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DSD-NL 2017 Anura3D MPM for Geotechnical Engineering _ Achtergrond - Rohe

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Presentatie door Alexander Rohe (Deltares) op de Geo Klantendag, tijdens de Deltares Software Dagen- Editie 2017. Donderdag 15 juni 2017, Delft.

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DSD-NL 2017 Anura3D MPM for Geotechnical Engineering _ Achtergrond - Rohe

  1. 1. Anura3D MPM for Geotechnical Engineering Alexander Rohe 15 June 2017 Deltares Software Dagen, GeoKlantendag
  2. 2. Anura3D MPM Research Community - 6 universities and Deltares - Joint coordination - research & projects - functionality - Regular activities - training - management - workshops / conferences: www.mpm2017.eu - website www.anura3d.com
  3. 3. Team at Deltares – Developers & Users + Developers/Users 4x PhD students 2x MSc students 2x guests + Basic Users at Deltares Faraz, Amine, Joost, David, Mark, Maria Luisa, Sanjay, Geeralt, Esther, Bernadette, Cor, Jarno, Arjan, Remco, Suzanne, Gijs, Hans, …
  4. 4. Product & Experimental Environment Research Software Software Product v2017.1 (beta)MPM Research Community www.anura3d.com
  5. 5. Focus applications at Deltares dikes, dams, landslides installation, impact flowslides, erosion, liquefaction
  6. 6. Plan for development and release - main releases in January: v2017.1, v2018.1, etc… - update releases in September: v2017.2, v2018.2, etc… Upcoming functionalities for product release: - Excavation - CPT simulation - Improved contact algorithm - Improved user-defined soil models interface - Absorbing boundaries - Combination of FEM-MPM - Implicit time integration - … à What is required?
  7. 7. Anura3D v2017.1 (beta)
  8. 8. Manuals Tutorial Scientific Validation
  9. 9. Calculation process
  10. 10. User interface for input
  11. 11. User interface for output
  12. 12. Anura3D Background
  13. 13. Basic FEM approaches as basis of MPM - mesh deforms as the body deforms - material does not cross elements - nodes remain on boundary - mesh distortion? - material flows through a fixed mesh - no mesh distortion - state parameters in history dependent materials? Lagrangian : mesh deforms as the body deforms à “SOIL MECHANICS” Eulerian : material flows through a fixed mesh à “FLUID MECHANICS”
  14. 14. Lagrangian Eulerian initial configuration deformation after resetting the mesh in each calculation step : Basic concept of MPM
  15. 15. Basic idea: material points move through mesh initial position of material points final position of material points material points move through mesh total displacements [m]total displacements [m] collapsing soil column: total displacements in [m]
  16. 16. Soil as a multi-phase material solid grains liquid gas porous media FTotal stresses in saturated soil are distributed between liquid and solid grains according to Terzaghi’s effective stress principle: intergranular forcesliquid pressure Porosity: VVn v= n n VVe sv - == 1 Void ratio: Saturation: v w r V V S = = + total stress effective stress pore pressure
  17. 17. Modelling multi-phase material in MPM
  18. 18. Two-phase formulation SOIL (solid grains and groundwater) SOLID LIQUID total representative volume solid volume liquid volume ( 0)nÑ » Hypotheses: - no free-water - negligible gradient porosity - no shear stresses in water (only isotropic p) - linear and laminar water flow (Darcy law) Primary unknowns: Lv Sv velocity field (3+3) Lr n porosity and density field (1+1) Derived unknowns: S ¢s S &eL &e Lp stress field (1+6) strain rate field (6+6) Total = 27 unknowns
