Abstract:

On the basis of slice-dividing method and limiting equilibrium principle,a critical formula was set up by relating the shear strength of soil with the dip angle of critical landslide surface. The formula was employed to analyze the variation of dip angle with overburden pressure. It’s verified that shear failure of the slope would not occur when the height of slope is less than a limit value with the slope angle in the range of 0-90°. In addition,two ideas were developed from the formula to analyze the causes of instability of two landslide cases. The results were consistent with monitoring data,and two methods of calculating the residual sliding force were given. In the second landslide case,another formula which calculates the influence of thrust on slope’s critical state was also built. The advantage of this method which relates the shear strength of soil with the critical dip angle of landslide surface is that the sliding surface is analyzed point by point,and the steady-state at each point is identified. But the method still needs to be improved and explored in calculation. The method which associates the mechanical roperties with geometric shape provides new idea for the evaluation of slope stability.

Key words: shear strength , limit equilibrium , critical dip angle , critical formula , thrust