Page 367 - Engineering Rock Mass Classification_ Tunnelling, Foundations and Landslides

322 Engineering Rock Mass Classification

TABLE 26.1 Terms to Describe Large-Scale Waviness (JW)

Waviness Rating for
terms waviness
Undulation (JW)
Interlocking
(large-scale) 3

Stepped 2.5

Large >3% 2

undulation

Small to 0.3–3% 1.5
moderate
undulation

Planar <0.3% 1

Sources: Palmstrom, 1995; Cai et al., 2004.

TABLE 26.2 Terms to Describe Small-Scale Smoothness (JS)

Smoothness Description Rating for
terms smoothness (JS)
3
Very rough Near vertical steps and ridges occur with 2
interlocking effect on the joint surface
1.5
Rough Some ridges and side-angles are evident; asperities
are clearly visible; discontinuity surface feels 1
very abrasive (rougher than sandpaper grade 30) 0.75
0.6–1.5
Slightly rough Asperities on the discontinuity surfaces
are distinguishable and can be felt
(like sandpaper grade 30–300)

Smooth Surface appears smooth and feels so to the touch
(smoother than sandpaper grade 300)

Polished Visual evidence of polishing exists; this is often
seen in coating of chlorite and especially talc

Slickensided Polished and striated surface that results from
sliding along a fault surface or other movement
surface

Sources: Palmstrom, 1995; Cai et al., 2004.