循环荷载条件下原煤力学性质及损伤演化规律

发布时间：2018-01-13 19:33

本文关键词：循环荷载条件下原煤力学性质及损伤演化规律　出处：《煤炭学报》2016年07期 　论文类型：期刊论文

【摘要】：对原煤试样分别进行了常规加载和循环荷载条件下的单轴和三轴力学强度试验,借助声发射技术,系统研究了单轴循环荷载及三轴循环荷载条件下原煤的损伤演化规律并对比分析。常规循环荷载试验结果显示:从循环初始至结束,煤岩内部损伤过程具有明显的3阶段,即初始损伤阶段,微裂纹扩展萌生稳定增长阶段,裂纹贯通破坏阶段;定量分析了应变峰值、卸载刚度及损伤变量在循环荷载过程中的变化规律,单轴循环试验初始损伤阶段的损伤程度较大,第3阶段损伤变量变化显著;三轴循环试验损伤过程中第1阶段最显著,而在损伤第3阶段,煤样临近破坏时损伤变量略微升高,与单轴试验损伤变量显著增加的情况不同;循环应力上限处声发射现象最强烈,说明循环过程中应力上限时的内部损伤程度最大。分级循环荷载试验结果显示:分级荷载增加初期应变回滞环较密集,声发射现象显著,试样破坏时声发射计数最大;各级循环也具有损伤不同阶段特征,达到损伤稳定阶段的损伤变量近似值与均值压力呈指数型变化关系。
[Abstract]:The coal samples were investigated by single axis and three axis mechanical strength test of conventional loading and cyclic loading conditions, using acoustic emission technique, uniaxial cyclic loading and three axial cyclic loading conditions of coal damage evolution and comparative analysis of system research. Conventional cyclic loading test results showed that: from the end to the initial cycle. The internal damage process of coal rock has 3 obvious stages, namely the initial damage stage, micro crack initiation and stable growth stage, crack failure stage; the quantitative analysis of the variation of peak strain, unloading stiffness and damage variable in the cyclic loading process, uniaxial cyclic tests of initial damage stage damage degree third stage of damage variables change significantly; three axis cycle test during the first stage of the most significant, and damage in the third stage, the coal sample near destruction damage variable is slightly higher, and the single axis test Check the damage variable significantly increased the different cyclic stress; the upper limit of the acoustic emission phenomenon is most intense, that cycle should be the upper limit of the damage degree of internal force. The maximum grade cyclic loading test results show that the classification of load increase initial strain hysteresis loops were intensive, significant acoustic emission phenomenon, the sample failure acoustic emission count the maximum; the levels of circulating injury also has different characteristics, to achieve stable stage of damage damage variable approximation is an exponential change and mean pressure.

【作者单位】：中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室;山东大学岩土与结构工程研究中心;
【基金】：国家自然科学基金杰出青年基金资助项目(51225902)
【分类号】：TD315
【正文快照】： 250061)地下工程硐室开挖卸载后,硐室围岩附近产生2次应力场,切向主要表现为加载,而径向表现为卸载。在煤矿开采过程中,采煤工作面综合机械化施工时,预留煤柱和工作面附近的煤会受到各种采动应力的反复作用,产生持续反复的损伤变形,降低其承载能力[1-4]。针对原煤进行循环加卸

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