Free Web Tool · FHWA / O'Neill-Reese

Drilled Shaft Capacity

Axial capacity of drilled shafts (bored piles) — cohesive (α-method) and cohesionless (β-method) shaft resistance plus tip bearing.

Input

cohesive only
cohesive only
cohless only
cohless only
cohless only

Results

Side resistance Qs
Tip resistance Qt
Ultimate Qult = Qs + Qt
Allowable Qa = Qult/2.5
Method

Cohesive (α-method): fs = α·su; Qs = fs·π·D·L. Tip: qt = 9·su (clay), capped at 4 MPa. Cohesionless (β-method): fs = β·σv\'·avg ; Qs = fs·π·D·L. Tip: qt = Nq·σv\'(L), capped at 5 MPa. Total Qult = Qs + Qt; Qa = Qult / FS (typical FS ≈ 2.5).