Geology Reference
In-Depth Information
Figure 6.25
Schematic
representation of
various measures
for stabilising rock
slopes or protecting
public.
Surface channels to prevent
water ingress/surface
erosion
Scaling or
buttressing/restraining
of loose blocks
Pattern
doweling
especially of
key blocks
Anchoring of
slabs shown to
have low F of S
Catch
nets to
stop rock
falls
reaching
facility
Drains
Bioengineering is used to generally improve the stability and reduce
erosion from natural slopes. Roots bind the soil and vegetation can
increase surface runoff. Most bioengineering solutions cannot, how-
ever, be relied upon to improve the long-term stability in risky slopes,
because vegetation can rot and die or be destroyed by
re.
Furthermore, root growth can lead to rock blocks becoming loosened
and detached.
6.6.5.2 Rock and boulder falls
Where individual rockfall sources are identi
ed, these can be scaled
off, reinforced by dowels, bolts, cables or dentition buttresses and/or
netted where the rock is in a closely jointed state. Removing large
blocks can be dif
cult because of the inherent risks associated with
breakage techniques, including blasting and chemical splitting, which
can dislodge blocks unexpectedly. Care must be taken to protect the
public and workers during such operations. The most dif
cult zones to
deal with are those with poor access. Implementing passive or active
protection needs to start from safe ground and move progressively into
the areas of more hazardous stability.
Rockfall trajectory analysis, using widely available software, allows
prediction of energy requirements and likely bounce heights and run-
out damage zone extent. Where energy considerations allow, toe zone
protection measures, catch benches, catch ditches and toe fences
 
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