扫描电镜下页岩微观断裂原位观测与变形表征  

IN SITU OBSERVATION AND DEFORMATION CHARACTERIZATION OF MICROSCOPIC FRACTURES IN SHALE UNDER SCANNING ELECTRON MICROSCOPE

作　　者：张建勇 崔振东[3,4,5] 韩伟歌 李晓 刘大安[3,4,5] ZHANG Jianyong;CUI Zhendong;HAN Weige;LI Xiao;LIU Da'an(College of Geological Engineering,Institute of Disaster Prevention,Sanhe 065210,China;Hebei Key Laboratory of Earthquake Disaster Prevention and Risk Assessment,Sanhe 065210,China;Key Laboratory of Shale Gas and Geoengineering,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Innovation Academy for Earth Science,Chinese Academy of Sciences,Beijing 100029,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;Key Laboratory of Roads and Railway Engineering Safety Control(Shijiazhuang Tiedao University),Ministry of Education,Shijiazhuang 050043,China)

机构地区：[1]防灾科技学院,地质工程学院,三河065210 [2]河北省地震灾害防御与风险评价重点实验室,三河065210 [3]中国科学院地质与地球物理研究所,中国科学院页岩气与地质工程重点实验室,北京100029 [4]中国科学院地球科学研究院,北京100029 [5]中国科学院大学,地球与行星科学学院,北京100049 [6]石家庄铁道大学,道路与铁道工程安全保障省部共建教育部重点实验室,石家庄05004

出　　处：《工程地质学报》2024年第4期1199-1208,共10页Journal of Engineering Geology

基　　金：中央高校基本科研业务费专项资助项目(资助号:ZY20230219);中国科学院战略性先导科技专项(B类)(资助号:XDB10030301);国家自然科学基金项目(资助号:41972296);廊坊市科学技术研究与发展计划自筹经费项目(资助号:2023013094)。

摘　　要：为定量化获取页岩微观裂纹萌生、连接过程中的变形量,从而揭示页岩微观裂纹的变形、演化规律及破裂机理。本研究探索并对比了基于页岩表面天然斑点、表面光刻处理、表面金属纳米颗粒处理的微观DIC应变表征方法,研究了微观裂纹萌生、扩展中的变形演化过程。得出结论如下:(1)3种表面处理方法均可实现DIC变形表征,利用页岩表面天然斑点较为简单、方便,但无法在高放大倍数下进行变形表征;光刻处理相对廉价,对页岩物理力学性质不产生影响,但最小散斑尺寸为2μm,且光刻胶不随页岩的微小破裂而破裂,易遮挡微观裂纹;表面金属纳米颗粒处理所形成散斑较为精细、散斑尺寸可人为控制,DIC变形表征较为准确,但页岩需经过300℃处理,可能影响页岩物理力学性质。(2)非连续裂纹的萌生、连接是微观裂纹扩展的重要形式,非连续裂纹形成前存在非连续应变集中现象。非连续裂纹具有层级展布特征,这可能是微观裂纹曲折复杂的原因;(3)相互连接的非连续裂纹形成主裂纹,未与主裂纹连接的非连续裂纹由于应力释放而闭合,形成分支裂纹。本研究为页岩微观变形演化表征提供了新的技术手段与研究思路,同时也为微观裂纹扩展规律及非连续裂纹形成演化研究提供了试验证据。To quantitatively obtain the deformation of microscopic fractures in shale during their initiation and coalescence,thus revealing the deformation evolution law and fracture mechanism of microscopic fractures in shale,this study explores and compares three micro-digital image correlation(DIC)strain characterization methods based on natural speckles,surface photolithography,and surface metal nanoparticle treatment of shale.The deformation evolution process during the initiation and propagation of microscopic fractures is investigated.The following conclusions are drawn:(1)All three surface treatment methods can be used for DIC deformation characterization.Utilizing natural speckles on the shale surface is relatively simple and convenient,but it cannot be used for deformation characterization at high magnifications.Photolithography is relatively inexpensive and does not affect the physical and mechanical properties of shale.However,the minimum speckle size is 2μm,and the photoresist does not fracture with the microfractures of the shale,which can obscure the microscopic fractures.Surface metal nanoparticle treatment creates finer speckles with controllable speckle size,resulting in more accurate DIC deformation characterization.However,the shale needs to be treated at 300℃,which may affect its physical and mechanical properties.(2)The initiation and coalescence of discontinuous fractures are important forms of microscopic fracture propagation.Non-continuous strain concentration occurs before the formation of discontinuous fractures.Discontinuous fractures exhibit a hierarchical distribution,which may be the reason for the tortuous and complex nature of microscopic fractures.(3)Interconnected discontinuous fractures form the main fracture,while discontinuous fractures that are not connected to the main fracture close due to stress release,forming branch fractures.This study provides new technical means and research ideas for the characterization of microscopic deformation evolution in shale.It also provides experi

关 键 词：页岩 微观裂纹 原位观测 应变表征 非连续裂纹 

分 类 号：P642.3[天文地球—工程地质学]