Laboratory and Field Investigations of Dynamic Effects in Soil Water Retention Curve

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Project title

Code/計畫編號

MOST104-2116-M019-005

Translated Name/計畫中文名

以砂箱實驗與現地試驗探討動態效應下之土壤保水曲線

Project Coordinator/計畫主持人

Yung-Chia Chiu

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Institute of Earth Sciences

Website

https://www.grb.gov.tw/search/planDetail?id=11486943

Year

2015

Start date/計畫起

01-08-2015

Expected Completion/計畫迄

31-07-2016

Bugetid/研究經費

1921千元

ResearchField/研究領域

地球科學
水土資源保育

"未飽和層土壤為一多相系統，其複雜之物理與化學反應環境，使得未飽和層內流體流動特性與溶質傳輸機制至今仍無法完全釐清。為解析未飽和層土壤內流體之流動情形，土壤保水曲線扮演相當重要之角色，然而過去之研究指出，土壤保水曲線之量測與計算均在靜態或穩態的狀況下獲得，並未考慮動態效應下之情形，所描繪的毛細張力與飽和度關係是否有充分的代表性有待考慮。有鑑於此，本專題計畫驥望藉由室內砂箱實驗與現地試驗進行動態土壤保水曲線與遲滯效應現象探討，在室內實驗方面，透過邊界條件的改變及土壤粒徑大小的更換，探討毛細張力、土壤飽和度、含水量變化率及動態常數間之相關性，嘗試以定量的方式推導其關係式，並搭配數值模擬進行實驗結果與理論之驗證，在現地試驗方面，藉由人工降雨與蒸發散之方式，進行現地動態土壤保水曲線描繪。本專題研究亦驥望利用動態露點潛勢分析儀，分析土壤樣本之遲滯效應現象，並將分析結果與室內砂箱實驗及現地試驗結果進行比對，探討尺度差異所造成的影響。本專題計畫期望經由一系列之試驗，完整建立動態效應下，毛細張力與飽和度之關係，嘗試探討動態效應之理論基礎及產生機制，期望提供往後未飽和層水文地質調查與污染整治之資訊及建議。""The unsaturated soil is a multi-phase system and the embedded physical mechanisms and chemical reactions are very complicated. The characteristics of groundwater flow and mechanisms of mass transport are still ambiguous so far. In order to fully understand the flow and transport in the unsaturated zone, the soil water retention curve plays an important role in description of water flow. However, the measurements and calculations of soil water retention curve are usually obtained under the static condition or steady state (equilibrium), in which the dynamic effects (non-equilibrium) are not considered, and the obtained relationship between capillary pressure and saturation is skeptical. Therefore, the sandbox experiments and field tests will be conducted to discuss the dynamic effects in the soil water retention curve and hysteresis effect in this study. In the laboratory, the relations between capillary pressure, saturation, the rate of change of water content, and dynamic constant will be evaluated through different setting of boundary conditions and different sizes of particles. The empirical relationship will be developed quantitatively and numerical simulations will be implemented for the cross validation. In the field, the tests will be conducted to describe the soil water retention curve through the rain simulator and artificial evaporation. Besides, the dynamic dewpoint potentiameter will be used to analyze the hysteresis effect of soil samples, and its results will be compared with the results obtained from sandbox and field experiments. The effecting of heterogonous on hysteresis will be also addressed. Finally, through a series of experiments, the relationship between capillary pressure and saturation under the dynamic effects will be established, and the associated theories and mechanisms will be discussed. The works developed in this study can provide as reference tools for the hydrogeological investigation and contaminated site remediation in the future."

Keyword(s)

毛細張力
飽和度
土壤保水曲線
遲滯效應
砂箱實驗
數值模擬
capillary pressure
saturation
soil water retention curve
hysteresis
sandbox experiment
numerical simulation

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Laboratory and Field Investigations of Dynamic Effects in Soil Water Retention Curve

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