Changes Application - MCU15/0023.02

ProjectNo. 112-14608
January, 2013   REF: 1-14608, 2013-01-15, BR VER O.                                          Page 11

      It is recommended that the designers satisfy themselves that the use of AS.2870 is
      applicable for the proposed design.


      From a different classification viewpoint, this site has been classified by Sunshine Coast
      Council to be within a sand dune problem area, based on its location on the sloping side
      of a sand dune. Additional discussion on the stability of this site is included in Section
      4.6.

      4.4.2     Shallow Foundations

      It is recommended that footings should extend to a minimum depth of 1.0m below a 25
      degree line from the toe of the slope, and into medium dense sands (as a minimum).


      The base of all footings should be individually recompacted using a vibrating plate
      compactor prior to placement of reinforcing steel and concrete as soils may be loosened
      during the excavation process by machinery action. If the sand is dry, it should be
      saturated and left for a short period prior to vibration.        Should any loose areas be
      encountered in the footing excavations the density of these areas must be improved.
      Dynamic Cone Penetrometer (DCP) tests should be carried out to confirm the adequacy
      of the founding soils. Note that it may be necessary to use formwork to prevent trench
      side collapse in the sand profile.


      Table 2 outlines allowable bearing capacities for high level footings on the site


      TABLE 2            ALLOWABLE         BEARING CAPACITIES FOR HIGH LEVEL FOOTINGS

                        Material                          Allowable Bearing Capacity (kPa)
                                                      Strip Footing               Pad Footing
      Sand             - Loose                              NR                        NR
                       - Medium Dense                       100                       150
                       - Dense to Very Dense                150                       225


      4.4.3     Deep Foundations

      It is considered that the most appropriate piling system would be that which involves the
      least amount of ground vibration during construction.       Therefore. continuous flight auger
      (CFA) grout (or concrete)       piles or screw-in   piles are considered      to be suitable.
      Conventional bored piles are considered unsuitable for construction of piles in loose
      sand. as the excavations would collapse.




                                                          #. SOIL SURVEYS ENGINEERING