sand-cement grout, and a new hole drilled as directed by the Contracting
Officer. Slight adjustments to inclinations indicated on the drawings may
be required, as directed by the Contracting Officer. The Contractor shall
be responsible for all drilled holes until accepted by the Contracting
Officer. Holes to replace incorrectly drilled holes shall be drilled at no
additional cost to the Government. All equipment for checking alignment of
anchor holes shall be operated by personnel experienced in the operation of
such equipment.
][3.2.7.3
Alignment Checking Equipment
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NOTE: Because of the expense involved, the
down-hole gyrocompass should only be used when there
is a reasonable anticipation that embedded metal
will be encountered within the structure in
sufficient mass to affect the magnetic compass. In
such case, an appropriate payment item for a cost
per day should be included.
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Alignment of holes shall be checked by means of a magnetic single shot
survey instrument, or equal equipment. The camera and plumb-bob assembly
shall be selected based on the maximum expected range of angle deviation to
be measured. [If embedded metal within the structure is reasonably
believed to have affected the standard magnetic compass, then a down-hole
gyrocompass may be required. Payment for use of the gyrocompass will be
made at the contract unit price per day.]
][3.2.8
Watertightness Testing
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NOTE: Anchor holes should be watertight to prevent
loss of grout from the rock zone, prevent dilution
of grout prior to setting, and prevent corrosion of
the tendon. Watertightness testing should be
performed where any of the following conditions are
known to occur or where sufficient data is not
available to adequately determine the integrity of
the rock:
a. the rock formation has open fractures which
would permit loss of grout from around the
prestressing steel after initial placement.
b. artesian water flow or seepage exists in the
strata where the rock anchor is located.
c. interconnection exists between drilled holes.
Watertightness testing may be performed after
drilling the hole or after pregrouting the hole.
Where the rock is known to be highly fractured,
pregrouting and redrilling should be considered
prior to watertightness testing.
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The rock portion of all drilled holes shall be watertightness tested in
accordance with the procedures of PTI 4, paragraph 7.4. A packer shall be
used where necessary to facilitate pressure testing of the bond zone.
Holes which have a water loss in excess of [9.5] [_____] liters [2.5]
SECTION 02490
Page 33
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