循环加卸载下岩样变形与强度特征试验

基于在伺服试验机上对不同晶粒大理岩样进行单轴循环加卸载试验,研究了岩石的变形与强度特征.结果表明,岩石材料具有明显的记忆性,岩样循环加卸载过程的外包络线与单调加载的全程应力-应变曲线相吻合,加卸载路径不能完全重复,应力与应变之间不存在一一对应关系,岩样的线性变形并不意味着弹性变形;循环加卸载对岩石力学参数的影响不是很大,其偏差在正常离散范围以内;整个循环加卸载过程中,岩样的杨氏模量及能耗并非常数;弹性阶段加卸载的平均杨氏模量基本一致,能够表征岩石材料的变形特性,且在弹性阶段能耗较少,而在裂隙压密、屈服和破坏阶段耗能较多;软弱岩样在加卸载过程中需要消耗更多的能量.

Experimental study on deformation and strength characteristics of rock specimens under cyclic loading and unloading

Uniaxial cyclic loading and unloading experiments were performed on marble specimens with different grain sizes by use of servo-controlled testing machine to investigate the deformation and strength properties of rocks.Some conclusions are drawn as follows: the rock material shows distinct memorability;the envelope curve for rock specimens under cyclic loading and unloading accords well with the complete stress-strain curve under monotonic loading;the loading and unloading paths cannot be completely repeated,and one-to-one correspondence relationship does not exist between stress and strain,therefore,the linearity of rock specimens does not mean the elasticity;cyclic loading and unloading has little influence on mechanical parameters of rock specimens,and the deviations of the parameters are within the normal range of dispersion;the Young's modulus of rock specimens and energy dissipation vary in the whole process of loading and unloading;the average values of Young's modulus of rock specimens during loading and unloading processes are almost the same at the elastic stage,which can reflect the deformation property of rock material,while the energy dissipation at this stage is less than that at fissure closure,yielding,and failure stages;the energy dissipation of weak rock specimens is great during the loading and unloading processes.