Responses of piles subjected to excavation-induced vertical soil movement considering unloading effect and interfacial slip characteristics

Abstract

Soil excavation inevitably affects the work performance of adjacent on-service piles. It is of practical importance to estimate the excavation-induced pile responses accurately. Existing methods tend to ignore the impacts of the interfacial slip characteristics and the loading history. In this study, modified load-transfer models are first developed for the surrounding soil and the pile–soil interface. Then, a nonlinear two-stage analysis method is proposed by introducing a Double-Spring model. In comparison with existing methods, the proposed method models the interfacial slip characteristics more realistically, and, more importantly, it is able to consider the impact of the working load in the active stage. The results of parametric studies show that the impacts of the working load in the active stage and the interfacial slip characteristics on the excavation-induced pile responses are significant; unacceptable deviation could be induced if an elastic-perfectly plastic model or a rigid-plastic model is adopted instead of the damage model to describe a rough pile-sand (or soft rock) interface. Moreover, with the increase in the working load, the excavation-induced pile settlement increases, whereas the additional axial force decreases.