Abstract: Anti-slide pile, as a common structure for slope reinforcement, has been widely used around the world. In traditional anti-slide pile design, only the factor of safety is used to evaluate the reinforcement effectiveness, which is not able to account for the effect of inherent spatial variability of soil parameters and economic costs on the anti-slide pile design. To this end, a bi-objective weighted optimization design method for anti-slide pile is proposed considering the spatial variability of soil parameters. This method regards pile diameter, pile length, pile spacing, and pile location as design parameters. By coupling the reliability analysis of pile-reinforced slopes with Pareto optimization theory, the best design parameters are obtained through maximizing reinforcement effectiveness and minimizing economic costs. The validity of the proposed method is illustrated by a case study of a single-row pile-reinforced slope. The results indicate that this method can effectively balance the conflict between safety and cost, yielding the best trade-off solution. Engineers can also determine different safety and economic weighting factors based on engineering grade and failure consequence, in order to select a safer or more economical design solution on the Pareto front. Under the random field condition, the design length of anti-slide pile is larger than that under the deterministic condition, and the best reinforcement effect is achieved when the pile is located near the middle of the slope. The bending moment of the pile body and the displacement at the pile top may be significantly underestimated under the deterministic condition, leading to a high-risk design and misleading the operational monitoring.

Key words: slope, anti-slide pile, spatial variability, bi-objective optimization, reliability design