ITEM 507 BEARING PILES
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
507.10 Defective Piles
507.11 Prebored Holes
507.12 Method of Measurement
507.13 Basis of Payment
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.
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
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:
1 - (U × G)
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.)
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.
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) =
t (mm) =
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.
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.
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.
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.
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
___" (___ mm) Cast-In-Place,
Reinforced Concrete Piles, Furnished
___" (___ 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