IN-PLACE OCEAN SOIL STRENGTH BY ACCELEROMETER

The in-place measurement of the shearing strength of ocean-floor soils, although desirable, is difficult because of the problems involved in all work at sea. A single-axis, self-contained recording accelerometer was designed for attachment to conventional core-barrel samplers, which are usually released a few feet above the ocean floor, and fall freely to penetrate the sea-bed soil. Successive integrations of the acceleration record produced by the impact provide the time-history of velocity and displacement of the corer. These results, together with the known mass of the corer, enable the shearing resistance of the soil to be calculated as a function of depth below the soil surface. The paper describes the accelerometer and its operation, and illustrates the calculations with reference to typical records obtained at sea.