Stress state and 3D model¶
The Stress state and 3D model tabs show how the load spreads into the soil and how the contact pressure distributes. The previews are generated without consuming credits.
Stress bulb¶
The stress bulb shows the isolines of the vertical stress increment Δσ produced by the foundation, computed with the Boussinesq solution (Newmark/Fadum factors). The bulb starts at the founding plane (depth D) and is drawn inside the actual stratigraphic section, with coloured layers and the water table.
With the combination selector you choose the load to represent: the assigned pressure q, or the one derived from N and the eccentricity.
Colour map¶
The colour map is the same quantity as the bulb rendered as a continuous gradient heatmap (blue to red as Δσ increases), with the vertical-stress legend. It helps to read the load's influence zone at a glance.
Contact pressures at the founding plane¶
The contact pressures diagram shows how the soil reacts beneath the foundation, as a function of the load eccentricity:
- e ≤ B/6 — trapezoidal diagram (the whole base reacts): σ_max and σ_min;
- B/6 < e < B/2 — triangular diagram (partialised reaction);
- e ≥ B/2 — overturning.
The diagram reports σ_max, σ_min, the eccentricity and the outcome.
3D model¶
The 3D model tab shows the foundation embedded in the layered soil. Available controls:
- view mode — Solid, Transparent (to see the embedded foundation) and Excavation (soil as a frame around the footprint);
- 3D bulb — the Δσ field as translucent stacked shells below the foundation;
- Moving section plane — a slider moves a coloured slice along the length L, to see how the bulb changes section by section;
- Rotate — automatic rotation of the model.
The bulb is a 3D field
The 2D views of the bulb are sections of the same three-dimensional solid: the 3D model makes it explicit.
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