True triaxial testing of sandstones and shales

Abstract

In this study deformational and failure properties of sandstones and shales have been evaluated through laboratory experiments under true triaxial stress conditions. The impacts of intermediate stress and water saturation were investigated. The results indicated that rock strength, elastic moduli, dilatancy behaviour, failure mode and fractures pattern are affected by both the minimum and intermediate principal stresses. Variable water saturation also influences mechanical response of shales. Finally, multistage true triaxial testing was used and examined.