Experimental study on influence of reinforcing modes on behavior of piled embankment

In order to study the effect of the geosynthetic reinforcement on the behavior of the piled embankment, a series of three-dimensional model tests are carried out. In the tests, single and double layers of geotextiles or geogrids are used. The pile-soil stress ratio, stress reduction ratio, and vertical stress distribution in the embankment fill and differential settlement are compared with the data measured from the unreinforced embankment. It is found that the inclusion of geosynthetic reinforcements can enhance the efficiency of load transfer and reduce differential settlements, but the mechanisms of load transfer are different depending on the types and numbers of the geosynthetic reinforcement. When one or two layers of geotextiles are used, the load transfer from soil to piles is mainly caused by the combination of soil arching effect and tension membrane effect, and the latter acts later. In the case of piled embankment reinforced by two layers of geogrids, the mechanism of stiffened load transfer platform works due to the interaction of reinforcement and the surrounding fill. The piled embankment with a single layer of geogrid acts between the above two cases. Because only the geosynthetic strip between adjacent piles is assumed to be effective in the load transfer, the tensile force is overestimated in the conventional design methods.