Dynamic simulations of geological materials using combined FEM/DEM/SPH analysis

Abstract

An overview of the Lawrence Discrete Element Code (LDEC) is presented, and results from a study investigating the effect of explosive and impact loading on geological materials using the Livermore Distinct Element Code (LDEC) are detailed. LDEC was initially developed to simulate tunnels and other structures in jointed rock masses using large numbers of polyhedral blocks. Many geophysical applications, such as projectile penetration into rock, concrete targets and boulder fields, require a combination of continuum and discrete methods in order to predict the formation and interaction of the fragments produced. In an effort to model this class of problems, LDEC now includes implementations of Cosserat point theory and cohesive elements. This approach directly simulates the transition from continuum to discontinuum behaviour, thereby allowing for dynamic fracture within a combined finite element/discrete element framework. In addition, there are many applications involving geological materials where fluid–structure interaction is important. To facilitate solution of this class of problems a smooth particle hydrodynamics (SPH) capability has been incorporated into LDEC to simulate fully coupled systems involving geological materials and a saturating fluid. We will present results from a study of a broad range of geomechanical problems that exercise the various components of LDEC in isolation and in tandem.

Keywords:

• geomechanics
• fluid–solid coupling
• numerical methods

Acknowledgements

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory in part under Contract W-7405-Eng-48 and in part under Contract DE-AC52-07NA27344.

Also, the authors would like to acknowledge helpful discussions with L. Glenn, M. B. Rubin and T. Antoun.