Tensile force of geogrids embedded in pile-supported reinforced embankment: A full-scale experimental study

In this study, a full-scale high-speed railway embankment model was established for assessment of the tensile force of the geogrid embedded in the sand cushion. Water bags were distributed around pile caps to create a model of the subsoil. The settlement of the subsoil was determined by the vertical deformation of the water bags. The tensile force of the geogrid, induced by the spreading force of the embankment, and caused by the vertical loads applied to the geogrid, were separately measured by two types of optical fiber sensing approaches, i.e., the pulse-prepump–Brillouin optical time domain analysis (PPP–BOTDA) and fiber Bragg grating (FBG) sensors. After the completion of the construction of the embankment, the measured tensile force of the geogrid, caused by the spreading force, is about 12% of that calculated by using the BS8006 standard. During the process of subsoil consolidation, the soil arching in the embankment fully develops as the subsoil settlement increases. At the ultimate limit state, the largest tensile force of the geogrid caused by the vertical loads occurs at the edge of the pile cap, which is about 34% of that calculated by using BS8006. As a design method, BS8006 calculates the tensile force of the geogrid at the ultimate limit state, and the experimental results reveal that the computational procedure specified in BS8006 is safe for determination of the tensile force of the geogrid.