Analytical assessment of dynamic stability in 2D unsaturated soil slopes reinforced with piles

The stabilizing pile represents a promising solution for enhancing the seismic resilience of unsaturated slopes. This study introduces a novel analytical framework for assessing the stability of unsaturated slopes reinforced with piles, amalgamating the minimum potential energy approach with the pseudo-dynamic method. The formulation of the external potential energy arising from the self-weight of the landslide mass and seismic forces is derived. Furthermore, traditional plasticity theory is extended to unsaturated soil slopes to account for the augmenting influence of matric suction on the lateral pressure exerted by stabilizing piles. The efficacy of reinforcing unsaturated soil slopes with piles is gauged through the definition of the safety factor (SF), delineated as the ratio of resistance moment to sliding moment. Additionally, a fresh interpretation of the critical slip surface (CSS) for unsaturated soil slopes is proposed, alongside an original criterion for identifying CSS, introduced herein for the first time. The validity of the proposed methodology is substantiated through examination of three case studies, yielding results indicative of its efficacy and rationality. The analysis underscores the substantial fortifying impact of matric suction on the stability of unsaturated slopes, as well as the reinforcing influence of piles. Moreover, an exploration into the ramifications of seismic and pile-related parameters on slope performance and CSS is conducted. In conclusion, this approach serves as a valuable reference for the design of unsaturated slopes fortified with stabilizing piles.