Development of soil–pile interactions and failure mechanisms in a pile-reinforced landslide

The reinforcement effect of stabilizing piles is significant for ensuring the stability of major landslide mitigation projects. To investigate the work performance of piles under different boundary conditions, we introduce two physical modelings of a pile-reinforced landslide with the same pile parameters and soil conditions but different load conditions and analyze the consequent differences in the responses of the soil and piles and their interactions in these two physical modelings. Results show that piles in the same landslide/pile systems may have different reinforcement effects; this phenomenon has been explained by quantitatively describing the role of piles and analyzing the processes of soil–pile interactions in the physical modelings. Further, the dynamic responses between the excess pore pressure and the soil–pile interaction are investigated and the excess pore pressure-dependent mechanisms of soil–pile interactions are revealed. The generation of excess pore pressure and its accumulation around piles leads internally to a mechanism in which the arching effect is weakened and externally to a phenomenon in which the progressive failure of pile-reinforced landslides is accelerated. Eventually, we calculate the effective stress in the soil around piles, and the results reveal that a sharp reduction in effective stress in the soil around piles causes failure of the pile reinforcement. In addition, for a pile-reinforced landslide with a strong soil–pile interaction, an imbalance of soil arch footholds is the main failure macro-mechanism. Based on the analysis results, we present some feasible suggestions for the installation of rowed pile and their monitoring to ensure the long-term stability of a pile-reinforced landslide. • Piles in the same landslide/pile systems may have different reinforcement effects due to different soil-pile interactions. • The generation of excess pore pressure around pile and its accumulation accelerate the progressive failure of the system. • The developments of excess pore pressure and soil-pile interaction present significantly dynamic response characteristics. • A sharp reduction of effective stress in the soil around piles brings the pile-reinforced landslide to failure. • An imbalance between footholds of soil arch leads to the failure of the strong soil-pile interaction.