Geotechnical Engineering

DHARM

694 GEOTECHNICAL ENGINEERING

The Engineering News Formula and Hiley’s formula are the most commonly used dynamic pile

formulae; the former is simple, while the latter is more complete. Load test on a pile is one of the

best approaches for determining pile capacity.

4. Negative skin friction tends to develop when a soil layer surrounding a pile settles more than the
   pile. This decreases the factor of safety.


5. Pile groups need not have a capacity equal to the number of piles multiplied by individual piles.
   Usually group capacity is smaller than this and the ratio is termed group efficiency; the group
   efficiency is less than unity for piles in clays, especially where skin friction is involved. This may
   be occasionally greater than unity for piles in sands. Pile spacing is an important factor in this
   regard.
   Block failure must be checked for pile groups in clay.


6. Settlement of a pile group is many times that of an individual pile.


7. Laterally loaded piles are analysed based on Winkler’s hypothesis and the concept of the coeffi-
   cient of sub grade reaction.


8. Batter piles are used to carry large lateral loads.


9. Pile-driving records must be carefully kept and studied for a proper evaluation of a pile or Pile
   group.

References

1. Alam Singh & B.C. Punmia: Soil Mechanics and Foundations, Standard Book House, Delhi-6,
   1970.


2. V.G. Berezantzev, K.S. Khristoforov and V.N. Golubkov: Load Bearing Capacity and Deforma-
   tion of Piled Foundations, Proc. Fifth International Conference on Soil Mechanics and Founda-
   tion Engineering, Paris, 1961.


3. Bharat Singh and Shamsher Prakash: Soil Mechanics and Foundation Engineering, Nem Chand
   & Brothers, Roorkee, 1976.


4. L. Bjerrum: Norwegian Experiences with Steel Piles to Rock, Geotechnique, June 1957.


5. B.B. Broms: Lateral Resistance of Piles in Cohesive Soils, Jl. of Soil Mechanics and Foundations
   Division, ASCE., Vol. 90, No. SM2, Mar., 1964.


6. P.L. Capper, W.F. Cassie and J.D. Geddes: Problems in Engineering Soils, E & F.N. Spon Ltd.,
   1971.


7. R.D. Chellis: Pile Foundations, McGraw Hill Book Co., Inc., NY., USA, 1961.


8. A. Hiley: Pile Driving Calculations with Notes on Driving Forces and Ground Resistance, The
   Structural Engineer, Vol. 8, July-Aug. 1930.


9. A. Hrennikoff: Analysis of Pile Foundations with Batter Piles, Trans. ASCE, Vol. 115, 1950.


10. I.S: 2911 (Part I)—1974: Code of Practice for Design and Construction of Pile Foundations Part I
    Load-bearing Concrete Piles, 1974.


11. J. Kerisel: Deep Foundations—Basic Experimental Facts, Proc. of the Conference on Deep Foun-
    dations, Mexico City, 1964; also J.L. Kerisel: Vertical and Horizontal Bearing Capacity of Deep
    Foundations in Clay, symposium on bearing capacity and settlement of Foundations, Duke Uny.
    Duham N.C., U.S.A., 1967.


12. G.A. Leonards; Foundation Engineering, McGraw-Hill Book Co., Inc., NY., USA., 1962.


13. D.F. McCarthy: Essentials of soil Mechanics & Foundations, Reston Publishing Inc., Reston, Va.,
    USA, 1977.