Abstract - The Particle Flow Code (PFC, Itasca Consulting Group) is a discrete element method used mainly by engineers for solving problems that cannot be addressed with methods that are based on continuum mechanics, e.g. finite difference and finite element. The model material consists of elastic spherical particles that can be bonded with each other. By choosing the appropriate parameters it is possible to reproduce material behaviour that is consistent with laboratory data on natural rocks. The rheologies of both competent (e.g. limestone, sandstone) and incompetent (e.g. shale) rocks can be calibrated by means of biaxial compression tests. These calibrations provide a means of performing 2-D numerical experiments that focus on the growth of normal faults in multilayered sequences. The earliest stages of deformation are characterised by monocline development within the competent units. Folding is accommodated by flow within the incompetent layers and by slip along the layer interfaces. Faults in the multilayer sequence generally show a staircase geometry caused by refraction across mechanical interfaces. The model faults reproduce the bifurcation of fault surfaces and subsequent evolution to a throughgoing fault observed in analogue models and in nature (i.e. normal faults in the limestone-mudstone sequence at Kilve, Somerset, UK).
Abstract of talk given to:
Irish Geological Research Meeting, Dublin, February 2002