Using Geogrid Encased Granular Columns for Embankment’s Slope Protection: 3D-Finite Difference Analysis

Abstract

The stability of the embankment’s slopes is a critical aspect of geotechnical engineering and it is essential to guarantee the effectiveness of the factor of safety to prevent any potential failures in the slope both during and post-construction. The current study consists of two parts; the first part is the study of the behavior of the geogrid-encased granular columns and their interaction with the soil at the shear surface generated by the slippage of the soil, while the second part is a study of the stability of slopes by changing several factors, including the area replacement ratio (Ar %) of the granular columns, the angle of the embankment slope (β), and different elastic modulus (Eg) of geogrid on the stability of an embankment. About 90 analyses were conducted on a clayey sand embankment over a clayey layer. The area replacement ratios (Ar %) were changed by using different values of the diameter of the column; from 50 to 100 cm. The angle of the embankment slope was changed from 28 to 36 degrees. Furthermore, three different values, 0.12, 2.625, and 6.552 GPa, of modulus of elasticity were used. The results show that increasing the modulus of elasticity of the geogrid increases the normalized shear strength and decreases the lateral displacement in the column. Furthermore, the factor of safety was increased as the stiffness ratio between the geogrid and the materials increased. However, the factor of safety was noted to decrease when the angle of the embankment slope was increased.