Benefits of geosynthetic reinforcement in widening of embankments subjected to foundation differential settlement

In the present study, physical model tests were conducted to investigate the effect of the geogrid reinforcement on the reduction of the differential settlement in widening of a highway embankment. A water bag filled with water and placed beneath an embankment was used to simulate the soft foundation of the widened portion of the embankment in the physical model test. Water from the water bag was drained to simulate the development of differential settlements between the existing and widened foundations of the embankment. The geogrid layers were installed with one side fixed in the existing embankment to provide enough anchorage in the physical model tests. Settlements of the embankment, strains in the geogrids and earth pressures were monitored during the test. The test results show that the geogrid layers stabilised the soil arching in the embankment, reduced the differential settlement on the embankment surface, and enhanced the serviceability of the widened embankment. The differential settlement reduction by geogrid reinforcement in the model tests was about 20 to 30 mm. Finally, the benefits of the geogrid reinforcement in the Jiang-Liu highway widening project including controlling the differential settlement in the embankment were validated based on the observed data.