Method for predicting deformation field of deep foundation pit considering spatial effect

Abstract

Urban underground spaces have experienced significant development and utilisation due to the rapid progress of urban construction and continuous advancements in construction technology. The number of foundation pit projects immediately adjacent to buildings, structures and pipelines has been increasing. When ensuring the safety of construction and surrounding facilities, it is essential to predict deformation caused by foundation pit excavations. In this study, a simple calculation method is proposed for predicting the deformation of an envelope structure and surface settlement caused by deep foundation excavation with spatial effects. First, the principle of minimum potential energy is applied and the lateral displacement equation of the envelope structure is derived, considering spatial deformation effects. Second, based on linear elasticity theory, a surface settlement expression is formulated utilising the plane-strain boundary. Finally, the stratigraphic loss method is used to establish a connection between horizontal envelope deformation and surface settlement, allowing for calculations of surface settlement at any position behind the envelope structure. The effectiveness and practicability of the proposed method are demonstrated by comparison of two existing foundation pit engineering examples.