Use this geological calculation for a transparent first-pass interpretation of measured rock, soil, fluid, well, stratigraphic, isotopic, geophysical, or seismic data under an explicitly selected model.

phi

Friction angle phi in degrees.

Surcharge bearing capacity factor Nq = tan^2(45 + phi/2) * exp(pi * tan(phi)), common to Terzaghi, Meyerhof and Vesic; equals 1 at phi = 0. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Nq

Surcharge bearing capacity factor Nq, dimensionless.

• Geotechnical correlations and idealized failure models depend on stratigraphy, sampling disturbance, drainage, stress history, groundwater, density, anisotropy, scale, construction sequence, and laboratory or field method. Site-specific design requires investigation and code factors.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Compare independent measurements and models, retain units and analytical metadata, propagate uncertainty, and validate interpretations against logs, cores, maps, laboratory data, or field observations.

• Bearing Capacity Factor Ngamma Calculator

  Unit-weight bearing capacity factor Ngamma = 2 * (Nq + 1) * tan(phi) with Nq = tan^2(45 + phi/2) * exp(pi * tan(phi)); this is the Vesic (1973) convention, which differs from Terzaghi's and Meyerhof's original third factors. Equals 0 at phi = 0.

• Bearing Capacity Factor Nc Calculator

  Terzaghi/Meyerhof/Vesic cohesion bearing capacity factor Nc = (Nq - 1)*cot(phi), with Nq = exp(pi*tan(phi))*tan^2(45 + phi/2); the exact limit Nc = pi + 2 applies at phi = 0.

• Bearing Capacity Terzaghi Calculator

  Ultimate bearing capacity of a shallow strip footing qu = c*Nc + q*Nq + 0.5*gamma*B*Ngamma. Factors: Nq = exp(pi*tan(phi))*tan^2(45 + phi/2), Nc = (Nq - 1)*cot(phi), Ngamma = 2*(Nq + 1)*tan(phi) (Vesic convention for Ngamma; Terzaghi's original third factor differs). Base equation without shape or depth corrections. c and q in kPa, gamma in kN/m3, B in m.