Appendix D Geotechnical report · MCU18/0013

Project No. 304-2014
November, 2004 Page 11

 

Broms (1966) relates the lateral earth coefficient (K) and pile-soil friction angle (6) to the

internal angle of friction of the soil (¢)and pile material as follows:

 

 

 

 

 

TABLE 5 LATERAL EARTH COEFFICIENTS
Pile Material 3 Ks
Loose Medium Dense Dense
Steel 20° 0.5 0.75
Concrete 0.75*¢ 1 1.5 2

 

 

 

 

 

 

 

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.

According to the limit state design approach in AS2159-1995 (Piling Code), the design
geotechnical strength R,* is calculated by multiplying the ultimate geotechnical strength
Rug (which is equivalent to Q. above) by the geotechnical strength reduction factor ($s).

For static design for piles on this project, we would consider $y = 0.45 to be appropriate.

Uplift and lateral capacities of piles are not considered, as these are both wholly

dependent on the specific pile type selected.

6.3.5 Construction Considerations
Inspections

It is recommended that inspections be undertaken by an experienced and qualified
geotechnical engineer following footing excavations to confirm the adequacy of the
founding soils. Inspections should be carried out prior to placement of reinforcing steel

and ordering of concrete.

Underground Services

Where footings are located adjacent to underground services, the footings should extend
to base a minimum of 200mm below the trench base level for a distance of 1.0m out from
the trench. Beyond 1.0m the footings should be taken a minimum of 200mm below an

imaginary line drawn up at 45° from the trench base level (Figure 1).

 

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