The Influence of Cyclic Load Amplitude on Mechanical Response and Acoustic Emission Characteristics of Granite

Cyclic loading and unloading tests with varying stress amplitudes were carried out to study the evolution trends of elastic modulus, plastic strain, dissipated energy density, acoustic emission events for granite under cyclic accidental extreme stress. The results as follows: (1) deformation modulus before after is different. In addition, at levels, specimens decreases by approximately 5~13%, but does not change significantly. (2) When causes rock damage, most potential this level released in advance. constantly varies subsequent low-amplitude cycle, strain caused partly recovered. (3) As increases, cumulative density increases Compared control group without a extremum, samples two groups extrema 20 kN 40 increased 48% 153%, respectively. (4) A significant event occurs only when subjected load exceeding maximum historical first time, intensity positively correlated difference between value. (5) Extreme values below crack damage threshold reduce growth advance, above aggravates damage.