Dynamic Deformation Control of Retaining Structures of a Deep Excavation

Abstract

Many uncertain factors in the excavation process may lead to excessive deformations and internal forces of retaining structures; therefore, the design of deep excavations should be adjusted according to real-time monitoring data. This paper presents a case study of dynamic control of excavation deformations. The preliminary design adopted bored piles as retaining structures braced by three levels of steel-reinforced concrete struts, while the final design used only two levels of struts to reduce the construction duration. The final design reduced the safety degree of the project to a certain extent and brought the excavation to a state of emergency. Fortunately, the designers adjusted the excavation sequence based on feedback information from the field monitoring data. In addition, a variety of deformation control measures, aimed at reducing the horizontal displacement of the retaining walls, were used, such as strengthening the chamfer of the retaining structures, adjusting the excavation sequences, and strengthening support nodes. The monitored excavation performance demonstrated that these remedial measures were feasible and effective for controlling excavation-induced deformations and minimizing the relevant risks.