Abstract: The failure characteristics of rock mass under different widths of rock bridge and normal stresses were revealed through mechanical model test in association with analyzing the characteristic parameters of acoustic emission during the failure process. Results showed that with the increase of the width of the rock bridge, the fluctuation of failure surface and the roughness of the surface both increased. With the increase of normal stress, the peak shear stress increased continuously but the degree of fluctuation and roughness of the failure surface decreased. The failure modes of rock bridges of different widths under different normal stresses varied, including cutting damage, tensile-shear composite failure, and shear failure.The characteristics of acoustic emission were consistent with the failure process of the rock bridge, and the peak value of AE events, which appeared after the peak of shear stress, increased with the increase of the width of rock bridge and the normal stress.The results provide basis for identifying different destruction stages of rock bridge with different widths.

Key words: direct shear test, rock bridge, acoustic emission, normal stress, failure characteristics