Table 1.

Shear strength parameters

TypeLithologyHoek–BrownMohr–Coulomb
RMRσc (mPa)φ (°)c (mPa)
IInterbedded shear zone220.10
IIMedium fine sandstone (lower section with moderate weathering)6660450.60
IIIArgillaceous siltstone (lower section with moderate weathering)4735390.40

The value of the Hoek-Brown constant mi for the intact rock is 17.