PLAXIS LIQUEFACTION MODEL UBC3D-PLM - Knowledge Base

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List of Tables1.1 Input Parameters for the UBC3D. . . . . . . . . . . . . . . . 191.2 State variables of the UBC3D. . . . . . . . . . . . . . . . . . 202.1 Model parameters used to simulate undrained behaviour ofloose Syncrude sand. . . . . . . . . . . . . . . . . . . . . . . . 232.2 Boundary values for simulating a cyclic simple shear test ina single stress point. . . . . . . . . . . . . . . . . . . . . . . . 262.3 Input parameters for modelling the undrained cyclic behaviourof loose Fraser sand. . . . . . . . . . . . . . . . . . . . . . . . 263.1 Input parameters for modelling the dynamic centrifuge. . . . 366
AbstractIn this report the formulation of the UBC3D constitutive model as implementedin PLAXIS is presented. The UBC3D is a 3-D generalized formulationof the original 2-D UBCSAND model introduced by Puebla et al. (1997).The initial 3-D implementation in PLAXIS was presented by Tsegaye (2010).An improved version is developed by the authors and the final model is presentedtogether with a validation in different monotonic and cyclic stresspaths. UBC3D-PLM consists a relatively simple but powerful approach inorder to model the onset of the liquefaction phenomenon. In Chapter 1the main features of the UBC3D-PLM are presented. The improvementsmade by the authors are also highlighted in order to distinguish the changesof the latest version. Briefly, the formulation of the plastic multiplier iscorrected and higher accuracy achieved for the monotonic case, a soil densificationrule was implemented and a second yield surface introduced inorder to ensure a smooth transition into the liquefied state and finally apost liquefaction factor introduced as an input parameter in order to modelthe post-liquefaction behaviour. The latter should be used for modelling elementtests leading to liquefaction of the soil, and extra attention is advisedduring modelling boundary value problems. In Chapter 2 the validationof the model in monotonic and cyclic stress paths is discussed. Finally, inChapter 3 the performance of the model in a finite element scheme is investigatedand the numerical modelling of a dynamic centrifuge test withPLAXIS 2D Dynamics is presented. The ability of the model to capturethe onset of liquefaction is thoroughly discussed. The capabilities and thelimitations are highlighted and recommendations for the use of the modelare summarized.
Page 1: PLAXIS LIQUEFACTION MODELUBC3D-PLMA
Page 5: 3.6 Reproduced stress path in p ′
Page 9 and 10: Comparing with the previous version
Page 11 and 12: Figure 1.2: Projection of the yield
Page 13 and 14: ( ) mepK = KBP e A (1.9)P ref( ) ne
Page 15 and 16: The plastic potential function is f
Page 17 and 18: the secondary loading in order to e
Page 19 and 20: loading surface is used again. A ne
Page 21 and 22: The drained bulk modulus of the soi
Page 23 and 24: modelling the inherent and induced
Page 25 and 26: Table 1.1: Input Parameters for the
Page 27 and 28: whereas the P P RMAX can reveal if
Page 29 and 30: Chapter 2Validation of the UBC3D in
Page 31 and 32: Pore Pressure, u (kPa)UBC3DEx.Pore.
Page 33 and 34: first cycle of post-liquefaction be
Page 35 and 36: Shear Stress , τ (kPa)1086420-2-4-
Page 37 and 38: 1.2Excess Pore Pressures\nitial Ver
Page 39 and 40: Chapter 3Validation of theUBC3D-PLM
Page 41 and 42: Figure 3.2: The finite element mesh
Page 43 and 44: checked but the results are not fur
Page 45 and 46: used again when the stress path exc
Page 47 and 48: EPP (kPa)EPP (kPa)EPP (kPa)Measurem
Page 49 and 50: Figure 3.8: Reproduced stress path
Page 51: S.S. Park and P.M. Byrne. Practical

PLAXIS LIQUEFACTION MODEL UBC3D-PLM - Knowledge Base

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