Engineers Australia

Development on soft clays in Port Hedland

David Foulsham

Abstract

Iron ore developments have taken place in Port Hedland over the past 45 years and these developments were initially located on competent ground at Nelson Point (BHPB North Yard) and Finucane Island (Goldsworthy). The large ground pressures imposed by the iron ore stockpiles in the past have resulted in settlements that could be readily managed in the design of stackers and reclaimers.

However, as the competent ground has been developed, the peripheral “tidal” areas became the focus of development. Initial development is generally focussed on gaining access to these tidal areas by construction of embankments / containment bunds. Large scale reclamation is then achieved using dredged spoil from various harbour developments. These “tidal” areas contain soft clays or “muds” which when loaded, initially by construction equipment, then by bunds and dredged fill and finally by heavily loaded iron ore stockpiles, have the potential to cause stability failures / excessive settlements resulting in time delays, trafficability problems for equipment and ultimately damage to infrastructure such as stackers and reclaimers.

This paper presents a preliminary design approach and construction methodology that incorporates various aspects of ground improvement techniques to achieve access for conventional construction equipment in the development of these peripheral “tidal” areas.