(a) Rock-wall contact (no clay fillings, only coatings) | |
Tightly healed, hard nonsoftening, impermeable filling, i.e., quartz or epidote | 0.75 |
Unaltered joint walls, surface staining only | 1 |
Slightly altered joint walls. Nonsoftening mineral coatings, sandy particles, clay-free disintegrated rock, etc. | 2 |
Silty- or sandy-clay coatings, small clay disintegrated rock, etc. | 3 |
Softening or low friction clay mineral coatings, i.e., kaolinite or mica. Also chlorite, talc, gypsum, graphite, etc., and small quantities of swelling clays | 4 |
(b) Rock-wall contact after some shearing (thin clay fillings, probable thickness & 1–5 mm) | |
Sandy particles, clay-free disintegrated rock, etc. | 4 |
Strongly over-consolidated nonsoftening clay mineral fillings | 6 |
Medium or low over-consolidation, softening, clay mineral fillings | 8 |
Swelling-clay fillings, i.e., montmorillonite. Value of Ja depends on percent of swelling clay-size particles and access to water | 8–12 |
(c) No rock-wall contact when sheared (thick clay/crushed rock fillings) | |
Zones or bands of disintegrated or crushed rock and clay | 6–12 |
Zones or bands of silty or sandy clay, small clay fraction (nonsoftening) | 5 |
Thick, continuous zones or bands of clay | 13–20 |
Kovanlik | 0.58 |
Gure | 0.19 |
Gulyali | 12.25 |
Piraziz | 2.10 |
Slight loosening due to surface location, disturbance from blasting or excavation | 2.5 |
*Loose blocks, tension cracks, joint shearing, weathering susceptibility, severe blasting disturbance | 5 |
As above (*), but strong susceptibility to weathering | 10 |
Slope is in advanced stage of erosion and loosening due to erosions by water and/or ice-wedging effects | 15 |
Residual slope with significant transport of material downslope | 20 |
Stable structure; competent rock | 1.0 | 0.7 | 0.5 | 0.9 |
Stable structure; incompetent rock | 0.7 | 0.6 | 0.3 | 0.5 |
Unstable structure; competent rock | 0.8 | 0.5 | 0.1 | 0.3 |
Unstable structure; incompetent rock | 0.5 | 0.3 | 0.05 | 0.2 |
Moderate stress-strength range | 50–200 | 2.5–1 |
High stress-strength range | 10–50 | 5–2.5 |
Localized intact rock failure | 5–10 | 5–10 |
Crushing or plastic yield | 2.5–5 | 15–10 |
Plastic flow of strain softened material | 1–2.5 | 20–15 |
Massive, no or few joints | 0.5–1 |
One joint set | 2 |
One joint set plus random joints | 3 |
Two joint sets | 4 |
Two joint sets plus random joints | 6 |
Three joint sets | 9 |
Three joint sets plus random joints | 12 |
Four or more joint sets, random, heavily jointed | 15 |
Crushed rock, earthlike | 20 |
Discontinuous joints | 4 |
Rough or irregular, undulating | 3 |
Smooth, undulating | 2 |
Slickensided, undulating | 1.5 |
Rough or irregular, planar | 1.5 |
Smooth, planar | 1.0 |
Slickensided, planar | 0.5 |
Zone containing clay thick enough to prevent rock-wall contact | 1.0 |
Sandy, gravely, or crushed zone to prevent rock-wall contact | 1.0 |
Major discontinuity with little or no clay | 1 | 2 | 4 | 8 |
Major discontinuity with RQD100 ≈ 0 due to clay and crushed rock | 2 | 4 | 8 | 16 |
Major discontinuity with RQD300 ≈ 0 due to clay and crushed rock | 4 | 8 | 12 | 24 |