Geology topics
Homa J. Lee
Publications and source records attributed to Homa J. Lee.
Consolidation, triaxial shear-strength, and index-property characteristics of organic-rich sediment from the Peru continental margin: Results from Leg 112
Sites 679, 680, and 681 of the Ocean Drilling Program were drilled along an east-west transect across an organic-rich, diatomaceous, coastal upwelling facies that occurs as a shelf/slope lens along the Peru continental margin. Seven 60-cm-long, unsplit core sections from these sites were tested for consolidation, triaxial shear strength, and geotechnical index properties. The testing showed that the sediment has unusually high water content, Atterberg limits, degree of overconsolidation, compressibility, and shear strength. The sediment has unusually low density and grain specific gravity. Atterberg limits, grain specific gravity, compressibility, and apparent excess maximum past stress increase linearly with organic-carbon content, which also correlates positively with diatom content. Overconsolidation measured in these tests is probably not a result of sediment erosion or slumping, but rather the result of diagenesis or interparticle bonding by organic matter. High shear strengths were measured throughout, but particularly high relative shear strengths (as indicated by friction angles and degrees of dilatancy during shear) occur near 20 mbsf. This "crustlike" behavior is probably produced by early diagenesis (perhaps including dolotomization) within the upper 20 m, and is complemented by interlocking of diatoms.
Geotechnical engineering for ocean waste disposal. An introduction
As members of multidisciplinary teams, geotechnical engineers apply quantitative knowledge about the behavior of earth materials toward designing systems for disposing of wastes in the oceans and monitoring waste disposal sites. In dredge material disposal, geotechnical engineers assist in selecting disposal equipment, predict stable characteristics of dredge mounds, design mound caps, and predict erodibility of the material. In canister disposal, geotechnical engineers assist in specifying canister configurations, predict penetration depths into the seafloor, and predict and monitor canister performance following emplacement. With sewage outfalls, geotechnical engineers design foundation and anchor elements, estimate scour potential around the outfalls, and determine the stability of deposits made up of discharged material. With landfills, geotechnical engineers evaluate the stability and erodibility of margins and estimate settlement and cracking of the landfill mass. Geotechnical engineers also consider the influence that pollutants have on the engineering behavior of marine sediment and the extent to which changes in behavior affect the performance of structures founded on the sediment. In each of these roles, careful application of geotechnical engineering principles can contribute toward more efficient and environmentally safe waste disposal operations.
Geotechnical framework, Northeast Gulf of Alaska
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