Maximum principal stress failure (Hoek and Brown)
Input(s)
\(\sigma_{b}\): Second Largest Stress (psi)
C: Rock Compressive Strength (lbf)
m: Hoek - Brown Constant Dependent on Rock Type (dimensionless)
s: Hoek and Brown Constant Dependent on Shape (dimensionless)
Output(s)
\(\sigma_{a}\): Principal Stress (psi)
Formula(s)
\[
\sigma_{\mathrm{a}}=\sigma_{\mathrm{b}}+\left(\mathrm{C} *\left(\mathrm{~m}_{*} *\left(\frac{\sigma_{\mathrm{b}}}{\mathrm{C}}\right)+\mathrm{s}\right)^{0.5}\right)
\]
Reference(s)
Mark D. Zoback, Reservoir Geomechanics, Cambridge University Press, UK, Page: 98.