Royal Domain Tower is a residential tower development of about 40 levels currently under construction in Melbourne. The subsurface stratigraphy is variable, and comprises extremely weathered to moderately weathered siltstone (unconfined compressive strength (UCS) values of about 0.7 – 5.0 MPa) from the surface. Several dykes were encountered during the site investigation. The strength of the dykes varied from clay to relatively fresh rock, and the occurrence of dykes was difficult to predict. The dykes therefore posed a significant risk to foundation design.

The tower is supported on approximately 85 piles, ranging in diameter from 0.75 m to 1.5 m. Serviceability loads ranged between 5 MN and 15 MN, and design pile head settlement is 1% of diameter. A detailed ground investigation was carried out, and ROCKET was used to establish pile lengths. The cost of the additional soil and rock testing was about A$10000. The application of ROCKET by Golder Associates to this project resulted in reduction in socket lengths of up to 13 m when compared with traditional design approaches.

lnstalled socket lengths varied generally between about 5 m and 11 m depending on observed ground conditions and load. Total savings of around 950 m of socket length, 900 m3 of concrete, 1400 m3 reduction in spoil and several weeks in construction time were achieved as a result of the use of this design approach.