关键词: 长江Ⅰ级阶地, 分层抽水试验, 群井抽水试验, 渗透系数, 各向异性, 三维渗流分析

Abstract: The permeability coefficient of the aquifer in the first terrace of the Yangtze River in Wuhan is inevitably anisotropic under the effect of the sediment dynamics sorting and consolidation pressure of the overlying soil. Therefore, the dewatering design based on the isotropic permeability coefficient of aquifer and the hydrogeological parameters obtained from a single well and steady flow pumping test is inevitably different from the actual engineering. Based on the stratified pumping test, the group drilling pumping test and combined with three-dimensional numerical inversion simulations, the basic laws and characteristics of the aquifer hydrogeological parameters are concluded in the first terrace of Yangtze River in Wuhan. The permeability coefficients gradually increase from top to bottom and show anisotropy in different aquifers. The horizontal permeability coefficient is greater than the vertical permeability coefficient, and the ratios of them are between 1.6 and 2.6. The case study shows that the dewatering design of deep foundation pit made in accordance with the result of the anisotropy of hydrogeological parameters and the three-dimensional seepage analyses is much more approximate to the actual situation. In addition, this method reduces the project cost and minimizes the impact of foundation pit excavation on surrounding environments. Moreover, it is also conducive to save precious groundwater resources.

Key words: the 1st terrace of Yangtze River, stratified pumping test, group drilling pumping test, permeability coefficient, anisotropy, three-dimensional seepage analysis