Strength Testing of Marine Sediments


Book Description

Philadelphia, PA : ASTM, 1985.













Deep-Sea Sediments


Book Description

As part of its continuing program to stimulate superior basic research in the marine environment, the Office of Naval Research, Ocean Science and Technology Division, sponsored a series of closed seminar-workshops in 1972-1973. Each seminar focused upon one re search area of marine geology which is relatively new and in need of a critical evaluation and accelerated support. The subjects areas chosen for the seminars were: 1. natural gases in marine sediments and their mode of distribution, 2. nephelometry and the optical properties of ocean waters, 3. physical and engineering properties of deep-sea sediments, and 4. physics of sound in marine sediments. The objectives of each seminar-workshop were to bring into sharper focus the state-of-the-science within each subject area, to effect some degree of coordination among the investigators working within each of these areas and to provide the Ocean Science and Technology Division guidance for national program support. This volume.contains most of the papers presented at the semi nar on the physical and engineering properties of deep-sea sediments. The seminar was held at Airlie House, Airlie, Virginia on April 24- 27, 1973 and was organized and chaired by A. Inderbitzen. The at tendees were invited from among the leading investigators in this field from both the engineering and scientific disciplines. Each attendee was requested to prepare a paper within his area of spe ciality.




DOSIST II


Book Description

DOSIST II (Deep Ocean Sampling and In-Situ Testing) was a cruise in the Western North Atlantic Ocean conducted to evaluate the in-place engineering behavior of several typical deep ocean sediments. In-place vane shear tests were performed, and sediment cores (gravity, piston, and box) were taken. Laboratory tests were conducted on the cored samples to classify the sediments and to determine which testing procedure best reproduces the measured in-place strength. This was found to be consolidated-undrained triaxial testing. The sediments tested in-place were a foraminifera-dominated calcareous ooze and a proximal turbidite. Both of these sediments are nearly cohesionless and retain little of their in-place strength when sampled. A deep sea pelagic clay was cored and subjected to laboratory testing, but was not tested in-place. Estimated in-place strength profiles were derived for each of these sediments to subbottom depths in excess of 50 feet (15 m).




Direct Shear Testing of Marine Sediment


Book Description

Traditionally, the methods used to determine the mechanical properties of marine sediments were those used in the field of soil mechanics. These methods are generally acceptable when the sediment tested is plastic or at water contents below the liquid limit. However, for predicting in-situ conditions, that is for sediment at water contents above the liquid limit, the problem is complex. Specifically, the determination of shear strength of an unconsolidated-undrained sample by the direct shear method was found to exhibit an angle of internal friction ranging from 19 degrees to 23.5 degrees. This indicates that the shear strength of the sediments is dependent on the normal load applied to it. (Author).







An Unconfined Compression Testing Machine for Marine Sediments


Book Description

The two most common laboratory test methods used for measuring the undisturbed or original shear strength of marine sediments are the vane shear test and the unconfined compression test. The application of the load in the unconfined compression test is accomplished either in a strain-controlled or a stress-controlled manner. An unconfined compression testing machine was constructed to allow application of the load by either the strain-controlled or stress-controlled method, and it was specifically designed to accurately test marine sediments having relatively low values of shear strength. A unique feature of the apparatus is that it provides a continuous plot of displacement versus load throughout the test procedure. Tests for shear strength in the two load application modes were conducted on gravity cores taken on the continental slope between San Francisco and Monterey. Results of the tests compared favorable with each other, as well as with values secured from vane shear testing. The tests suggest that these particular sediments have friction angles approximating 30 degrees. (Author).