水-力作用下红砂岩多裂纹宏-微观断裂机理研究  

Macro-micro fracture mechanisms of multiple cracks in red sandstone under hydro-mechanical actions

作　　者：沈晴晴 饶秋华[2] 易威 孙栋良 SHEN Qingqing;RAO Qiuhua;YI Wei;SUN Dongliang(School of Civil and Architectural Engineering,Hunan Institute of Technology,Hengyang 421002,China;School of Civil Engineering,Central South University,Changsha 410075,China)

机构地区：[1]湖南工学院土木与建筑工程学院,湖南衡阳421002 [2]中南大学土木工程学院,湖南长沙410075

出　　处：《铁道科学与工程学报》2023年第12期4701-4711,共11页Journal of Railway Science and Engineering

基　　金：国家自然科学基金资助项目(51874351,52078495);湖南工学院引进人才科研启动经费资助项目(HQ22016)。

摘　　要：在深部开采工程中,裂隙岩石在水-力作用下容易发生起裂、扩展而导致失稳破坏。针对目前关于水-力作用下多裂纹断裂机理大多为定性研究而缺乏相关定量研究的问题,基于水-力作用下多裂纹扩展准则预测水-力作用下含双裂纹红砂岩的扩展过程和断裂模式,并通过开展含不同相对位置非等长非平行双裂纹的红砂岩长方体试样的水-力作用双轴压缩断裂试验和断口扫描电镜试验,研究裂纹几何参数和外载条件对多裂纹应力-应变曲线及扩展轨迹的影响规律,揭示水-力作用双轴压缩下岩石多裂纹宏-微观断裂机理。研究结果表明:对于水-力作用双轴压缩下含双裂纹的红砂岩试件,当裂纹相对倾角和相对垂直间距减小(或增大)且减小(或增大)幅度越大时,峰值荷载均随之减小(或增加)且减小(或增加)幅度也越大。对于任意相对位置的双裂纹,水力裂纹总是先起裂,天然裂纹一般后起裂或不起裂;断裂机理多为Ⅱ型(剪切)断裂,裂尖断口亦可观察到强烈的剪切断裂特征;增加水平侧压可抑制Ⅰ型断裂而促进Ⅱ型断裂。预测结果和试验结果吻合较好,验证了水-力作用多裂纹扩展准则。研究成果可为深部岩体工程的强度计算、止裂控制和安全评估等提供重要的理论和现实依据。In deep mining engineering,fractured rock is prone to crack initiation and propagation,resulting in instability and failure under the coupled hydro-mechanical actions.The majority of the research studies on the multi-crack fracture mechanisms under hydro-mechanical actions are qualitative with quantitative studies lacking.The propagation process and fracture mode of red sandstone with double cracks were predicted based on the multi-crack propagation theory under the coupled hydro-mechanical actions.Hydro-mechanical biaxial compression fracture tests and fracture scanning electron microscope tests of the red sandstone cuboid specimens with non-equal length and non-parallel double cracks of different relative positions were carried out to study the influences of geometry parameters and external load conditions on the stress-strain curves and propagation trajectories of multiple cracks.The fracture mechanisms of rocks with multiple cracks were revealed under biaxial hydro-mechanical compression.Results showed that for red sandstone specimens with double cracks under hydro-mechanical biaxial compression,as the relative crack inclination angle and relative vertical spacing decrease(or increase),the peak load decreases(or increase)with greater decrease in amplitudes of the former corresponding to greater decrease(or increase)in amplitudes of the latter.For double cracks with arbitrary relative positions,the hydraulic cracks always start to initiate first while the natural cracks usually initiate later or remains dormant.The fracture mechanism is predominantly Mode II(shear)with strong shear fracture characteristics observed in multiple crack tips.Increasing lateral confining pressure can restrain Mode I fracture and promote Mode II fracture.The predicted results are in good agreement with the experimental results,which verifies the hydro-mechanical propagation criterion of multiple cracks.The research results can provide important theoretical and practical significance for strength calculation,crack arrest control,and

关 键 词：水-力作用 脆性岩石 多裂纹 宏-微观 断裂机理 

分 类 号：TU45[建筑科学—岩土工程]