Research On Simulation Of Land Subsidence Caused By Urban Construction In Tanggu District Of Tianjin

The research area Tianjin city is belong to the typical inshore soft soil area. The soil has high moisture content, low intensity,high hole ratio, strong sensitivity, and clear structure effect. As the building become more and more higher and dense, the intensity and scale of the buildings'load are more and more bigger. To research the land subsidence caused by city construction in soft soil area has the grave significance for setting down the layout of the city.Land subsidence is the result of the underground water seepage and the under force distortion coupling in soil. It can also say that the soil under force distortion is aroused by seepage, and conduce the land subsidence, however the soil distortion change the pore-solids ratio and hydraulic conductivity in porous media, and it effect the water seepage and consolidation. So in calculating the seepage and sedimentation we should consider the coupling effect. When using the traditional analytic equation to calculate the problem of the factual aquifer, it should accord the Theis equation or other formulas'assumption, so it can only solve the planar 2-D flow model automatically. It is very difficult to fulfil the requirements of the formulas, So we should recur to numerical method.In response to the special geological condition there abroad distribute soft soil in Tianjin and the consideration of the drain consolidation, we can use the united calculate model with combining the stress-strain software SIGMA and the seepage software SEEP in the software GEO-SLPOE. We can choose the Cam-Clay model to simulate the stress-strain relationship of clay in Tianjin. The sedimentation of the clay ground includes those three parts: the initial sedimentation in undrained and volume invariableness saturated clay. the consolidation that is caused by the generation and dissipation of excess pore water pressure in saturated clay. the secondary consolidation is cause of the structure creep deformation.Compared with the natural ground, setting the same purdah which is economic and effective, adopting box base or changing the soft soil could reduced the maximum sedimentation effectively by 67.5% and 70.2%. The model has open quality, which can forecast sedimentation under different ground disposal mode and base form, and optimize the ground and the base type when acquiring the exact geological parameters.