*2.5. Material Properties*

The physical and mechanical properties of the shale and sandstone were obtained from laboratory testing at the University of Oviedo Rock Mechanics Laboratory on intact rock samples following International Society Rock Mechanics (ISRM) methods [34]. Table 1 shows the properties of the intact rocks and the geological strength index (GSI). The rock mass properties were determined by means of empirical methods considering a blast damage factor *D* = 0.8. Table 2 shows the rock mass properties of the shale and sandstone formations that have been employed as input data in the numerical analysis.


**Table 1.** Properties of intact rocks.


