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Geomechanics and FracturingIn-Situ Stress and Rock Mechanics

Hoek and Brown Criteria for Principal Stress Failure Calculator

σa=σc+Comσc/Co+s\sigma_a=\sigma_c+C_o\sqrt{m\sigma_c/C_o+s}

Enter the required inputs, confirm the units, and run the calculator to solve sigma_a. Review the formula source and assumptions before using the result in engineering work.

Tabular solver

Inputs

Defaults provide a quick field-unit example for the equation.

4 variables

Calculation runs locally with the shared TypeScript engine.

Formula reference

Hoek and Brown Criteria for Principal Stress Failure calculates maximum effective principal stress at failure for in-situ stress and rock mechanics workflows in geomechanics and fracturing.

View formula, units, and source

Assumptions

  • Input values are representative for the well, reservoir, fluid, or equipment case being evaluated.
  • The declared units match the field-unit constants used in the formula.
  • The cited formula applies to the selected petroleum engineering workflow.

Common mistakes

  • Mixing unit systems without converting the inputs.
  • Using default example values as field recommendations.
  • Applying the formula outside the source assumptions.