3D Physical Modelling of Dalrymple Bay Coal Terminal Apron Widening, Queensland

Client: Connell Hatch
Year: 2006
Project Reference: 05107
WRL Technical Report: Three Dimensional Physical Modelling of Dalrymple Bay Coal Terminal Apron Widening (2006/13)

A proposal has been put forward to increase the coal export capacity at Dalrymple Bay, Queensland, through the widening of an existing breakwater extension. Connell Hatch in providing services to Babcock and Brown Infrastructure, engaged WRL to undertake a 3D physical model study of the proposed extension with a variety of monochromatic and cyclonic wave climates (height, period and direction).

Several breakwater configurations were constructed and tested at a scale of 1:42 with the bathymetry at the site reproduced in the wave basin model using recycled road base capped with concrete.

The purpose of the study was to optimise the density and positioning of 11.5 t and 5 t hanbars, and confirm the breakwater’s ability to withstand 100 year wave climate conditions at various water levels, and incident wave directions.

Correctly scaled hanbar concrete armour units were custom fabricated by injection moulding. The breakwater core was built from a fine gravel and sand base. Secondary armour consisted of gravel and primary armour on the end section of the breakwater consisted of hand-sorted rock.

WRL testing highlighted vulnerable points in the initial design, and areas of the breakwater that were overdesigned. A modified design was tested that was found to be structurally stable and reduced the number of 5 t hanbar units required by more than 500. This revised design strengthened the vulnerable points in the initial design, and the reduction in the number of hanbars required, was a significant cost saving for Babcock and Brown Infrastructure.