石英砂岩三轴剪切力学特性及裂隙面形态特征  

Mechanical Properties and Fracture Surface Morphology of Quartz Sandstone Under Triaxial Shear

作　　者：林志南 冯世宏 王家全[1,2] 张强 龙海锋[1,2] LIN Zhinan;FENG Shihong;WANG Jiaquan;ZHANG Qiang;LONG Haifeng(College of Civil and Architectural Eng.,Guangxi Univ.of Sci.and Technol.,Liuzhou 545006,China;Geotechnical Disaster and Ecological Control Eng.Research Center of Guangxi Zhuang Autonomous Region,Liuzhou 545006,China;China Inst.of Water Resources and Hydropower Research,Beijing 100038,China)

机构地区：[1]广西科技大学土木与建筑工程学院,广西柳州545006 [2]广西壮族自治区岩土灾变与生态治理工程研究中心,广西柳州545006 [3]中国水利水电科学研究院,北京100038

出　　处：《工程科学与技术》2024年第4期161-172,共12页Advanced Engineering Sciences

基　　金：广西自然科学基金项目(2021GXNSFBA196043,2023GXNSFAA026185,2022GXNSFDA035081);国家自然科学基金项目(41962017);国家自然科学基金雅砻江联合基金项目(U1965204);广西科技大学博士基金项目(校科博19Z42);广西高等学校高水平创新团队及卓越学者计划项目(桂教人才[2020]6号);广西高校中青年教师科研基础能力提升项目(2020KY08023);中国水利水电科学研究院科研专项项目(GE110145B0022021);广西研究生教育创新计划项目(YCSW2022441)。

摘　　要：为研究3维压剪应力状态下岩质边坡中完整岩石的剪切损伤破坏特征,采用RockTop-50HT全应力多场耦合三轴试验系统,对成分简单、结构均质及饱和完整的细粒石英砂岩进行16组不同围压的三轴剪切试验,获得相应的三轴剪切应力-应变曲线和含有原岩屑碎片的剪切破坏裂隙面,分析三轴剪切应力作用下石英砂岩的非线性强度变化特征,探究石英砂岩的三轴剪切破坏模式和裂隙结构面形态粗糙特征。基于德洛内(delaunay)点云离散算法重构石英砂岩破坏裂隙结构面,分析剪切破坏结构面的潜在接触部分随着表面有效倾角门槛值的变化特征。结果表明:1)随着围压逐渐增大,石英砂岩的三轴剪切破坏模式先由脆性破坏转变为塑性破坏,再逐渐转变为塑形流动破坏;2)石英砂岩的三轴剪切强度随着围压的递增呈现出明显的非线性变化特征,可用幂函数描述,并采用摩尔-库仑准则(Mohr-Coulomb)对石英砂岩的三轴剪切强度进行分段线性拟合,可知随着围压的增大,黏聚力逐渐增大,内摩擦角逐渐减小;3)剪切破坏裂隙面3维粗糙特征可用传统的Grasselli模型评估,其非线θ_(max)^(*)性拟合参数和粗糙度参数c能充分描述三轴剪切破坏裂隙的粗糙度特征。研究成果对岩石在复杂应力状态下的三轴剪切强度评价、岩石工程中边坡的稳定性分析和支护设计方案优化具有重要意义。To study the shear damage deformation characteristics of intact rock in rock slopes under three-dimensional compressive-shear stress conditions,16 sets of triaxial shear tests were conducted on saturated intact fine-grained quartz sandstone with simple composition and homogeneous structure under different confining pressures by using the Rock Top-50HT full-stress multi-field coupling triaxial test system.In the tests,the corresponding triaxial shear stress-strain curves and the shear-failure fracture surfaces containing original rock debris were obtained,the nonlinear variations of the strength characteristics of quartz sandstone under triaxial shear stress were analyzed,and the triaxial shear failure mode and the roughness characteristics of the fracture-surface morphology of quartz sandstone were explored.Also,based on the Delaunay point-cloud discretization algorithm,the failure fracture surface of quartz sandstone was reconstructed,and the variation characteristics of its potential contact part with the effective inclination threshold of the surface were analyzed.The results show that with increasing normal stress,the triaxial shear failure mode of quartz sandstone changes gradually from brittle failure to plastic failure and finally to plastic flow failure.The triaxial shear strength of quartz sandstone shows obvious nonlinear variation with increasing confining pressure.The Mohr-Coulomb criterion is used to fit the triaxial shear strength of quartz sandstone via piecewise linear fitting,and it is found that with increasing confining pressure,the cohesion increases while the internal friction angle decreases.The three-dimensional roughness characteristics of the shear-failure fracture surface are evaluated using the traditional Grasselli model,and its nonlinear fitting parameters θ_(max)^(*)and c fully describe the roughness characteristics of the fracture surface under triaxial shear failure.The present results are very important for predicting the triaxial shear strength of rock under complex stress and f

关 键 词：岩石力学 三轴剪切试验 破坏模式 非线性剪切强度 裂隙面形态特征 

分 类 号：TU45[建筑科学—岩土工程]