Creep Constitutive Models in 3DEC and FLAC3D

Introduction

Creep modeling capabilities are built into 3DEC and are available as an option in FLAC3D. These facilities are used to simulate the behavior of materials that exhibit creep (i.e., time-dependent material behavior). The following creep models have been implemented:

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-Ubiquitous model — 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. Soft-Soil-Creep model — A soft soil model considering the time-dependent secondary compression (FLAC3D only).
10. 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
  • Soft-Soil-Creep Model*
• Solving Creep Problems
  • 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
  • Soft-Soil-Creep Model: Triaxial Consolidated Undrained Loading
• References