Field permeability tests are used to evaluate the local hydraulic conductivity. Their interpretation requires knowing the value of a shape factor, c. Regular values for shape factors were obtained for fully saturated conditions in an infinite material. However, many tests are performed in unconfined aquifers, with a bottom impervious boundary, and partly unsaturated seepage. This paper questions the applicability of the regular c values to field conditions. It presents numerical ways to model field permeability tests in unconfined aquifers and deduce the c value, under steady and transient states, with partly unsaturated seepage. Two series of monitoring wells were analyzed and compared; they have either a filter pack or not. The influences of four variables (radial distance of the external boundary, dimensions and positions of the water injection zone, and aquifer material type) on the numerical c values were studied. The results show that the boundary radial distance markedly affects the numerical c value. Therefore, practical approaches were proposed by reconciling the numerical and realistic test conditions, to determine the representative boundary radial distances for each type of test model. Additionally, the numerical values are compared with the theoretical values of Bouwer and Rice (Water Resour Res 12(3):423–428, 1976) and Hvorslev (Time-lag and soil permeability in ground water observations, U.S. Army Eng Waterw Exp Stn, Vicksburg, 1951).

中文翻译：

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无限制含水层中渗透率测试的形状因子数值

现场渗透率测试用于评估局部水力传导率。他们的解释要求知道形状因子c的值。对于无限材料中的完全饱和条件，可以获得形状因子的常规值。但是，许多测试是在无底层的含水层中进行的，其底部不透水边界，且部分为不饱和渗流。本文质疑正则c值对现场条件的适用性。它提出的数值方法来模型场渗透性测试中承压含水层，并推导出Ç在稳态和瞬态下的数值，部分渗流不饱和。分析和比较了两个系列的监测井；他们有没有过滤器包。研究了四个变量（外边界的径向距离，注水区域的尺寸和位置以及含水层材料的类型）对数值c的影响。结果表明，边界径向距离明显影响数值c。值。因此，通过调和数值和实际的测试条件，提出了实用的方法，以确定每种类型的测试模型的代表性边界径向距离。此外，将数值与Bouwer和Rice（Water Resour Res 12（3）：423-428，1976年）和Hvorslev（地下水观测中的时滞和土壤渗透率）的理论值进行了比较，美国陆军工程水务局（维克斯堡，1951年）。