Effects of geogrid reinforcement on slope stability of different soils using finite element analysis

Purpose This study aims to determine the effects of geogrid reinforcement on the stability of slopes constructed of two different poor-quality soil types, namely, soft clay and loose sand, to represent fine and coarse-grained soils. Design/methodology/approach The effects of geogrid reinforcement on the stability of slopes of different poor-quality soils were determined using a numerical analysis method. Symmetrical homogeneous earth dam models with specific heights and varied slopes were analyzed for the selected soil types. Each model was scrutinized under different conditions using finite element-based PLAXIS 2D software. Findings The stability for each model was checked in terms of factor of safety (FOS), and deformation magnitude was computed for the end-of-construction loading condition, which is critical to both upstream and downstream slopes of embankments. The analysis showed that FOS tends to increase with increases in the reinforcement layers for both soil types and all the geometries considered. Moreover, the Geogrid reinforcement stabilized the soft clay soil slopes better than the loose sand analogous slopes under similar conditions. The effects of geogrid on the embankment models were observed, and FOS increased in the range of 72% to 126% for a side slope of 1V:1.5H for soft clay, while in the case of loose sand, it ranged between 19% and 63% for the same side slope for various vertical reinforcement spacing. FOS values for the final steepened (1V:1.5H) soft clay models: without reinforcement were found to be 1.25; whereas, with reinforcements spaced at 3 m, 2 m and 1 m were: 2.15, 2.74 and 2.83, respectively. In case of loose sand for the same models and conditions, the values were 1.05, 1.25, 1.40, and 1.71, respectively. Moreover, the geogrid reinforcement spacing variation showed variation in total displacement for the deformation of the models. Based on the results of this study, the trend of deformation variations with respect to both slope angles and reinforcement layer variations could not be concluded precisely. Thus, further study is needed in this regard. Originality/value Analysis of the embankment using PLAXIS 2D gave the numerical solution for the stability condition of the slope.