Experimental and numerical studies of geosynthetic-reinforced sand slopes loaded with a footing

This paper presents the results of a series of plane strain model tests carried out on both reinforced and unreinforced sand slopes loaded with a rigid strip footing. The objectives of this study are to (i) determine the influence of geosynthetic reinforcement on the bearing-capacity characteristics of the footing on slope, (ii) understand the failure mechanism of reinforced slopes, and (iii) suggest an optimum geometry of reinforcement placement. The investigations were carried out by varying the edge distance of the footing for three different slope angles and three different types of geosynthetic. It is shown that the load-settlement behaviour and ultimate bearing capacity of the footing can be considerably improved by the inclusion of a reinforcing layer at the appropriate location in the fill slope. The optimum depth of the reinforcement layer, which resulted in maximum bearing capacity ratio (BCR), is found to be 0.5 times the width of the footing. It is also shown that for both reinforced and unreinforced slopes, the bearing capacity decreases with an increase in slope angle and a decrease in edge distance. At an edge distance of five times the width of the footing, bearing capacity becomes independent of the slope angle. The effectiveness of the geosynthetic in improving the bearing capacity of the footing is attributed to its primary properties such as aperture size and axial stiffness. A numerical study using finite element analyses was carried out to verify the model test results. The agreement between observed and computed results is found to be reasonably good in terms of load-settlement behaviour and optimum geometry of georeinforcement placement.