Controlling the Settlement of the Low Embankment on Soft Ground by Surcharge Preloading Method

Abstract

Preloading with surcharge is the most common technique of ground improvement used in highway engineering. At the end of the preloading period, the surcharge load is removed, and most or all of the primary settlement and some of the secondary settlement would have occurred. The soil beneath the embankment becomes over-consolidated, resulting in the elimination or a huge reduction in post-construction settlement. When pre-compression is applied to a relatively free-draining material, consolidation times are short, and therefore primary settlements can be effectively controlled by using a preload equal to the final load over a limited period of time. The subsequent movements associated with unloading/reloading will be small and will occur rapidly. In these cases, the main source of long-term displacements is likely to be secondary compression settlements. In this paper, a laboratory investigation of one-dimensional consolidation of clayey soils was carried out and a formula has been proposed to compute the postconstruction settlement of low embankment. The results show that the settlement increases with the increasing amplitude of the cyclic load, and the effectiveness of surcharge preloading depends on the difference between the surcharge and the amplitude of the cyclic load.