矽卡岩单轴循环加卸载试验及声发射特性研究

Experimental study of skarn under uniaxial cyclic loading and unloading test and acoustic emission characteristics

利用MTS岩石力学试验系统和PAC声发射信号采集系统,研究了单轴循环加卸载作用下矽卡岩强度变化及声发射特征。在矽卡岩循环加卸载过程中,若加载过程中岩样没有明显局部破坏,则随着循环次数的增加,弹性模量逐渐增大,岩样强度略有提高;若加载过程中岩样内部已经出现明显的局部破坏,产生了不可恢复的宏观裂纹,则循环加卸载会促进宏观裂纹层面间的滑移,从而加速岩样失稳破坏。矽卡岩在单轴压缩作用下声发射曲线大体可分为压密、弹性、塑性、峰后屈服4个阶段,并伴随有不同的声发射情况。此外,矽卡岩在循环加卸载作用下具有反凯塞效应,并且随着加卸载循环次数的增加,费拉西蒂比逐渐变小;岩样卸载阶段仍然有大量声发射产生。

Strength variation and acoustic emission characteristics of skam under uniaxial cyclic loading and unloading test are studied by using MTS equipment and PAC acoustic emission acquisition system. The results indicate that： in the loading and unloading processes, if there is no remarkably local failure in the loading process, then the cyclic loading and unloading processes might strengthen the rock sample, and Young＇s Modulus increases gradually with the increasing of cyclic times; and if the local failure happens and the nonrenewable cracks appears in the loading process, then the cyclic loading and unloading processes will facilitate the slippage of planes of cracks and accelerate the breakdown rate. Meanwhile, the results also indicate that： the uniaxial compression curve of skarn can be generally divided into four stages： pressure consolidation, elastic, plastic, peak post which with different acoustic emission characteristics. In addition, skarn has the anti-Kaiser effect under cyclic loading and unloading; and the Felicity ratio decrease with the increasing of cyclic times. Acoustic emission also exists in the unloading process.