Mechanics of Slides

This chapter describes three types of failure surface: circular, noncircular, and composite. It also explains the method of slices and the sliding-block analysis for determining the factor of safety. The two methods for analyzing the stability of slopes are total stress analysis and effective stress analysis. The major difference between these methods is that total stress analysis does not require knowledge of the pore pressure, whereas effective stress analysis does. Two examples illustrate the total stress analysis for circular and noncircular failure surfaces. The circular failure surface is analyzed with the well known Fellenius method, and the noncircular failure surface is analyzed with the sliding-block method. The drawback of the Fellenius method is discussed, and the normal method, which is based on the concept of submerged weight, is then introduced. Finally, the chapter discusses the minimum factors of safety required under various conditions.