  19. 19. Two-phase MPM formulation balance equation for the conservation of linear momentum L L L L d L D p Dt r rÑ× + - = v g fliquid phase mixture balance equation for the conservation of mass (1 ) ) ) 0 ( ( 0 L L L S S L D n n Dt D n n Dt r r - - = = Ñ× + Ñ× v vliquid phase solid phase Constitutive equations [ ], , 1 ; ( ) (1 )( ) L LL v L v LL L L S D DD p K n n Dt Dt Dt n e e = = Ñ× + - Ñ×v vliquid phase solid phase ( , , ) S S S S D f Dt b Ñ ¢ ¢= & s s ,a e Compatibility equations 1 [ ( ) ] 2 S TS S S D Dt = Ñ + Ñ e v v 1 [ ( ) ] 2 L TL L L D Dt = Ñ + Ñ e v vliquid phase solid phase 3 eqs. 3 eqs. 1 eq. 1 eq. 1 eq. 6 eqs. 6 eqs. 6 eqs. Total = 27 unknowns (1 ) S S L S L L D n D Dt D n t r rr-= +Ñ +gs v g v
  20. 20. MPM solution algorithm • Update stress • Update Stress • Update Material Point Volume and density (solving mass balance equation liquid) • Calculate new position of Material Point • Update Material Point Volume, density and porosity (solving mass balance equation solid) • Calculate new position of Material Point End of time step : t = t + Dt • Calculation of volumetric strain liquid • Calculation of nodal acceleration field (solving momentum balance equation liquid) • Calculation of nodal momentum field • Calculation of nodal velocity field • Calculation of nodal velocity field (solving momentum balance equation mixture) • Calculation of nodal momentum field • Calculation of nodal velocity field Liquid phase SOLID Beginning of time step : t = t
  21. 21. MPM computational cycle Map MP info to nodes Solve equilibrium equations Map acceleration field to MPs Update position and info of MPs
  22. 22. Modelling multi-phase material in MPM
  23. 23. Dynamic equilibrium water Dynamic equilibrium mixture Mass balance water Constitutive equation Summary equations (fully coupled 2-phase problems) ( )w w w w s w n p k g r r= Ñ - - +v v v g& ( )1 s s w wn nr r r- + = Ñ × +v v σ g& & (1 ) vol volw s w K p n n n e eé ù= - +ë û& && =σ D εg& &g Soil skeleton velocity Water velocity Porosity Solid density Water density Density of the mixture Water pressure Total stress tensor Strain tensor Tangent stiffness tensor Water bulk modulus Gravity vector wv sv n sr wr r p σ ε D wK g MPM is a continuum-based method
  24. 24. strain [-] 0 100 200 300 400 500 600 700 0 0.1 0.2 0.3 0.4 0.5 0.6 Relative density = 80% Relative density = 63% Relative density = 30% s1–s2[kPa] 0.1 0.2 0.3 0.4 0.5 0.6 advanced material models can depend on: plastic strain, stress and strain rates, density, … handling the correct history of state parameters is essential triaxial conditions 1s 1s 2s2s Constitutive model
  25. 25. Drainage type Porous media Dry Saturated Unsaturated Fully coupledDrained Undrained Effective stress analysis Total stress analysis 1-phase: = − 1-phase: / = − 2-phase: = − − = − − = + ̇ = ′ ̇ ̇ = ̇ ̇ = ̇ 3-phase: = − − , = − − , = − − −
  26. 26. Multi-phase material in Anura3D
  27. 27. Anura3D applications: Overview
  28. 28. Modelling large deformation multi-phase problems Unsaturated soils • Rain effects • Slope stability • Collapses Internal erosion (migration of solid particles under action of flow) • Internal instability (suffusion) • Piping • Stability of water retaining structures Soil-water-structure interaction • Seepage flow • Slope liquefaction • Submerged collapses • Dropping geocontainers • Erosion (macro/external) Applications • Slope failures • Column collapse • Consolidation problems • Dike stability • Pile installation • Shallow foundation • Impacts on structures • Water reservoir Anura3D v2017.1
  29. 29. Anura3D examples à workshop!
  30. 30. Summary Development, validation and application of advanced Anura3D MPM Software for modelling soil–water–structure interaction problems involving • (very) large deformations, • quasi-static/dynamic behaviour, cyclic loading, earthquakes, • (very) soft soils, consolidation and creep, • (internal) erosion, piping and scour, • sedimentation, • static/dynamic liquefaction and breaching, • installation problems (piles, CPT), • reinforcements, flood defences Focus: applications beyond standard geotechnical or hydraulic software

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