利用MTS815 Flex Test GT岩石力学试验系统，对雪峰山隧道围岩中的砂质板岩开展三轴加卸载试验，研究这种具微面理砂质板岩的变形特性、强度特性及破坏规律，结果表明：平行面理试件(微面理平行最大主应力)加、卸载条件下峰值强度相近；垂直面理试件(微面理垂直最大主应力)卸载条件峰值强度低于加载条件约20%，残余强度低于加载条件25%。平行面理时砂质板岩表现为弹脆性特征，且卸载条件下的脆裂破坏特征比加载条件下更强。平行面理试件破坏面基本沿试样中的微面理面方向发育，破坏是横向强烈扩容引起的张性破坏。垂直面理时，加载条件下破裂面呈现对角线贯通性剪切破坏特征，卸载条件下破坏面从试件两端的剪切屈服面向中部扩展，中部在剪张作用下破裂，与加载条件下单个贯通剪切面有显著差别。

To research the strength characteristics, deformation properties, and failure regularities of sandy slate which has micro-bedding, triaxial compressed tests in loading and unloading conditions are carried out by MTS815 Flex test GT rock mechanics test system. The test results show that the peak intensities under loading are close to those under unloading condition when the bedding parallels to the maximum principal stress (parallel bedding). When the bedding is vertical to the maximum principal stress (vertical bedding), peak intensity and residual strength under unloading condition are respectively 20% and 25% lower than those under loading condition. The sandy slate with parallel bedding shows elastic brittle feature, and this brittle failure under unloading condition is stronger than that under loading condition. Failure surfaces of parallel bedding samples develop along the bedding planes direction, and the failure is caused by strong lateral expansion under tension. The failure faces of vertical bedding samples under loading condition display shear feature with diagonal transfixion plane, and the failure faces under unloading condition develop from the shear yielding planes at both ends to the center of the sample.  