Geotechnical News • March 2018
45
THE GROUT LINE
assist in mass production of grout.
The mixing plants have silos to
store cement, dry bentonite, ben-
tonite slurry and water. The grout
batching units on the mixing plants
can prepare 1500 liters of base
grout mix per batch. Each plant
is equipped with a group of grout
pumps with a capacity to pump
at 300 L/min. The pumps have a
capacity to keep the grout in con-
tinuous circulation in the grout line
circuit, 3000 m long.
• Grout conveyance systems: The
grout mixed at the main mixing
plants is conveyed to the gallery
and crest through the grout deliv-
ery and distribution system. The
system includes a series of pipes
to keep grout and bentonite slurry
in continuous circulation. The
grouting units positioned at the
injection holes draw the base mix,
bentonite slurry, water from the
conveyance systems and perform
volumetric batching to produce the
appropriate mix. The conveyance
system initiates and ends at the
grout mixer on the mixing plants.
The conveyance system has been
designed to be easily configured in
multiple loops of varying length
each. This facilitates grout deliv-
ery to where it is needed at the
required volumes. Loops in excess
of 2 Km in length are currently
being used at the site.
• Communication/internet: To con-
duct a massive grouting operation
of this magnitude, a robust com-
munication network was critical.
The entire gallery and crest were
equipped with a Local Area Net-
work (LAN) using the 2500 m of
fiber optic cable newly installed.
This has facilitated computeriza-
tion of the operations. Wireless
hotspots with internet connection
were setup across the entire dam
to enable communication among
teams working simultaneously
throughout the dam. The entire
communication network is con-
nected to a centralized operations
center (“Control Room”), from
where the entire drilling and grout-
ing operations are supervised.
• Lighting: New lighting systems
were provided in the gallery and
crest for safer and more effective
operations.
• Ventilation: A new ventilation
system was designed and installed
to draw fresh air in through the
right access gallery, circulate it
throughout the gallery and then out
through the left access gallery.
• Concrete delivery system: The
concrete delivery system was es-
tablished through existing vertical
shafts constructed in the dam to
deliver concrete mix from the crest
to the gallery.
Equipment
Drill rigs needed for this project were
expected to drill through different
types of geology, fit in limited spaces,
work on steep slopes, drill holes up
to 150m deep, core holes and work
through artesian conditions. To meet
these needs, different types of custom-
ized rigs were used on the site and
were equipped with drilling parameter
recorders (DPR) that collect various
parameters for analysis.
Two double-rotary SM-16 diesel rigs
where purchased for outdoor drill-
Figure 6. Typical mixing plant setup.
Figure 7. Grouting gallery with legacy and updated infrastructure.
Figure 5. Grouting gallery profile.
