三轴多级循环加载下不同类型岩石的应力应变响应特性研究  

Dynamic stress and strain characteristics of different types of rock mass under triaxial multi-stage cyclic loading

作　　者：徐鸿彪 刘汉香 别鹏飞[2] XU Hongbiao;LIU Hanxiang;BIE Pengfei(Sichuan Highway Planning,Survey,Design and Research Institute Co.,Ltd.,Chengdu 610041,China;College of Environment and Civil Engineering,Chengdu University of Technology,Chengdu 610059,China;State Key Laboratory of Geohazard Prevention and Geoenvironment Protection,Chengdu 610059,China)

机构地区：[1]四川省公路规划勘察设计研究院有限公司,成都610041 [2]成都理工大学环境与土木工程学院,成都610059 [3]地质灾害防治与地质环境保护国家重点实验室,成都610059

出　　处：《有色金属（矿山部分）》2022年第2期61-68,共8页NONFERROUS METALS(Mining Section）

基　　金：国家创新研究群体科学基金(41521002);四川省科技计划项目(2019YJ0534);地质灾害防治与地质环境保护国家重点实验室自主研究课题(SKLGP2018Z015)。

摘　　要：岩石在动荷载作用下将表现出与在静荷载作用下显著不同的力学特性。采用MTS-815 Flex Test GT岩石力学试验机对从某一地震滑坡区采集的两种岩石(白云岩和千枚岩)开展了三轴多级循环加卸载试验,旨在获得这两种岩石在循环荷载下的力学特性。试验采用的围压为10 MPa,正弦波加载频率为2 Hz,每级应力水平下的循环周次为60。基于试验获得的轴向应力—应变全过程曲线,着重分析了两种岩石的应力—应变曲线特征、累积残余应变特征和回滞环特征,并分析了循环周次和应力幅值对这些特征的影响。结果表明:1)两种岩石在一次循环加卸载过程中产生的应力应变回滞环具有相似的窄尖叶形状。在加载过程中,岩样以线弹性变形为主,应力—应变曲线为近似直线;在加载与卸载的过渡阶段,曲线迅速逆转,表明弹性应变迅速恢复;卸载过程中出现了相对于应力的小应变滞后现象,应力—应变曲线为上凹形;2)两种岩石的累积残余应变和回滞环特征参数随着循环周次和应力幅值增加呈现出三阶段变化规律,但此规律受岩石初始缺陷的影响很大。对于非均质化程度高的千枚岩样而言,上述规律性明显弱得多;3)在多级循环加载作用下,两种岩石均为剪切破坏,峰值强度都较静态峰值强度有所降低,表现出了疲劳破坏特性。本研究成果有助于更好地理解岩石在动态循环荷载下的力学响应行为,也可为后续从岩石力学角度分析地震作用下大型岩质滑坡的形成机理提供理论支撑。Rock mass under dynamic load shows significantly different mechanical properties from that under static load.In order to obtain the mechanical characteristics of two types of rock masses(dolomite and phyllite)which were sampled from an earthquake-triggered landslide area,a series of triaxial multi-stage cyclic loading and unloading tests were carried out on the MTS-815 Flex Test GT Rock Mechanics Test System.The confining pressure was 10 MPa,the loading frequency of sine wave was 2 Hz,and the cycle number under each level of cyclic loading was sixty.Based on the dynamic stress-strain curves,the dynamic stress-strain characteristics,cumulative residual strain and hysteresis loop of two types of rock masses were mainly analyzed,and the influences of cycle number and stress amplitude on these characteristics were also analyzed.The results show that:1)For two types of rock masses,their stress-strain hysteresis loops under one cyclic loading and unloading process had a similar shape of narrow pointed leaves.In the loading progress,the rock sample mainly demonstrated the linear elastic response and the stress-strain curve was a straight line;at the transition between loading and unloading,the curve rapidly reversed,indicating the rapid recovery of the elastic strain;the small strain hysteresis relative to stress occurred in the unloading progress,and the stress-strain curve was concave;2)For two types of rock masses,both the cumulative residual strain and the characteristic parameters of hysteresis loops exhibited a three-staged evolution law as the cycle number and stress amplitude increased;however,this law was greatly affected by the initial defects of rock mass,which is significantly manifested in the highly heterogeneous samples such as phyllite;3)Under the action of multi-stage cyclic loading,two types of rock masses showed a shear failure mode,and their peak strength was lower than that under static compression,suggesting the fatigue failure of these rock masses.The research results can help to understand the me

关 键 词：白云岩 千枚岩 循环加卸载 疲劳强度 残余应变 回滞环 岩石力学 应力 

分 类 号：TD315[矿业工程—矿井建设]