Soil-Wave Tank Studies Of Marine Soil Stability

Abstract

Soil instability 0ccurred off the Mississippi River Delta during hurricane Camille due to large wave induced bottom pressures. This paper discusses the effect of such waves on soft clayey soils.In particular, the paper is based upon the results acquired from a large model tank which was constructed to study the effect of surface water waves on a clay soil under controlled conditions. The primary motivation for the tank studies was to provide a qualitative means by which an engineer could evaluate the progress of instability under wave loading.Within the scope of the tank study, soil displacement patterns were observed with depth and related to field conditions. Investigations were made into the effects on the soil continuum of wave height and period, soil shear strength, slope variations, and repeated wave loading. Measurements of wave height and period, bottom pressure, and in-situ soil shear strength were obtained to evaluate References and illustrations at end of paper. simple analytical methods for predicting instability.

Wave‐induced liquefaction: a modern example from the Bay of Fundy

“…Engineers have been aware for some time that waves can produce liquefaction in sands (Bjerrum, 1973;Christian, Pt a/., 1974;Lee & Focht, 1975;Palmer, 1976) and deformation in muds (Henkel, 1970;Mitchell, Tsui & Sangrey, 1972;Bea & Arnold, 1973;Doyle, 1973;Singh, 1974;Palmer, 1976). Unfortunately, these studies have focused on the stress that wave-induced hydrostatic pressure variations exert on low permeability sediments.…”

Design of Pipelines in Mudslide Areas

“…Analysis of the Line 6 The pipeline and its surrounding media (soil and water) must be idealized through a structural model for either specific design sections or for the entire line. The line is usually modeled as a simple structural member with nodal forces representing the loads from the design hazard, while discrete springs represent the restraint from the soil continuum.…”

“…With continued and intensifying wave action, the layer becomes thicker. 6 When the wave action ceases, the sediments settle, thixotropy and consolidation start, and the sediment again assumes a solid consistency. Given sufficient time NOVEMBER 1983 without significant agitation, the soils consolidate to less than their liquid limit and have engineering characteristics that are plastic in nature.…”

The instability of surface sediments on parts of the Mississippi delta front

“…The reasoning for this delineation is as follows: Henkel (1970) and Mitchell and others (1972) have worked on the role of wave forces in causing submarine landslides. In addition, the very thorough but only partially published investigations by Shell Oil Company into the Block 70 failure indicate the extreme importance of the wave factor (Doyle, 1973;Bea and Arnold, 1973;Sterling and Strohbeck, 1973;Arnold, 1973). It therefore seems reasonable to suspect that whatever the combination of forces required to trigger a failure, they are most likely to occur in underconsolidated sediments whose interstices might be saturated with in situ generated methane and CO2 gases and lying in parts of the delta subject to the greatest amplitude storm waves.…”