Environmental Engineering Reference
In-Depth Information
FIGURE 9.102
Folded, vertical beds in highly fractured, hard arenaceous shale, are stable in near-vertical cuts (Sidikalang,
Sumatra). Decreasing the slope inclination would increase susceptibility to erosion.
and shale (see
Figure 6.48)
are often cut to 1H:4V. The shale beds in Figure 6.48 should be
protected from weathering with shotcrete or gunite if they have expansive properties or
are subjected to intense fracturing and erosion from weathering processes. Note that the
steeper the cut slope the more resistant it is to erosion from rainfall.
Clay shale, unless interbedded with sandstone, is often excavated to 6H:1V (9.5°).
Weathered or closely jointed masses (except clay shale and dipping major discontinu-
ities) require a reduction in inclination to between 1H:2V 1H:1V (63-45°) depending on
conditions, or require some form of retention.
