Strength and deformation properties of a schist rock in Isfahan

Document Type : Research Paper



In most parts of the city of Isfahan, at depths of 5 to 20 meters from the ground surface, schist is the predominant rock. This schist is a layered rock with variable thickness of 3 cm or more. Triaxial tests were conducted on the specimens with various anisotropic angles under confining pressures of 0, 7 and 15 MPa, and axial stress-axial strain were measured and plotted for various conditions.
The results obtained reveal the effects of schistosity on the strength and deformability of the rock very clearly. The modulus of deformation of this rock varies with the anisotropic angle. For zero orientation, the modulus of deformation increases to a maximum. The results show that the friction angle and cohesion are affected by the anisotropic orientation, which is more important for the cohesion than the friction angles. It is not possible to apply failure criteria such as Mohr–Coulomb and Hoek–Brown for this rock without consideration of anisotropy orientation.