Environmental Engineering Reference
In-Depth Information
FIGURE 9.114
Support of granite overhang with pedestals (Rio de Janeiro). Ancient slide mass of colluvium appears on lower
slopes. (a) Side view and (b) face view.
A major installation of bolts and straps is illustrated in Figure 9.120, part of a 60-m-high
rock slope ( Figure 9.121), at the base of which is to be constructed a steel mill. The con-
sultant selected the support system rather than shaving and blasting loose large blocks for
fear of leaving a weaker slope in a high-risk situation.
Rock Dowels are fully grouted rock bolts, usually consisting of a ribbed reinforcing bar,
installed in a drill hole and bonded to the rock over its full length (Franklin and Dusseult,
1989). Rock movement results in the dowels being self-tensioned. Grouting with resins is
becoming more and more common because of easy installation and the rapid attainment
of capacity within minutes of installation. Sausage-shaped resin packages are installed in
the drill hole and a ribbed bar inserted and rotated to open the packages which contain
resin and a catalyst ( Figure 9.119c) .
Shotcrete , when applied to rock slopes, usually consists of a wet-mix mortar with aggre-
gate as large as 2 cm (3/4 in.) which is projected by air jet directly onto the slope face. The
 
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