ABSTRACT

In recent years, there has been increased land development and construction in unsaturated soil slopes in Northern Taiwan due to economic growth and urbanization (Lin et al., 2016). Consequently, slope stability problems have received increased attention. Since most soils occur in unsaturated state in nature, it is prudent to incorporate the contribution of apparent cohesion in slope stability analysis which is attributable to the presence of matric suction in the unsaturated layer of the soil. Consequently, a parametric study is conducted on c-Ф’ soils taking into consideration the apparent cohesion in the unsaturated layer by dividing the substrata into different layers and conferring to each layer a particular cohesion value. A parallel set of analyses is carried out by directly inputting unsaturated soil parameters, ψ_aev, Ф^b in the RS2 program. The two approaches use the strength reduction technique. According to the findings of this study, the first approach named ‘apparent cohesion method’ yields consistent, reliable and conservative results in comparison with the second approach, ‘the unsaturated effect method.’ Thus, it is a viable alternative slope stability analysis method.

ABSTRACT

In recent years, there has been increased land development and construction in unsaturated soil slopes in Northern Taiwan due to economic growth and urbanization (Lin et al., 2016). Consequently, slope stability problems have received increased attention. Since most soils occur in unsaturated state in nature, it is prudent to incorporate the contribution of apparent cohesion in slope stability analysis which is attributable to the presence of matric suction in the unsaturated layer of the soil. Consequently, a parametric study is conducted on c-Ф’ soils taking into consideration the apparent cohesion in the unsaturated layer by dividing the substrata into different layers and conferring to each layer a particular cohesion value. A parallel set of analyses is carried out by directly inputting unsaturated soil parameters, ψ_aev, Ф^b in the RS2 program. The two approaches use the strength reduction technique. According to the findings of this study, the first approach named ‘apparent cohesion method’ yields consistent, reliable and conservative results in comparison with the second approach, ‘the unsaturated effect method.’ Thus, it is a viable alternative slope stability analysis method.

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