多轴压缩条件下层状硬质片岩的力学特性研究

在深部工程中经常会遇到层状岩体，由于高应力的影响，在工程活动中发生因层状结构面诱发的岩体灾害问题。这与深部工程中的真三向高应力环境及层状结构面产状密切相关。为此，基于一种取自某深部金属矿山的层状硬质片岩，开展了考虑片理方位的真三轴压缩试验研究，获取了该片岩在两种片理加载方位下，不同应力差条件时，试样的变形、强度及破裂数据。结果表明，该硬质片岩的力学特性受片理加载方位和应力条件影响较大。具体表现在，当中间主应力σ₂平行片理走向时，试样的脆性更强，且最小主应力σ₃ 越小脆性越强。当σ₂垂直片理走向时试样的强度更高，但强度随σ₃增加而增加的敏感性较弱。当σ₂平行片理走向时，试样的破坏均以沿片理的剪切为主；而当σ₂ 垂直片理走向时，试样在低σ₃ 时，主要发生穿片理的拉破坏，高σ₃ 时，则转变为沿片理的剪切破坏。试验结果对陡倾层状硬质岩体工程的稳定性评价有一定的启示意义，即当片理走向与洞轴线的夹角较小时，浅层围岩片理面的法向应力释放程度较高，易发生受片理结构控制的脆性破坏；反之，夹角较大时，岩体的稳定性较强。

Experimental study on mechanical properties of layered hard schist under multiaxial compression

Layered rock masses are often encountered in deep engineering. Due to the influence of high stress, rock mass hazards induced by layered structures often occur in engineering activities. This is closely related to the true three-dimensional high-stress environment and layered structures in deep engineering. For this reason, the test considering the orientation of schistosity was carried out under true triaxial compression based on a layered hard schist taken from a deep metal mine, and the deformation, strength and fracture characteristic of the samples with two schistosity loading orientations were obtained under different stress conditions. The results show that the mechanical properties of the hard schist are greatly affected by schistosity loading orientation and stress conditions. More specifically, when σ₂ is parallel to the strike of schistosity, the brittleness of the sample is stronger, and the smaller the σ₃, the stronger the brittleness. The strength of the sample is higher when σ₂ is perpendicular to the strike of schistosity, but the sensitivity of the increase in strength with the increase of σ₃ is weaker. When σ₂ is parallel to the strike of schistosity, the shear failure along the schistosity prevails. When σ₂ is perpendicular to the strike of schistosity of the specimen, the tensile failure through the schistosity mainly occurs at a low σ₃ , and it transforms into shear failure along the schistosity at the high σ₃ . The test results have certain enlightenment significance for the stability evaluation of steep layered hard rock engineering: when the included angle between schistosity strike and tunnel axis is small, the normal stress release degree of schistosity of shallow rock is high, and brittle failure controlled by schistosity structure is easy to occur; on the contrary, the rock mass is relatively more stable when the included angle is large.