CG1 Chile May 15-18, 2006: Introduction to Plaxis 1
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
Introduction to Plaxis
Dennis WatermanPlaxis BV
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
General modelling aspects
Defining a project:• Define geometry• Generate mesh• Define initial conditions• Define calculation phases• Calculate• Inspect results
CG1 Chile May 15-18, 2006: Introduction to Plaxis 2
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
General modelling aspects
The geometry is the representation of the physical problem
• Consists of points, lines and clusters• Definition of soil layers, structural elements
and loads
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
General modelling aspects
Points• Start and end of lines. • Positioning of anchors• Point forces, • Point fixities • Local refinements of the finite element mesh.
CG1 Chile May 15-18, 2006: Introduction to Plaxis 3
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
General modelling aspects
Lines• Define the physical boundaries of the
geometry• Define discontinuities in the geometry:
• Sheet pile walls, distributed loads• Separations of distinct soil layers or construction
stages.• A line can have several functions or
properties
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
General modelling aspects
Clusters• Automatically generated enclosed areas• Homogeneous soil properties.
CG1 Chile May 15-18, 2006: Introduction to Plaxis 4
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
(a) 6-noded triangle (b) 15-noded triangle
stress points
nodes
General modelling aspects
Mesh• 6-noded or 15-noded triangular elements• Displacements calculate in nodes• Stresses calculated in Gaussian integration
points
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
Input program
CG1 Chile May 15-18, 2006: Introduction to Plaxis 5
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
Input
• Composing a geometry model• Creating and assigning data sets• Generating a finite element mesh• Generating initial conditions
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
Composing a geometry model
• Graphical input of geometry contour, soil-layers, construction stages, plates, geogrids, interfaces, anchors
• Designer for circular or non-circular tunnels
• Input of loads and boundary conditions
CG1 Chile May 15-18, 2006: Introduction to Plaxis 6
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
• Geometry lines (between soil layers, etc.)
• Plates (Walls, Plates & Shells)
• Hinges (free rotation between beams)
• Geogrids
• Interface elements (soil-structure interaction)
• Anchors (node-to-node, fixed end)
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
Creating and assigning material data sets
• Enter model parameters as data sets in a material data base
• Assigning data sets to geometry components by means of ‘drag and drop’
CG1 Chile May 15-18, 2006: Introduction to Plaxis 7
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
Generating a finite element mesh
• Fully automatic mesh generation based on geometry model
• Global and local refinement options
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
Generating initial conditions
• Generating initial pore pressures by means of phreatic line or groundwater flow calculation
• Flip switch - gives: Initial stresses and geometry mode
• Setting initial geometry configuration• Generating initial stresses (K0 procedure)
CG1 Chile May 15-18, 2006: Introduction to Plaxis 8
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
Calculation program
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
Defining calculation phases
• Plastic calculation, Consolidation, Phi/c reduction and Dynamic analysis.
• Updated mesh.• Loading input: Multipliers or Staged
Construction.• Changing water conditions• Multiple calculation phases can be pre-defined
and executed at once.
CG1 Chile May 15-18, 2006: Introduction to Plaxis 9
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
Output program
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
View results
• Graphical and tabulated output of displacements, stresses and structural forces
• Output in cross sections• Multiple output windows can be opened
simultaneously (comparison of results)
CG1 Chile May 15-18, 2006: Introduction to Plaxis 10
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
First Exercise
Resume of input steps
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
Input geometry
Draw geometry
CG1 Chile May 15-18, 2006: Introduction to Plaxis 11
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
Input boundary conditions
Default fixities
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
Input loads
Point force A & B
CG1 Chile May 15-18, 2006: Introduction to Plaxis 12
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
Input material properties
General properties, model parameters
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
Mesh generation
Full automatic mesh generator
CG1 Chile May 15-18, 2006: Introduction to Plaxis 13
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
Initial conditions
Water pressures, Initial stresses
PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES
See course manual