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MVP-FFCPT Paper from UDT Conference Dec 2006
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PowerPoint Presentation from Canadian Hydrographic Conference 2006
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Moving Vessel Profiler
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Free Fall Cone Penetrometer (FFCPT)
Geotechnical Applications of the FFCPT
The Free Fall Cone Penetrometer (FFCPT) was developed to collect geotechnical and geophysical data during route location surveys for seabed cable and pipeline installations, for bottom classification and acoustic ground-truthing, as well as for mine countermeasures and geo-environmental studies.
FFCPT is a very robust device designed to free fall through the water column, then impact the seabed. Onboard acceleration and pressure sensors monitor the sediment penetration response, producing continuous profiles similar to a conventional piezocone penetrometer. FFCPT test results can be used to evaluate:
FFCPT results provide information on:
Interpreted profile of undrained shear strength, determined from two (2) independent measurements (dynamic penetration resistance and pore pressure response).
Pore pressure data have been used to calculate the normalized penetration resistance (Qn) and the pore pressure ratio (Bq), used to classify the sediment, as indicated by the Sediment Behaviour Type (SBT).
The photograph shows FFCPT being readied for deployment. The lightweight version typically penetrates to depths of 1-2m in silts and 2-3m in soft clays. Weighted ballast sections are added for deeper penetration testing. Stabilizing fins allow for stable vertical free fall into the seafloor.
Seafloor Sediment Classification Using the FFCPT
The FFCPT offers a low-cost, rapid, reliable method for obtaining information on the engineering and sedimentological characteristics of sediment at the seafloor. The equipment can be rigged to optimize testing within a given depth window of soft sediment. This feature makes it ideal for route location surveys, where regional coverage of the seafloor is more desirable than detailed information at any particular site.
FFCPT testing can be performed using a freewheel-capable winch such as an MVP200 or a variety of recovery winches / capstans, if they permit free fall during deployment. Data from an FFCPT test is shown plotted on a Robertson chart (below), which is useful in evaluating sediment composition.
Please note the elements of the animation shown above are not to scale.
FFCPT is designed to survive impact with a hard bottom (bedrock). Acquired data is used to distinguish between rock, gravel, sand, silt and clay, as well as to provide index information on density and stiffness. FFCPT testing can be accomplished from the same vessel used for geophysical surveying, giving immediate feedback on bottom sediment classification, dynamic moduli, density, porosity and shear strength.
FFCPT deployed using ODIM Brooke Ocean's MVP™200
FFCPT can also be fitted with an optional SV&P sensor. This permits sound velocity and pressure readings to be collected from the water column as the probe freefalls to the seafloor.
ODIM Brooke Ocean and its development partners are continuing to test FFCPT as a payload on our MVP (Moving Vessel Profiler™), a commercial winching / telemetry system for underway sound-velocity profiling of the water column. Deploying FFCPT on station using the MVP enables simultaneous collection of high-quality geotechnical data during geophysical surveying operations. FFCPT / MVP packages are currently available for stationary (on station) and underway deployment applications. Underway geophysical surveying increases the number of sites that can be tested per day. Contact ODIM Brooke Ocean if underway FFCPT testing can benefit your application!
A variety of configurations of the FFCPT are now available that provide different instrument packages and seabed penetration characteristics (see photo to the left). Contact ODIM Brooke Ocean for more information.
The HARPOON FFCPT was developed for use with conventional piston or gravity corer systems. Find out more information here.
The following testimonials are available regarding FFCPT:
For more information, please contact ODIM Brooke Ocean.
The Free Fall Cone Penetrometer (FFCPT) was developed jointly with Defence Research and Development Canada Atlantic.
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