三轴加载充填体围岩耦合体声发射特征研究

Study on acoustic emission characteristics of combination of surrounding rock and backfill body under triaxial loading

根据矿山开采状况设计了三种不同采场规格尺寸的充填体围岩耦合体模型,采用双轴试验机、拟真三轴装置结合声发射系统对耦合体进行了三轴加载下的破裂演化监测,研究了耦合体破裂过程声发射特征。结果表明:AE事件率和AE能量在塑性阶段前处于“平静期”,塑性阶段出现突增现象,突增现象可作为应力峰值附近宏观破裂预警;AE事件率峰值、AE能量峰值随着侧压增加推迟产生,耦合体稳定性随着侧压增加逐渐增强。AE事件率峰值、AE能量峰值随着规格尺寸的增加则与之相反;AE能量峰值随着侧压增加逐渐增大,随着规格尺寸增加逐渐减小。AE能量预警阶段突增值随着侧压增加逐渐降低,随着规格尺寸增加逐渐增大;Kaiser效应出现在耦合体应力峰值的70%~85%范围内,Kaiser效应点对耦合体塑性阶段宏观破裂具有一定的预警作用。研究结果有望为充填体与围岩作用机理研究提供参考。

According to the mining conditions,three combination models of surrounding rock and backfill body stope sizes were designed.The fracture evolution of the combination under triaxial loading was monitored by using biaxial testing machine,pseudo triaxial device,and acoustic emission system,and the acoustic emission characteristics of the combination fracture process were studied.The results show that the AE event rate and AE energy are in the“quiet period”before the plastic stage,and there is a sudden increase in the plastic stage,which can be used as a macroscopic fracture early warning near the stress peak;AE event rate peak and AE energy peak are delayed with the increase of side pressure,and the stability of the combination gradually enhances with the increase of side pressure.AE event rate peak and AE energy peak are opposite with the increase of size;AE energy peak increases with the increase of side pressure and decreases with the increase of size.The sudden increment of AE energy in the early warning stage decreases gradually with the increase of side pressure and increases gradually with the increase of size;Kaiser effect appears in the range of 70%~85%of the peak stress of the combination,and the Kaiser effect point has a certain early warning effect on the macroscopic fracture of the combination in the plastic stage.The research results are expected to provide a reference for the study of the interaction mechanism between backfill body and surrounding rock.