| 层状土毛细水上升过程中Lucas-Washburn模型评价及修正 |
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| 引用本文： | 郝瑞,施斌,曹鼎峰,孙梦雅,魏广庆.层状土毛细水上升过程中Lucas-Washburn模型评价及修正[J].水文地质工程地质,2018,0(6):84-84. |
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| 作者姓名： | 郝瑞 施斌 曹鼎峰 孙梦雅 魏广庆 |
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| 作者单位： | 1. 南京大学地球科学与工程学院，江苏 南京210023；2. 苏州南智传感科技有限公司，江苏 苏州215123 |
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| 基金项目： | 国家自然科学基金重点项目资助（41230636）；国家重大科研仪器研制项目资助（41427801） |
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| 摘 要： | 受界面效应影响，毛细水在层状土中运移规律还难以用描述均质土中水分运移规律的Lucas-Washburn（LW）渗吸模型进行描述。基于此，本文设计了层状土室内模型试验，采用分布式的主动加热光纤法（简称AHFO）监测毛细水上升过程。根据AHFO测试结果，进一步对LW模型进行了修正，提出了适用于描述层状土中毛细水上升规律的ILW模型，并对ILW模型进行了试验验证。试验结果表明:（1）当毛细水湿润锋抵达“黏土（下部）-砂土（上部）”界面时，会产生“毛细屏障作用”，从而导致上部砂土中毛细水含水率急剧下降；（2）“毛细屏障作用”由砂土和黏土中的基质吸力不均衡造成，基质吸力大小由含水率决定；（3）当毛细水湿润锋抵达“砂土（下部）-黏土（上部）”界面时，在界面处出现“反毛细屏障作用”，从而导致上部黏土层中的含水率比相邻下部砂土层含水率更高；（4）虽然常见的LW模型可准确预测均质土中毛细水上升高度及速率，但受“毛细屏障作用”和“反毛细屏障作用”影响，LW模型在层状土中失效；（5）相比LW模型，ILW模型精度更高，能够更加准确地描述层状土中毛细水上升规律。
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| 关 键 词： | 层状土 主动加热光纤法（AHFO） 毛细水 Lucas-Washburn渗吸模型 |
| 收稿时间： | 2018-04-12 |
| 修稿时间： | 2018-07-03 |
Evaluation and modification of the Lucas-Washburn model during capillary water rising in the layered soil |
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| HAO Rui,SHI Bin,CAO Dingfeng,SUN Mengya,WEI Guangqing.Evaluation and modification of the Lucas-Washburn model during capillary water rising in the layered soil[J].Hydrogeology and Engineering Geology,2018,0(6):84-84. |
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| Authors: | HAO Rui SHI Bin CAO Dingfeng SUN Mengya WEI Guangqing |
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| Institution: | 1.School of Earth Sciences and Engineering, Nanjing University, Nanjing, Jiangsu210023, China; 2.Suzhou Nanzee Sensing Technology Co., Ltd. Suzhou, Jiangsu215123, China |
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| Abstract: | In the layered soils, the common Lucas-Washburn (LW) model that describes water movement in homogeneous soil always loses effectiveness under the influence of interfaces between adjacent layers. To characterize vertical water rise under capillary force, a laboratory model test was performed, in which soil moisture content profiles were monitored using the actively heated fiber optic method (AHFO). Based on the results obtained using the AHFO method, the LW model was revised, and an improved LW model (ILW) model was proposed. The experimental results show that (1) when the capillary water wetting front arrives at a “lower clay-upper sand interface”, a “capillary barrier ” can obviously be observed, which makes the soil moisture content above the interface much less than that in the lower soil; (2) the “capillary barrier effect” is caused by the unbalanced matrix suction between sand and clay; (3) while the capillary water wetting front reaches a “lower sand-upper clay” interface, the “anti-capillary barrier effect” around the middle interface appears, which leads to the soil moisture of the upper clay much larger than that of the lower sand; (4) the LW model becomes inaccurate due to the impacts of the “capillary barrier action” and “anti-capillary barrier action”, and (5) compared with the LW model, the ILW model has higher accuracy in the layered soils. |
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