加载速率影响下的岩石尺寸效应及声发射特征
投稿时间:2020-02-28  修订日期:2020-05-21  点此下载全文
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作者单位E-mail
张嘉凡 西安科技大学 1396663154@qq.com 
基金项目:国家自然科学基金(11172232,51774231)
中文摘要:为研究岩石在不同加载速率条件下,岩样尺寸对峰值强度、声发射时空特征等力学性质的影响,采用数值模拟和数据拟合相结合的分析方法,对5组不同高径比试件进行了不同加载速率条件下的单轴压缩模拟试验。结果表明:岩石峰值强度与加载速率呈正相关,与岩样高径比呈负相关,二者关系均可用多项式进行表述。不同高径比试件,加载速率对岩石尺寸效应起主导因素,当L/D≥2时,岩样尺寸效应逐渐减弱。同时岩石在不同加载速率条件下对声发射影响也比较显著,当试样高径比L/D≤2时,声发射数在峰值强度后较多,整个过程中声发射数先逐渐增加后逐渐减少,呈现出渐进型变化规律;当L/D>2时,声发射数较少,在峰值强度之后出现很明显的声发射事件,属于突跃型变化规律,对利用声发射特性来预测不同尺寸岩样单轴压缩破裂来临有一定的参考意义。
中文关键词:岩土工程  尺寸效应  加载速率  声发射
 
ROCK SIZE EFFECT AND ACOUSTIC EMISSION CHARACTERISTICS UNDER THE INFLUENCE OF LOADING RATE
Abstract:In order to study the influence of rock sample size on mechanical properties such as peak strength and acoustic emission space-time characteristics under different loading rates, numerical simulation and data fitting were combined to conduct uniaxial compression simulation tests on five groups of test pieces with different height to diameter ratios under different loading rates. The results show that the peak strength of rock is positively correlated with the loading rate, and negatively correlated with the ratio of height to diameter of rock sample. For the test pieces with different diameters, the loading rate plays a leading role in the rock size effect. When L/D≥2, the rock sample size effect gradually weakens. At the same time, rock also has a significant influence on acoustic emission under different loading rates. When the ratio of height to diameter of the sample L/D is less than or equal to 2, the number of acoustic emission is more after the peak intensity. During the whole process, the number of acoustic emission increases gradually and then decreases gradually, showing a gradual change law. When L/D > 2 occurs, the number of acoustic emission is small, and obvious acoustic emission events occur after the peak intensity, which belongs to the change law of abrupt jump type, and has certain reference significance for predicting the arrival of uniaxial compression fracture of rock samples of different sizes by using acoustic emission characteristics.
keywords:geotechnical engineering  size effect  loading rate  acoustic emission
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