摘要
软弱层间带裂隙岩石的水压弱化效应是水利工程长期稳定研究的重要方向。针对锦屏一级坝肩软弱层间带裂隙大理岩在高水压力作用下的长期变形特性,采用特定的岩石流变试验系统,开展不同水压作用下预制裂隙大理岩的蠕变试验;结合典型蠕变过程曲线分析水压对裂隙岩石蠕变变形、蠕变速率、蠕变破坏荷载及长期强度的影响,并基于蠕变破坏断口的电镜扫描成果,从细观角度分析岩石蠕变破坏机制。结果表明:裂隙大理岩宏观破裂现象与断口微观特征相吻合,随着水压的增加,岩石破裂形式逐渐由张拉破裂向剪切破裂过渡,破裂断口由凹凸锯齿状逐渐趋于平滑。压力水沿大理岩裂隙的“楔入”可加速原始裂纹的发育,促进岩石的蠕变发展,水压越大,“楔入”效应越明显,加速蠕变速率越大,加速阶段持续时间越短,蠕变破坏的分级荷载越小;相较于稳定蠕变阶段,水压对加速蠕变阶段的影响效应更大。裂隙大理岩长期强度约占完整岩石峰值强度的50%~70%,水压的增大会降低岩石的长期力学性能,并加速岩石的蠕变破坏;工程中,建议取稳定蠕变阶段最大一级强度作为裂隙大理岩的长期强度。研究成果的应用可提高锦屏一级水电站长期稳定运行评估的准确性,并为裂隙岩石蠕变本构模型研究提供重要支撑,具备显著的工程应用与理论研究价值。
Water pressure weakening effect of fractured rock in weak interlayer zone is an important direction of long-term stability research of hydraulic engineering.To study the long-term deformation characteristics of fractured rock in weak interlayer zone of Jinping Ⅰ arch dam under real water pressure,creep tests of pre-fractured marble under different water pressures were carried out on a specific rheological test system.According to the typical creep process curve,the influence of water pressure on the creep deformation,creep rate,creep failure load and long-term strength of fractured rock was analyzed,and the creep failure mechanism of rock was analyzed from the micro perspective basing on the creep failure surface scanning results of marble carried out by SEM.The results showed that with the increase of water pressure,the rock failure modes gradually transit from tensile to shear,and the failure surface tends to be smooth from concave convex serrated shape.The“wedging effect”of pressure water along the fracture accelerates the development of original cracks and promotes the creep development of rock.The larger the water pressure is,the more obvious the“wedging effect”is,the higher the accelerated creep rate is,the shorter the duration of acceleration stage is,the smaller the load grade of creep failure is,and the lower the long-term strength is.The effect of water pressure on the accelerated creep stage is greater than that of the stable creep stage.The increase of water pressure will reduce the long-term mechanical properties of rock and accelerate the creep failure of rock,the long-term strength of fractured rock accounts for 50%~70% of the peak strength of intact rock.It was suggested that the maximum first-order strength in stable creep stage should be taken as the long-term strength of fractured rock.The application of the research results can improve the accuracy of long-term stable operation evaluation of Jinping Ⅰ arch dam,and provide important support for the study of creep constitutive model of fractured rock,which has significant engineering application and theoretical research value.
作者
陈英
谢辉
杨俊
王皓冉
刘昭伟
CHEN Ying;XIE Hui;YANG Jun;WANG Haoran;LIU Zhaowei(College of Water Resource&Hydropower,Sichuan Univ.,Chengdu 610065,China;Sichuan Water Resources and Hydroelectric Investigation&Design Inst.Co.,Ltd.,Chengdu 610015,China;Sichuan Energy Internet Research Inst.,Tsinghua Univ.,Chengdu 610042,China;Sichuan Electic Power Design&Consulting Co.,Ltd.,Chengdu 610041,China;State Key Lab.of Hydroscience and Eng.,Tsinghua Univ.,Beijing 100084,China)
出处
《工程科学与技术》
EI
CSCD
北大核心
2021年第4期149-157,共9页
Advanced Engineering Sciences
基金
国家重点研发计划项目(2019YFB1310504,2016YFC0401908)
四川省科技计划资助项目(2020JDRC0130,2021YFG0100)。
关键词
水压
大理岩
裂隙岩石
电镜扫描
分级加载
蠕变特性
长期强度
water pressure
marble
fractured rock
scanning electron microscope(SEM)
stepped load
creep property
long-term strength
