武汉地区某基坑二元结构地层渗透系数反演

Permeability Inversion of Dual Structure Formation of a Foundation Pit in Wuhan

武汉地区广泛分布二元结构地层,其渗透系数对于该地区基坑降水工程而言具有重要研究意义。依托该地区某基坑勘察期静力触探试验和抽水试验,采用最优分割法对二元结构地层进行了定量划分。基于此,建立了抽水试验的三维数值模型,结合该地区经验数据设计了正交试验,并对试验结果进行了回归分析,根据回归模型反演得出其中的含水层渗透系数,并对反演值正确性进行了评价。研究表明,研究区静力触探范围内可划分为5层,地下水位以下各层渗透系数反演值分别为:0.46,1.19,5.45,10.73,21.82m/d,且反演值可信度较高,与实际抽水试验计算值接近。

Dual structure formation is widely distributed in Wuhan. Its permeability has a great significance for dewatering of foundation pit in this area. Based on the cone penetration test and pumping test of a foundation pit in Wuhan, dual structure formation is divised quantitively with the optimum partition meth- od. According to this division result, three-dimensional numerical model of pumping test is established. Combined with the empirical data of this area, orthogonal experiment is carried out and orthogonal experi- ment＇s results are analyzed by regression method. Then aquifer＇s permeabilities are inversed through re- gression model. Furthermore, the correctness of permeabilities is evaluated. The study shows that there are five layers within the scope of cone penetration test in research area. There are five layers below the water table and the inversed permeabilities are as follows; 0.46 m/d, 1.19 m/d, 5.45 m/d, 10.73 m/d, 21.82 m/d. The inversed permeabilities have high reliability,and which is closed to calculation value of the actual pumping test.