Abstract: The failure modes of soft and hard rock inter-bedded slope were simulated by FLAC^3D, and the stability coefficient k in the presence of different dip angles θ and rock thicknesses h was analyzed by using strength reduction method. Results show that h has small influence on slope failure mode, while θ has obvious effect on the failure mode. For horizontally layered slope, the failure mode is slipping-ripping; whereas for consequent slope, with the increase of θ, the failure mode experiences a progress of sliding-ripping, sliding, sliding-buckling, and bending-buckling; while for vertically layered slope, the failure mode is bending-slump; and for anti-dip rock slope, the failure modes are sliding-buckling and bending-toppling. Moreover, for gentle bedding rock slope, the thickness of the rock has little impact on the stability coefficient k, which is determined by the soft rock near the slope toe. As for the other types of layered slope, when the thickness of soft rock is constant, the stability coefficient increases with the increase of hard rock thickness, while when hard rock thickness is constant, the stability coefficient decreases with the increase of soft rock thickness. With the increase of θ, the k value of consequent slope first decreases and then increases, while the k value of anti-dip rock slope increases and then decreases and finally increases. The overall stability of soft and hard rock slope follows the order of vertical layered slope>steep bedding rock slope>anti-dip slope> horizontal layered slope> gentle bedding rock slope.

Key words: layered slope, inter-beddings of soft and hard rock, failure mode, stability, strength reduction method