Geohazard Caused by Groundwater in Urban Underground Excavation

Figure 9

Change of pore pressure at various depths and locations at different phases of launching of a shield in plane view at 16 mbgl. (a) Initial phase. (b) Main excavation. (c) Launching of the shield. Note: A-A: left side of tunnel eye; B-B: center of tunnel; C-C: right side of tunnel eye; and D-D: 5 m away from the right side corner and “-” in pore pressure distribution contour is positive pore pressure.