A common problem across greater Melbourne's expanding land development, both residential and commercial, is encountering sites that have incredibly stiff and undulating bedrock. This is experienced on sites with Newer Volcanic Basalt which accounts for two thirds of greater Melbourne, the weathered profile of these once lava flows produces a highly variable depth and strength bedrock interface. The acquisition of bedrock survey data has been shown to reduce site uncertainty, unforeseen earthwork costs and financial risk. Working hand in hand with traditional intrusive geotechnical methods, the Multi-channel Analysis of Surface Waves (MASW) method can connect the dots between boreholes generating 2D geological cross-sections of the subsurface. These 2D cross-sections when combined can create a 3D subsurface model of the bedrock. This data can be presented in a variety of ways, including contour plots in either elevation or depth below ground level (BGL), overlying clay volumetric calculations to user friendly 3D AutoCAD TIN files which can be encompassed with a topography model. Producing a very comprehensive site classification package, a useful tool for the investigatory stage for any land development project.

Open-Access Online Publication: May 29, 2023