充填体损伤演化量化研究

Quantitative study on damage evolution of filling body

为构建充填体声发射特征参量与力学参量之间的本构关系,分析并量化充填体损伤演化过程,开展了单轴压缩声发射监测实验。通过拟合实验数据,获取了累计振铃计数与应变的耦合关系,并将其与岩石损伤力学理论及微破裂服从Weibull分布的假设相结合,推导出累计振铃计数与应力、损伤变量之间的本构模型,并进一步验证该模型的准确性。研究结果表明:峰值应力前夕,裂隙的不断汇集使其尺度不断扩大,声发射信号在裂隙的影响下不断发生折射或反射,部分信号组分不能通过裂隙等能量衰减现象,使其以累计振铃计数下降的形式逐步进入峰后破坏阶段。模型推算出的损伤理论值与实验值的平均误差为3.47%,证明模型具有较高的准确性,可有效描述充填体的损伤演化过程。此外,充填体的损伤由整体无序向局部有序发展,应力变化率的降低象征着损伤的局部化。该特征可将充填体的损伤演化过程量化,为充填体损伤评估提供理论依据。

In order to construct constitutive relation between acoustic emission characteristic parameters and mechanical parameters of filling body, and to analyze and quantify the damage evolution process of filling body, uniaxial compression acoustic emission monitoring experiment was carried out. By fitting experimental data, the coupling relation between accumulative ringing counting and strain was obtained. Combining it with rock damage mechanics theory and with micro-fracture Weibull distribution hypothesis, the constitutive model among accumulative ringing counting, stress and damage variables was derived, the accuracy of it was further verified. Results show that on the eve of peak stress, the continuous accumulation of cracks makes the scale of cracks expand continuously. Due to the influence of cracks, energy attenuation phenomenon occurs, such as acoustic emission signals refraction or reflection, some signal components can not pass cracks, which makes them gradually enter post-peak failure stage in the form of cumulative ring count decline. The average error between theoretical damage value calculated by the model and experimental value is 3.47%, which proves that the model has high accuracy and can effectively describe the damage evolution process of the filling body. In addition, the damage of filling body develops from overall disorder to local ordering. The decrease of stress rate represents the localization of damage. This feature can quantify the damage evolution process of filling body, and provide theoretical basis for damage assessment of backfill.