考虑围压效应的深埋大理岩强度变形特性研究

Research on Strength and Deformation with Marble of Deep Rock Mass Considering Confining Pressure Effect

高地应力是深部岩体的重要特性之一,是岩体强度和变形特性的重要影响因素。针对锦屏Ⅱ级水电站深部大理岩的高地应力特点,利用MTS伺服机开展三轴压缩试验,研究不同围压下深部大理岩强度变形特性,结果表明:深部岩体的强度、弹性模量、变形模量均具有明显的围压效应,随着围压的增加,大理岩模量及各特征点强度增加;岩体赋存的初始地应力影响着岩体的变形规律,围压低于初始地应力时,深部大理岩以弹性变形为主,破坏模式主要为脆性破坏,围压高于初始地应力时,大理岩延性特征明显,扩容点前移,大理岩从脆性破坏向延性转化;基于三轴压缩试验数据求解出的深部大理岩黏聚力为54.53 MPa,内摩擦角为38.06°。这些研究成果揭示了高地应力环境下深部岩体的强度变形特性,可为深埋工程的开挖、支护设计提供理论参考。

High in-situ stress is one of the important characteristics of deep rock mass,and it is an important factor on the strength and deformation characteristics of rock mass. In light of that the high in-situ characteristics of deep marble of Jinping Ⅱ hydropower station,strength and deformation characteristics of the marble were studied under different confining pressure by means of MTS. The results show that： the strength of the deep rock mass is of great concern to confining pressure,and so do the elastic modulus and deformation modulus. The initial in-situ affects the deformation law of the deep rock mass,when the confining pressure less than the initial in-situ,and the deep marble is given priority to elastic deformation and failure mode is brittle failure. The ductility characteristics are obvious and the dilatation point moves forward when the confining pressure is higher than the initial in-situ. With the increase in confining pressure,the failure of the marble transforms from brittle fracture to ductile fracture. The cohesion of marble is 54. 53 MPa and the internal friction angle is 38. 06° by the triaxial compression test. These conclusions reveal the strength and deformation properties of marble under high in-situ stress and provide valuable theoretical reference for excavation,supporting design and stability analysis of underground engineering.