Free Soil Bearing Capacity Calculator
Estimate the ultimate bearing capacity of shallow foundations using Terzaghi bearing capacity factors.
Ultimate Bearing Capacity
643.8 kPa
Ultimate Bearing Capacity vs Soil Cohesion (c)
Terzaghi's Bearing Capacity Theory
The bearing capacity of a shallow foundation depends on soil properties, foundation depth, and width.
Formula (strip footing)
q_u = c Nc + gamma Df Nq + 0.5 gamma B Ngamma
The three terms represent cohesion resistance, surcharge (overburden) resistance, and self-weight resistance. Nc, Nq, and Ngamma are dimensionless bearing capacity factors that depend on the soil friction angle.
Example Calculation
A 2 m wide strip footing at 1.5 m depth, c=20 kPa, gamma=18 kN/m^3, phi=20 deg.
- 01Cohesion term: 20 x 17.7 = 354 kPa
- 02Surcharge term: 18 x 1.5 x 7.4 = 199.8 kPa
- 03Width term: 0.5 x 18 x 2 x 5.0 = 90 kPa
- 04q_u = 354 + 199.8 + 90 = 643.8 kPa
- 05q_a = 643.8 / 3 = 214.6 kPa (with FoS = 3)
Frequently Asked Questions
Learn More
Beam Stress Calculation Guide: From Theory to Practice
Learn how to calculate beam stress step by step. Covers bending stress, shear stress, the flexure formula, stress distributions, and practical design checks for structural beams.