异性结构面抗剪特性试验研究

Experimental Study on Shear Characteristics of Heterosexual Structural Plane

异性结构面的抗剪特性研究有助于分析与评价工程岩体的稳定性。为研究粗糙度与法向应力对异性结构面抗剪强度、变形特征以及结构面损伤特征的影响,进行了两组异性结构面的直剪试验。研究结果表明:异性结构面剪应力剪切位移曲线为具有明显阶段性特征的峰值型曲线,法向位移剪切位移曲线呈现出先剪缩后剪胀的趋势;随着粗糙度增大,结构面峰值抗剪强度与残余抗剪强度增大;随着法向应力增大,结构面峰值抗剪强度增大,峰后应力降低幅度增大,且高法向应力对结构面剪胀效应有抑制作用;异性结构面壁面损伤系数随结构面粗糙度与法向应力的增大而增大,且上盘软岩损伤面积增幅大于下盘硬岩损伤面积增幅;异性结构面破坏不是单一的剪切行为,而是滑移、剪断、张拉多种破坏形式复合作用的结果,结构面破坏模式可分为剪切滑移破坏、剪切啃断破坏与张拉破坏。

The study on the shear characteristics of heterosexual structural plane is helpful to analyze and evaluate the stability of engineering rock mass.In order to study the influences of roughness and normal stress on the shear strength,deformation characteristics and damage characteristics of heterosexual structural plane,two groups of direct shear tests of heterosexual structure plane were carried out.The results show that the shear stress-shear displacement curve of heterosexual structure plane is a peak curve with obvious stage characteristics,and the normal displacement-shear displacement curve shows the trend of shear contraction first and then shear dilation.With the increase of roughness,the peak shear strength and residual shear strength of the structural plane increase.With the increase of normal stress,the peak shear strength of the structural plane increases,and the decrease of the post-peak stress increases,and the high normal stress has an inhibitory effect on the shear dilation effect of the structural plane.The damage coefficient of the wall surface of the heterosexual structural plane increases with the increase of the roughness and normal stress of the structural plane,and the increase of the damage area of the soft rock in the upper plate is greater than that of the hard rock in the lower plate.The failure of heterosexual structural plane is not a single shear behavior,but the result of the combined action of slip,shear and tension.The failure modes of structural plane can be divided into shear slip failure,shear gnawing failure and tension failure.