ABSTRACT: In this study, the relationships between shear strength of a blocky rock mass consisting of pyroclastic depositsand  the fractal dimension of the blocks within n the rock mass were investigated. Within the scope, triaxial shear testswere performed on specimens extracted from a blocky pyroclastic rock mass that defined as “bimrock” in termsof jeo-mechanical description. Thereby, cohesion (c) and internal friction angle (ɸ) values of the blocks withinin the rock mass were calculated through the fractal dimension solutions and digital image processing analysis Inaddition, uniaxial compressive strength of the rock and d the matrix component of this rock mass were determined Theresults revealed that there are positive and negative linear relationships between DR and c, ɸ and between DF and c,ɸ pairs. It is determined that while the values of both DR and DF increase, the values of ɸ increase and vice versa forcohesion The increase of ɸ with the increase of DR is an indication that the friction also increases by applied shearstresses due to  the increase in the roughness of the block surfaces. Finally the increasing of DR yielded an increasein the sum of the surface areas of the contacts between he matrix and blocks. Thus, the cohesion decreases due to the probable increase of weakness zones that loosen the rock mass.