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SUMMARY:Multi-directional simple shear response of soils - Dr Giovanna Bis
 contin
DTSTART:20131017T150000Z
DTEND:20131017T163000Z
UID:TALK47396@talks.cam.ac.uk
CONTACT:Jen Fusiello
DESCRIPTION:To be confirmedIncreasing interest in submarine slope stabilit
 y\, especially related to seismic loading\, was the motivation for the dev
 elopment of a new multi-directional simple shear device at Texas A&M Unive
 rsity. Submarine landslides can involve vast areas and considerable depths
 . A number of the failures takes place on slopes inclined 5 or less and
  typical soil profiles consist of almost parallel layers of normally conso
 lidated clay. The submerged slope under earthquake loading can be modeled 
 using simple shear conditions to describe the response of the soil. Most e
 xperimental results for fine grained soils concentrate on one-dimensional 
 response\, both for monotonic and cyclic tests. In addition\, experimental
  information on marine clays mostly comes from marine deposits that are no
 w onshore and easily accessible\, such as Boston Blue Clay and San Francis
 co Young Bay Mud\; however\, these deposits have a different stress histor
 y than offshore deposits. \n\nThe new multi-directional simple shear devic
 e developed at Texas A&M University allows loading along three independent
  axes\, two perpendicular horizontal directions to allow any stress or str
 ain paths in the horizontal plane\, and a third in the vertical direction.
  The device is also fitted with a pressure vessel providing the ability to
  control cell pressure and backpressure independently\, in a manner simila
 r to triaxial systems\, for truly undrained tests. The experimental progra
 m focused on sample of clay from the Green Canyon in the Gulf of Mexico. T
 he goal of the investigation was to study the effects of anisotropy\, and 
 multi-directional loading in particular\, on the monotonic and cyclic resp
 onse of normally consolidated Gulf of Mexico clay. \n\nThe test results we
 re used to develop and validate constitutive models. Even if simplistic\, 
 the SIMPLE DSS formulation can handle the generation of excess pore pressu
 re as a by-product of stress-strain-strength relationships that require a 
 small number of basic parameters. Examples of predictions and comparisons 
 with test data will illustrate the potential of the SIMPLE DSS model. Diff
 erent scenarios for slide initiation will be identified and predictions of
  slope response analyses with a one-dimensional finite element code implem
 enting SIMPLE DSS will be presented. Modelling challenges for multi-direct
 ional loading will be presented.\n\nFinally\, an experimental program test
 ing steel ballotini in simple shear was paired with discontinuous element 
 method (DEM) simulations for validation. The goal of this program is to pr
 ovide conditions as similar as possible during all the phases of the physi
 cal and numerical processes. This allows us to be confident that the infor
 mation obtained at the particle level from the simulations is reliable bec
 ause backed by the macroscopic validation. The simulations\, validated by 
 the experimental results\, provide invaluable information on the micro-mec
 hanical response of granular materials.  
LOCATION:Engineering Department - Lecture Room 6
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