ITEM 507 BEARING PILES
507.01
Description
507.02 General
507.03
Materials
507.04 Driving
of Piles
507.05
Determination of Required Driving Criteria
507.06
Cast-in-Place Reinforced Concrete Piles
507.07 Steel
H-Piles
507.08 Timber
Piles
507.09 Splices
507.10
Defective Piles
507.11 Prebored Holes
507.12 Method
of Measurement
507.13 Basis of
Payment
507.01 Description. This work consists of
furnishing and driving bearing piles.
507.02 General. Install piles of the specified
type, length, and sizes shown on the plans. Furnish the piles according
to the itemized order list shown on the plans. If additional length is
needed to obtain bearing, furnish the additional length as determined by the
Engineer. The length of the piles given in the order list is not necessarily
based on available or practical lengths, but the estimated length from the
bottom of each pile to the elevation of the cutoff. The Contractor may
increase or decrease the pile lengths to suit the lengths available, to
facilitate the method of operation, which may involve providing fresh heading
as a result of hammer misalignment or a worn hammer cushion, or to provide
lengths determined practical to have delivered to the project site and driven.
507.03 Materials. Furnish materials conforming to
the following:
Reinforcing
steel........................................................... 509
Concrete, Class
QC1.................................................... 511
Chemical admixture for concrete,
Type F................ 705.12
Steel
H-piles............................................................ 711.03
Steel pile
points........................................................ 711.07
Steel for reinforced
concrete piles…………………711.03
Galvanized
steel....................................................... 711.02
Timber.....................................................................
711.26
Provide
a concrete slump from 6 to 8 inches (150 to 200 mm) with the use of a superplasticizer.
507.04
Driving
of Piles.
Drive piles to refusal on bedrock; until obtaining the required ultimate
bearing value, which may include a modification for scour, set-up, or negative
skin friction; or to the minimum penetration pile tip elevation shown on the
plans.
If
piles begin to crush, immediately cease driving and repair or replace the
pile. The counting of blows will cease until the crushed pile is either
repaired or replaced.
For
piles subject to scour, notify the DGE if the required
ultimate bearing value is obtained before the pile has penetrated 80 percent of
its estimated depth before appreciably overdriving the pile. The DGE will study the conditions and determine the final
penetration, the driving requirements, the use of another pile type, and the
use of prebored holes.
All
piles raised during the driving of adjacent piles shall be driven down again.
Use
a hammer that will achieve the required ultimate bearing value for the pile and
large enough to permit a dynamic load test to verify that the ultimate bearing
capacity shown on the plans can be achieved.
The
ram of an air-operated or diesel hammer shall weigh at least 2700 pounds
(12,000 N).
The
ram of a drop hammer for permanent piles shall weigh at least 3000 pounds (13,300
N). The height of fall for drop hammers shall not exceed 7 feet (2.1
m). Do not use drop hammers to drive piles that are to be driven to an
ultimate bearing value in excess of 70 tons (620 kN).
When
using open ended diesel hammers, provide equipment for the Engineer’s use to
accurately measure each stroke within 6 inches (150 mm).
Attach
a gage to closed end diesel hammers, accessible to the Engineer, to monitor the
pressure in the bounce chamber. Include a graph with the gage to convert
pressure to energy.
Attach
an impact energy monitor, or a method to accurately measure the stroke within 2
inches (50 mm) to hydraulic hammers, accessible to the Engineer, to monitor the
energy of each blow.
Use
securely anchored driving leads and a cap device with sliding jaws to engage
the leads to guide the pile and maintain the pile alignment with the stroke of
the hammer. Accurately align the travel of the hammer with the axis of
the pile.
Cushion
the hammer and pile to prevent the impact of driving forces from damaging the
top of the pile. Shape the cap and pile top to uniformly distribute the
hammer blow to the top surface of the pile.
Do
not use a follower unless approved by the Office
of Structural Engineering. If the Office
of Structural Engineering does approve the use of a follower, account for
the increased energy loss when determining the required driving criteria.
If
a static load test is required, the Contractor may not drive piles except the
test and anchor piles before conducting the test and the required depth of
penetration has been determined.
Do
not use water jets.
After
being driven, cut off the piles at the elevation and angle shown on the plans.
