CAREER: Characterization and Modeling of Marine Clays for Slope Stability

Texas A&M Engineering Experiment Station, College Station TX

Investigators

Abstract

Increasing attention is being focused on the problem of submarine slope stability. The global economy requires a better, wider reaching infrastructure, able to quickly distribute resources, such as oil and gas, from the point of production to the points of use. An expanding network of telecommunication cables cross the ocean floors and breakages caused by slope failures would interrupt or delay the flow of information around the world. Large submarine slides can cause tsunamis, which can be devastating for the coastal communities in the wave's path. This research contributes to the understanding of failure mechanisms for submarine slopes in soft marine sediments subjected to dynamic loading. One of the primary goals is to develop an extensive database of soil behavior in simple shear, specifically targeting offshore clays from the Gulf of Mexico and off the coast of West Africa. The experimental results are obtained using a new advanced testing device, which has been specifically constructed for multidirectional loading at a wide range of frequencies. The testing is used to characterize the response of the soils subjected to different initial and drainage conditions, and a variety of loading paths, replicating more closely the effects of earthquakes or storm waves. The importance of strain rate on the behavior of soft clays is also investigated. The test results are essential for the refinement and validation of a constitutive model, able to replicate the response of the marine clays, and implemented in a finite element program for the analysis of submarine slope response. The importance of the different factors contributing to the triggering of failures is investigated through parametric studies. The predictive tools are validated through the study of selected case histories. The broader impacts of this work include increasing awareness among students and the general public of how earthquakes affect soils, and how ground shaking is also changed by the soils. Undergraduate students are involved in building visualization tools targeting users at different levels of ability, using the model developed by the graduate students. The activities also involve development of educational materials integrating research into the teaching of math and science, and the training of teachers, through a Research Experience for Teachers Program and in collaboration with the South Texas Rural Systemic Initiative. The research is introduced in courses at the undergraduate and graduate level. The PI, in partnership with the Forth Worth Museum of Science and History, is developing an exhibit on natural hazards.