Analysis of horizontal pile displacement caused by pit excavation

Abstract

In the case of thick soft and unstructured soils, pit excavation causes 20-75% of pile heads to have higher-than-normal horizontal displacements. The paper presents the results of statistical analysis for 9865 piles installed in pile fields at 17 construction sites in St. Petersburg, Perm, and Volgograd. We note that the distribution of frequencies of horizontal pile displacements follows a normal law. During the analysis, we identified the main factors affecting pile displacement: the time when a pile is in the slope, the properties of the cut soils, their tendency to softening, the excavation scheme, and the availability of pile head anchorage. The paper justifies the effectiveness of pit excavation in work zones of up to two meters deep with changes in the direction of machinery movement. We provide recommendations for raft design and analysis with account for possible displacement of pile heads.