STP501

    A Static Cone Penetrometer for Ocean Sediments

    Published: Jan 1972


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    Abstract

    A static cone penetrometer for deep ocean exploration has been developed and successfully tested in soft sea floor sediments at an ocean depth in excess of 1200 m. The penetration resistance of a standard 60-deg cone is detected by appropriately insulated strain gages whose output may be monitored remotely from the sensing unit. Initial deployment of the device was aboard the submersible Deep Quest in the San Diego Trough off the coast of southern California. Resistances as low as 7 N (1.6 lb) were measured near the surface of the sediment, generally increasing with depth. At the maximum depth of penetration of 1.1 m (restricted by the limited negative buoyancy of the submersible), tip resistance reached 80 N (18 lb). By means of a conventional bearing capacity analysis, the cone resistance was converted to in situ strength and compared to vane shear measurements taken in the immediate vicinity of the penetration tests. Reasonable agreement between vane shear and penetration strengths were obtained for an assumed bearing capacity factor No = 9.

    Keywords:

    underwater structures, cone crushers, deep ocean vehicles, deep water, ocean bottom, sediments, soil profiles, strain gages, remote control, monitors, soil mechanics, penetration tests, vane shear tests, bearing capacity, shear strength


    Author Information:

    Hirst, TJ
    Assistant professor of civil engineering and associate director, Marine Geotechnical Laboratory, Lehigh University, Bethlehem, Pa.

    Richards, AF
    Professor of oceanography and ocean engineering and director, Marine Geotechnical Laboratory, Lehigh University, Bethlehem, Pa.

    Inderbitzen, AL
    Senior scientist, Lockheed Ocean Laboratory, Lockheed Missile and Space Corporation, San Diego, Calif.


    Paper ID: STP38794S

    Committee/Subcommittee: D18.02

    DOI: 10.1520/STP38794S


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