The Research On The Stability Calculation Of Slopes With A Toe-berm

Toe-berm project is a commonly used measure for slope reinforcement. However, no systematic numerical aspect has been proposed for toe-berm measurement. In existing cases, the engineering toe-berm and slope are calculated as a whole without considering the difference between their soil materials, which may have an impact on the computational accuracy. Besides, current design cases of engineering toe-berm are deficient in obtaining the optimal cross section of the banket, thus resulting in a waste of material. According to the exclusive features of engineering toe-berm, three limit equilibrium computational methods have been concluded in this paper, including the Simplified Bishop method, the modified Unbalanced Thrust method and the Passive Earth Pressure under limited banket width. The Finite Difference method has been adopted for contrastive study. Specifically, main work of this paper can be summarized as follow:(1) In homogeneous slopes with a toe-berm made of similar material, the Simplified Bishop method can be employed for engineering calculation. Through analyzing the effect of toe-berm geometry on the stability of the slope, the relationship between the slope material and optimal banket geometry has been summarized as this:the ratio of width to height in banket geometry increases with the increased ratio of cohesion to the tangent value of friction angle in slope material. On the basis of the aforementioned correlation law, the design scheme of the optimal toe-berm geometry in homogeneous slope is proposed.(2) In slopes whose failure mode is broken line slip, if the material properties of the toe-berm is quite different from that of the slope, the inclined slope surface existing between slope and toe-berm can’t be ignored, which may cause calculation error if no extra attention has been paid to. Based on the static equilibrium analysis of the blocks on both sides of the slope surface, the Unbalanced Trust method implicit solution is modified for the overall stability assessment for slopes with toe-berm. In a practical example, the results of Unbalanced Thrust method implicit solution, modified Unbalanced Thrust method implicit solution, numerical simulation solution are compared to evaluate the rationality of the modified method.(3) In rock slopes, if the potential slip surface is either plastic deformation type or brittle deformation type in residual deformation stage, the Passive Earth Pressure model can be applied to appraise the bearing capacity of the toe-berm. On the basis of classical earth pressure theory, the Passive Earth Pressure under limited banket width is derived. Besides, numerical stimulation has been employed to probe the influencing factor of the Passive Earth Pressure under limited banket width.