Influence of Dissipation of Negative Pore Water Pressure on Retaining Structure during Excavation

The dissipation rule of excess pore water pressure induced by unloading in excavation is studied. Analytical formulas for calculating negative excess pore water pressure and effective stress are derived based on Terzaghi's diffusion equation. The influence of the dissipation of negative excess pore water pressure on lateral pressure acting on retaining structure is analyzed through a numerical example. The results indicate that the dissipation of negative excess pore water pressure is harmful to the stability of foundation pit and fast construction can make full use of the negative pore water pressure.