Buried sleeper research site – remotely measuring buried material characteristics
Winwell Foundation, supported both in the field and in the lab by the WA Museum and Acoustic Imaging Pty Ltd, will use SBP (Sub-bottom Profiler) technology to re-examine the site and condition of timber and iron sleepers, purposely buried five years’ earlier under the seabed.
The project aims to conduct an SBP survey along the line of iron and ‘partially- degraded’ sleepers in order to interpret acoustic characteristics against independently measured material (density) properties.
This controlled in-situ testing site was established in 2017-18 following the burial of 23 fresh pine, oak and jarrah timber sleepers in either single or multiple stacked arrangements with different grain orientations and burial depths ranging between 10cm-50cm below the seabed. Three iron sleepers were also buried at similar depths.
Results from the first SBP survey shortly after the sleepers were buried revealed highly accurate estimates of burial depths and acoustically identifiable groupings for each of the sleeper types; these groups however partially overlapped, limiting any predictive capacity.
More than five years after the burial some of the timbers are expected to have degraded (reduced density), especially the very shallow pine sleepers.
Results from the new survey will further examine the potential to determine material differences, and their respective burial depths, using non-invasive SBP site surveys.
This would be a significant benefit to those wishing to characterise sub-seabed finds and to develop more informed in-situ management plans to protect sites as required.
Acoustic Imaging Pty Ltd, https://www.acousticimaging.com/
WA Museum, https://visit.museum.wa.gov.au/
