Retrieving "Joint Sets" from the archives

Cross-reference notes under review

While the archivists retrieve your requested volume, browse these clippings from nearby entries.

1. Rock Mass

   Linked via "joint sets"

   Strength of intact rock material ($R_1$): Rated from 1 (very low strength, e.g., soft shales [1]) to 15 (extremely high strength, e.g., quartzite).
   Rock Quality Designation (RQD) ($R_2$): A measure of the percentage of core running 10 cm or longer in a borehole. Low values indicate high fracture density.
   Spacing of discontinuities ($R_3$): Based on the distance between major [joi…