Research On Buoyancy Of Groundwater Based On Geological Conditions Of Wuhan

With the development of economy, the urban developed in the way of using the underground space, instead of expansion of plane. The effect of buoyancy of groundwater on underground structure was a very important factor, which restricted the exploitation of underground space. The method used to calculate the buoyancy should be reasonable, which was not only related to the safety of structure, but also related to the cost and time of construction, etc. Carrying out research of action of buoyancy was essential, for research results could be used to guide the anti-floating design, in order to ensure the safety of structure, save the anti-floating cost, and arrange construction time reasonably.Buoyancy of groundwater, was virtually the pore water pressure in soil, which produced pressure on structure basement, so, research on pore water pressure field was crucial. Conditions required to solve pore water pressure field were as follows: Firstly, hydrologic geology data of the construction site should be mastered through investigation, Secondly, type of groundwater, water head bound and seepage type of groundwater should be clarified based on data, Thirdly, based on seepage theory, adopting FEM software of seepage to calculate the pore water pressure field.Based on mechanism of groundwater buoyancy, combining with hydrologic geology data of Wuhan, the job was done and research results were obtained in this article were as follows:Firstly, hydrologic geology data of Wuhan was investigated, then, hydrologic geology characteristics of this area were summarized briefly, methods were summarized to determinate the bound of water head of Wuhan, and types of groundwater seepage were introduced in this article. Secondly, pore water pressure field was formed due to action of three elements, soil, groundwater and structure. According to different combination among soil, groundwater and structure, eight work conditions were defined in this paper. Then, based on theory of seepage, FEM software of seepage was applied to simulate these work conditions, research results included distribution of pore water pressure of soil layer and structure basement were received. Thirdly, buoyancy situation of an underground passage, located in Wusheng Road, a typical area of Wuhan, was analyzed in this article. Compared with buoyancy value calculated by traditional method, buoyancy value calculated by FEM software was much smaller. It could be found that limitations existed when traditional method was applied to calculate buoyancy value, for it could increase anti-floating cost.