崩塌体失稳关键区岩石损伤特性试验研究

针对导致大型高陡危岩失稳的底部关键区域损伤劣化问题,通过声发射试验以及数值模拟试验获取关键区岩石试样在三轴压缩过程中的应力应变及声发射特征参数,利用损伤理论对试样的损伤特性与演化规律进行分析。研究结果表明:试样呈现出典型的脆性岩石破坏特征,伴随能量集中释放,在主破裂出现时刻声发射计数骤增;随着围压升高,声发射活跃频度增大,沉寂期缩短;不同围压下累计声发射计数曲线均呈现出初期平缓—中期缓增—后期陡升的阶段性特点,并与应力应变曲线具有良好对应关系;数值模拟试验所得到的力学及声发射数据能够合理反映并补充声发射试验结果,两种试验方法获取的岩石损伤性质参数及其趋势规律基本一致;基于累计声发射计数构建损伤变量,据此可定量化分析试样及危岩失稳关键区的损伤演化状态。本研究对具有相同失稳模式的高陡危岩损伤特性分析具有重要参考。

Experimental Study on Rock Damage Characteristic of the Key Zone for Collapsed Rock Mass

Acoustic emission experiment and numerical experiment were carried out for solving the problem of damage-induced deterioration of the key zone at bottom of high-steep unstable rock mass. Based on damage theory, damage characteristic and its development tendency of rock samples were analyzed by the data from experiments, such as stress, strain and parameters of acoustic emission. The result shows that these rock samples present typical failure characteristics of brittle. With concentrated release of energy, acoustic emission count suddenly increased when the main fracture appear. The frequency of acoustic emission increases and the silence period becomes shorter as the confining pressure goes up. The curve of accumulated acoustic emission count increases gently, gradually, sharply in early stage, middle stage and later stage, respectively. It is consistent with the stress-strain curve. Damage variable was built based on the accumulated acoustic emission count. This damage characteristic can be used to make quantitative analysis for the damage development of the rock samples and the key zone of rockfall during failure process. The research can serve as an important reference for the damage characteristic of the same type of rockfalls.