THE MOST DANGEROUS DIP ANGLE AND SIMPLIFIED SINGLE BEDDING PLANE MODEL OF FLYSCH LAYERED SLOPE

The most dangerous dip angle is the bedding plane angle which makes the safety factor of the slope minimum. This is the most unfavorable attitude of rocks for the stability of bedding slope. Taking the layered slope composed of rock mass and bedding planes as the research subject, the most dangerous dip angles for slopes with different slope angles were analyzed by the finite element limit analysis method applying an implicit joint model. The results show that:as the increasing of the slope angle, the most dangerous dip angle of bedding planes increases while the corresponding safety factor decreases. Failures under the most dangerous dip angle are all overall shear failure. The theoretical formula for the most dangerous dip angle was deduced by the limit equilibrium method. The deviation of result calculated by theoretical formula and that analyzed by the finite element limit analysis method is less than 2%. Among the many bedding planes, the one through slope toe plays a critical role in the stability of a gently inclined bedding slope. With the deviation of safety factors less than 3%, the slope failure mode analyzed by a simplified model with a single bedding plane is very close to that analyzed by a normal sophisticated model, which supports the applicability of the simplified analysis method.