Near-surface seabed characterisation in deep water using shallow penetrometers
Characterising the mechanical response of soft surficial soil in deep water is difficult using conventional probe tests (CPT and T-bar) performed from a surface vessel due to the low strength of the soil. For the same reason, capture and recovery of tube samples or box cores that are then subjected to conventional laboratory tests (e.g. simple shear, triaxial) may suffer from significant sampling induced disturbance. An alternative approach is to measure the near-surface soil properties in deep water by using shallow penetrometers, such as the hemiball and toroid developed at COFS. The aim of the project is to develop our understanding of these devices.
With suitable interpretation techniques shallow penetrometers are envisaged to be able to measure and infer parameters to describe: (i) penetration resistance, (ii) pore pressure dissipation and (iii) axial friction developed during axial and torsional loading. The aim is to develop our understanding of these devices such that their response can be used to directly predict the performance of offshore structures, such as surface pipelines.