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Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 20201
Getting more out of PLAXIS 2D and PLAXIS 3D: Workflow Tips
Micha van der SlootBentley Systems, Inc.Senior Manager, User Success, Geotechnical
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 20202
Getting more out of PLAXIS 2D and PLAXIS 3DTopics
• More efficient PLAXIS usage
• Getting forces from structural elements
• Importing geometry in PLAXIS
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 20203
More efficient PLAXIS usage
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 20204
PLAXIS: More efficient workflow: commandsCommands– All actions using the mouse or the explorers are translated into commands
– All model changes go through it, even when using the mouse
– Direct input of commands possible using command line:
• Session tab: commands executed in the current session
• Model history tab: all the commands executed in the project
– Help → Command reference for all available commands and syntax
– Simple low-overhead syntax
– Offers commands not exposed by the UI tools
– Store and run commands and macros
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 20205
PLAXIS: More efficient workflow: command lineVisual features on the command line
• syntax highlighting
• error indicators
• comments
Quicker usage of the command line
• recent commands (using ↑/↓)
• Command auto-complete
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 20206
PLAXIS: More efficient workflow: command runner• When executing more than one command
• Available in Expert menu
• Possible to load command log files
• Copy + paste commands from spreadsheet programs like Excel
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 20207
PLAXIS: More efficient workflow: macroMacros:
• Possibility to re-use series of commands
• We can store these as series of commands as Macros
• Available in Expert menu
• Macros can have keyboard shortcut:Shift+Ctrl+Alt+[1-9]
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 20208
PLAXIS: More efficient workflow: macro (2)Extra features: Array indexing syntax
Plaxis stores similar objects in containers / lists:
• Points, Lines, Plates, Phases, and Groups
Listable can be followed by square brackets with integer or a string
• e.g. Points[1], Plates[0], Phases[6], Lines[−1], Interfaces[−2]
• Note: indexing is zero-based!
• Negative numbers count the end of the list
Q: What is a listable?
A: Any object that can be treated as a list:
• Usage: Indexing and commands as e.g. count, filter, tabulate
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 20209
PLAXIS: More efficient workflow: demo
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202010
PLAXIS: More efficient workflow: next?Commands runner and macros
Limitations
• Not much interaction with data
• Results only available in the command line’s Session
• No use of results, values, or arithmetic expressions
• No conditional expressions (if/case) or loops
• No use of external libraries
• No export to files or spread sheets
Great for
• Repetitive commands
• Easy setup of list of commands in text file and spread sheet
Beyond the command line
• Remote scripting interface
• With nice Python wrapper
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202011
PLAXIS: More efficient workflow: next: Python
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202012
PLAXIS: What level of automation?
Pros Cons
No scripting
Can do (almost) anything PLAXIS can do Repetitive tasks can be boring
Easy to learn Repetitive tasks: time consuming
Built-in command line
Can do anything PLAXIS software can do Cannot script outside a project context
Low learning curve Cannot take runtime decisions (all pre-defined)
Spreadsheets / commands runner / macros for some automation
Remote scripting (Python)
Go beyond native PLAXIS functionality Small upfront investment in learning
Automated actions and decisions at run time Not worth for simple and straightforward projects
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202013
Getting forces from structural elements
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202014
Getting forces from structural elementsThin wall
Wall thickness << wall length
No end-bearing, only friction
→ Plate element suffices
→ Structural forces direct result (N, M, Q)
Thick wallWall thickness significant
End-bearing capacity needed
→ Use “soil” elements with material set representing wall material
→ In order to obtain structural forces
A) a plate with fictitious properties may be inserted
B) or use structural forces from volumes
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202015
Structural forces wall: A) fictious/dummy plate (1)Soil elements with material set representing wall material
Difficult to obtain structural forces from soil elements, therefore introduce plate:
• No influence on deformation: low stiffness, no weight
• Located in on the neutral line (usually the middle)
• Tight bonding to the concrete elements: no interfaces
Assumptions:
• tight bonding of dummy plate with volume-”plate” (εsoil_element = εdummy_plate ; κsoil_element = κdummy_plate)
• presence of the dummy plate should not change result: dummy plate stiffness E should be sufficiently small
d
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202016
Structural forces wall: A) fictious/dummy plate (2)How does dummy plate work?
