A numerical interpretation of the soil-pile interaction for the pile adjacent to an excavation in clay

Abstract

Failure accidents of pile foundations caused by underground excavations have become a concern for design in recent years. Adjacent excavations can cause stress release and displacement of the ground, and hence affect the lateral pile performance (passive loading pile). Consequently, it is significant to properly evaluate the mechanism of lateral soil-pile interaction behavior subjected to adjacent excavations. In this paper, the soil-pile interaction p-y curve of the pile adjacent to an excavation in clay was numerically investigated, and its different evolution characteristics were highlighted compared to the active pile p-y curve. Results reveal that the p-y curve for the passive pile adjacent to an excavation performs a significant strain-softening characteristic, which is closely related to the excavation process and locations. The ultimate soil-pile interaction force for the passive pile approximately equals 7.5 times the undrained shear strength of clay (≈ 7.5su). Analyses also demonstrate that the corresponding p-δ curve (δ is the relative soil-pile displacement) for the passive pile conforms to the hyperbolic characteristics and exhibits unloading effects associated with excavation-induced soil movements. Furthermore, a parametric study was carried out to examine the excavation induced soil-pile interactions varying soil properties and excavation processes, showing that the p-y and p-δ responses depend on soil properties and excavation processes.