458 SECTION 616 STEEL BEARING PILING
616.1 -DESCRIPTION : This work shall consist of furnishing and driving steel bearing piles, of the kind and dimensions designated, to the required bearing or penetration in accordance with these Specifications and in reasonably close conformity with the lines and spacing shown on the Plans or established by the Engineer.
616.2 -MATERIALS : Materials shall conform to the requirements specified in the following subsections:
MATERIAL SUBSECTION Steel Bearing Piles and Splices * 709.12 Steel Pile Points 709.50
* The piling section shall be of the H form and with total flange width substantially equal to the depth of the section. No section shall have a thickness of metal less than 0.4 inches, nor a depth less than 8 inches.
CONSTRUCTION METHODS
616.3 -PREPARATION FOR DRIVING : Unless the Contractor demonstrates to the Engineer for site access reason, piles shall not be driven until required excavation or em bankment is completed. Pre -drilled boreholes shall be drill and backfilled with sand prior to placement of the pile and driving. Material forced up between the piles shall be removed to correct elevation, without cost to the Division, before concrete for the foundation is placed. Piling driven within seventy -five ( 75) feet of any privately owned structure, that is not being dismantled during the project, shall require pre -construction and post-construction survey to assure damages are not caused by the selected driving method.
616.4 -EQUIPMENT FOR DRIVING : 616.4.1 -General: When a diesel hammer is used for driving piles, both the fuel setting and stoke height of the hammer, shall be maintained at refusal to insure full energy of the driving blows a nd the target capacity as noted on the Plans is achieved. All hammers shall be in good working order, in the opinion on the Engineer, and be warmed up prior to refusing any pile. Before pile driving is started, the Contractor shall provide written certi fication to the Engineer of the pile hammer type(s) and rated energy, and that the hammer has been inspected and found to be in good working condition. In case the required penetration is not obtained using a hammer complying with the minimum requirements in subsection 616.4.2 the Contractor shall provide a heavier hammer or resort to predrilling at their own expense.
616.4.2 -Hammers for Steel Piles: Open and closed end diesel hammers are commonly required to drive steel piles. Vibratory hammers can be used to extract piles. Vibratory hammers shall not be used to set the piles to the tip elevations and target capacity, unless specified in the Plans. External combustion hammers shall not be used to set the piles to the
459 tip elevations and target capaci ty, unless specified in the Plans. All hammers used to drive steel piles shall have a minimum equivalent energy rating of 25,000 ft -lbs or as specified on the Plans. Gravity hammers for driving steel piles shall not be allowed unless noted otherwise on the Plans.
616.4.3 -Leads, Cushion Material, and Helmet: Pile driver leads, cushion material, and helmet shall be in accordance with the hammer manufacture’s specifications. Substitute materials will only be allowed at the Engineers discretion.
616.5-METHOD OF DRIVING : Drive the piles at the locations and to the vertical or battered lines shown in the Plans. Use full-length piles where practicable. Unless otherwise approved by the Engineer, dri ven piles shall reach the required tip elevations and blows per inch at refusal. Harden steel pile point shall be used for all piles driven to refusal on bedrock. Pile points shall be welded as required in these specifications. Unless the Contractor dem onstrates to the Engineer for site access reasons, piles shall not be driven until the required excavation or embankment is complete. Piling driven within twenty ( 20) feet of freshly placed concrete, shall not be ed until after the minimum compressive strength has been achieved per Table 601.8.7 for Superimposed Concrete Elements. When required, pre -drilled borehole diameters shall be as specified on the Plans. Drill the holes accurately so that the piles are set at the locations as shown in the Plans. Place clean, dry sand in all borehole before placing and driving the piles, unless otherwise noted on the Plans.
616.6 -ACCURACY OF DRIVING : All piles shall be driven with a variation of not more t han 2% from the vertical or from the batter line indicated. The plan elevation for cut off shall be measured from the lowest point of the pile head with a maximum deviation of two ( 2) inches above plan cut off providing this deviation does not interfere wi th other construction requirements. The cut off shall be made at right angles to the pile. The concrete cover from the face of the concrete to any face of the pile shall not be less than nine ( 9) inches except on the side the pile penetrates the structure. Additional concrete cover may be monolithically added to the structure to maintain the minimum nine ( 9) inches cover at no cost to the Division.
