This study aims to investigate the anisotropic characteristics of phyllite in Maoxian group from the northwest of Sichuan province in China. A series of uniaxial and triaxial compressive tests is conducted on phyllite samples by using the MTS815Teststar rock mechanics testing system. Experimental results show that the large deformation and partial failure generally appear before samples reach half of their peak strengths. However

the occurrences of large deformation or initial dilatancy do not indicate that rock completely loses its bearing capacity. If the targeted support or protection can be applied on surrounding rock in time

rock strength is still strong. Damage dilation is regarded as a typical deformation and failure characteristic of phyllite. Furthermore

it affects lateral deformation more easily than axial deformation. Thus

lateral deformation can reflect rock yield or weakening more sensitively. Results show that the anisotropy of rock strength decreases with increasing water content and confining pressure. Moreover

Young’s modulus and Poisson’s ratio vary with the loading direction and translated-confining pressure. From the obtained results of phyllite at different water contents

the strength of phyllite under dry condition presents the most obvious anisotropic characteristics in uniaxial compressive tests. It is found that the anisotropic ratios of compressive strength are mainly below 0.8. Especially

sericite phyllite exhibits the strongest anisotropy with a ratio of 0.48

and the following anisotropic orders from strong to weak are sericite phyllite

chlorite phyllite

quartz phyllite

and carbonaceous phyllite. Moreover

there are different failure modes of phyllite

which also change with the increase of confining pressure and water content. Shear failure occurred uniformly along the weak planes

which indicates that the anisotropic mechanical characteristics of phyllite are controlled by shear mechanism independently.