CALCULATION OF SETTLEMENT CONSIDERING UNSATURATED SOIL INFLUENCE ON THE DEWATERING OF FOUNDATION PITS

As the bottom of most foundation pits is below the underground water level, dewatering is necessary to provide a dry and safety environment for the construction before excavation. Dissipation of pore water pressure and increasing of the effective stress in soil cause consolidation of the soil and the depression-cone around the pits. These can bring the non-uniform consolidation settlement which would influence the roads, buildings and underground pipelines around the foundation pits. By ignoring the lateral displacement and the effect of the group wells, the effective stress principle of unsaturated soil was induced and the equation of the water-table depression was solved on the supposition of Dupuit presupposition. Then the settlement of the soil layers above and below the cone of water-table depression was calculated respectively based on the layer-wise summation method, and the actual settlement was the sum of them. Comparison of numerical simulation results with monitoring results of the engineering examples show that the calculation method is of practical engineering value.