616.6.1 -Foundations: The location in plan for piles in foundations may have a maximum deviation of six (6) inches from that shown in the contract documents except as provided in subsection 616.6.2.
616.6.2 -Abutments with Single Lines of Piles: The location in plan for piles in an abutment with a single line of piles may have a maximum deviation of three ( 3) inches from that shown in the contract documents.
616.6.3 -Combination Pile and Trestle Bents: The location of the top of a combination pile and trestle bent may have a maximum plan deviation of 1 ½ inches.
616.7 -DEFECTIVE PILES : The procedure incident to the driving of piles shall not subject them to excessive and undue abuse producing deformation of the steel. Any pile driven out of the tolerances required in subsection 616.6, or any pile damaged by reason of internal defects or by improper driving shall
460 be removed or, at the option of the Engineer, a second pile may be driven adjacent thereto if this can be done without detriment to the structure. All piles so driven shall be at the expense of the Contractor.
616.8 -DETERMINATION OF BEARING VALUES : 616.8.1 -From Blow Count at Refusal: The size of piles, energy rating of hammer, fuel setting, stoke height, and target capacity will be designated on the Plans. All piles shall be driven to refusal into bedrock as indicated by the estimated pile lengths o r pile tip elevations. Refusal is defined as the blows for one (1) inch of penetration for the hammers as listed on the Plans. The minimum number of blows in the last inch of penetration shall be as specified on the Plans. If a different hammer or fuelse tting is used the Contractor shall submit driving criteria using a wave equation analysis, such as that provided by GRLWEAP. The driving criteria shall be submitted to the engineer at least 14 days prior to installation of the first pile. The driving cri teria shall include the fuel setting(s), stoke height(s), and required blows per one (1) inch to achieve the target capacity. The maximum compressive driving stress shall be submitted and shall not exceed 45 ksi at the target capacity. A minimum of 6 blo ws per one (1) inch may be allowed by the Engineer based on the wave equation analysis. As an alternate to blow count at refusal to control pile driving, the Contractor, or the Engineer, may allow the use of a Saximeter to determine the refusal stoke heig ht. Any wave equation analysis performed by the Contractor and associated costs due to delays and driving equipment mobilization shall be at the Contractor’s expense.
616.9 -STEEL PILING : 616.9.1 -General: Steel piles shall consist of structural steel shapes of the kind and size specified. Only new piles shall be furnished and used by the Contractor. Full -length steel piles shall be used where practicable. Splicing of piles is permitted subject to the ap proval of the Engineer and shall be in accordance with this Specification. The number of welded connections in the length of a pile shall be preferably as few as practicable.
616.9.2 -Splicing Steel Piles: If splices are made in steel piles by welding, the abutting surfaces must be true planes. The top surface of the lower pile shall be straightened if bent during the driving process or cut off (flame cutting permitted, 615.4.3.2.2) below the bent portion if it cannot be satisfactorily straightened. The bottom surface of the upper pile shall be beveled on the inside edges of the flanges and along one edge of the web. The bevel shall be made at an angle of approximately 40° with the horizontal. A surface of ⅛ inch may be left unbeveled. The upper pile sha ll be securely clamped to the lower pile and separated there from ⅛ inch, care being taken to make the axis of the two piles coincide. The entire periphery of the pile joint shall then be butt welded, by properly certified welders, with sufficient passes t o completely fill the joint, the slag of each pass being removed before beginning the next pass.
616.10PREDRILLED PILING :
Holes shall be drilled or bored to the diameter and depth as specified on t he Plans. Prior to placement of the pile or the driving operations, the Contractor shall fill the open borehole with concrete sand Test requirements for this material are waived, except that the material shall be dry and free flowing. After driving, the Contractor shall fill the voids around the piles with additional concrete sand to the satisfaction of the Engineer.