Abstract: Tingzikou dam is a concrete gravity dam built in typical red rockbed region. The rock geological characteristics are of gentle dipped strata containing several weak interlayers, unfavourable to the deep anti-slide stability of the dam. At present, equal K value method is still the main method of analysing the deep stability against sliding of gravity dam. In practice, the variation of resistance angle greatly influences the result of the safety factor. The focus of this paper is to analyze Tingzikou gravity dam’s stability safety against deep sliding. The difference of the deep sliding surfaces and their variation law using finite difference based strength reduction method and rigid body limit equilibrium based equal safety coefficient method. The reasonable value of resistance angle in the rigid body limit equilibrium method is discussed. This research provides sound basis for the design of gravity dam’s foundation stability against sliding.

Key words: red bed region, gravity dam foundation, factor of safety against sliding, rigid limit equilibrium method, finite difference