Ensure that the actual pile embedment into the concrete is within 2 inches
(50mm) of the embedment shown in the plans.
507.05 Determination of Required Driving Criteria. Determine
the required driving criteria to achieve the ultimate bearing value of a driven
pile as if the pile was a single isolated pile using the results of dynamic
pile testing as specified in Item 523. The driving
criteria may consist of a minimum blow count with a minimum hammer stroke, a
minimum depth of penetration, or both.
To
determine the minimum blow count for battered piles, divide the minimum blow
count for vertical piles with the same ultimate bearing value by an efficiency
factor (D) that is less than one. This will result in an increased
minimum blow count for the battered piles. Compute the efficiency factor
(D) as follows:
D= |
1 - (U × G) |
(1+G²)0.5 |
Where:
U = Coefficient of friction
use 0.05 for double-acting air operated or diesel hammers,
use 0.1 for single-acting air operated or diesel hammers, and
use 0.2 for drop hammers.
G = Amount of batter (H/V; 1/3, 1/4, etc.)
507.06 Cast-in-Place Reinforced Concrete Piles. Provide
cast-in-place reinforced concrete piles conforming to one or more of the types
described below. Measure the pile diameter as follows:
A. Plain cylindrical casing, the outside
diameter.
B. Cylindrical casings with vertical fluting,
the diameter of a circle circumscribing the outermost points or ridges.
C. Cylindrical casing with
circumferential corrugations, the average of the outside diameters measured at
the bottom and top of the corrugations or continuously welded helical
corrugations with diameters measured at tops of the corrugations.
D. Tapered piles, the top diameter as
determined in 507.06.A, 507.06.B, or 507.06.C,
but the pile tip diameter shall not be less than 8 inches (200 mm).
Ensure
that the pile casings are watertight after being driven. If furnished,
shoes or points shall not project more than 1/4 inch (6 mm) outside the
vertical surface of the casing.
For
plain cylindrical casings, the minimum pile wall thickness, t, is the greater
of either 0.250 inches (6.66 mm) or the thickness determined using the
following formula:
t (inches) = |
R
(lb) |
|
t (mm) = |
R
(N) |
900,000 |
|
157,606 |
Where:
R = Ultimate bearing value in pounds (newtons)
For
fluted piles, the minimum pile wall thickness shall be t/1.4.
For
cast-in-place piles containing reinforcing steel, place reinforcing steel as
stated in the second and third paragraph of 524.09 and place concrete according
to 524.11.
After
installation, cover the tops of driven casings until the concrete is
placed. Before placing concrete, remove accumulated water or other
foreign matter in a driven casing. Maintain a minimum radius of 15 feet
(4.5 m) between simultaneous work of placing concrete and driving pile
casings. If concrete is placed within the 15-foot (4.5 m) radius, suspend
driving operations until the concrete has cured for 5 days. Place concrete
for cast-in-place piles using methods that prevent voids, however, do not
vibrate the concrete.
507.07 Steel H-Piles. Steel H-piles shall
consist of structural steel shapes of the kind and size specified.
The
Engineer may allow installation of steel piles of the specified type, which the
Contractor has from previous projects or stock, if the Contractor furnishes
mill certifications and the pile sections are identified with the material
specification number, grade, and heat number. This identification may be
in the form of information painted on the steel piles or a tag physically
attached to the steel.
507.08 Timber Piles. Provide timber piles of
sufficient length to remove broomed or split portions
caused by driving. Symmetrically trim piles right truncated cone at the
tip. If steel shoes or points are specified, carefully shape the tip of
the pile so that the steel shoe or point fits snugly and symmetrically.
Handle
and store timber piles to prevent warping.
If
specified, provide creosoted piles conforming to 712.06.
507.09 Splices. To the fullest extent practical,
avoid splicing steel casings and structural shapes. Splice pile casings
and structural shapes either before or after driving a segment. If
spliced after driving a segment, splice the piles at least 3 feet (1 m)
above the ground and inspect the splice while the pile is driven a minimum of
150 blows.
Align
segments to make the axis of all segments common.
Use
full penetration butt welds to splice structural shapes according to 513.21, except delete the requirement to use
temporary extension bars.
