Stability Evaluation Of Soil Foundations Beneath Artificial Hills In Tianjin

The project of forming hills by building wastes is the reuse of city wastes resources, which is the proposed project for gymnasiums used for 2008 Olympic Games, it also will become leisure squares for the citizens because of its graceful environment, even be a scenic spot in Tianjin.The "hill" site distributes rinse fill widely, which has high water content, high pore ratio, high compressibility and low strength. The other layers are typical soft soil in Tianjin, having good flexibility and high compressibility, so the stability of foundation in site is the main geo-engineering problem in the period of construction and using.Based on the Biot's consolidation theory of soft soil foundation and numeric computations model, the consolidation deformation of soft soil foundation, the press distribution of pore water and so on, which are analyzed by elastic-plastic finite element computational method, using the ANSYS finite element computational method to deal with consolidation effect, the paper evaluates the stability of soft soil foundation from the two points of view of stress and displacement, adopting the methods of safe mapping judgment, a side displacement ratio and effect stress route during the construction by adding burden step by step.The results show that the shallow silt soft soil in site has key function in foundation stability, especially, the ratio and increment of adding burden has leading effect. The stability of soft soil foundation can be improved by long static press time with low pore water press in foundation. Under the time limitation available for project, stack and press in advance it is the most economical, reasonable plan using reasonable break form and adding load plan. Also, the paper puts forward some useful measures, such as cleaning up slit, setting up counter-press flat, quickening up drainage and controlling the ratio of stack. The pore water pressure, lateral displacement, soil press and subsidence should be monitored in site during the period of construction and the analysis of site monitoring datum shows that there are lateral displacements and upheaval in the feet of hill because of added load. The methods and conclusions, introduced in the paper, are meaningful in practice for other analogous engineering during its design, construction, monitoring, etc.