Full-flow penetrometer testing in box core samples offers the ability to collect high resolution data on very soft clay sediments in the upper half meter of the seabed. This information is useful for consideration of seabed pipeline behavior starting from construction and continuing throughout the operational life of the pipeline. The paper presents experience gained using a portable test kit that was developed to conduct miniature full-flow penetrometer and motorized laboratory vane tests in box core samples immediately after retrieval to the vessel deck. The computer-controlled load frame, data acquisition system, and software provides for constant velocity penetration of T-bar and ball full-flow probes and conduct of cyclic testing at selected depths. Likewise, a companion system provides for computer-controlled rotation of a miniature laboratory vane and continuous recording of test data using a torque transducer. Results are presented from six pipeline investigations and empirically derived generic full-flow N factors are provided in reference to the motorized vane data for the T-bar and ball for intact and remolded conditions. The paper concludes with a recommended protocol for box core testing.
Adriane G. Boscardin, Don J. DeGroot and Tom Lunne
Keywords: box core, full-flow penetrometers, pipelines, undrained shear strength
Publisher: DFI