Abstract Considering the construction of a foundation pit above an existing shield tunnel and its actual working conditions, a plane strain finite element simulation of the excavation and supporting measures was carried out and a modified Cam-clay model was employed for the soil body. The results show that due to the tunnel excavation, an X-shaped plastic zone emerges from the surrounding soil body, the diaphragm wall has a shelter effect on the development of this zone, almost no horizontal displacement occurs for a tunnel just below the excavation centerline, and the effect of the foundation pit construction on the vertical displacement of the tunnel built below is greater than that of the horizontal displacement. Thus, provided there is sufficient vertical distance between the end of the diaphragm wall and the tunnel, the horizontal displacements of crown and bottom tend towards equalization.
Abstract：
Considering the construction of a foundation pit above an existing shield tunnel and its actual working conditions, a plane strain finite element simulation of the excavation and supporting measures was carried out and a modified Cam-clay model was employed for the soil body. The results show that due to the tunnel excavation, an X-shaped plastic zone emerges from the surrounding soil body, the diaphragm wall has a shelter effect on the development of this zone, almost no horizontal displacement occurs for a tunnel just below the excavation centerline, and the effect of the foundation pit construction on the vertical displacement of the tunnel built below is greater than that of the horizontal displacement. Thus, provided there is sufficient vertical distance between the end of the diaphragm wall and the tunnel, the horizontal displacements of crown and bottom tend towards equalization.
.Analysis of the Effects of Foundation Pit Construction
on the Structural Deformation of an Existing Underlying Shield Tunnel[J] MODERN TUNNELLING TECHNOLOGY, 2013,V50(3): 94-100
2013, Vol. 50 