Do
not splice timber piles.
Pile Points. When specified
in the plans, select a product from the Department’s approved list. Weld the
pile points to the pile according to AWS
D1.5 or the manufacturer’s written welding procedure supplied to the
Engineer before the welding is performed. Submit a notarized copy of the mill
test report to the Engineer.
507.10 Defective Piles. Piles entirely underground
are defective if the pile location at the ground surface is more than the 1
foot (0.3 m) from the location shown on the plans.
Piles
projecting above the ground are defective if the pile location at the ground
surface is more than 3 inches (75 mm) from the location shown on the plans.
Pipe
piles are defective if not water tight or if damage reduces the cross-sectional
area by more than 20 percent. Provide the Engineer with a light that allows
inspection of the entire length of the interior of a driven casing.
Replace,
repair, or drive a substitute pile beside the defective pile. The
location tolerance for underground piles does not apply to substitute piles
beside defective underground piles. The off-location limits do apply to
the substitute pile that project above the ground. If a defective pile is
removed, fill the hole remaining in the ground with
sand. Cut off a defective pile left in place under a footing 3 inches (75
mm) above the elevation of the bottom of the footing. Cut off a defective
pile left in place but not under a footing at least 1 foot (0.3 m) below ground
level. Fill defective pipe piles left in place with concrete.
When
the outside rows of bearing piles are not located within tolerances specified
above, increase the size of the footing to provide a minimum distance between
the pile and footing edge of at least 75 percent of that shown on the plans.
507.11 Prebored Holes. Locate prebored holes as shown on the plans. Provide augured
hole diameters:
A. For round piles, from 2 inches (50 mm)
less to 4 inches (100 mm) more than the pile diameter.
B. For steel H-piles, from 6 inches (150
mm) less to 2 inches (50 mm) more than the pile’s diagonal dimension but shall
be such as to produce satisfactory pile driving results.
Backfill
voids between the pile and the prebored hole with a
granular material satisfactory to the Engineer.
507.12 Method of Measurement. The
Department will measure piles driven by the number of feet (meters). The
Department will determine the sum as the lengths of all non-defective piles
measured along the axis of each pile from the bottom of each pile to the
elevation of cutoff. Unless a separate pay item is specified in the
Contract, the Department will include Steel Points or Shoes in the measured
length of driven piles. If a separate pay item is specified in the
Contract, the Department will measure Steel Points or Shoes by the number of
each.
The
Department will measure piles furnished by the number of feet (meters) of plan
specified order length plus any additional order length specified by the
Engineer. The Engineer will include the length of undriven
piles as furnished, but the Contractor will not receive additional compensation
for hauling the piles off the project.
For
plan specified prebored holes, the Department will
measure Prebored Holes by the number of feet (meters)
of prebored hole lengths for non-defective piles
measured from the surface of ground at the time of boring to the bottom of the
hole. The Department will not measure preboring
to facilitate the pile driving operation.
507.13 Basis of Payment. When the
Contractor elects to prebore to facilitate the pile
driving operation, include the cost for preboring in the
unit price bid for piles driven.
The
Department will consider the cost of furnishing and installing the reinforcing
steel to be included in the unit price bid for piles driven.
The
Department will not pay for any splices due to the Contractor furnishing pile
lengths shorter than plan order lengths. The Department will not pay for
increased pile lengths made by the Contractor unless the Engineer determines
that the additional lengths are needed to achieve bearing. If additional
penetration is necessary in order to achieve the required bearing, the
Department will pay for required splices at a negotiated price.
The
Department will pay for accepted quantities at the contract prices as follows:
Item
Unit
Description
507
Foot
(Meter)
Steel Piles HP____´____, Furnished
507
Foot
(Meter)
Steel Piles HP____´____, Driven
507
Foot
(Meter)
___" (___ mm) Cast-In-Place,
Reinforced Concrete Piles, Furnished
507
Foot
(Meter)
___" (___ mm) Cast-In-Place,
Reinforced Concrete Piles, Driven
507
Foot
(Meter)
Timber Piles, Creosoted
507
Foot
(Meter)
Timber Piles, Untreated
507
Foot
(Meter)
Prebored Holes
507
Each
Steel Points or Shoes