Robust optimization of the constructional time delay in the design of double-row stabilizing piles

Double-row stabilizing piles are widely used to stabilize large-scale landslides. The construction process of double-row stabilizing piles is often accompanied by constructional time delay (CTD), which is defined as the time interval between the installation of front-row and rear-row stabilizing piles. The CTD is often selected based on the designer’s experience and the construction arrangement due to the lack of design guidelines for double-row stabilizing piles. In this paper, the CTD is considered as a design parameter and optimized based on the robust design concept. The signal-to-noise ratio, which is a function of the mean and standard deviation of factors of safety (FOS) of the stabilizing piles, is used as a measure of the design robustness. The FOS of the double-row stabilizing piles are computed using an analytical model that considers the CTD. A framework based on the concept of robust design is proposed for determining the most preferred CTD considering multiple objectives, including safety, cost, and design robustness. This framework is illustrated with a case study, the Hongyan landslide project, Taizhou, Zhejiang, China. Based on the outcome of this study, the most preferred CTD is obtained.