Abstract - Laboratory tests of sedimentary rocks (e.g. sandstones, limestones) indicate that rock strength, angle of internal friction and stiffness decrease with increasing porosity. We used the Discrete Element Method (DEM), in which rock is represented by bonded spherical particles, to investigate the shape of failure envelopes and relations between friction angle and porosity. We performed a series of confined triaxial extension and compression tests on samples that were generated with different particle packing methods in order to test whether the mechanical properties of the model material are predominantly controlled by particle size distribution or porosity.
Our 3D DEM models for different particle size distributions and cement content demonstrate the sensitivities of given material properties, such as friction angle and the unconfined compressive strength to tensile strength (UCS/T) ratio. All our 3D DEM model property relations (strength, friction angle, stiffness) are consistent with those described for real rocks.
Abstract of talk given to:
Mechanics of Materials: Perspectives and Recent Advances, Joint meeting of Irish Mechanics Society, the Swedish National Committee for Mechanics, and the Irish Society for Scientific Engineering & Computation, May 2007.