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Allowable loads on piles

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The most commonly used formula to determine the allowable static load on a pile is the Engineering News formula.

Case-1 The allowable load for piles driven by a drop hammer
Pa=(2WH)/(p+1)

Case-2 The allowable load for piles driven by a steam hammer
Pa=(2WH)/(p+0.1)

where
Pa=allowable pile load, tons (kg)
W= weight of hammer, tons (kg)
H= height of drop, ft (m)
p= penetration of pile per blow, in (mm)

A safety factor of 6 is included in the above both equations. Now when we have a group of piles driven in a soil with good bearing characteristics and these piles transfer the load to soil by point bearing at the end, we take the total allowable load as the sum of individual allowable loads for each pile.

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But in case of loads transferred by skin fraction, due to shearing stress and strain we take the total allowable load less than the sum on the individual allowable loads for each pile.

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Comments
  • SELVA April 30, 2009 at 7:29 am

    Dear Sir,
    Informations are so useful.. i have some doubts. In Pile foundation Under reamed bulb are possible in driven piles. Which pile is suitable for sandy soil a. Bored cast-in-situ piles or b. Driven cast-in-situ piles? Kindly reply me as soon as possible
    Thanks & Regards,
    E. Selva
    Chennai

  • S K TRISAL June 13, 2009 at 5:44 am

    the factor of safety is 6 only when the measurements are in ft and inches
    suitable alteration in metric system

  • GULSHAN KHAN July 13, 2010 at 6:24 am

    I NEED PILE LOAD TEST CONCERNED IS CODE . IF SOME KNOWS PLZ SEND ME

  • james selvarajan July 30, 2010 at 11:09 am

    Dear Sir,

    Kindly give me the details of Dynamic load test and also how to approve the pile based on the above test.

    Regards,

    James

    • Yogeshwar Rao August 24, 2010 at 8:46 am

      Pls refer to ASTM D 4945-89 & compare dynamic pile capacity with IS 2911 part IV

  • Yogeshwar Rao August 24, 2010 at 8:42 am

    Dear Sir,
    can anybody pls. suggest me what steps need to be taken to avoid ingress of sand/silt into the pile bore.which brand bentonite slurry & what pH need to be maintained
    M.S liners has been driven but don’t go below 6-7m below bed lvl.

  • R.C.TARKAR June 25, 2011 at 1:13 pm

    PL.SAND ME REQUIREMENT OF PILE& DESIGN OF PILES INCL. LOAD TESTS.

  • Amol Gaikwad November 21, 2011 at 9:20 am

    Pile installed as can be designed for an allowable capacity . . . Across the pile cross sectional area.

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