不同成因结构面各向异性特征及其剪切力学特性

岩体结构面具有明显的各向异性，其直接影响岩体的变形特性、力学特性与渗流特性，因此对结构面的各向异性特征开展量化分析尤为重要。针对不同成因（劈裂、剪切）结构面，利用结构面量化参数（节理粗糙度系数JRC、节理平均倾角θ、分形维数DB）对其各向异性特征进行了分析，研究了各向异性特征对其剪切力学特性的影响。研究结果表明：（1）在劈裂断裂结构面中，平行劈裂方向的JRC与θ值普遍大于垂直方向，且随角度变化波动较小，DB在对角线方向变化较大，其值与所取剖面线长度有关；而在剪切断裂结构面中，平行剪切方向的JRC和θ值与垂直方向无明显差别，但DB同样在对角线方向变化较大；（2）在评价结构面各向异性时，采用θ、DB等参数评价时，劈裂断裂结构面与剪切断裂结构面各向异性系数无明显差别，采用JRC作为评价参数时，其各向异性系数差异较大，能较好反映不同结构面之间的差异特征；（3）剪切断裂结构面的峰值剪切荷载和法向位移均高于劈裂断裂结构面，两种结构面的剪胀角达到峰值时的剪切位移相近，剪切断裂结构面的开度分布较为集中且普遍较大，劈裂断裂结构面开度分布则较为分散。

Anisotropic characteristics and shear mechanical properties of different genetic structural planes

The structural plane of rock mass shows obvious anisotropy, which directly influences the deformation characteristics, mechanical properties and seepage characteristics of rock mass. It is significant to conduct the anisotropic quantitative analysis of the structure surface. In this paper, the anisotropy characteristics of different genetic structure planes are analyzed by the common structural surface quantization parameters (joint roughness coefficient JRC, the average joint angle θ, and fractal dimension DB), and their influences on the shear mechanical properties are also studied. The results show that in the tensile structure plane, the values of JRC and θ along the direction of splitting are larger than the values of these parameters perpendicular to the splitting direction and fluctuated slightly with the change of the angle. DB fluctuated largely in the diagonal direction, and its value is related to profile length. In shear structure plane, the values of JRC and θ parallel to the splitting direction have no significant differences from those perpendicular to the splitting direction. However, DB changes greatly in the diagonal direction. When θ and DB are used to evaluate the anisotropy of the structure plane, there is no obvious difference in anisotropy coefficients of splitting fracture plane and shear fracture plane. While, when JRC is used as evaluation parameter, the anisotropy coefficient is quite different, which could better reflect the different characteristics of different structural planes. The peak shear load and normal displacement of shear fracture plane are higher than those of splitting structure plane. The shear displacements of the two structural planes are similar when the dilation angle reached the peak value, and the aperture distribution of shear fracture structural plane is relatively concentrated and generally larger. The aperture distribution splitting fracture plane is more dispersed.