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.

Total stress

Total (normal) stress in kilopascals.

Pore pressure

Pore water pressure in kilopascals.

Compute Terzaghi effective stress as the total vertical stress minus the pore water pressure, both in kPa. 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]

Effective stress

Effective stress in kilopascals.

• 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.

• Overconsolidation Ratio Calculator

  Overconsolidation ratio OCR = sigma_p' / sigma_v0' where sigma_p' is the maximum past effective vertical stress (preconsolidation pressure) and sigma_v0' the present effective overburden stress, both in kPa.

• Preconsolidation Pressure Calculator

  Maximum past effective vertical stress sigma_p' = OCR * sigma_v0' from the definition of the overconsolidation ratio. Stresses in kPa; use a Casagrande construction on the oedometer curve for direct measurement.

• Earth Pressure At Rest Calculator

  At-rest lateral earth pressure for a normally consolidated soil via Jaky K0 = 1 - sin(phi): horizontal effective stress sigma_h' = K0 * sigma_v'. Stress in kPa, angle in degrees.