# Anisotropy and Directivity Effects on Uniaxial Compression of Carbonaceous Slate Form Jinman Mine
## 1 Introduction  
With the gradual implementation of a deep exploitation strategy, the geotechnical engineering field has been demanding space resources from deep rock mass [1; 2; 3; 4]. In 1991, the Tokyo Declaration was adopted after the International Academic Conference on the Utilization of Urban Underground Space held in Tokyo proposed that the 21 st Century would be the century for the development and utilization of underground space [3; 5; 6; 7]. Weak metamorphic rocks such as slate, phyllite, and schist are widely distributed in northwestern the Yunnan Province in China. The presence of rich mineral resources such as copper, lead, zinc, and silver has resulted in the mining of these resources, which has been associated with frequent accidents. Slate rock is a type of metamorphic rock that is widely distributed in northwestern Yunnan. There are a large number of weak structural surfaces such as fractures, slabs, and bedding that are composed of clay minerals. The fillers near the structural surface are composed of mineral particles with cohesion and strength that are lower than that of intact rock, which causes the physical and mechanical properties ofslate to have significant anisotropy. Hence, isotropic assumptions are used for calculating the stability of stope overestimate the bearing capacity of surrounding rock. With the rapid development of underground engineering [8; 9; 10; 11], a substantial amount of data is now available for the study of rock anisotropy. [PERSON] et al. [12] studied the anisotropic behavior of tensile strength and fracture mode of Mosel slate, Postaer sandstone, and Boryeong shale. [PERSON] and [PERSON] [13] analyzed the different characteristics of the variations of mechanical parameters of layered rocks. [PERSON] et al. [14] found that the acoustic emission event rate and dominant frequency of layered rocks showed anisotropy. [PERSON] et al. [15] found that slate bedding is an important cause of anisotropy of mechanical parameters and fracture modes. [PERSON] et al. [16] studied the anisotropic characteristics of silty slate. In addition, some researchers have studied the anisotropy of the Wudang group schist, phyllite. [PERSON] et al. [17] conducted microanalysis to explore anisotropic behavior associated with the fracture morphology of marble. [PERSON] et al. [18] studied the macro-mechanical behavior of jointed rock masses. To study the micro-mechanical characteristics of rocks, [PERSON] et al. [19] conducted related scanning electron microscopy (SEM) experiments. The above analysis shows that the rock bedding, fragments, and faults cause large differences in the mechanical properties of complete blocks, but the natural anisotropy has not been considered while testing for usual rock strength, such as for compression, tensile, and shear tests. The results of rock mechanics tests show that physical and mechanical properties have a significant anisotropy. Even for rock masses retrieved from the same location, the strength for different directions of stress loading often show differences of 1 to 2 orders of magnitude. Therefore, if mechanical parameters of engineering rock are calibrated under the assumption that natural rock, especially highly weathered slates, are isotropic then such data are not suitable for engineering applications. Hence, it is necessary to consider the natural discrete characteristics of various mechanical parameters, which is of great significance in revealing anisotropic characteristics after transformations, such as joints, fragments, fractures, etc. that are caused by excavation-related unloading [20; 21]. The Jinman mine is located in the Lancang River Gorge in Lamping County of the Yunnan province. Field investigations have found that carbonaceous slates in roadways show floor heave and slabbing failure. The fracture characteristics of slate rock masses of different colors are significantly different.