软弱夹层结构面剪切特性各向异性试验研究

Experimental study on anisotropic shear features ofweak interlayer rock joint

【目的】研究不同剪切方向下软弱夹层结构面剪切特性的差异。【方法】选取各向异性特征明显的天然三维结构面形貌,制作了具有不同充填度的含淤泥质黏土结构面试样;基于自主研发的软弱夹层岩石结构面各向异性直剪仪,开展了不同充填度下含有软弱夹层岩石结构面各向异性直剪试验,分析了软弱夹层结构面剪切特性的各向异性规律。【结果】1)不同剪切方向下无充填结构面剪应力剪切位移曲线具有峰前硬化和峰后软化特征,其法向与剪切位移曲线表现出先剪缩后剪胀的变化趋势;2)相同充填度不同剪切方向下软弱夹层结构面剪应力剪切位移变化规律存在差异,且剪应力与剪切位移的峰后软化特征随着充填度的增大逐渐消失;3)同一充填度下结构面峰值抗剪强度随着剪切方向的变化呈现差异;各向异性程度随着充填度增大呈现出先增大后减小的规律;4)同一充填度下软弱夹层结构面法向与剪切位移曲线随剪切方向差异呈现不同的变化规律,剪切特性随充填度增大由剪胀转变为剪缩,各向异性程度降低。【结论】本试验结果对研究岩体滑坡的破坏机理具有一定的参考价值。

[Objective]Study the difference of shear features of weak interlayer rock joint in different shear directions.[Method]The natural three-dimensional rock joint morphology with obvious anisotropic features was selected,and the rock joint samples of muddy clay with different filling degrees were made;based on the self-developed anisotropic direct shear apparatus of weak interlayer rock joint,the anisotropic direct shear tests were carried out for weak interlayer rock joint with different filling degrees,probing into the anisotropic regularities in shear features of weak interlayer rock joint.[Result]1)The shear stress-shear displacement curves of rock joint without weak interlayer filled in different shear directions have the features of pre-peak hardening and post-peak softening,and the normal and shear displacement curves show the trend of shear contraction first and then dilatancy;2)under the same filling degree,the shear stress-shear displacement regularities of weak interlayer rock joint vary with different shear directions,and with the increase of filling degree,the post-peak softening feature of the shear stress-shear displacement gradually disappears;3)under the same filling degree,the peak shear strength of weak interlayer rock joint varies with the change of shear direction,and with the increase of filling degree,the degree of anisotropy increases first and then decreases;4)under the same filling degree,the normal and shear displacement curves of the weak interlayer rock joint exhibit different regularities with the difference in shear direction.The shear features change from shear dilation to shear contraction as the filling degree increases,and the degree of anisotropy decreases.[Conclusion]The results of this experiment have certain reference value for studying the failure mechanism of rock mass landslides.