Geocell-Reinforced Embankment on Soft Clay Overlying Dense Sand

This paper summarizes the influence of geocell reinforcement on the performance of earth embankments on soft clay overlying dense sand. The geocell reinforcement can enhance the bearing capacity of the soft clay apart from reducing settlement. Correspondingly, the fill height can be increased significantly. Prototype simulations indicate that the geocell mattress can enhance the embankment height in the range of about 50%–64%, compared with the unreinforced case. In addition, the geocell mattress can effectively share the embankment loading even at a very low level of settlement that exhibits its structural ability. The strain measurement indicates that the geocell mattress acts like a wide slab and thereby effectively supports the embankment even after yielding of the foundation bed. The enhanced bearing capacity of the foundation bed owing to provision of the geocell mattress was estimated through the slip-line field theory. For relatively shallow soft clay with thickness less than 1/12th of the embankment base width, the estimated bearing capacity was comparable to the test data. However, with an increase in the thickness of the soft clay, the prediction has tended to diverge from the experimental result, in the range of about 16%–21%. This is attributed to the difference in the failure mechanism such that the thinner soft clay failed through lateral extrusion as assumed in the slip-line theory, while the deeper one was prone to rotational slip. The finite element analysis of prototype embankments indicates that the general behavior and mechanisms observed in the model tests are reproduced at large scale.