Experimental Research On Deformation Characteristics Of Rock Under Cyclic Loading

Mechanical property of rock mass under cyclic loading is one of the important factors which effect on long-term stability of rock mass engineering, researching on deformation characteristics of rock under cyclic loading is very useful for us to understand correctly the mechanics of rock fatigue damage under cyclic loading, and evaluate the long-term stability scientifically.This article uses MTS815 mechanics test system, carried on the different stress levels, the different load rates, the different water saturation, the different confining pressure and different rock type the rock class material experiment in cyclic loading as well as corresponding stress-strain entire process experiment. Through the analysis to stress-strain hysteresis curve of rock class material under the different experiment condition influence, analysis to fitting parameter of hysteresis curve versus cycle number, analysis to elative remnants of hysteresis curve strain versus cycle number, analysis to area and perimeter of hysteresis curve, in order to study rock deformation and evolution characteristics of hysteresis curve. This article has given below main fruits:(1). All deformation of rock class material under cyclic loading all has obvious hysteresis characteristics, and forms stress-strain hysteresis curve. The plastic-loop also gradually changes little and maintains stable condition with the increase of cyclic number,besides initial several plastic-loop has the obvious change in the stress-strain hysteresis curve.(2).The stress-strain hysteresis curve shows an obvious evolvement tendency with the increase of stress levels and water saturation, which make the rock material be easier failure, simultaneously, rock permanent deformation and area of hysteresis curve have the same tendency. Rock deformation have the up-tendency with the increase of water saturation at the same time, young's modulus and the shape of hysteresis curve change, too.(3). The slope and young's modulus of hysteresis curve also have an up-tendency with the increase of load rates, which make the rock material be easier failure; The corresponding stress levels and area of hysteresis curve also have an up-tendency with the increase of confining pressure, the hysteresis curve have the a stable evolution tendency with the increase of cyclic numbers.(4). Although different kinds of rock have different strength and deformation ,and the shape of hysteresis curve and area size are dissimilar, that is similar that the hysteresis curve have the stable evolution tendency with the increase of cyclic numbers.