Abstract: The slope stability analysis methods can be divided into two parts: the total strength method and the effective strength method according to the different shear strength parameters selected. Since the pore water pressure is often unknown or difficult to obtain in the engineering practice, the total strength method is therefore widely used. When the total strength method is used, the result of the slope stability analysis is often erroneous due to the confusing in the actual shear strength and shear strength parameters of the soil. This paper utilizes the circular arc sliding method as an example to illustrate the relationship between the shear strength and the undrained strength of the potential sliding surface and the effective internal friction angle and the total internal friction angle. The basic reason for the difference between the effective strength method and the total strength method in the safety factor is proposed. Basic on this, a method for correctly evaluating the factor of safety of the slope stability is proposed when the pore pressure is unknown or difficult to obtain in an actual slope. At the same time, the slope stability analysis method proposed in this paper is verified by an example by using MATLAB software.

Key words: Slope Stability Analysis, MATLAB, Undrained Shear Strength, Total Strength Method, Effective Strength Method