Dilatancy Instability as a Possible Seismic Mechanism

Abstract : Dilatancy instability as a possible seismic mechanism is studied theoretically, numerically, and experimentally in the laboratory. The theoretical study concentrates on the fundamental nature of mechanical instability. The numerical portion of the study consists of the development of a 1-dimensional model that couples fluid flow phenomena with a sliding block model. Fluid injection and withdrawal experiments can be run on the numerical model to verify the results of the theoretical study. The experimental phase of the study concentrated on measuring dilatancy behavior of intact samples of Weber Sandstone under triaxial conditions using both a hydraulic system and electrical resistance strain gases. Results indicate that the volumetric behavior of the sandstone samples tested is similar to that reported by other investigators for dense sand. (Author)