PREDICTING RESIDUAL FRICTIONAL ANGLE BY ATTERBERG LIMITS FOR RESERVOIR EMBANKMENT SOILS

Abstract

Slope stability is one of the greatest issues of concern in geotechnical engineering. In slope
stability analyses, the residual strength of slip zones is the most important parameter for evaluating slope
stability and for understanding the reactivation mechanisms. However, it is time-consuming and costly to
obtain the residual frictional angle through shear tests. This paper presents the results of a laboratory study
designed to evaluate the correlations between the residual frictional angle and the Atterberg limits, which
include the liquid limit, the plastic limit and the plasticity index, using eight kinds of reservoir embankment
soil samples. The residual frictional angle was measured by the Bromhead ring shear apparatus using remolded
samples. Based on the laboratory study, significant correlations between the residual frictional angle and the
different indexes were proposed for the reservoir embankment soil, especially in terms of the particle size of
the soil, which was less than 0.425 mm. Processing the data on the shear tests led to the discovery that the
quantity of eight tests was sufficient for obtaining relevant accuracy in determining the residual frictional angle.
Based on the results of the tests, the relationships between the residual frictional angle and all the indexes were
found. Compared with the other indexes, the liquid limit had a better correlation with the residual frictional
angle. Formulas were predicted in this study that can provide a convenient and highly accurate means for
calculating the residual frictional angle value for application to worldwide geotechnical engineering projects.