Pile / Pier Capacity

Deep foundation axial capacity — skin friction + end bearing (alpha-clay / beta-sand).

Soil strength values (c, φ, γ, lateral-bearing) must come from a project-specific geotechnical report — the pre-filled defaults are illustrative placeholders, not safe assumptions.

Design diagram — updates live with your inputs

Pile & Soil Type

Soil type

Pile diameter (in)

Embedded length (ft)

Cohesive (clay) Parameters

Undrained shear c_u (psf) Clay

Adhesion factor alpha Clay skin friction

Cohesionless (sand) Parameters

Friction angle phi (deg) Sand

Soil unit weight (pcf) Use buoyant if submerged

Lateral pressure coef K Sand skin friction

Interface friction delta (deg) Sand

Design

Factor of safety On ultimate capacity

Applied axial load (lb) Optional

IBC 2021

Validation, assumptions & limitations Download validation report (PDF) ↗

This calculator is verified by 4 independent tests comparing its output against closed-form statics, NDS/SDPWS design-standard values and published worked examples. Full case-by-case results are in the PDF report.

Assumptions

Single pile, homogeneous soil over the embedded length.
Clay: Tomlinson alpha-method; sand: Burland beta-method.
End bearing N_c=9 for deep clay; Vesic N_q for sand.

Limitations

Soil parameters are geotechnical INPUTS — confirm with the soils report.
No group effects, downdrag, negative skin friction or settlement.
Layered profiles and submerged unit weight must be entered manually.

Results are for preliminary design and must be confirmed by a licensed engineer against the current adopted code and project-specific conditions.