St John’s Shopping Centre, Perth

LocationSt John’s Shopping Centre, Perth City Centre
RequirementBearing Piles
Techniques
Main ContractorGraham Construction Limited

Project Overview

After providing early feasibility advice, TechnikGS (TGS) tendered and was then awarded the contract for the design and installation of the bearing piles for a new lift. The works were carried out in a stripped unit inside an operational shopping centre.

Access to the working area was gained via a double doorway from one of Perth’s busiest shopping streets.

The works included the installation of four piles to a depth of approximately 5 metres below ground level to carry working loads of up to 165kN.

Project Challenges

  • Restricted access requiring compact minipiling rig and careful planning with regard to material and concrete deliveries.
  • Solution required low noise and low vibration so as not to disturb adjacent operational shop units.

Solution Delivered

TGS provided a low noise, low vibration bottom driven pile solution using a restricted access minipiling rig. The crimped ended thin wall casings were successfully installed using an internal drop hammer to the required design criteria.

The pile installation system used was particularly appropriate as it ensured that the driving energy was delivered directly to the toe of the pile without the level of vibration generated by alternative top-­‐drive systems. The noise levels generated by this technique were also significantly less than those generated with other driven techniques.

As this was a fully displacement pile type, there was not the requirement for spoil disposal and consequently the empty pile casings were reinforced using full length H25s reinforcing bar prior to placement of the high slump C32/40.

These piles were dynamically tested one week after installation by an independent testing specialist who confirmed that their load carrying capacity was more than sufficient.