About

Calculating the bearing capacity of a single pile is a fundamental problem in geotechnical engineering. The total capacity is derived from two mechanisms: Skin Friction (the resistance along the shaft surface) and End Bearing (the resistance at the pile toe).

This professional-grade tool estimates the Ultimate Bearing Capacity ($Q_{ult}$) based on soil type (Cohesive vs. Cohesionless). It utilizes standard soil mechanics formulas (Alpha and Beta methods) to help engineers perform quick checks on site or during the preliminary design phase without needing manual lookup tables.

Formulas

The Ultimate Bearing Capacity is the sum of skin friction and end bearing:

Q_ult = Q_skin + Q_end

For Cohesive Soils (Clay), using the Alpha method:

Q_skin = α × c_u × A_surface

For Cohesionless Soils (Sand), using the Beta method:

Q_skin = β × σ'_v × A_surface

Reference Data

Soil Type	Cohesion (c) kPa	Friction Angle (φ)	Adhesion Factor (α)
Soft Clay	10 - 25	0°	1.0
Medium Clay	25 - 50	0°	0.7 - 1.0
Stiff Clay	50 - 100	0°	0.5 - 0.7
Very Stiff Clay	100 - 200	0°	0.4 - 0.5
Loose Sand	0	28° - 30°	N/A
Medium Sand	0	30° - 36°	N/A
Dense Sand	0	36° - 41°	N/A
Gravel	0	35° - 50°	N/A

Frequently Asked Questions

The Alpha (α) method is an empirical approach used to calculate the skin friction of piles in clay. It relates the undrained shear strength of the clay to the adhesion along the pile shaft.

No, this tool calculates the Ultimate Bearing Capacity ($Q_{ult}$). To get the Allowable Bearing Capacity ($Q_{all}$), you must divide the result by a Factor of Safety (typically 2.0 to 3.0 depending on building codes).

The formulas are optimized for circular bored piles. However, you can approximate square piles by using an equivalent diameter, though skin friction mechanics differ slightly.

This value ($c_u$) is obtained from geotechnical soil tests like the Triaxial Test or Unconfined Compression Test. Our tool provides standard ranges for estimation.