Sliding criterion (geotechnical engineering)

The sliding criterion (discontinuity) is a tool to estimate easily the shear strength properties of a discontinuity in a rock mass based on visual and tactile (i.e. by feeling) characterization of the discontinuity.[1][2][3][4] The shear strength of a discontinuity is important in, for example, tunnel, foundation, or slope engineering, but also stability of natural slopes is often governed by the shear strength along discontinuities.

The sliding-angle is based on the ease with which a block of rock material can move over a discontinuity and hence is comparable to the tilt-angle as determined with the tilt test, but on a larger scale. The sliding criterion has been developed for stresses that would occur in slopes between 2 and 25 metres (6.6 and 82.0 ft), hence, in the order of maximum 0.6 megapascals (87 psi). The sliding criterion is based on back analyses of slope instability and earlier work of ISRM[5] and Laubscher.[6] The sliding criterion is part of the Slope Stability Probability Classification (SSPC)[3] system for slope stability analyses.

Table 1. Discontinuity characterization & factors.
characterization factor
Roughness large scale (Rl) wavy 1.00
slightly wavy 0.95
curved 0.85
slightly curved 0.80
straight 0.75
Roughness small scale (Rs) rough stepped/irregular 0.95
smooth stepped 0.90
polished stepped 0.85
rough undulating 0.80
smooth undulating 0.75
polished undulating 0.70
rough planar 0.65
smooth planar 0.60
polished planar 0.55
Infill material (Im) cemented/cemented infill 1.07
no infill - surface staining only 1.00
non-softening & sheared material, e.g. free of clay, talc coarse 0.95
medium 0.90
fine 0.85
softening & soft-sheared material, e.g. clay, talc coarse 0.75
medium 0.65
fine 0.55
gouge < irregularities 0.42
gouge > irregularities 0.17
flowing material 0.05
Karst (Ka) none 1.00
karst 0.92
  1. ^ Cite error: The named reference HackPrice1995 was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference Hack1998 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference HackPriceRengers was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference Price2008 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference ISRMbluebook was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Laubscher was invoked but never defined (see the help page).