煤岩组合体循环加卸载变形及裂纹演化规律研究  

Deformation and crack evolution of coal-rock combined body under cyclic loading-unloading effects

作　　者：陈岩[1] 左建平[1,2] 宋洪强[1] 冯路路 邵光耀 CHEN Yan;ZUO Jianping;SONG Hongqiang;FENG Lulu;SHAO Guangyao(School of Mechanics and Civil Engineering,China University of Mining ＆ Technology（Beijing）,Beijing 100083,China;State Key Laboratory of Coal Resources and Safe Mining,China University of Mining ＆ Technology（Beijing）,Beijing 100083,China)

机构地区：[1]中国矿业大学(北京)力学与建筑工程学院,北京100083 [2]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：《采矿与安全工程学报》2018年第4期826-833,共8页Journal of Mining & Safety Engineering

基　　金：国家自然科学基金优秀青年基金项目(51622404);国家自然科学基金项目(11572343);中国矿业大学(北京)越崎杰出学者奖励计划项目;国家重点研发计划项目(2016YFC0801404);国家"万人计划"青年拔尖人才项目(W02070044)

摘　　要：利用MTS 815试验机对煤岩组合体进行循环加卸载试验,分析了煤岩组合体循环加卸载中弹性应变和残余应变,而后得出加载时裂纹闭合应力和闭合应变,最后利用加载试验数据验证了轴向裂纹闭合模型和峰前应力-应变关系模型。结果表明:随着循环次数的增加,煤岩体内部的原生裂纹逐渐被压密,进而轴向弹性应变比重增大,而轴向残余应变比重减小;环向弹性应变所占比例先增大后减小,主要是由于荷载的增加加剧了煤体的环向扩容,并产生环向裂纹。计算得出每次加载下的轴向裂纹应变,发现随着应力增大,轴向裂纹应变先增大后基本保持不变,其拐点为裂纹闭合点,所对应的应力为轴向裂纹闭合应力,应变为轴向裂纹闭合应变。由于新裂纹和孔隙较难闭合,二者随加载次数增加有增大趋势。最后利用轴向裂纹闭合模型和峰前应力-应变关系模型对循环加卸载煤岩组合体的试验数据进行评价,理论值与试验值吻合度较高,能够很好地反映岩石峰前非线性行为。The testing machine MTS 815 is applied to carry out a cyclic loading-unloading experiment for analyzing coal-rock combined body and elastic strain, residual strain. Then, the axial crack closure stress and axial crack strain are calculated. Finally, the axial crack closure model and pre-peak model were verified. The results show that with increasing of cyclic times, the proportion of axial elastic strain increases and the axial residual strain drops and the radial elastic strain proportion increases at first then decreases according to the dilatancy of coal body and radial crack produce. The axial crack strain are calculated and it increases with axial stress increasing and keeps unchanged with increasing axial stress. The inflection point is the axial crack closure point and the stress and strain at this point are named as the axial crack closure stress and strain. Because of the hard closure of new crack and pore, the axial crack stress and strain increases with the loading times. Finally, the cyclic loading experimental data of coal-rock combined is evaluated by the axial crack closure model and the pre-peak stress-strain model. The theoretical curves are agreed to the experimental curves, which can reflect the nonlinear characteristics of pre-peak stress-strain curves.

关 键 词：煤岩组合体 残余应变 弹性应变 裂纹应变 非线性模型 

分 类 号：TD313[矿业工程—矿井建设]