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工程岩体一般都含有各种不同级别的地质构造节理和软弱面,使得岩体的强度弱化。含有节理的岩体和完整岩石具有完全不同的力学性质。本文在三轴压缩试验的基础上,对不同节理倾角的三峡库区砂岩开展研究,探讨其变形及破坏特征。试验结果表明:(1)在同种围压下,节理岩样峰值强度的大小关系为:σ60°<σ30°<σ90°<σ完整。(2)相同围压下,完整岩样弹性模量及变形模量均高于节理岩样,随着围压升高,岩样弹性模量和变形模量逐渐增大,其增长速度随围压增大而逐渐降低。(3)在低围压下(<5 MPa),节理倾角对岩样弹性模量和变形模量影响较大,相比完整岩样有较大幅度地降低,其中30°倾角和60°倾角岩样降低程度较高,弹性模量最高达31%,变形模量最高达40%;随着围压增大(大于10 MPa),节理倾角对岩样变形参数影响逐渐减小,相比完整岩样,节理岩样弹性模量降低幅度小于15%,变形模量降低幅度小于10%。(4)节理倾角和围压对岩石的破坏机制均有较大的影响,节理倾角及围压不同,岩样破坏形式不同。
Engineering rock mass generally contains a variety of different levels of geological structure joints and weakness, making the strength of rock mass weakened. The jointed rock mass and intact rock have completely different mechanical properties. Based on the triaxial compression tests, the paper studies the sandstone in the Three Gorges reservoir area with different joint inclination, and discusses its deformation and failure characteristics. The experimental results show that: (1) Under the same confining pressure, the relationship between the peak strength of jointed rock samples is: σ60 ° <σ30 ° <σ90 ° <σ complete. (2) Under the same confining pressure, the elastic modulus and deformation modulus of intact rock samples are higher than those of jointed rock samples. With the increase of confining pressure, the elastic modulus and deformation modulus of rock samples increase gradually, Pressure increases and gradually reduced. (3) Under low confining pressures (<5 MPa), the joint inclination has a greater influence on the elastic modulus and deformation modulus of rock samples, and decreases greatly compared with the intact rock samples. Inclination angles of 30 ° and 60 ° The rock samples are highly degraded, the elastic modulus is up to 31%, and the deformation modulus is up to 40%. With the confining pressure increasing (more than 10 MPa), the influence of joint inclination on rock deformation parameters decreases gradually, The decrease of elastic modulus of rock samples and jointed rock samples is less than 15%, and the decrease of deformation modulus is less than 10%. (4) The joint dip and confining pressure have a great influence on the rock failure mechanism. The joint inclination and the confining pressure are different, and the rock failure forms are different.