Examinando por Materia "Deposits"

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    Modeling added spatial variability due to soil improvement: Coupling FEM with binary random fields for seismic risk analysis
    (Elsevier Ltd, 2018-01-01) Montoya-Noguera, Silvana; Lopez-Caballero, Fernando; Mecánica Aplicada
    A binary mixture homogenization model is proposed for predicting the effects on liquefaction-induced settlement after soil improvement based on the consideration of the added spatial variability between the natural and the treated soil. A 2D finite element model of an inelastic structure founded on a shallow foundation was coupled with a binary random field. Nonlinear soil behavior is used and the model is tested for different mesh size, model parameters and input motions. Historical evidence as well as physical and numerical modeling indicate that improved sites present less liquefaction and ground deformation. In most cases this improvement is modeled as homogeneous; however, in-situ measurements evidence the high level of heterogeneity in the deposit. Inherent spatial variability in the soil and the application of some soil improvement techniques such as biogrouting and Bentonite permeations will necessary introduce heterogeneity in the soil deposit shown as clusters of the treated material in the natural soil. Hence, in this study, improvement zones are regarded as a two-phase mixture that will present a nonlinear relation due to the level of complexity of seismic liquefaction and the consequent settlement in a structure. This relation is greatly affected by the mechanical behavior of the soils used and the input motion. The effect on the latter can be efficiently related to the equivalent wave period as the proposed homogenization model depends on the stiffness demand of the input motion. © 2017 Elsevier Ltd
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    Regional controls in the distribution and morphometry of deep-water gravitational deposits along a convergent tectonic margin. Southern Caribbean of Colombia
    (Elsevier BV, 2020-08-06) Naranjo Vesga, Julián Francisco; Ortiz Karpf, Andrea; Wood, Lesli; Jobe, Z.; Paniagua, J.; Shumaker, L.; Mateus Tarazona, Darwin; Universidad EAFIT. Departamento de Geología; Ciencias del Mar
    Deep-water fold and thrust belts often develop in convergent tectonic margins, creating irregular slope profiles that control the distribution of deep-water gravity deposits. However, in areas with high sediment supply, the erosion and sedimentation can minimize structural relief and smooth the slope. Using multibeam bathymetry with 3D seismic data, we analyze the distribution of deep-water gravity-driven deposits along the convergent margin of the southern Caribbean of Colombia, comparing areas with different continental sediment supply, slope profile, and shelf width. We identify three geomorphological zones: The Northern, Central and Southern Zones. The Northern Zone is characterized by a gentle slope topography, high sediment supply, and large (>100 km length) channel-levee systems traversing the slope and basin floor. In this zone, shelf-attached mass-transport deposits erode and smooth sea-floor topography. The Central Zone is characterized by low sediment supply and steep and irregular slope topography. Here, short-runout mass-transport deposits sourced from the crests and steep flanks of emergent anticlines are common. The irregular relief created by tectonic deformation forms barriers for sediment transport, leading to tortuous sediment-flow pathways. Submarine canyons incise the thrust-cored anticlines, transporting sediment through interconnected, adjacent piggyback sub-basins. Finally, the Southern Zone is characterized by steep slope and moderate sediment supply. Here, tectonic deformation has been smoothed by numerous shelf-attached mass-transport deposits. The erosional scours carved by mass flows merge downslope and evolve into submarine canyons that can deliver mass-transport deposits more than 80 km into the basin. We analyze the impact of slope profile, sediment input and shelf width on the distribution and morphology of deep-water deposits along the southern Colombian Caribbean margin, and present a predictive model for the depositional patterns more likely to develop in other continental margins affected by deep-water fold and thrust belts. © 2020 Elsevier Ltd