缺陷数目对岩样声发射及应变能降低的影响

Influence of imperfection number on acoustic emissions and elastic strain energy decrease of rock specimens with initially random imperfections

利用拉格朗日元法(FLAC)模拟了单轴平面应变压缩条件下缺陷数目对含初始随机材料缺陷岩石试样声发射及弹性应变能降低的影响。比密实岩石弱的缺陷在破坏之后经历理想塑性行为。密实岩石在破坏之后先是经历线性应变软化行为,然后是理想塑性行为。随着缺陷数目的增加,每10个时间步内弹性应变能降低量(弹性应变能降低率)的峰值有下降的趋势。峰后的应力—应变曲线越陡峭,弹性应变能降低率的峰值越高。弹性应变能降低率的峰值发生于应变软化阶段。随着缺陷数目的增加,弹性应变能降低总量有降低的趋势。密实岩石的破坏使弹性应变能降低总量快速增加,随着施加应变的增加,其增加速度变缓。含缺陷试样可以较好地模拟岩石类材料的真实破坏过程,均质试样(不包含任何缺陷)则不然。

The acoustic emissions and elastic strain energy decrease of rock specimens with initially random material imperfections in uniaxial plane strain compression were numerically modeled by using FLAC. Beyond the failure of the imperfection that is weaker than the intact rock element, it undergoes ideal plastic behavior, while the intact rock element exhibits the linear strain-softening behavior and then the ideal plastic behavior once failure occurs. As the imperfection number increases, the peak of elastic strain energy decrease rate （elastic strain energy decrease per 10 timesteps） decreases. The steeper the post-peak stress-axial strain curve is, the higher the peak of elastic strain energy decrease rate is. The peak of elastic strain energy decrease rate occurs in strain-softening stage. As the imperfection number increases, the total elastic strain energy decrease has a decreasing tendency. The failure of intact rock elements leads to a rapid increase in the total elastic strain energy decrease. As the exerted axial strain increases, its increasing tendency becomes slow. The numerical rock specimen with initially random material imperfections can better model the actual failure process of rock material, while the homogeneous specimen cannot.