Ho sottoposto una simile domanda a GPT5, il quale mi ha fornito una lunga trattazione, ma le conclusioni sono simili alle precedenti.

Citazione
Practical summary
For permeable silty‑sand with metre‑scale drainage to the open excavation, expect most heave and pore‑pressure equilibration at the bottom within minutes to a few hours.

Expect equilibration times to increase rapidly with drainage length squared and with decreasing permeability; delays to many hours or days appear when k ≤ 1·10−6 m/s or L is several metres.

Bottom behaviour is strongly controlled by drainage geometry, presence of low‑permeability lenses, groundwater, temporary slabs/support and the sequence of reloading; always run sensitivity bounds and verify with in‑situ monitoring.

"Data speak for themselves" -Reverend Thomas Bayes 1702-1761
P(Ai|E)=(P(E|Ai)P(Ai))/P(E)