and we keep increasing the load on it, the soil will deform slightly at first. But after a certain point, it will fail — the foundation will start to sink or tilt.

⏺That maximum safe pressure just before failure = Ultimate bearing capacity.

📘 Formula (general form):

qu = c * Nc + q * Nq + 0.5 * γ * B * Nγ

= ultimate bearing capacity
= cohesion of soil
= overburden pressure at foundation level
= unit weight of soil
= width of foundation
= bearing capacity factors (depend on soil friction angle)

🧱 In practice:

⏺We don’t use the ultimate value directly.

⏺We divide it by a factor of safety (usually 2.5–3) to get the safe bearing capacity, which ensures no failure happens.

🚧 qsafe = qu / F.S.

🏷In short:

➡ Ultimate bearing capacity = maximum load soil can carry before failure.
➡ Safe bearing capacity = load we can safely apply in design.

@etconp