Critical Flotation Density of Pipelines in Soils Liquefied by Waves and Density of Liquefied Soils

Abstract

This paper summarizes the results of an experimental and theoretical investigation of: (1) pipeline flotation in a soil (liquefied under waves); and (2) density of the liquefied soil. In the experiments, the soil was silt with d50 =0.078 mm . Pipeline models of 2 cm diameter were used. They were buried in the soil at different depths in the range 3–15.5 cm . The total depth of the silt layer was 17.5 cm . Waves (with 17 cm wave height and 1.6 s wave period, the water depth being 42 cm ) were used to liquefy the soil. The pipes with specific gravity smaller than 1.85–2.0 floated when the soil was liquefied, the critical specific gravity for pipe flotation. The lower bound of the above range corresponds to the initial pipe position near the surface of the bed, and the upper bound to that near the impermeable base. Furthermore, the pipe floated (or sank) to a depth where the pipe specific gravity was equal to the previously mentioned critical specific gravity for flotation. The density of liquefied soil was ...