What Is the Terzaghi Bearing Capacity Shallow Foundation Calculator?
Bearing capacity is the maximum load intensity that soil can sustain without experiencing shear failure or excessive settlement.
Terzaghi developed the first comprehensive analytical formulation dividing the failure soil mass into active, radial, and passive shear zones.
How Does the Terzaghi Bearing Capacity Shallow Foundation Calculator Work?
Calculates dimensionless bearing capacity factors Nc, Nq, and Nγ as functions of soil friction angle φ.
Computes surcharge pressure q = γ · Df from soil overburden.
Applies geometric shape modification factors (sc, sγ).
Divides ultimate capacity by factor of safety to establish allowable design bearing pressure.
Terzaghi Bearing Capacity Shallow Foundation Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
Terzaghi superposition equation summing soil cohesion, surcharge overburden pressure, and soil wedge self-weight.
How to Use the Terzaghi Bearing Capacity Shallow Foundation Calculator
- Input soil shear parameters (c, φ, γ) from triaxial or direct shear tests.
- Specify footing width B and embedment depth Df.
- Select footing shape and factor of safety.
Step-by-Step Example Calculation
Isolated Square Pad Footing
Input Values:
Understanding Your Result
Primary output indicates safe allowable bearing pressure q_all.
Summary displays ultimate failure pressure and bearing capacity factor values.
Factors That Affect the Result
- Soil internal friction angle φ (bearing capacity grows exponentially with φ).
- Groundwater table location (submergence halves effective unit weight).
When Should You Use This Calculator?
- Preliminary sizing of building foundations, column footings, and retaining wall bases.
Assumptions & Limitations
- Assumes general shear failure mechanism in dense or stiff soils; local or punching shear requires reduced parameters.
- Ground surface and footing base assumed horizontal.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Standard Terzaghi equations implemented per geotechnical textbook formulations.