EDG assisted McConnell Dowell with geotechnical analysis to assess the feasibility of adopting barges to support large crawler cranes during the construction of the New Bridgewater Bridge in Hobart, Tasmania. Much of the length of the new bridge extends over very shallow mud flats and McConnell Dowell approached us to investigate the feasibility of positioning the barges at high tide, ballasting them into the soft river mud and using them to carry out heavy crane lifts with cranes situated on the barges. This provided McConnell Dowell with significant savings to the alternatives of earth embankments or structural solutions.
We carried out 3D finite element and limit analysis to assess barge settlement and rotation, and overall stability under loading. The analysis considered the combined effects of buoyancy and bearing capacity provided by the riverbed. It demonstrated suitable deformation and stability during loading and supported the use of a crane lift radius greater than that associated with a floating barge, assisting construction operations. We were on hand to review monitoring data as the cranes accessed the barges to confirm the analysis outcomes.
