Study on the Analysis of Pile Foundation Deformation and Control Methods during the Excavation of Deep and Thick Sludge Pits

Abstract

This study aims to apply performance-based safety-assessment methods to the monitoring and numerical simulation of excavation engineering projects in order to comprehensively enhance engineering risk management and decision support. In this paper, a deep excavation project in Hefei with thick silty clay layers was studied. The analysis included the surface settlement, the deformation of support structures, the vertical and horizontal displacements of pile tops, axial forces in steel braces, settlement, and the horizontal displacement of a gravity retaining wall on the south side of the excavation using field-monitoring data. A refined three-dimensional finite element model was established to further analyze the distribution of uplift displacement at the bottom of the excavation, horizontal displacement, and bending moments of piles based on simulation results. The research findings indicate that phased excavation can reduce the spatial extent of disturbance to the surrounding soil caused by excavation. Additionally, the closer the location to the excavation and the thicker the underlying silty clay layer, the faster the rate of settlement change and the greater the surface settlement. The spatial structure formed by steel braces and pile foundations effectively reduced the horizontal displacement of the engineering piles. The study’s use of field monitoring and finite element simulation provided valuable insights into the deformation of support structures and the response of the surrounding soil to excavation, confirming the rationality and applicability of the support structure in this paper. The proposed method can serve as a reference for similar complex stratum excavation design and construction. The performance-based safety assessment is introduced, and the monitoring data, numerical simulation results, and performance targets are comprehensively analyzed to provide a reliable scientific basis for engineering decision making.