271117 Techtonic GeoTech Cooroy Mtn Rd

Mr Ken Freeman                                                                                 17385-001-Rev0
                                                                                             27 November 2017

5.3     Retaining Structures
Retaining structures for the proposed works must be engineer designed in accordance with AS4678-2002
Earth retaining structures, and must be founded as described in Section 5.4 below. The following
parameters may be adopted for retaining wall design.

Table 4: Retaining Wall Design Parameters
                                                           Lateral earth pressure coefficients
                              Unit     Friction
Retained material           weight      angle
                                                         Ka                   Ko
                            (kN/m3)   (Degrees)                                                  Kp
                                                  (Cantilever wall)   (Non-yielding wall)
Existing fill material to
north of house (firm to       18         22             0.46                 0.63                2.2
stiff silty clay)

Natural residual soils
(very stiff to hard silty     19         26             0.39                 0.56                2.56
clay)


Highly weathered
                              22         35             0.27                 0.43                3.69
rock

Note: These parameters do not include allowance for surcharge above the wall, or additional loads imposed
by sloping ground.

A retaining wall is recommended to support the cut adjacent to the proposed carport (Refer Text Figure 6).

Engineer design of retaining walls should include global stability modelling, which can be carried out by
Tectonic once retaining wall design details are available.




                                                      10/13