柱状节理玄武岩各向异性特性的调查与试验研究

针对几何形状特殊且为镶嵌结构的柱状节理岩体，为认识其各向异性力学特点和开挖卸荷下的破坏模式，首先在柱状节理玄武岩截面几何特征的现场调查统计和3类结构面的扫描电镜(SEM)分析基础上阐述柱状节理岩体在结构上的横观各向同性特点，然后通过垂直其柱体轴线方向和平行其柱体轴线方向的柱状节理岩体原位声波测试揭示柱状节理玄武岩的变形各向异性，进而通过不同取样方向岩芯的单轴压缩试验和现场岩块的点荷载试验阐明其强度各向异性特点，最后结合上述所获得的柱状节理玄武岩各向异性认识分析其开挖卸荷下的“结构–应力”控制型破坏模式及其结构劣化的具体表现形式，所得认识和结论对柱状节理岩体地层中地下洞室稳定性分析和支护设计具有参考意义。

SURVEY AND LABORATORY STUDY OF ANISOTROPIC PROPERTIES FOR COLUMNAR JOINTED BASALTIC ROCK MASS

Columnar jointed basalt is a specially compositional rock mass by many prismatic rock blocks with the irregular polygon on the transverse section. For documenting the anisotropic properties and unloading failure mechanism of jointed basalt rock，detailed in-situ and laboratory investigation have been carried out. First，the geometrical anisotropy property of columnar jointed basaltic rock was summarized by detailed in-situ statistic for irregular polygon of its transverse section and the scanning electron microscope(SEM) analysis of different kinds of joint faces. Then，the deformational anisotropy property was checked by the ultrasonic testing with the direction which was parallel to the axis of the columnar block and the direction which was vertical to the axis of the columnar block in field. And，the strength anisotropy property was also tested by two ways，i.e. point load test for in-situ rock block with different directions and uniaxial compression test for standard cylindrical specimens with different loading directions. According to above resultant investigation，the basic failure mode of structure-stress control for columnar rock mass and its specific failure performances have been discussed，so as to provide helpful recognition and suggestion for reasonable excavation and supporting design for the underground caverns and tunnels in similar rock mass with columnar joint sets.