层理页岩单轴压缩下的声发射分形特征研究  

Study on Acoustic Emission of the Fractal Characteristics of the Stratified Shale Under Uniaxial Compression

作　　者：田耕 王超林 郑坤 唐伟 TIAN Geng;WANG Chaolin;ZHENG Kun;TANG Wei(School of Civil Engineering,Guizhou University,Guiyang 550025)

机构地区：[1]贵州大学土木工程学院,贵阳550025

出　　处：《土工基础》2024年第3期562-566,共5页Soil Engineering and Foundation

基　　金：国家自然科学基金资助项目(No.52004072)。

摘　　要：研究不同角度层理页岩的力学特征,通过合理的监测技术检测层理页岩裂缝失稳过程,对保证页岩气的生产效率和钻井作业的稳定性具有重要意义。对含不同角度层理的页岩试样进行了单轴压缩试验,并采用声发射监测技术记录页岩破裂过程。试验结果表明:层理页岩单轴抗压强度具有较强的各向异性特征,随着层理角的增大,单轴抗压强度呈现先减小后增大的趋势;不同角度层理页岩的单轴压缩破坏类型具有明显的差异性,角度为0°和90°时破坏类型主要为张拉破坏,角度为30°和60°时破坏类型主要为剪切破坏;基于分形理论的声发射时间序列关联维数D可以很好地表征层理页岩内部损伤破坏的发展演化规律,关联维数D处于高值状态波动,表明层理页岩内部主要以形成微裂纹为主,关联维数D急剧下降表明出现了大尺寸裂纹,即关联维数D的急剧下降可以作为层理页岩即将发生失稳破坏的预警信息。It is of great significance to study the mechanical characteristics of the stratified shale from different angles and detect the fracture instability process of the stratified shale through the reasonable monitoring technology to ensure the production effi-ciency of the shale gas and the stability of drilling operations.In this paper,the shale samples with different bedding angles were tested by the uniaxial compression,and the fracture process was recorded by the acoustic emission monitoring method.The experimental results show that the uniaxial compressive strength of the stratified shale has strong anisotropy characteris-tics.With the increase of the bedding angle,the uniaxial compressive strength decreases first and then increases.The uniaxial failure types of the bedding shale at different angles are obviously different.The failure types are mainly tensile failure at o°and 90°,and shear failure at 30°and 60°.The correlation dimension D of the acoustic emission time series based on the fractal theo-ry can well characterize the development and evolution law of damage and the failure inside the stratified shale.The fluctuation of the correlation dimension D at a high value indicates that the microcracks are mainly formed inside the stratified shale,while the sharp decline of correlation dimension D indicates the occurrence of large-size cracks.That is,the sharp decline of the cor-relation dimension D can be used as the early warning information of the imminent instability failure of bedding shale.

关 键 词：层理 页岩 破坏类型 声发射 关联维数 

分 类 号：TU457[建筑科学—岩土工程]