Abstract: With the development of underground space engineering, the phenomenon of adjacent deep foundation pits is becoming more and more common. Due to the influence of narrow width soil between adjacent deep excavations, the lateral earth pressures on both sides of foundation excavation are asymmetric and it’s difficult to analyze the internal forces and deflections of the excavation support and the effect on the environment based on the classical excavation design theories. The design and practice of an adjacent deep excavations in Shanghai are presented. The numerical analysis method is used to analyze the internal forces and deflections of the excavation support and the effect on the environment based on HS-Small Strain model. The analytical results are compared with the measured data. The results show that the deflections and internal force of supporting structure on the side away from the adjacent excavation will be underestimated and the design on the side near the adjacent excavation is conservative through the traditional symmetrical excavation design method. Besides the deflections of the adjacent excavation and the lateral earth pressure between the excavation become larger while the stiffness of the adjacent excavation becomes smaller.

Key words: Adjacent Deep Foundation Excavations, Narrow Width Soil, Numerical analysis, Asymmetric foundation pit excavation