Numerical Simulation on Ultra-Large Seven-Ring Internal Support System Considering the Effects of Soil-Structure Interaction and Temperature

The foundation pit area of Kunming International Comprehensive Transportation Hub is 56,000 m2, and the excavation depth ranges from 18m to 25m. Because the surrounding environment is very complex, the foundation pit is supported by underground continuous wall and three layers of internal support system with seven rings. The force of this internal support system is coupled in-tegrally, and the number of rings is the most in the world at present. In this work, a finite element model considering the interaction between soil and retaining structure is established. Hardening Soil model with small strain stiffness is used to simulate and analyze the whole excavation process of the foundation pit. Considering the ultra-large plane size of the foundation pit, we cannot ignore the temperature effect, so that the deformation of the underground continuous wall and the force of the internal support system under seasonal temperature variation are investigated. By comparing numerical simulation results with field measurements, deformation of the ultra-large seven-ring internal support system, deformation of the surrounding soil and axial force of the supports are analyzed. The results show that the finite element simulation agrees well with the measured data. This work provides a reliable method for analyzing ultra-large deep foundation pit.