Evaluating stability of rigid column-supported and geosynthetic-reinforced embankments

Field observations and centrifuge tests indicate that progressive column bending failure accompanies most instabilities of rigid column-supported and geosynthetic-reinforced (RCGR) embankments. However, recognized guidelines specifically for evaluating the overall stability of such systems featuring bending failure remain limited. This study presents a general methodology to calculate the factor of safety (FS) for RCGR embankments using the limit equilibrium method. The focus is on deep-seated slope failures, wherein rigid columns progressively fracture due to subsoil overstressing. The Concentric Arches model, along with tensioned geosynthetic analysis, informs the determination of vertical and horizontal loads on the column heads. The column's resisting moment stems from its flexural and compression resistance. A mobilization factor for the net thrust on each column is defined to capture the progressive failure. The methodology involves an iterative computational procedure to identify the critical slip surface and the FS utilising Fellenius’ method. The solution is validated against three case studies, including both centrifuge models and field tests, as well as finite element analysis. The results indicate that the soil mass contributes the most to resisting sliding and overall stability, followed by the columns and geosynthetics. In addition, axial force mainly provides the resisting moment of columns.