عنوان مقاله [English]
نویسندگان [English]چکیده [English]
The main aim of this research is assessing strength properties of Alvand monzogranite under different loading conditions. For this reason, at the first step, static tests under uniaxial and triaxial states were done to evaluate the effect of confining pressure on mechanical behavior of the rock. Furthermore, fatigue behavior of the rocks subjected to triaxial cyclic loading was evaluated. The fatigue tests were done in load control condition with 1Hz frequency and two states of loading including constant stress level and amplitude, and variable state of them. The results of the fatigue tests have been evaluated by fatigue damage parameters including maximum and minimum axial strain, maximum and minimum lateral strain, tangent and secant modulus, energy density and hysteresis energy. The static tests results show that confining pressure has a remarkable effect of strength and deformability properties of these rocks and has induced increasing in strength and per failure plastic phase. Elastic modulus of the rocks have been increased with increasing confining pressure in a linear function. Evaluation of the fatigue damage parameters indicated that fatigue damage process in triaxial condition shows three stages including crack initiation phase, uniform velocity phase and acceleration phase, as well. Among the fatigue damage parameters, lateral strain, secant modulus and hysteresis energy show better three-stage fatigue damage behavior.