Robert Caulk

Micromechanical modeling of acoustic emissions in heterogeneous rocks during tensile fracture

The presentation will cover a micromechanical investigation of acoustic emissions (AE) in heterogeneous rocks. First, the heterogeneity of a sandstone rock is statistically quantified using cathodoluminescent image analysis of interacting grains. Next, the statistical description of heterogeneity is used to augment the micromechanical contact model in Yade DEM. The heterogeneity model is then validated by modeling AE as a strain energy change based process in Yade. We validate the combined heterogeneity and AE models using experimental three point bending tests. Further validation is performed by collecting DEM wave propagation associated with broken bonds. Traditional arrival time based source localization is performed and compared to strain energy based AE locations. We conclude that the stochastically augmented DEM model can accurately model the spatial and temporal development of AE during tensile fracture of heterogeneous rock, but the process of statistically quantifying rock heterogeneity may be limited to single scale heterogeneity descriptions of sedimentary rock types.