A Numerical Simulation Study on the Influence of Foundation Pit Excavation Unloading on Lateral Tunnel:A Metro Station Foundation Pit Excavation in Nanjing as an Example
To study the impact of excavation and unloading of the foundation pit on the enclosing structure,the deformation of the soil behind the wall,and the tunnel,the impact of the foundation pit excavation at the metro station in Nanjing on the adjacent existing tunnel is investigated.A two-dimensional numerical model of the tun-nel-pit interaction was established using ABAQUS software,focusing on the analysis of tunnel horizontal and verti-cal displacements,structural stress of the tunnel,horizontal displacements of the supporting piles,and settlement of the ground surface around the foundation pit.It shows that the maximum horizontal displacement occurs at the south tunnel vault due to the thin concrete thickness and poor resistance to deformation at this location.The exca-vation of the second and third layers of soil has the greatest influence on the vertical displacement of the tunnel during the foundation pit excavation process.The tensile stress of the tunnel structure exhibits a gradual increasing trend with the excavation of the foundation pit,with the second layer of soil having the greatest influence on both the tensile and compressive stress of the tunnel structure.The tunnel increases the stiffness of the surrounding soil to a certain extent,reducing soil deformation.The horizontal displacement curve of the supporting piles shows a pattern of"small at both ends,large in the middle"due to the"shielding effect"of the tunnel,with horizontal displacement near the tunnel being smaller than that further away.During the excavation of the foundation pit,the deformation pattern of surface settlement is"notch-type",and the presence of the tunnel structure effectively in-hibits surface deformation on the near-tunnel side.
excavation of foundation pittunnel deformation analysisnumerical simulationground settlementtunnel structural stresses
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