# Mining: joint spacing, persistence and the rock mass

> For each joint set, its normal spacing, frequency, trace length and ISRM persistence; Jv and an RQD estimate; and the blind zone of a drill hole on the stereonet.

Page: https://finitor.cl/learn/desktop-mining-joints

Video: https://finitor.cl/learn/desktop-mining-joints-en.mp4 — Rock slope IV-4, captured by drone photogrammetry for "Automatic Planar Discontinuity Identification with Comprehensive Error Quantification" (Han et al., Rock Mechanics and Rock Engineering, 2025). Data: Zenodo 16934958, CC BY 4.0.

## Spacing and persistence

1. Find planes, then read each set under the stereonet: median normal spacing, joints per metre, mean and longest trace, and the persistence class.
2. With three sets or more, Jv (joints per cubic metre), RQD ≈ 110 − 2.5 Jv (Palmström 2005) and the block volume.

## Drill holes

1. Blind zone of a drill hole draws on the net the planes a hole of that plunge would barely cross (Terzaghi), and says how many fall there.

The RQD is an estimate from the face: compare it with the core. Part of the Mining add-on.

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