Abstract: As a temporary retaining system, the design service life of the deep excavation support structure is generally 1~2 years, however, many excavation supporting projects often have undertaken the extended service. At present, there is no technical specification to determine how to define the safety of the supporting structure, how to determine the reinforcement scheme or the supporting structure sustained service life after the expiration date. Based on an actual overdue foundation pit project, from the perspective of supporting structure entity detection, identification and deformation monitoring data analysis, combined with supporting structure calculation and numerical simulation, this paper summarizes a set of ideas and methods suitable for overdue evaluation of pile anchor structure, which is intended to provide reference for similar projects.

Key words: Deep Excavation, Design Service Life, Extended Service, Structure Inspection, Safety Assessment