GROWTH OF PILE BEARING CAPACITY OVER TIME CONSIDERING THE DISSIPATING OF EXCESS PORE PRESSURE

The dissipating of excess pore pressure caused by pile sinking is one of the main factors result in time effect of ultimate bearing capacity of pile. This paper discusses the change rule of pile bearing capacity with time through the finite element simulation under the geological conditions of the pile foundation in the second phase project of the free port logistics processing zone in Dongjiang, Tianjin. It finds that the formula of pile bearing capacity about time effect in dredge fill can be used as reference for engineering use. It monitors the excess pore pressure at each observing point in order to verify the numerical simulation results. It discusses the change law of the distribution and dissipation of excess pore water pressure. Numerical simulation shows that the dissipation rate at the tip of pile can reach 97% 20d after pile sinking. The ultimate bearing capacity of pipe pile increases over time basically in accord with the dissipation of excess pore water pressure. It also introduces a formula of pile aging bearing capacity in dredge fill. Measured results show that the effective range of construction on dredger fill around the pile is 9-10 times the diameter of pile. The excess pore pressure increases with the depth increasing. The closer it from the pile, the greater the excess pore pressure is. The smaller the permeability coefficient of soil is,the more slowly the excess pore pressure dissipates.