What it does
Interactive multi-footing vertical-stress-increase (pressure bulb) studio. Place rectangular, square, strip, and circular footings in plan with draggable / rotatable / precisely-typed geometry, per-footing base elevation, and gross / net / applied-load contact pressure. Computes the vertical stress increase Δσz beneath each footing by the Boussinesq elastic method (analytical Newmark rectangular area integral with signed corner superposition; polar integration for circles with the centreline closed-form check; finite-length strip primary model with an explicitly-labelled infinite-strip plane-strain alternate) or the approximate 2:1 (2V:1H) load-spread method, and combines footings by superposition (Combined Δσz = ΣΔσz,i).
Renders calculated plan-slice and section contour fields (filled heatmap + marching-squares iso-lines + % isobars referenced to a stated pressure), a depth slider, a point probe that reports each footing's contribution, the combined increase, initial overburden and total vertical stress, and a user-defined subsurface stress-threshold ratio. Tracks footing-base bearing utilization (gross vs allowable gross, net vs allowable net, never mixed) and a clearly-distinguished user-defined subsurface stress-threshold ratio. Lightweight layered soil profile with optional groundwater for initial overburden.
Project-linked save/reload, pinned probes, PNG / CSV / JSON / print exports, deterministic suggested coordination actions, a mock-safe AI explainer (never in the calculation path), and project-memory capture.