| 不同沉积环境下马兰黄土孔隙分布与土水特征的模式分析 |
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| 引用本文： | 李同录,张辉,李萍,康海伟,葛书磊.不同沉积环境下马兰黄土孔隙分布与土水特征的模式分析[J].水文地质工程地质,2020,47(3):107-114. |
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| 作者姓名： | 李同录 张辉 李萍 康海伟 葛书磊 |
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| 基金项目： | 国家自然科学基金项目(41877242；41772278) |
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| 摘 要： | 为研究黄土的孔隙分布(PSD)和土 -水特征曲线(SWCC)与黄土沉积环境的关系，在甘肃榆中县和平镇和正宁县及陕西泾阳县等黄土台塬上部采取原状马兰黄土样，先测定其基本物理指标，再用压汞法测得各土样的PSD曲线，同时用滤纸法测得其SWCC。结果表明:和平镇马兰黄土的PSD曲线为单峰形态，泾阳县马兰黄土的PSD曲线为双峰形态，正宁马兰黄土的PSD曲线具有三峰特点。各土样的SWCC具有与PSD曲线相对应的阶梯状形态。SWCC与PSD曲线之间的对应关系，说明黄土的土水特征受孔隙分布的控制。获取3个原状样扫描电镜图像，微结构显示出这种地域性分异现象。对各采样点的气候环境分析表明，黄土PSD曲线之间的差异主要是由成土作用强弱决定的。将降水量与蒸发量的比值定义为蒸渗系数 (CEI)，作为刻画成土作用强弱的指标。发现当CEI≤0.3时，PSD曲线为单峰模式；0.3＜CEI≤0.4时，PSD曲线为双峰模式；0.4＜CEI≤0.5时，PSD曲线为三峰模式，相应的SWCC分别为单拐点、双拐点和三拐点模式。
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| 关 键 词： | 马兰黄土 土 -水特征曲线 孔径分布 成土作用 滤纸法 蒸渗系数 |
| 收稿时间： | 2019-09-17 |
Mode analysis of pore distribution and soil -water characteristic curve of Malan loess under different depositional environments |
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| Abstract: | In order to examine the relationship between pore size distribution (PSD) and soil -water characteristic curve (SWCC) of loess and its depositional environment, intact Malan loess samples were taken from the upper parts of Loess Plateau in Hepingzhen in Zhengning county of Gansu Province and Jingyang county of Shaanxi Province. On the basis of measuring physical indexes of specimens，mercury intrusion method was used to measure PSD curves of soil samples, and filter paper method was adopted to measure SWCC. The result shows that the PSD curve of Hepingzhen is unimodal; for Jingyang, the PSD curve is bimodal; the PSD curve of Zhengning sample is trimodal while the corresponding SWCC of each soil sample has a stepped shape. The relationship between SWCC and PSD indicates that pore distribution controls the mode of the soil -water characteristic curve. Scanning electron microscope (SEM) photographs of three samples were obtained and the microstructure also showed this phenomenon of regional differentiation. Climatic analysis for each sampling point shows that the difference of PSD curves of the Malan loess in different regions is determined by the strength of pedogenesis. In this paper, the ratio of precipitation to evaporation is defined as the coefficient of evaporation and infiltration (CEI), which is used as an index to describe the strength of pedogenesis. According to the CEI, the model of PSD is classified as follows: when CEI≤0.3, PSD is unimodal; when 0.3＜CEI≤0.4, it is bimodal; when 0.4＜CEI≤0.5, it is trimodal, and the corresponding SWCC is single inflection point, double inflection point and three inflection point mode. |
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