The 4 National project involved the construction of a large multi-storey office building and a four-level basement car park.
The site’s geology comprised underlying bedrock, mostly dipping beds of very strong calcareous siltstone and limestone. A north-south aligned fault running through the middle of the site resulted in a sheared zone of very weak rock, as well as strong groundwater flows.
- a temporary support solution of the deep basement excavation, and
- careful consideration of the footing system in the weak faulted rock area.