Abstract: Rock bridge plays a controlling role in rock slope stability, and non-penetrative jointed rock mass is a kind of rock bridge widely exists in rock slope. The purpose of this paper is to provide theoretical basis and experience for the stability evaluation of high rock slope through investigating the influence of connectivity rate of coplanar intermittent jointed rock bridges on the shear properties of rock.The failure mode,the evolution mechanism of the failure process and mechanical parameters of coplanar intermittent jointed rock bridge are analyzed by direct shear test.Three coplanar intermittent joints of the same length are reserved on test samples prepared with quartz sand,cement, gypsum and water.Results showed that tension failure,tension-shear failure and shear failure are failure modes of the samples,among which shear failure is the dominant one.The joint planes are the controlling discontinuities.Samples experienced three phases of failure: the steady development of cracking, the coalescence failure of discontinuous joints, and the residual strength stage. With the increase of connectivity rate,the shear strength and cohesion of sample reduced,and internal friction angle changed slightly.The larger the connectivity rate of the coplanar intermittent jointed rock bridge,the worse the shear performance of rock,and the lower the stability of rock slope.

Key words: rock slope, non-penetrative joint, coplanar discontinuous rock bridge, connectivity rate, shearing properties