r7.01.14 Law of Behaviour CAM_CLAY

Summary:

The Cam-Clay model is one of the best known and most used elastoplastic models in soil mechanics. It is specially adapted to clay materials. There are several types of Cam-Clay models, the one shown here is the most common and is called modified Cam-Clay. This model is characterized by collapsible load surfaces in the form of ellipses in the diagram of the first two stress invariants. Within these reversibility surfaces, the material is non-linear elastic. In addition, at one point of each ellipse, there is a critical state characterized by zero volume variation. All of these points constitute a line separating the zones of expansion and contraction of the material as well as the zones of negative and positive work hardening. Work hardening is governed by a single scalar variable and the normal flow rule is adopted.

• 1. Ratings
• 2. Introduction
  • 2.1. Phenomenology of soil behavior
  • 2.2. Behaviour under hydrostatic compression
  • 2.3. Behaviour under deviatoric loading
• 3. Cam Clay’s law as amended
  • 3.1. Modeling hypotheses
  • 3.2. Charging surface
  • 3.3. Elastic law and work hardening law
  • 3.4. Plastic flow law
  • 3.5. Energy writing and plastic work hardening module
  • 3.6. Incremental relationships
  • 3.7. Summary of behavioral relationships
• 4. Digital integration of behavioral relationships
  • 4.1. Problem reminder
  • 4.2. Calculation of constraints and internal variables
  • 4.3. Calculating the unknown \({\mathrm{\Delta \epsilon }}_{v}^{p}\)
  • 4.4. Determining the limits of the function
  • 4.5. Special case of the critical point
  • 4.6. Summary
• 5. Tangent operator
  • 5.1. Nonlinear elastic tangent operator
  • 5.2. Plastic tangent operator in speed. Option RIGI_MECA_TANG
  • 5.3. Implicit tangent operator. Option FULL_MECA
• 6. Material parameters and internal variables
  • 6.1. Material parameters
  • 6.2. Internal variables
• 7. Implementation of a calculation with law CAM_CLAY
  • 7.1. Initializing the calculation
  • 7.2. Examples of results obtained on triaxial tests
• 8. Appendix: Implicit tangent operator. Option FULL_MECA
  • 8.1. General case
  • 8.2. Tangent operator at the critical point
• 9. Bibliography
• 10. Verification
• 11. Description of document versions