Matthew graduated from the University of Western Australia in 2003 with a double degree in Geology and Civil Engineering with Honours, and was awarded the Australian Geomechanics Society Prize. He then worked in the Perth office of WorleyParsons Services Ltd for three years as a geotechnical engineer.
Matthew began his PhD at Cambridge in January 2007 under the supervision of Professor Malcolm Bolton and is funded by the Poynton Scholarship awarded by the Cambridge Australia Trust. He is a member of King's College and is currently the co-president of the Christian Graduate Society.
In water depths of 500 m to greater than 2000 m off the coast of Angola, West Africa, surficial sediments comprise very soft clays with extremely high water contents and plasticities. In situ CPT and T-bar testing in these areas have encountered ‘crusts’ of unknown origin, with undrained shear strengths typically rising to beyond 10 kPa at 0.5 m below sea floor, before dropping rapidly back to about 2 kPa by 1 m. Hot oil pipelines that undergo hundreds of thermal cycles during operation are laid on these crusts. Therefore adequate characterisation of these surficial sediments, including an understanding of their origin, is required.
An interdisciplinary investigation into the hypothesis that the crust is of bacterial origin is currently underway.
Bacteria exude extracellular polysaccharides (EPS) that may bind together and structure clay platelets whilst allowing very high water contents to remain. Through the application of microbiological techniques, the culturable bacterium Marinobacter aquaeolei has been identified in these sediments. 
Using a ball-penetrometer and Cam-shear device, the influence of M. aquaeolei on the shear strength is being investigated, as will the
effect of high temperatures associated with pipelines.
Matthew has formed links with the Department of Biochemistry and the McDonald Institute of Archaeological Research to complete this research, and is very grateful for the assistance given by Dr Ellen Nisbet and Dr Diane Lister.
This research has also formed links with BP, the National Oceanography Centre and Fugro Pty Ltd.
Initial results suggest that if bacteria influence the shear strength, their presence may only be a minimal contribution compared with macro influences of other biological factors such as burrowing invertebrates. Visual examination of sediment cores from offshore Angola show the presence of intact faecal pellets of <75 μm to to about 4mm in length. These are likely to influence the geotechnical properties of the clay, in particular shear strength and rate effects during shearing. The process of ingestion of 'normally consolidated' sediment, 'modification' within the gut and expulsion in the form of faecal pellets may overconsolidate the sediment by a process similar to osmosis.
Imaging with computer tomography shows the presence of open burrows throughout core samples (shown in yellow) and large open voids adjacent to faecal pellets.
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