Deformation Behavior of Foundation Pit Considering the Variation of Permeability Coefficient of Soil Mass

The permeability coefficient of soil mass will vary with the change of effective stress when a foundation pit is excavated in soft soil area. A three-dimensional fluid-solid coupling program was developed that can consider the change of permeability coefficient of soil with the effective stress by introducing the relationship between the permeability coefficient and the effective stress increment of soil. The foundation pit of Shanghai Bank Building in Lujiazui, Pudong District, Shanghai, China was simulated and the numerical results were compared with the ones without considering the change of permeability coefficient of soil. It is shown that the trend of the horizontal displacement of retaining structure is consistent whether or not the permeability coefficient of soil varies. The results considering the change of permeability coefficient of soil with the effective stress, however, are smaller and agree better with the measured results. As for the heave of pit base, the deformations considering the change of permeability coefficient are smaller than the results without considering it. However, the ground settlements around the pit considering the change of permeability coefficient of soil are contrary to the heave of pit base and they are bigger than the results without considering it. Therefore, the change of permeability coefficient of soil with the effective stress should be considered in excavation engineering of soft soil area.