Limit equilibrium analysis of large-scale reinforced and unreinforced embankments loaded by a strip footing

The paper describes limit equilibrium analyses of two large-scale geosynthetic reinforced soil embankments and one unreinforced soil embankment that were taken to collapse under a strip footing placed close to the crest. One reinforced embankment was constructed with a relatively extensible and weak polypropylene geogrid and the second with a relatively strong and stiff high-density polyethylene geogrid. The geometry of the embankments and the loading arrangement were the same for all three structures. The focus of the paper is on a comparison of the predicted collapse load for the three structures and the actual observed values. A three-dimensional analytical approach is used to account for possible side-wall friction effects due to the test facility in which the large-scale experimental models were built. The paper also reports details on the interpretation of in-isolation constant load tests and strain measurements used to infer tensile loads in the reinforcement at failure. An important conclusion is that a general two-part wedge analysis approach can be used to predict the collapse footing load for both unreinforced and reinforced sand embankments in this investigation provided careful attention is paid to the selection of soil shear strength and reinforcement tensile capacity.