Numeric Simulation Of Foundation Pit Dewatering Surface In Silty Sand In Hangzhou

With the development of city construction foundation pits are becoming bigger and deeper. Successful dewatering is a key to guarantee pit security in silty sand, therefore the calculation of dewatering surface is rather important. Groundwater seepage is three-dimensional for dewatering of foundation pits. Owning to complexity of boundary conditions the theoretical solution is difficult to calculation. On the other hand Numerical calculation has become conventional method. Although the results by numerical simulation are approximate, numerical simulation is not restricted in many ways such as the shape and property of aquifer, and overcomes many limitations of conventional analytical method. Application of numerical simulation into dewatering in foundation pits is promising.In the paper numerical simulation is applied into dewatering of foundation pit by finite element method. Meanwhile the capillary is taken into account. By the analysis of groundwater seepage field of foundation pit the calculation of dewatering surface is done.First the groundwater movement equations and continuum equations are derived, and accordingly the differential equations of groundwater steady seepage are derived. Meanwhile the influence of capillary on seepage is introduced, and the differential equations of unsaturated seepage are deduced. By the FEM software of ABAQUS groundwater seepage of dewatering in foundation pit is simulated numerically, and results separately give the influence on dewatering surface of different permeability coefficients, different inserting depth of Waterproof Curtain Wall and recharge system. Finally take China Water Museum for example three-dimensional groundwater seepage field is simulated. Owning to the asymmetry of hydraulic head boundary conditions the anisotropy penetration of soil layers is taken into account, so the different penetration coefficients of vertical and horizontal direction are separately given in the model. By comparison the simulated results basically accord with the observed results.