Example: Bending
Soil elements: Esoil_elem = Ereal, Ireal = 1/12*d3 , d = wall thickness
Curvature: M = EI κ → κ = M / EI
κ = κreal = κdummy = Mreal / Ereal*Ireal = Mdummy / EIdummy
→ Let’s take EIdummy sufficiently small, let’s say EIdummy = EIreal / X (with X = 106)
Then Mdummy = Mreal* (EIreal / EIdummy) = Mreal/ X
→ real plate result Mreal = Mdummy * X = Mdummy * 106
Similar for Axial forces
ε = Nreal / Ereal*Areal = Ndummy / EAdummy
→ real plate result Nreal = Ndummy * X = Ndummy * 106
→ Hence, it relies on strain (ε) and curvature (κ)
NOTE: Nwall = Nplate + σy,0 * A, σy,0 = “initial” vertical stress in soil elements
d
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202017
Structural forces wall: B) stress integration
→ Hence, it relies on the integrated stresses in the elements
N M N and M
σNσN σN
Str
es
se
sIn
teg
rati
on
: F
orc
es
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202018
Structural forces wall: B) stress integrationAlso available in PLAXIS 2D Output
• Select a region or material
• PLAXIS will determine centerline (- - - - -)
• Then cross sections determined
• For each cross section:
• Normal stress σN gives N and M
• Shear stress τ gives Q
→ Hence, it relies on the integrated stresses in the elements
d
σN
N
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202019
Structural forces wall: demo case
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202020
Structural forces wall: notesDummy plate
• Results not directly available in graph/table (needs factor manually applied)
• Dummy plate needs to be added before analysis
• Large local shear force may not be accurate
Stress integration
• Post processing on any geometry
• Internal cross section determined based on element distribution
• So results can be come inaccurate with too coarse mesh
• Results based on internal stresses
• Be aware of construction sequence
• (WIP/ wished in place)
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202021
Importing geometry in PLAXIS
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202022
Importing into PLAXIS Importing 2D geometry
dxf, txt
Importing 3D geometry
step, dxf, brep
Importing tunnel geometry
.tnl, dxf
Importing soil investigation: CPT
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202023
Import geometry: PLAXIS 2DSupported formats
• DXF: Interchange files
• TXT/CSV: text files (tab-separated values or comma-separated values)
• BRep: Open CASCADE BRep file format
• STEP/STP: Standard for the Exchange of Product model data files
• GEO/STI: Delft GeoSystems M-Series geometry files
Notes
• The DWG file format is no longer supported since PLAXIS 2D 2018
• Lines as part of polylines(AcdbPolyLine) are not imported.
• In the cases where the imported geometry contains curved elements as well (like arcs), the geometry will be partly imported (only points and straight lines).
• Since PLAXIS 2D AE, PLAXIS will not automatically create clusters when lines enclose an area. For this, a polygon needs to be created.
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202024
Import geometry
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202025
Import geometry
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202026
Import geometry
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202027
Import geometry
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202028
Import geometry: PLAXIS 3DPLAXIS 3D can import different formats
• STEP/STP: "Standard for the Exchange of Product model data" files
• BRep: Open CASCADE BRep file format
• DXF: supports only parametric geometry
• IFC: Industry Foundation Classes files
• Pointcloud from text files
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202029
Import geometry: PLAXIS 3D
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202030
Import geometry: PLAXIS 3D
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202031
Import geometry: PLAXIS 3D top surface
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202032
Import geometry: PLAXIS 3D top surface
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202033
Import geometry: PLAXIS 3D top surface
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202034
After import: Finetune geometry qualityWhy finetune geometry quality?
Goal: good quality mesh to capture geomechanical mechanism
How to finetune?
Detection
Adjustments and repairing
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202035
After import: Finetune geometry quality - detect
tabulate volumes and areas[command]
checkgeometry[command][button] NEW
Inspecting geometry — Structures mode
Not only imported geometry, but also
geometry in the model:
• Soil layers from boreholes
• Structural elements
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202036
After import: Finetune geometry quality - detectInspecting geometry — Mesh mode
tabulate volumes and areas
checkgeometry [NEW]
Enhanced feedback from mesh generation when using EMR [NEW]
NEW
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202037
After import: Finetune geometry quality — detectCommon issues: causes and cases
• Tolerance difference settings between CAD and PLAXIS program
• PLAXIS uses 10−6 [length unit] as tolerance
• CAD image not optimized for FEM but for CAE
• Visually looks OK. For FEM it needs to be “perfect” for mesh creation
• Multiple import geometry: contacting geometry leaves gaps or small overlaps
• Two connecting volumes
• Tunnels with double linings
• Drawing geometry in PLAXIS does not match imported geometry
• Ground anchor connecting to retaining wall
• Plate or beams to connect to a volume
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202038
PLAXIS Import: tunnels
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202039
PLAXIS Import: tunnels
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202040
PLAXIS Import: tunnels
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202041
PLAXIS Import: tunnel definition
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202042
PLAXIS Import: tunnel definition
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202043
PLAXIS Import: tunnel definition
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202044
Generate the tunnel
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202045
Add tunnel geometry staged construction
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202046
Import field data: CPT
3. RobertsonCUR 3
1. Add field data file with CPT data
2. Select which file to use
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202047
Import field data: CPT (2D and 3D)
Micha van der Sloot, Bentley Systems, Inc.
XIII Russian PLAXIS User Meeting | October, 202048
Summary• More efficient PLAXIS usage
• Command line and macros
• Getting forces from structural elements
• Plates: thin and thick
• Structural forces from volumes
• Importing geometry in PLAXIS
• Issues in PLAXIS 2D
• Strategies in PLAXIS 3D
• Tunnel import
• Field data import: CPT