FP-96 English Version - Eastern Federal Lands Highway Division

Section 551551.07 Preboring. Prebore holes to natural ground when piles are driventhrough compacted embankments more than 5 feet in depth. Use augering, wetrotary drilling, or other approved methods of preboring. Except for piles endbearingon rock or hardpan, stop preboring at least 5 feet above the estimatedpile tip elevation and drive the pile with an impact hammer to a penetrationwhich achieves the required ultimate pile capacity. Preboring may extend tothe surface of the rock or hardpan where piles are to be end-bearing on rockor hardpan. Seat the piles into the end-bearing strata.Prebore holes smaller than the diameter or diagonal of the pile cross-sectionwhile allowing penetration of the pile to the specified depth. If subsurfaceobstructions such as boulders or rock layers are encountered, the hole diametermay be increased to the least dimension adequate for pile installation. Fill anyvoid space remaining around the pile after completion of driving with sand orother approved material. Do not use a punch or a spud in lieu of preboring.Do not impair the capacity of existing piles or the safety or condition of adjacentstructures. If preboring disturbs the capacity of previously installed pilesor structures, restore the required ultimate capacity of piles and structures byapproved methods.551.08 Preparation and Driving. Perform the work under Section 208.Make the heads of all piles plane and perpendicular to the longitudinal axis ofthe pile. Coordinate pile driving so as not to damage other parts of the completedwork.Drive piles to within 2 inches of plan location at cutoff elevation for bent capsand within 6 inches of plan location for piles capped below finished ground.The pile shall not be closer than 4 inches to any cap face. Drive piles so thatthe axial alignment is within 0.25 inch per foot of the required alignment. TheCO may stop driving to check the pile alignment. Check alignment of pilesthat cannot be internally inspected after installation before the last 5 feet aredriven. Do not pull laterally on piles or splice to correct misalignment. Do notsplice a properly aligned section on a misaligned pile.Place individual piles in pile groups either starting from the center of the groupand proceeding outward in both directions or starting at the outside row andproceeding progressively across the group.362