Accession Number : ADP002689

Title :   Piezometer Probe Technology for Geotechnical Investigations in Coastal and Deep-Ocean Environments,

Corporate Author : NAVAL OCEAN RESEARCH AND DEVELOPMENT ACTIVITY NSTL STATION MS

Personal Author(s) : Bennett,R. H. ; Burns,J. T. ; Lipkin,J. ; Percival,C. M.

Report Date : JUN 1983

Pagination or Media Count : 28

Abstract : Three multisensor piezometer probes were developed and field tested for use in coastal (shallow water) fine-grained marine soils. Offshore sites were investigated in the Mississippi Delta. Pore water pressure measurements were determined at several depths below the sea floor using both absolute and differential pressure sensors placed in a four inch diameter probe. Pressure sensors were hard-wired to nearby platforms where signals were conditioned and analog recording devices monitored pore water pressure changes in the marine soils. Pore water pressures were monitored for several months. Two single sensor piezometer probes, light millimeters in diameter, were developed for deep-ocean investigations. These probes use differential pressure sensors and were tested in a hyperbaric chamber pressurized to 55 MPa (8000 psi). Testing was performed for a period of five weeks under high hydrostatic pressure with the probes inserted in reconstituted illitic marine soil. Small differential pore water pressures responded to both mechanically and thermally generated forcing functions. During shallow water investigations and deep-ocean simulated pressure tests, the sensors exhibited excellent sensitivity and stability. These developments in piezometer probe technology provide a means of assessing important geotechnical parameters of fine-grained seabed deposits. (Author)

Descriptors :   *Pressure gages, *Probes, *Ocean bottom soils, Multisensors, Shallow water, Deep oceans, Pressure transducers, Hydrostatic pressure

Distribution Statement : APPROVED FOR PUBLIC RELEASE