煤岩卸荷破坏声学特性及变形破坏机理

Acoustic Characteristics of Unloading Failure and Deformation FailureMechanism of Coal-rock

我国很多工程建设逐渐向深部扩展,深部岩体复杂的结构和高应力等诸多因素对于工程安全提出了严峻的考验.本文以深部煤岩为研究对象,分别进行了单轴、三轴和三轴卸荷等试验下的声发射研究,得到以下结论:(1)单轴压缩下,声发射参数表现为前期平稳,塑性阶段后跳跃式发展.(2)三轴压缩下,试样整体更加稳定,声发射能量参数值先增后减再增,围压越大,试样出现相同破坏所需能量越大.(3)三轴卸荷与三轴压缩在卸荷之前声发射规律一致,卸荷后试样破坏加剧,声发射参数值增加.(4)分形维值D能很好地反应煤岩内部裂纹演变的规律.

Many engineering constructions in China are gradually extended to the deep,and many factors such as complex structure of deep rock mass and high stress have put forward severe test for engineering safety.In this paper,deep coal rocks are taken as research objects,and acoustic emission studies under uniaxial,triaxial and triaxial unloading tests are carried out respectively,and the following conclusions are obtained:(1)under uniaxial compression,acoustic emission parameters show a stable performance in the early stage and a leaping development after the plastic stage.(2)under triaxial compression,the overall sample is more stable,and the acoustic emission energy parameter value increases first,then decreases and then increases.The higher the confining pressure is,the more energy is required for the sample to have the same failure.(3)the coustic emissionlaw of triaxial unloading is consistent with that of triaxial compression before unloading.After unloading,the sample failure intensifies,and the coustic emissionparameter value increases.(4)fractal dimension value D can well reflect the law of crack evolution in coal and rock.