单轴压缩条件下破裂岩样声发射及能耗特性试验研究

为揭示岩石变形破裂的内在机理及正确评价工程破裂岩体的特性,本文对破裂岩石再破裂过程声发射、能耗特性进行了综合研究。借助MTS伺服试验机及AE21C声发射检测仪,对破裂岩样进行了单轴压缩条件下再破裂过程中的声发射及能耗特性实验研究。研究结果表明:破裂岩样声发射事件-时间曲线主要属于峰前阶段加速增长型,其声发射事件-时间曲线大致可分为声发射初始发展、剧烈、降低三个阶段;在整个压缩破裂过程中,声发射活跃程度总体上大于相对完整岩样;峰值点是声发射特征、能耗特征的转折点;岩样变形破裂过程中,声发射与能耗指标之间存在内在的、必然联系;随着破裂程度的提高,破裂岩样峰值点吸收能量与峰前段耗散能量均逐步降低;破裂岩样表面破裂面分布分形维数同峰值点吸收能量与峰前段耗散能量之间总体上均遵循非线性的二次多项式函数关系。

Experimental Study of Acoustic Emission and Energy Dissipation Characteristics of Cracked Rock Subjected to Uniaxial Compression

In order to reveal the internal mechanism of rock deformation and fracture and to correctly evaluate the characteristics of engineering cracked rock, comprehensive study of acoustic emission (AE) and energy dissipation characteristics during redestruction process of cracked rock subjected to uniaxial compression was carried out with the aid of MTS Servo Test Machine and AE21C acoustic emission detector. Results show that the event-time curve of cracked rock acoustic emission mainly belong to accelerated growth type before peak value point, which can be divided into three stages of development: initial development stage, violent and reducing stage, respectively. In the whole compression and fracture process, the AE activity degree of cracked rock is generally lager than that of relatively complete rock sample. The peak value point is the turning point of AE and energy dissipation characteristics. During the process of rock deformation and fracture, there is inherent and inevitable relation between acoustic emission and energy dissipation indicator. Both energy absorption at the peak value point and energy dissipation before the peak value point decrease gradually with the increase of fracture degree. Relations among the fracture surface distribution fractal dimension of cracked rock sample, the energy absorption at peak value point and the energy dissipation before peak value point generally follow a non-linear quadratic polynomial function.