Environmental Engineering Reference
In-Depth Information
Figure 18.3.
Grouting downstage without packer (WRC, 1981).
depths are reasonably well known, and in strong rock with holes not likely to collapse or
erode.
Full Depth
(
Figure 18.6
): Does not allow proper assessment of where grout take is
occurring or proper monitoring of reduction in Lugeon values with grouting. Depths are
predetermined so the method does not allow logical assessment of grout depth based on
closure requirements. Grouting pressures are limited. It is not an acceptable method
except for consolidation grout holes.
Full Depth Circuit
(
Figure 18.7
)
: Has the same limitations as full depth grouting, but by
injecting the grout into the base of the hole, the possibility of settled grout is lowered.
For stage grouting, the stage lengths are commonly predetermined depending on:
- The geological conditions and depths at which changes in degree of permeability are likely
to occur;
-The minimum length worth drilling, since short stages are more costly to drill because
of set up costs;
-
Allowable pressures in the upper part of the hole (dependent on geological conditions).
