Wayne A. Dunlap, 1981. "Geotechnical Applications in Soft Sediments", Offshore Geologic Hazards: A Short Course Presented at Rice University, May 2-3, 1981 for the Offshore Technology Conference, Arnold Bouma, Dwight Sangrey, James Coleman, David Prior, Anita Trippet, Wayne Dunlap, James Hooper
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It is the purpose of this portion of the short course to consider some of the quantitative aspects of geologic hazards in soft sediments. The landmark work by Coleman, Garrison, Prior and others in the Mississippi Delta has certainly shown that there can be major subbottom movements in soft sediments. However, this is not recent news. Shepard in 1955 concluded from bathymetric surveys that subaqueous slides occurred in the prodelta sediments of the Mississippi River. Later, Terzaghi (1956) provided a remarkably accurate engineering explanation for many of these slides. An added dimension was provided by Henkel (1970) regarding the role of storm waves in producing slides. But the recent painstaking and detailed research described at this short course by Coleman and Prior provides for the first time a complete description of the processes involved, the resulting morphology, and even some consideration of frequency of subbottom movements. Offshore platform and marine pipeline designers now have a relatively clear understanding of the problems they are facing, in-so-far as bottom movements are concerned. In light of the present fund of knowledge, it is probably not correct to consider these movements as “hazards.” Rather, they should be considered as design constraints, just as the structural steel designer considers the yield strength of steel as a constraint in his designs, not as a hazard.
Although recognition of the problem is a major step towards solution, a structure cannot be designed based on geological considerations alone. The remainder of this paper will consider geotechnical design aspects