Investigating Lateral Displacement of Pile Groups under Construction Loads and Excavation-A Case Study

Piles in weak soils are sensitive to adjacent excavation and construction loads. Excessive lateral displacement of piles during construction adds shear and bending moment to the piles. This is of great concern because these additional lateral loads are sometimes not accounted for when designing piles, and the horizontal bearing capacity as well as shear strength of the piles is low. This paper presents a case study of a recent project with severe pile damage and large soil displacement during construction due to the installation of adjacent piles and excavating foundation pits. With improper construction procedures, the piles were severely damaged and have almost no bearing capacity before the construction of the superstructure even begins. On-site measured data were used as inputs for numerical simulations, and analyses were carried out to study the behaviors of pile groups affected by construction activities. The simulation was for each construction activity/stage as well as the whole construction process to determine the effects of excavation and deep foundation construction equipment loadings used for pile installation. The effects on the lateral displacement of piles and surrounding soil were quantified. The results from finite element analysis on the lateral deformation of piles are in good agreement with the measured data, with differences of about 5%-10%. Several construction procedures are recommended, with recommendations made to mitigate pile damages and large soil displacement due to construction. With the recommended procedures, the lateral deformation of pile groups can be greatly reduced by at least 90% and pile damages can be eliminated.