Study of Anisotropic Shear Strength Parameters of Calc-Schist Case Study: Water Conveyance Tunnel Project of Kordestan Azad Dam

Anisotropy, which is a most important characteristic of metamorphic rocks such as schistose and gneissic rock, which should be considered in engineering evaluation. Most metamorphic rocks have foliated structure and they show considerable anisotropy in mechanical behavior. Therefore correct design and stability analysis of man made structures confined whit these rocks require enough knowledge about their anisotropic behavior. The purpose of this research, study of anisotropic shear strength parameters of Calc-schist sample that obtained from exploration geotechnical borehole number one tunnel of water conveyance system Kordestan Azad dam. Study area is located in Sanandaj- sirjan zone. To received objective of the present investigation is used from three generic experiments as petrography, physical and geotechnical properties for determine geotechnical properties, triaxial tests were conducted on the samples with various anisotropic angles (0, 30, 60, 90) under confining pressure of 2, 4, 6 MPa with using from their results, drown Mohr circles and obtained shear strength parameters. Also strength under confining condition of specimens is predicted with proposed an empirical strength criterion Ramamurty et al (1988) and used from their results predicted shear strength parameters. Results of this experiments show that shear strength parameters are anisotropic and is related to direction load, also changing curve of predicted results with experiment result showed good overlap.