1-22276-01 site plan

Project No. 1-22276                                                                                                                  Page | 27
February, 2020
Ref: 1-22276, 2020-02-28, BR VER 2
Wessel Petroleum Pty Ltd – GEOTECHNICAL INVESTIGATION - Proposed Service Station Reconstruction, 52-54 Mary Street and Weyba Road,
Noosaville




TABLE 6         GEOTECHNICAL DESIGN PARAMETERS
                                                   Angle of              Shear Strength
                               Unit Weight
         Material type                  3          Internal
                                 (kN/m )                             Cu (kPa)       C’ (kPa)
                                                 Friction (°)
Fill / Loose Natural Sands         18.5                26               NA              0
Medium Dense Sands                 19.5                33               NA              0
Dense Sands                        21.0                35               NA              5
Very Stiff Clays                   19.5                27               150             2
Note: The above parameters are based upon interpretations of the soil descriptions and the
reported DCP results.


The lateral earth pressure distribution that affects the retention systems on the site will depend
upon the following parameters:-

          Insitu material properties.
          Design water regime at the rear of the retention wall.
          Retention system type and cut geometry.
          Boundary conditions i.e., location and type (i.e., movement sensitivity) of nearby
           structures, need for underpinning, adjacent service, surcharges, etc.
          The structural bracing/anchoring of the system.

Construction Options

Options which may be considered for temporary retention include:

          Batter to safe angle – possible option only if adequate space is available and for shallow
           excavations. Refer to Section 6.2.8 of this report.
          Sheet piles – Steel sheets are driven or vibrated along the line of the proposed
           excavations. Difficulties expected in penetrating lower level soils with pre-boring
           expected to be required in the indurated sands.
          Pile type system (contiguous, secant, etc). These type of systems involves piers drilled
           at nominated spacings, including overlapping, with the spaces, where present, filled with
           sprayed concrete, etc. The piers would be drilled to below the depth of maximum
           excavation and suitably anchored (if required). The pier spacing depends on the
           stability and effect of seepage of the exposed materials during construction as well as
           required wall stiffness The Secant system would provide a better watertight retention
           system.
Whatever temporary retention system is adopted a detailed design will be required to
determine the appropriate support system. The magnitude of differential settlement /
displacement that may be acceptable will be subject to adjacent conditions (e.g.,
proximity of adjacent services, structures, boundaries). Soil Surveys Engineering is well
placed to assist with the design of any proposed system.




                                                                                                            SOIL SURVEYS