Abstract: According to the engineering characteristics that carbonaceous slates of Muzhailing tunnel Lanzhou-Chongqing railway riches in fracture water, softened into water, carried out tri-axial compression test and uniaxial cyclic loading and unloading test. The results showed that water bring about significant influence to deformation of carbonaceous slates. Compared with the dry rock, peak strength of saturated specimen is observably reduced, however the peak strain is dramatically raised; The results display that sample deformation curves shows distinct memory and good fitting in stress-strain curve between the cyclic loading and the continuous loading during the tri-axial cyclic loading; meanwhile, the plastic deformation caused by water is more than the corresponding value caused by load under loading and unloading conditions, and the elastic modulus of dry rocks is about 2 times to the saturated condition in each cycle, which is significance for the engineering constructions.

Key words: carbonaceous slate, dry and saturated, experimental study, deformation property