Stability Analysis and Performance of Soil-Nailing Retaining System of Excavation during Construction Period

摘要

In this paper, a system failure probability method, considering principal failure modes of the soil-nailing retaining structure and random factors of the system, is put forward. Taking the excavation of the east public square of the Jinan high-speed railway station as the case, the paper first defines principal failure modes of the soil-nailing system according to its working mechanism and collapsing characters. The failure probability of each mode and then the system failure probability were calculated by considering random factors of the retaining structure. The soil nailing-supported excavation was proved to be stable and some effective construction measures were put forward based on the failure probability result during the construction period. A numerical simulation was carried out to analyze the stability of the excavation during each construction step. By using a strength reduction method, safety factors of the excavation were determined. Displacement and shear stress of the excavation were within allowed limits during every calculation step. At the same time, vertical and horizontal displacement of the top point of excavation, horizontal displacement of different depths, and the force of the soil nails were monitored during the construction period. The monitoring data were reasonable and consistent with the results of theory and numerical calculation.