考虑三维片理效应的板岩巴西劈裂试验研究

Brazilian splitting tests of slate considering three-dimensional foliation effect

含片理板岩在物理力学特性方面表现出明显的各向异性。综合考虑片理角度(?)和加载方向(θ)两个影响因素开展板岩巴西劈裂试验,对片理面的三维结构效应进行深入研究。结果表明:(1)片理面三维结构效应对板岩力学强度和破坏特征有显著影响,不同片理角度条件下巴西劈裂强度随加载方向的变化趋势有明显差异。(2)在片理角度较小或较大的情况下,即0°≤?≤15°或75°≤?≤90°,破坏面的三维空间效应不明显,圆盘正反两面的宏观裂纹具有一定的相似性;当?和θ均位于[30°,60°]内,2种因素的耦合作用使破坏面呈现三维空间分布的特点,圆盘正反两面的宏观裂纹呈现近似反对称的位置关系。(3)板岩在巴西劈裂试验中的储能能力与片理角度呈负相关关系,与巴西劈裂强度呈正相关关系。(4)片理角度对巴西劈裂强度的影响更显著,加载方向对破坏形式的影响更显著。随片理角度增加,巴西劈裂强度和能量的各向异性比均呈现增大的趋势,即各向异性越来越明显。研究成果可为横观各向同性岩石张拉力学特性分析提供参考和试验依据。

The slate with foliations exhibits significant anisotropies in terms of physical and mechanical properties. Brazilian splitting tests were carried out considering two factors such as the foliation angle and the loading direction,and the three-dimensional structure effects of foliation planes were studied in depth. The results show that the three-dimensional structure effects of foliation planes have a significant influence on the mechanical strength and failure characteristics of slate and that the variation trends of Brazilian splitting strength with loading direction are obviously different at different foliation angles. When the foliation angle ranges from 0°to 15° or from 75°to 90°,the three-dimensional spatial effect of the fracture surface is not obvious and the macroscopic cracks on both sides of the disc have certain similarities. When both the foliation angle and the loading direction are in the range of 30° to 60°,however,the fracture surfaces present a three-dimensional spatial distribution due to the coupling effect of the two factors and the macroscopic cracks formed on both sides of the disc exhibit an approximately anti-symmetric positional relationship. The energy storage capacity of slate in Brazilian splitting tests is negatively correlated with the foliation angle but positively with the Brazilian splitting strength. It is also revealed that the foliation angle and the loading direction respectively have more significant effects on the Brazilian splitting strength and the fracture pattern,and that,with increasing the foliation angle,the anisotropy ratios of the Brazilian splitting strength and the energy show an increasing trend. The research results can provide a reference for the analysis of tensile mechanical properties of transversely isotropic rocks.