An Unconfined Compression Testing Machine for Marine Sediments.
Abstract:
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