单轴多级循环加载下原煤加卸载响应比演化特征  

Characteristics of the load/unload response ratio of raw coal under uniaxial multi-level cyclic loading

作　　者：赵毅鑫 龚爽[1,2] 滕腾 姜耀东[1,3] 杨志良 陈恺 ZHAO Yixin1,2, 3 GONG Shuang1, 2, TENG Teng1,2, JIANG Yaodong1,3, YANG Zhiliang1, 2, CHEN Kai1(1. Beijing Key Laboratory for Precise Mining of Intergrown Energy and Resources, China University of Mining and Technology（Beijing）, Beijing 100083, China; 2. College of Resources and Safety Engineering, China University of Mining and Technology（Beijing）, Beijing 100083, China; 3. State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology（Beijing）, Beijing 100083, China)

机构地区：[1]中国矿业大学(北京)共伴生能源精准开采北京市重点实验室,北京100083 [2]中国矿业大学(北京)资源与安全工程学院,北京100083 [3]中国矿业大学(北京)煤炭资源与安全开采国家重点实验室,北京100083

出　　处：《岩石力学与工程学报》2018年第5期1096-1105,共10页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家重点研发计划(2016YFC0600708;2016YFC0801401);中央高校基本科研业务费专项资金资助项目(2009QM01)~~

摘　　要：煤矿井工开采往往对采场周边煤岩体产生周期性扰动,研究单轴多级循环加卸载条件下煤变形及破坏特征有助于深入认识煤柱损伤、劣化及失稳破坏机制,并为获取煤柱失稳前兆提供有效分析手段。通过开展原煤单轴多级循环加卸载实验,利用弹性模量变化量提取加卸载响应比以描述原煤破坏前兆特征;并基于声发射累计振铃计数定义加卸载响应比,探讨原煤破坏过程中内部损伤演化特征及破坏前兆。此外,通过对实验前、后煤样内部结构的CT扫描,结合逆向化建模方法,分析煤样破坏特征及模拟单元数量对加卸载响应比数值计算结果的影响。研究发现:基于实验获得的单轴循环载荷下原煤加卸载响应比存在3个变化阶段,且在每级应力水平下均呈周期性"W"型变化特征;当荷载水平逐渐升高时加卸载响应比呈下降趋势,当荷载水平较高且接近峰值荷载时,加卸载响应比先下降后急剧上升;而基于声发射累计振铃数计算的加卸载响应比则呈持续减小趋势,并在破坏前接近1。In mining engineering,the periodic perturbation to rock mass induced by roadway excavation and mining affects the mechanical properties of surrounding rocks. Thus,studying the failure characteristic of raw coal under cyclic loading will help to understand the damage and deterioration mechanism of coal pillar,and to provide the effective means for the analysis of coal pillar instability. In this study,a uniaxial cyclic loading and unloading experiment at different stress levels on raw coal was conducted. Based on the experiment,a load/unload response ratio was defined according to the variation of elastic modulus to describe the failure characteristics of coal. Another response ratio was defined with the accumulative acoustic emission ring counts to describe the evolutionof internal damage of coal. A three-dimensional numerical model was established and studied based on the geometric data obtained by CT scanning. The results show that the evolution of the load/unload response ratio of raw coal under uniaxial cyclic loading has three stages,showing a periodic W-shaped variation at each stress level. Moreover,the load/unload response ratio decreases with the increase of loading stress level. It is also found that the load/unload response ratio drops a little bit and then increases suddenly as the loading stress close to the peak stress. However,the load/unload response ratio reaches minimal and fluctuates near 1 as the specimen is on the verge of damage based on the analysis of acoustic emission ring counts.

关 键 词：岩石力学 循环加卸载 加卸载响应比 三维逆向化 CT扫描 

分 类 号：TU45[建筑科学—岩土工程]