Changes Application - MCU15/0023.02

ProjectNo.112-14608
January,2013   REF:     1.14608,2013-01.15,BR VER O.                                          Page13
               where y Loose = 17kN/m'
                       Medium Dense = 18kN/m'
                       Dense = 19kN/m'

               Pd =        average effective overburden pressure
               K, =        lateral earth pressure coefficient
               <5   =      pile-soil angle of friction
               Nq =        bearing capacity factor


     (Nq = 60 for medium dense sands,            Nq = 100 for dense sands)


     Broms (1966) relates the lateral earth coefficient (K,) and pile-soil friction angle (0) to the
     internai angie of friction of the soil (,p)and pile material as follows:


     TABLE 3               LATERAL EARTH COEFFICIENTS

                                                                           K.
        Pile Material               <5
                                                         Loose        Medium Dense     Dense
            Steel                   20'                  0.50             0.75          1.00
          Concrete               0.75' ,p                1.00             1.50          2.00


     It should be noted that the calculated ultimate resistance of a given pile should also take
     into account the installation effects of that particular type, I.e. whether displacement or
     non-displacement pile performance can be expected.


     Uplift and lateral capacities of piles are not considered, as these are both wholly
     dependent on the specific pile type selected.


     Steel screw piles involve a hollow steel stem with a flight attached to the toe of the pile
     which are 'screwed' in the ground, reducing spoil and construction difficulties associated
     with loose sands. The compression capacity is calculated based dominantly on the end
     bearing capacity due to negligibie shaft friction. Shaft capacity of screw-in piles are
     generally minimal and should not be taken into consideration for calculating design values
     due to the nature of pile installation. Steel screw piles should also be suitably protected
     from corrosion, egogalvanised, additional sacrificial wall thickness, concrete filled.




                                                                 *   SOIL SURVEYS ENGINEERING