The failure mode and evolution process of geosynthetic reinforced embankments under rainfall

As global climate change continues, extreme rainfall events occur more frequently, exacerbating water-related damage to reinforced embankments. To solve this problem, 16 groups of reinforced embankment failure model tests were carried out using a self-developed model test device under multi-factor coupling, with rainfall intensity, gradient, and number of reinforcement layers used as variables. The distribution and evolution laws of pore water pressure and soil pressure were systematically analyzed, and the failure process of reinforced embankments was visualized. The failure mode, mechanism, and characteristics of the reinforced embankment were revealed, and the evolution of the failure process was determined. Finally, sensitivity analysis was conducted on rainfall intensity, slope, and number of reinforcement layers. The results show that both pore water pressure and earth pressure have obvious burial depth and near slope effects, but the burial depth effect on pore water pressure is opposite to that of earth pressure. Unlike traditional soil slopes, which fail through circular arc or broken-line slip, reinforced embankments exhibit progressive erosion failure under "hydro-mechanical coupling effect". The failure evolution of the reinforced embankment follows the sequence of water infiltration → soil softening → gully expansion → local failure → "pore erosion" failure → overall instability. The primary factor driving failure is the deterioration in soil strength caused by the decrease in matrix suction, rather than a sudden increase in pore water pressure. The results of this study have important theoretical value for reinforced embankments.