Experimental Research on Rock Energy Evolution under Uniaxial Cyclic Loading and Unloading Compression
Experimental Research on Rock Energy Evolution under Uniaxial Cyclic Loading and Unloading Compression
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单轴循环加卸载压缩下岩石能量演化实验研究
DOI：
10.1520/gtj20170233
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发表时间：
2018-07-01
影响因子：
1.6
通讯作者：
Pu, Hai
中科院分区：
文献类型：
--
作者：
Meng, Qingbin;Zhang, Mingwei;Pu, Hai
为了揭示岩石变形破坏过程中能量的积累与耗散特征，采用MTS 815岩石力学试验系统（MTS Systems Corporation，伊甸园草原，MN）对180个红砂岩试件进行了36种不同加卸载方案下的循环单轴压缩试验。基于热力学理论，通过对岩石综合应力-应变曲线的分析，提出了一种由岩石加卸载曲线特征计算岩石能量密度的方法。测定了岩石试件在不同加卸载速率下的能量密度。讨论了加卸载速率对岩石能量演化的影响，揭示了峰前阶段岩石能量积累与耗散的演化与分布规律。实验结果表明，在不同加卸载速率下，岩石能量密度随轴向加载应力的增加呈非线性增加。总吸收能密度的增加速度最快，其次是弹性能密度，耗散能密度的增加速度最慢。弹性能密度呈“先增后减”的趋势，而耗散能密度则呈相反的趋势。在静态和准静态加载范围内，加载速率和卸载速率对弹性能密度的影响不明显，但对耗散能密度的影响较大。加卸载速率越小，耗散能密度越大。
To reveal the characteristics of energy accumulation and energy dissipation during rock deformation and failure, cyclic uniaxial compression experiments under 36 different loading and unloading schemes were carried out on 180 red sandstone specimens using an MTS 815 rock mechanics test system (MTS Systems Corporation, Eden Prairie, MN). Based on the theory of thermodynamics and the analysis of the resultant stress-strain curves, a method of calculating the rock energy density from the characteristics of the loading and unloading curves was proposed. The energy densities of rock specimens under different loading and unloading rates were determined. The influence of loading and unloading rates on the rock energy evolution was discussed, and the evolution and distribution laws of energy accumulation and dissipation in the rock during the prepeak stage were revealed. The experimental results showed that rock energy density increases nonlinearly with an increase in the axial loading stress under different loading and unloading rates. The total absorbed energy density increases at the fastest rate, followed by the elastic energy density, and the dissipated energy density increases at the slowest rate. Elastic energy density shows a trend of “increasing first and then decreasing,” while the dissipation energy density shows the opposite trend. In the static and quasi-static loading ranges, the loading and unloading rates have no clear effect on the elastic energy density but have a considerable effect on dissipation energy density. The smaller the loading or unloading rate, the larger the dissipation energy density.