Hoek and Brown criteria for principal stress failure

Input(s)

Co: Unconfined Compressive Strength of Rock (psi)

m: Constant Depending on Property of Rock and Extent to Which It Is Broken (dimensionless)

s: Constant Depending on Property of Rock and Extent to Which It Is Broken (dimensionless)

$\sigma_{c}$: Minimum Effective Principal Stress (psi)

Output(s)

$\sigma_{a}$: Maximum Effective Principal Stress (psi)

Formula(s)

Reference(s)

Mark D. Zoback, Reservoir Geomechanics, Cambridge University Press, UK, Page: 98.