Explanation of Submarine Landslide Morphology by Stability Analysis and Rheological Models.

摘要

A theoretical study of mass movement on the Mississippi River delta front has been made using recently acquired field data and a simple rheological model. Recent measurements of sediment properties include cohesion, bulk density, pore pressure, and internal friction angle. Also, the geometry of a typical type of instability feature, an elongate slide, is examined in detail. A rheological model describing a Coulomb-viscous plastic in effective stress terms is proposed to describe certain features of the mass movement process. The model is used to derive equations defining the initial failure of the slopes, the mass movement thickness and accelerations, the velocity of flow in the gullies, and the shape of the mud nose scarp in the toe area. The model indicates the importance of pore pressure in controlling sediment dynamics. Results of the model compare favorably with the observed shapes of mud noses. Initial failures on low slopes approximately 0.5 deg are attributed to pore pressures apporaching geostatic values. Flow velocities are calculated to be several feet per second, based upon estimated sediment viscosities and pore pressures during flow. (Author)