Burger's Model in PFC

Introduction

The Burger's model provides a Kelvin model acting in series with a Maxwell model, in both the normal and shear direction. The Kelvin model is the combination of a linear spring and dashpot components that act in parallel with one another. The Maxwell model is the combination of a linear spring and dashpot components that act in series. The Burger's model act over a vanishingly small area, and thus transmit only a force.

Behavior Summary

The rheological components of the Burger's model are shown in the figure below, for both the normal and shear directions. In both directions, the model combines a Kelvin and a Maxwell model acting in series. In the normal direction, the Kelvin model provides a linear spring with stiffness Kkn and a dashpot with viscosity Ckn, and the Maxwell model provides a linear spring with stiffness Kmn and a dashpot with viscosity Cmn. The Burger's model can sustain tensile forces (Mt =0) or not (Mt =1). In the shear direction, , the Kelvin model provides a linear spring with stiffness Kks and a dashpot with viscosity Cks, and the Maxwell model provides a linear spring with stiffness Kmsand a dashpot with viscosity Cms. A slider with friction coefficient fs limits the value of the shear force according to a Coulomb law.

Rheological components of the Burger's model.

The following figure shows the time-decay of the normal force calculated by PFC2D, compared to the analytical solution for two balls fixed with a non-zero overlap. In both PFC2D and PFC3D models, the numerical solution shows that the contact force exponentially decreases as time increases, which coincides with the analytical solution shown by the blue dashed line in the figures.

Time history of normal contact force of Burger's model. The simulation results are shown in red marks, the analytical solution with the blue dashed line (2D model).

Latest News
  • Stability and Stress-Deformation Analyses of Reinforced Slope Failure at Yeager Airport This paper describes the material properties along with the inverse limit-equilibrium and permanent deformation analyses...
    Read More
  • Computers and Geotechnics: Scott Sloan Best Paper Award for 2019 Itasca is pleased to congratulate Dr. Branko Damjanac and Dr. Peter A, Cundall for their...
    Read More
  • Introducing Our New IMASS Constitutive Model The Itasca Constitutive Model for Advanced Strain Softening (IMASS) has been developed to represent the...
    Read More

Upcoming Events
19 Jan
Evaluation of impacts of lahars on structures using DEM numerical modelling
Lahars represent natural phenomena that can generate severe damage in densely populated urban areas. The evaluation of pressures genera... Read More
21 Jan
Griddle Version 2.0 has been Released | Learn What's New
Griddle 2.0 Has Been Released! Join us for a webinar on "What's New in Griddle 2.0?"... Read More
8 Mar
FLAC3D 2021 Online, Live Introductory Training
Three days of general feature training addressing basic concepts and recommended procedures for geotechnical numerical analysis.... Read More