分级循环加卸载煤体变形破坏特征试验研究  

Experimental research on deformation and failure characteristics of coal by staged cyclic loading and unloading

作　　者：李树刚 刘思博[1] 林海飞 双海清 李磊明[1] 于涵旭 罗荣卫 LI Shugang;LIU Sibo;LIN Haifei;SHUANG Haiqing;LI Leiming;YU Hanxu;LUO Rongwei(College of Safety Science and Engineering,Xi’an University of Science&Technology,Xi’an 710054,China;Key Laboratory of Western Mine Exploitation and Hazard Prevention Ministry of Education,Xi’an University of Science and Technology,Xi’an 710054,China;Western Engineering Research Center of Mine Gas Intelligent Extraction for Coal Industry,Xi’an 710054,China)

机构地区：[1]西安科技大学安全科学与工程学院,陕西西安710054 [2]教育部西部矿井开采及灾害防治重点实验室,陕西西安710054 [3]煤炭行业西部矿井瓦斯智能抽采工程研究中心,陕西西安710054

出　　处：《煤炭科学技术》2021年第4期199-205,共7页Coal Science and Technology

基　　金：国家自然科学基金重点资助项目(51734007);国家自然科学基金面上资助项目(51874236);陕西省联合基金培育重点资助项目(2019JLP-02)。

摘　　要：瓦斯抽采钻孔在采动影响下所处的应力状态比较复杂,随着工作面的推进,经历复杂的加载和卸载共同作用,易导致抽采钻孔失稳破坏。为深入研究采动影响下煤体钻孔的变形破坏特征,通过开展单调加载及分级循环加卸载试验,分析不同加载路径下试样的强度特征,并结合数字散斑技术(XTDIC)分析试样单轴压缩过程中裂纹扩展及孔周位移演化规律,通过布置"虚拟引伸计"分析试样局部化带位移演化特征。结果表明:与单调加载路径相比,分级循环加卸载路径下试样的抗压强度减小,减小幅度为4.59%;分级循环加卸载路径下,含钻孔试样的最终破坏是由远场裂纹与钻孔两侧的剪切裂纹贯通形成宏观破裂带导致的,不同加载路径下试样破坏模式均为拉剪复合破坏,破坏形态呈"X"状;试样加载顶点与卸载低点的张拉、错动位移随着循环次数增加逐渐增大,呈波动上升趋势,并且在时间上滞后于应力变化;孔周位移测点层位越高,试样加载至相同时刻的位移越大;分级循环加卸载路径下,试样卸载阶段的测点位移有轻微恢复现象,最大恢复量为0.149 mm,位移随时间增长表现为"台阶式"递增现象。The stress state of the gas drainage borehole under the influence of mining is relatively complicated.As the working face ad⁃vances,it experiences a complex combination of loading and unloading,which may easily lead to instability and destruction of the drainage boreholes.In order to investigate the deformation and failure characteristics of coal boreholes under the influence of mining,monotonic loading and multistage cyclical loading and unloading tests were carried out to analyse the strength characteristics of the samples under dif⁃ferent loading paths.Crack growth and the evolution of the displacement around the borehole during uniaxial compression of specimens were analyzed by using digital scatter technique(XTDIC)and the displacement evolution characteristics of the localized zone of the sam⁃pleswere analyzed by arranging the“virtual extensometer”.The results show that the compressive strength of the specimen is reduced by 4.59%under multistage cyclical loading-unloading path compared with monotonically loaded specimen.Under the multistage cyclical load⁃ing-unloading paths,the final failure of the specimens containing boreholes is caused by the penetration of the far-field cracks and the shear cracks on both sides of the borehole to form a macroscopic fracture zone.The failure mode of the specimens under different loading paths is tensile-shear composite damage with an“X”shape.The tension and misalignment displacement of the specimen at the top point of loading and the low point of unloading gradually increases with the number of cycles,presenting a fluctuating upward trend,and lagging behind the stress change in time.The higher the level of the displacement measurement point around the hole,the greater the displacement of the specimen loaded at the same time.Under the multistage cyclical loading and unloading path,the displacement of the measured point during the unloading stage of the specimen has a slight recovery,the maximum recovery is 0.149 mm,and the displacement increases with time i

关 键 词：分级循环加卸载 裂纹演化 局部化带位移 虚拟引伸计 抽采钻孔 

分 类 号：TD712[矿业工程—矿井通风与安全]