Load redistribution effect in an embankment founded on a new self regulating interactive membrane foundation system
A new innovative foundation system for embankments on soft soils is currently being analyzed at the Ruhr-Universität Bochum, Germany, in cooperation with HUESKER Synthetic GmbH, Germany. The foundation system consists of two parallel vertical walls, which are installed into the soft subsoil and connected at ground Ievel via a horizontal geosynthetic reinforcement which acts as a tension membrane (further called tension membrane). The embankment is constructed on top of the tension membrane. The system ensures global stability, controls the horizontal deformation and reduces the hori zontal thrust in the subsoil on either side of the embankment. The complex interactive system behaviour is analyzed by centrifuge model tests and numerical simulations. Results of the centrifuge model tests are presented and interpreted in this paper. Conclusions and presumptions from the measurements of the cen trifuge testswill be analyzed and verified thereafter by numerical simulations. One ofthe main findings is the activation of an arehing mechanism within the embankment even with the relatively low ratio of 0.25 between the final embankment height and base width. The relevance of this mechanism for the design will be discussed at the end ofthis paper.
Comparing the relation of embankment height and base width, whieh is 0.25 for the final embankment height, with the relation mentioned in the Iiterature for the formation of a full areh (70% to I 00% for an uniform thiek layer), it beeomes obvious that no full areh has developed within the embankment. How ever, the deerease of the vertieal stresses within the eonsolidation phases ean clearly be attributed to an arehing respeetively a Ioad redistribution meehanism probably enhaneed by spreading forees. For the safe system design, the deerease of the vertieal pressure beneath the embankment axis is less important. The eonsideration of this effeet would Iead to a better predietion of settlement. More important is the eonsideration of the Ioad redistribution towards the vertieal wall, sinee this Ieads to an inereased Ioad along the vertieal wall, whieh does have a signifieant influenee on the design for ULS as weil as the SLS ofthe system.