不同截面柱状节理岩体变形及强度各向异性研究

Deformation and strength anisotropy of columnar jointed rock mass with different cross-sectional shapes

柱状节理岩体的特殊节理网络使其各向异性显著,准确掌握其变形及强度特性对工程安全至关重要。针对柱状节理岩体自然结构特征,采用石膏等材料制作具有不同柱体走向角及倾角的四棱柱、五棱柱及六棱柱柱状节理岩体试样。通过开展单轴压缩试验,研究柱体截面形状、走向角及倾角对柱状节理岩体各向异性特性的影响。结合试样最终破坏形态,总结柱状节理岩体典型破坏模式及机制。根据试验结果,提出柱状节理岩体变形及强度经验公式。结果表明:柱体截面形状主要影响具有不同走向角的试样变形及强度参数,而对具有不同倾角的试样各向异性影响较小;四棱柱、五棱柱及六棱柱柱状节理岩体分别表现出正交各向异性、正交各向异性及准横观各向同性的特征;试样最终形态表现出4种典型破坏模式,且截面形状主要影响仅考虑走向角的试样破坏模式;同时,所提出经验公式的计算结果与已有成果吻合效果较好,具有较高的工程使用价值。

The special joint network of columnar jointed rock mass makes its anisotropy significant, and accurately understanding its deformation and strength characteristics are crucial for engineering safety. Based on the natural structure of columnar jointed rock mass, quadrangular, pentagonal and hexagonal prism columnar jointed rock mass specimens with different dip directions and dip angles were manufactured by using gypsum and other materials. Uniaxial compression tests were carried out to study the influence of cross-sectional shape, dip direction and dip angle on the anisotropic characteristics. The typical failure modes and the mechanisms of columnar jointed rock mass were summarised in accordance with the final appearances of specimens. The empirical equations were adopted to estimate the strength and deformation of the columnar jointed rock mass. The results show that the cross-sectional shape mainly affects the deformation and strength parameters of the specimens with different dip directions, but has little effect on the anisotropy of the specimens with different dip angles. The anisotropy of quadrangular, pentagonal and hexagonal prism columnar jointed rock mass are orthotropic, orthotropic and quasi-transverse isotropic, respectively. The final appearances of specimens present four typical failure modes, and the cross-sectional shape mainly affects the failure mode of the specimens with different dip directions. Furthermore, the calculated results of the proposed empirical equations are in good agreement with the existing results, and have high engineering value.