Geohazard Caused by Groundwater in Urban Underground Excavation

Figure 7

Change of pore pressure distribution at various depths and locations at different phases of launching of a shield in transverse direction. (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. “-“in pore pressure distribution contour is positive pore pressure and “Pwater” means pore pressure.