Control criteria for deformation of foundation pits based on protection requirements of adjacent pile foundations

The protection of adjacent pile foundations is always a key concern of the foundation pit engineering in urban areas. Controlling the deformation of the retaining wall is the most effective way to prevent the damage of the adjacent pile foundations induced by the excavation. Lack of control criteria for deformation of retaining wall of an excavation usually leads to difficulties for engineers to design the support system for the excavation near the existing pile foundations. The current deformation control criteria for the retaining wall come from the statistics derived from the measured results, which cannot reflect the real deformation bearing capacity of the existing pile foundations. In this study, a two-stage analysis method is proposed to calculate the impact of an excavation on the adjacent piled raft foundation. The relationship between the deformation of the retaining wall and the deformation of the pile foundations is investigated. A deformation impact factor is proposed through a series of parametric study taking account of the dimensions of the foundation pit and pile foundations. Based on the deformation control requirements of the adjacent pile foundations, the control and economic criteria of the deformation of the retaining wall are proposed.