Numerical Study for Geosynthetic Reinforced Revetments on Lateral Bearing Capacity

Geosynthetic-reinforced soil walls can be classified into two types according to the design concept: Mechanically Stabilized Earth Walls (MSEW) and Geosynthetics Reinforced Soil Composites (GRSC). The former is designed and constructed in the same manner as a tied-back wall; while the latter is treated and designed as a composite material. Compared to MSEW, GRSC is more deformable and can withstand higher impact force. In this study, the finite element software, PLAXIS 3D, was used to analyze the behaviors of the GRS barriers under quasi-static lateral pressures induced by debris flows. The influencing factors investigated were as follows: (1) grouted-facing and wrap-around facing barriers; (2) geometry of the barriers; (3) parameters of backfill and reinforcement; (4) load pattern; (5) scouring; (6) debris flow induced shear stress on the facing of the barriers. The results of finite element analysis indicated that the lateral bearing capacity depended on the aspect ratio (W/H: ratio of wall width to wall height), and that the failure mode depended on both facing type and aspect ratio. For grouted facing barriers with W/H < 1.0, they would fail in overturning. For 1.0 < W/H < 3.0, a sliding failure occurred along the backfill-foundation interface. For W/H > 3.0, passive soil failure occurred within the barrier and near the loading side. As for the wrap-around barrier, when W/H < 1.6, sliding failure occurred along the bottom layers of reinforcement. When W/H > 1.6, the ultimate lateral bearing capacity was reached due to local passive soil failure occurred on the top of loading side. The parametric study showed that the W/H ratio, backfill cohesion c, soil unit weight, and friction angle φ were the major influencing factor to the lateral bearing capacity. When the foundation of the barrier was scoured by debris flows, its lateral bearing capacity would decrease 30 to 50%. Considering the shear stress in addition to lateral pressures induced by debris flows, the lateral displacement would be much increased for both types of barrier.