薄层状红页岩细观破坏特性研究  

Study on mesoscopic failure characteristics of layered red shale

作　　者：马振乾[1] 周浪 左宇军[1] 张吉民 邹义怀[1] 曹云钦[1] MA Zhenqian;ZHOU Lang;ZUO Yujun;ZHANG Jimin;ZOU Yihuai;CAO Yunqin(School of Mining,Guizhou University,Guiyang 550025,China)

机构地区：[1]贵州大学矿业学院,贵州贵阳550025

出　　处：《煤田地质与勘探》2023年第10期104-113,共10页Coal Geology & Exploration

基　　金：国家自然科学基金地区科学基金项目(52164003);贵州省科技支撑计划项目(黔科合支撑〔2021〕一般352号);贵州省优秀青年科技人才项目(黔科合平台人才〔2021〕5610);贵州省教育厅科技拔尖人才项目(黔教技〔2022〕072号)。

摘　　要：为研究层状红页岩细观破坏特性,采用DSTD-1000型电液伺服刚性压力机对不同层理倾角红页岩进行单轴力学实验,对碎屑进行SEM电镜扫描和XRD衍射实验,获取其力学参数、破坏特征、微观结构及成分相对含量。基于此,利用离散元PFC3D构建不同层理倾角红页岩数值模型,并进行单轴压缩实验来研究红页岩细观破坏特征。结果表明:(1)层理倾角θ=30°、45°、60°、75°时,试样沿层理方向破坏产生滑移面。(2)不同层理倾角试样的裂纹演化过程都呈缓慢增长阶段、加速增长阶段、趋于稳定阶段的变化情况,当θ=45°、60°、75°时,裂纹演化过程中单位应变产生裂纹数较多,导致试样迅速沿层理弱面滑移破坏。(3)细观裂纹赤平极射投影和岩石组构图表明,θ=0°、75°、90°时,微观裂纹倾向分布较为均匀,主要平行于或次平行于加载方向,加载破坏后表现出强烈的各向异性;15°≤θ≤60°时,微裂纹倾向逐渐向层理方向平行。(4)考虑裂纹演化特征的弹性模量法求解的裂纹萌生应力阈值为各层理峰值强度的36.6%~60.3%,裂纹损伤应力阈值为各层理峰值强度的75.1%~90.4%,与大量物理实验所求阈值范围吻合,表明此法对于求解裂纹应力阈值具有一定的适用性。To study the mesoscopic failure characteristics of the layered red shale,uniaxial mechanical experiments were carried out by applying DSTD-1000 electro-hydraulic servo rigid pressure on the red shale with different bedding angles.Meanwhile,SEM and XRD experiments were implemented on debris to obtain its mechanical parameters,fail�ure characteristics,microstructure,and relative content of components.Based on this,models of the red shale with dif�ferent bedding angles were constructed using the discrete element PFC3D for the uniaxial compression experiments to study the mesoscopic failure characteristics of red shale.The results show that:(1)When the bedding angleθ=30°,45°,60°and 75°,the samples fail along the bedding direction to produce a slip surface.(2)The crack evolution process of samples with different bedding angles shows the changes in the slow growth stage,accelerated growth stage,and stable stage.Whenθ=45°,60°and 75°,more cracks are generated in the unit strain in the crack evolution process,which leads to the rapid slip failure of the sample along the weak plane of the bedding.(3)The stereographic projection of meso�cracks and the rock fabric diagram show that:the micro-cracks tend to be more evenly distributed,mainly parallel to or sub-parallel to the loading direction whenθ=0°,75°and 90°,showing strong anisotropy after loading failure.When 15°≤θ≤60°,the micro-crack tendency gradually parallels to the bedding direction.(4)The crack initiation stress threshold solved by the elastic modulus method considering the crack evolution characteristics is 36.6%‒60.3%of the peak strength of each bedding,and the crack damage stress threshold is 75.1%‒90.4%of the peak strength of each bedding,which is consistent with the threshold range obtained by a large number of physical experiments.It is indicated that the method has certain applicability for solution of the crack stress threshold.

关 键 词：红页岩 细观破坏 赤平极射投影 岩石组构 裂纹萌生应力 裂纹损伤应力 

分 类 号：P589.1[天文地球—岩石学]