Simplified Method for Analyzing Slope Stability of Clay Layer of Increasing Strength With Depth

Abstract

Stability analysis of slopes plays a crucial role in geotechnical engineering which is often associated with excavation and filling works.  It helps designing the layout of a newly constructed slope and assessing the risk of failure of an existing slope.  Moreover, it enables a strength of soil of a failed slope to be back-calculated.  Nowadays, there are a number of slope stability analysis methods, each of which has different hypothesis, limitations, and complexities.  Most detailed slope stability analyses involve computational tools, i.e. computer software with a finite element or limit equilibrium methods.  As a result, an initial assessment of slope stability on site is difficult in practice.  Therefore, the objective of this research is to propose a set of slope stability charts for homogeneous clay with increasing strength with depth by Morgenstern and Price method.  It also considers the factors affecting slope stability such as slope angle, slope height, depth of firm subsoil, surcharge factor, and tension crack factor.  The result will be beneficial for preliminary estimation of slope stability analysis.  Based on the findings, the slope stability chart developed in this study is considered reliable for practical applications. Errors of safety factors analyzed from the research are low in case of (i) the surcharge factor without considering the tension crack factor and (ii) the tension crack factor without considering the surcharge factor. Nevertheless, it is important to note that the safety factors obtained in this research are comparatively lower than those derived from the GeoStudio 2012 analysis when considering both the surcharge factor and tension crack factor simultaneously, particularly in situations with steep slope angles.