Pile Embedment Depth Calculator

Inputs

Soil model

Select the governing soil behavior at the pile depth.

Installation type

Used to prefill alpha/beta starting values.

Pile shape

Geometry affects perimeter and end area.

Diameter / width (m)

Circular: diameter. Square: width.

Required service load (kN)

Enter the service (working) axial load demand.

Factor of safety (FS)

Ultimate required = service x FS.

Minimum embedment (m)

Use for scour, frost, or constructability limits.

Undrained shear strength, cu (kPa)

kPa equals kN/m2.

Adhesion factor, alpha

Typical: 0.5 bored, 0.7 driven (starting values).

Bearing factor, Nc

Often around 9 for undrained tip bearing.

Effective unit weight, gamma' (kN/m3)

Approx. submerged unit weight if below groundwater.

Friction factor, beta

Typical: 0.25 bored, 0.35 driven (starting values).

Bearing factor, Nq

Varies strongly with density and phi'. Use project data.

Soil	Shape	Size (m)	Service load (kN)	FS	Key soil input	Computed embedment (m)
Clay	Circular	0.60	1200	2.5	cu=50 kPa, alpha=0.50, Nc=9	~ 24.2
Sand	Square	0.55	900	2.5	gamma'=10 kN/m3, beta=0.25, Nq=35	~ 12.6

Goal: find embedment depth D such that Qult(D) >= service x FS.

Clay (alpha-method + Nc)

fs = alpha x cu
Qs = P x D x fs
qb = Nc x cu
Qb = A x qb
Qult = Qs + Qb
D = max(min_embed, (service x FS - Qb)/(P x fs))

cu in kPa (kN/m2). P is perimeter; A is tip area.

Sand (beta-method + Nq) - simplified stress profile

sigma'v,tip = gamma' x D
sigma'avg ~ gamma' x D/2
fs = beta x sigma'avg
Qs = P x D x fs = (P x beta x gamma'/2) x D^2
qb = Nq x sigma'v,tip = Nq x gamma' x D
Qb = A x qb = (A x Nq x gamma') x D
Qult = a x D^2 + b x D
D = max(min_embed, (-b + sqrt(b^2 + 4a x service x FS))/(2a))

First-pass sizing only. Use report-based method for final design.

Select the soil model that governs along the pile length.
Choose installation type to auto-fill starting alpha/beta values.
Enter pile size and the required service axial load.
Provide FS and a minimum embedment constraint if needed.
Enter soil parameters from the geotechnical report.
Click Calculate to get embedment, capacity split, and checks.
Export the result to CSV or PDF for documentation.

Pile Embedment Depth Calculator

Inputs

Example data table

Formula used

How to use this calculator

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