| 引用本文: | 王翔翔,程志龙,苏光辰, 等.测定时间对淮北平原砂姜黑土饱和导水率的影响[J].灌溉排水学报,2021,(12):136-141. |
| WANG Xiangxiang,CHENG Zhilong,SU Guangchen, et al.测定时间对淮北平原砂姜黑土饱和导水率的影响[J].灌溉排水学报,2021,(12):136-141. |
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| 摘要: |
| 【目的】探究测定时间对淮北平原砂姜黑土饱和导水率的影响。【方法】采用定水头法测定原状土（0.96 g/cm3）及其不同体积质量扰动土（0.90、0.96、1.10、1.20、1.30 g/cm3）在长时间序列下的饱和导水率（KS）。【结果】所有试验土壤的Ks随时间先迅速降低到达拐点然后缓慢降低直至稳定的规律，对于原状土而言初始KS值为88.4 mm/h，拐点处（时间为0.98 d）的KS值为5.0 mm/h，终稳定点（时间为12.94 d）的KS值为0.8 mm/h。不同体积质量扰动土随着体积质量的增大，初始KS值减小，到达拐点所需要的时间短，各个关键节点所对于的KS值与体积质量负相关。【结论】初步建议用定水头法测定砂姜黑土饱和导水率的时间为1 d。 |
| 关键词: 砂姜黑土；饱和导水率；干缩湿胀；定水头法；稳定时间 |
| DOI：10.13522/j.cnki.ggps.20190292 |
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| Saturated Soil Hydraulic Conductivity is not Constant But Varies with the Time It is Measured |
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WANG Xiangxiang, CHENG Zhilong, SU Guangchen, et al
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| Abstract: |
| 【Background and objective】Saturated soil hydraulic conductivity (KS) is an important parameter characterizing the ability of soil to conduct water. It is often assumed to depend on soil structure and is hence constant for a given soil. The objective of this paper is to validate to what extent this common practice is valid. 【Method】We took vertisol soil in Huaibei Plain as an example, and conducted a series of experiments using both undisturbed soil cores with bulk density 0.96 g/cm3 and repacked soil cores with bulk density in the range of 0.90 to1.30 g/cm3. For each soil core, we measured a time sequence of its saturated hydraulic conductivity (KS) using the constant-head method.【Result】The KS of both intact and repacked soil cores showed a rapid decrease followed by a slow increase as time elapsed from inception of the experiment. For the undisturbed soil, its initial KS was 88.4 mm/h, but reduced to 5.0 mm/h 0.98 day (the deflection point) after inception of the experiment. As time elapsed, it eventually settled at 0.8 mm/h 12.94 day after commencing the experiment. Similar pheromone was also found for the repacked soil cores, although the deflection time and the time for Ks to asymptote varied with the repacking density. In general, as the bulk density increased, the initial KS was smaller and it took less time for its KS to reach the inflection point. The KS measured at any time was negatively correlated with soil bulk density.【Conclusion】Contrary to what have been commonly assumed, saturated soil hydraulic conductivity does not appear to be constant but varies with the time it is measured. For the vertisol soil we studied, its hydraulic conductivity decreased first followed by an increase when time elapsed passing the deflection point though the time for the deflection to appear varied with soil bulk density. |
| Key words: vertisol soil; saturation hydraulic conductivity; shrinkage-expansion; constant head method |
