Stability analysis of expansive soil slopes stabilized with geogrids

Abstract

Expansive soil slopes are vulnerable to climatic variations due to their swell-shrinkage behaviour, ultimately resulting in slope failures. In recent decades, geogrids have gained prominence for stabilizing such slopes due to their enhanced performance. However, geogrid properties such as length and spacing should be extensively studied for the optimal application. This study investigates the effect of such parameters in expansive soil slope stabilization. Numerical models were developed with finite element method (FEM) based PLAXIS 2D software and validated with the limit equilibrium method (LEM) based SLOPE/W software. A parametric study was conducted to analyze the stability of the expansive soil slopes treated with geogrids for various slope heights (4-16 m), slope angles (30-45º), geogrid lengths (0.7-1.2 times slope height), and geogrid spacings (0.25-1.0 m). Findings indicate that the inclusion of geogrid enhances the factor of safety (FOS) by 4% to 268%, depending on the slope geometry and geogrid configuration. For effective application, shorter slopes (4-8 m) require a geogrid length equal to the slope height, while taller slopes (8-16 m) need geogrid length of 1.2 times the slope height. Similarly, milder slopes (30-45º) require geogrid spacing of 0.5–1.0 m, and steeper slopes (45-75º) require a spacing of 0.25-0.5 m.