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Using the borehole permeameter to estimate saturated hydraulic conductivity for glacially over-consolidated soils
Hydrogeology Journal ( IF 2.4 ) Pub Date : 2020-04-17 , DOI: 10.1007/s10040-020-02149-3
J. Scott Kindred , W. Daniel Reynolds

The borehole permeameter (BP) method was developed in the 1950s by the United States Bureau of Reclamation to estimate saturated soil hydraulic conductivity (KS) in shallow boreholes completed above the water table. The approach has been improved over the years, and now accounts for flow due to pressure, gravity and soil capillarity. However, the BP method is calibrated only for normally consolidated soils and ponding depth (H) versus borehole radius (r) ratios (H/r) ≤ 22. The primary objective of this study was to recalibrate the BP method for use in glacially over-consolidated soils with H/r ranging from 0.05 to 200. Recalibration consisted of using numerically simulated steady BP flow for five representative glacially over-consolidated soils to update the BP shape function fitting parameters (Z1, Z2, Z3) for nine specified KS values and 15 test pit and borehole configurations. Four sets of fitting parameters were determined, which apply for H/r ≤ 20, H/r ≥ 20, soil with <12% silt content, and soil with >12% silt content. Relative to specified KS, the updated shape function parameters yielded BP estimates of KS with a maximum error of 13% and an average error of 3%, whereas the original shape function parameters (developed for normally consolidated soils and H/r ≤ 22) produced a maximum KS error of 94% and an average error of 23%. The numerical simulations were also used to develop criteria for estimating time required to achieve steady BP flow, and for correcting BP estimates of KS where steady flow was not achieved.



中文翻译:

使用钻孔渗透仪估算冰川过度固结土壤的饱和水力传导率

钻孔渗透率(BP)方法是1940年代由美国垦殖局开发的,用于估算地下水位以上完工的浅层钻孔中的饱和土壤导水率(K S)。这些年来,这种方法已经得到了改进,现在考虑了由于压力,重力和土壤毛细作用而产生的流量。但是,仅对正常固结的土壤和深水深度(H)与井眼半径(r)之比(H / r)≤22的BP方法进行了校准。本研究的主要目的是重新校准BP方法以用于冰河以上地区。H / r的固结土范围从0.05到200。重新校准包括对五个代表性的冰川过度固结的土壤使用数值模拟的稳定BP流,以更新BP形状函数拟合参数(Z 1Z 2Z 3)的9个指定K S值和15个测试井眼和井眼配置。测定四组拟合参数的,其申请ħ / [R  ≤20,ħ / [R  ≥20,土<12%粉粒含量,并用土壤> 12%粉粒含量。相对于指定的K S,更新的形状函数参数产生K的BP估计小号带的13%的最大误差和的3%的平均误差,而原来的形状函数的参数(对于正常固结土壤和开发ħ / [R  ≤22)产生的最大ķ小号的94%的误差和23的平均误差%。数值模拟还用于制定标准,以估算实现稳定BP流量所需的时间,并纠正未实现稳定流量的K S的BP估算。

更新日期:2020-04-17
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