A considerable amount of slope stability analysis has been observed in jointed rock masses in which the Geological Strength Index (GSI) estimated at the outcropping level is considered as input data to define the rock mass strength.
However, this procedure is unsuitable when the rock outcrop scale and the slope scale are significantly different (e.g. open-pit slopes), resulting in an overestimated rock mass strength.
For this reason, and in the absence of any criteria to modify the GSI based on scale effects, a new GSI version called GSIe or "equivalent GSI" is proposed.
This new formulation depends on the slope height, the joint spacing, the intact rock strength, the persistence, and the joint condition.
Finally, the formulation was applied and validated through the slope stability study of the Peña Colorada open-pit located in Colima-Mexico.
