using a coefficient of variation of 10 percent. Evaluate the strength of
concrete by averaging the test results (two specimens) of each set (four
specimens) of standard cylinders tested at 28 days. Not more than 10
percent of the individual specimens tested shall have an average
compressive strength less than specified average compressive strength.
PART 3
EXECUTION
3.1
PILE DRIVING
3.1.1
Driving Piles
Piles shall not be driven until 100 percent of design strength has been
attained and until at least 14 days after detensioning. Drive piles to the
indicated tip elevation and to the minimum embedment depth shown on the
drawings. Pile driving shall be conducted as one continuous operation.
The pile shall be driven until the resistance criterion is met. During the
initial driving and until the pile tip has penetrated beyond layers of very
soft soil or below the bottom of prejetted or preformed holes, use a
reduced rated driving energy of the hammer of not more than 20,235 Joules
15,000 foot-pounds per blow or as otherwise directed by the Contracting
Officer, to prevent high tension-wave driving stresses which could damage
the pile. Resistance criterion shall be 20 blows for 0.3 m one foot or
less. The Contracting Officer may modify the criteria based upon the
actual hammer being used and its rated energy and its compatibility as
verified by a pile test program. If a pile fails to reach the indicated
butt elevation or minimum embedment, the Contractor shall notify the
Contracting Officer and perform corrective measures as directed. Provide
hearing protection when noise levels exceed 140 dB.
3.1.2
Pile Driving Leads and Templates
Piles shall be driven with the hammer positioned in a fixed or swinging
lead. "Free hammer" will not be permitted. Swinging lead shall be used
only in conjunction with a template system to spot the piles.
3.1.3
Installation of Piles
Take care to avoid damage to piles during handling, when placing the pile
in leads, and during pile-driving operations. Inspect piles when
delivered, when in leads immediately before driving, and after
installation. No visible cracks will be permitted. Notify the Contracting
Officer of any visible cracks and perform corrective measures as directed.
Laterally support piles during driving, but allow rotation in leads.
Take special care to maintain the pile orientation during driving. Square
the top of the pile to the longitudinal axis of the pile. Maintain axial
alignment of pile hammer with that of pile.
3.1.4
Tolerances in Driving
Drive piles with a variation of not more than one percent from vertical for
plumb piles. Maintain and check axial alignment of pile and leads at start
of pile driving and when the pile top is approximately 1.5 m 5 feet above
the indicated elevation. Make intermediate checks of pile alignment if
there is evidence of pile drifting. If subsurface conditions cause pile
drifting beyond the allowable axial alignment tolerance, notify the
Contracting Officer and perform corrective measures as directed. Place
butts within 50 mm 2 inches of the location indicated.
Manipulation of
pile within specified tolerances is permitted, but do not manipulate piles
SECTION 02395
Page 18
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