Creep Constitutive Models

Introduction

This FLAC3D option can be used to simulate the behavior of materials that exhibit creep (i.e., time-dependent material behavior). Creep models have been implemented in FLAC3D. These include the following:

1. Maxwell model — A classical viscoelastic model known as the Maxwell substance.
2. Burgers model — A classical viscoelastic model known as the Burgers substance, composed of a Kelvin model and a Maxwell model.
3. Power model — A two-component power law model used for mining applications (e.g., salt or potash mining).
4. WIPP model — A reference creep model commonly used in thermomechanical analyses associated with studies for the underground isolation of nuclear waste in salt.
5. Burgers-Mohr model — A viscoplastic model combining the Burgers model and the Mohr-Coulomb model.
6. Power-Mohr model — A viscoplastic model combining the two-component power model and the Mohr-Coulomb model.
7. Power-Ubiqitous mdoel — A viscoplastic model combining the two-component power model and the ubiquitous-joint model.
8. WIPP-Drucker model — A viscoplastic model combining the WIPP model and the Drucker-Prager model.
9. WIPP-Salt model — A viscoplastic model modified from the WIPP model; includes volumetric and deviatoric compaction behavior for salt-like materials.

The models are presented in order of increasing complexity.

In addition, it is also possible for users to write their own creep constitutive models using the DLL user-defined models option described in Writing New Constitutive Models.

• Description of Creep Constitutive Models
  • Maxwell Model
  • Burgers Model
  • Power Model
  • WIPP Model
  • Burgers-Mohr Model
  • Power-Mohr Model
  • Power-Ubiquitous Model
  • WIPP-Drucker Model
  • WIPP-Salt Model
• Solving Creep Problems with FLAC3D
  • Creep Timestep
  • Automatic Adjustment of the Creep Timestep
  • Temperature Dependency
• Input Instructions for Creep Modeling
  • Creep Commands
  • Creep FISH Variables
• Verification and Example Problems
  • Maxwell/Kelvin/Burgers Model: Parallel-Plate Viscometer
  • WIPP-Type Models: Parallel-Plate Viscometer
  • Power Model: Cylindrical Cavity
  • Power-Mohr Model: Cylindrical Cavity
  • WIPP Model: Cylindrical Cavity
  • Power Model: Spherical Cavity
  • Maxwell Model: Oedometer Test
  • Kelvin Model: Oedometer Test
  • Maxwell/Burgers Model: Compression Test
  • Burgers-Mohr/Power-Mohr Model: Loading/Unloading Compression Test
  • WIPP-Drucker Model: Comparison with Drucker-Prager Model
  • WIPP-Drucker Model: Compression Test Showing Localization
  • WIPP-Salt Model: Hydrostatic Compression Test
  • WIPP-Salt Model: Shear Compression Test
• References