成果專區 - 土壤及地下水污染整治基金補助研究與模場專案宣導網

專案基本資料

年度	103	專案性質	實驗性質
專案類別	研究專案	研究主題	底泥
申請機構	國立交通大學	申請系所	防災與水環境研究中心
專案主持人	林志平	職等/職稱	教授
專案中文名稱	現場底泥電學性質感測貫入器研發
中文關鍵字	時域反射法；現地貫入器；底泥
專案英文名稱	Development of a field penetrometer for measurements of sediment electrical properties
英文關鍵字
執行金額
執行期間	2013/11/25 至 2014/11/24
計畫中文摘要	由於國內各主要河川於相關法令公告後，每年應至少於豐水期及枯水期各進行底泥定期檢測及品質狀況調查，建立「底泥品質基線資料檔」，以便適時更新河川水體底泥的基線資料檔。相關底泥調查與量測需求，除現有規定之相關取樣標準作業可能受限於取樣空間代表性以及其作業效率，國內外研究計畫均初步建議配合地球物理調查方法，以可大範圍輔助底泥範圍、厚度，甚至污染潛勢等相關特性之調查，但目前其技術限制因子為探測深度以及實際量化(Quantification)方法。本研究的目的在於發展一現地可直接貫入底泥之感測桿，該量測系統具備容易組裝及操作的特性，有助於探討底泥厚度與對應之電學特性，並配合時域反射技術(Time Domain Reflectometry, TDR) 於時域分析的介電度、導電度量測優勢，以及寬頻介電頻譜量測方法研擬，據以作為電學探測結果解讀與量化分析的依據，並延伸至地球物理試驗結合，提供其電學性質參數率定與驗證使用，以可充分達到快速檢測底泥範圍、厚度與對應可能污染潛勢調查。根據現場驗證的經驗，本研究研發之 TDR 現場底泥電學性質感測貫入器具有高空間解析、可於高導電度環境施作以及現場簡單操作等優點，但根據目前之設計其仍有四點使用限制，其一，在底床為較堅硬之材料時以致無法貫入時，會有約 5 公分的量測盲區，其二，由於其具高空間解析因此其感應量測之空間較小，易受不恰當之貫入影響，其三，對於低視介電度(<35)的量測靈敏度較差，其四，目前不建議在延長桿無側向支撐時使其超過 2 公尺進行貫入，以避免感測器受損。建議未來在本研究基礎上再行加以改善。
計畫英文摘要	According to recent regulations, sediment properties of major rivers should be conducted at least once during wet season and dry season to establish the sediment quality data base and update the baseline for each major river. Current standard practice of sediment sampling may be limited in terms of spatial representativeness and working efficiency. Geophysical methods are often suggested to complement sampling for investigation of sediment coverage, thickness, and even pollution potential in large scale. However, current geophysical practice has limited investigation depth and lacks quantification approach. The difference in physical and electrical properties of sediment affects electrical current flow and electromagnetic wave propagation in sediment, providing the basis for the application of geophysical methods in sediment investigation. Therefore, there is a need to better understand the electrical properties of sediments to improve interpretation of geophysical methods. The objective of this study is to develop a field measurement penetrometer that is easy to assemble and operate for measuring sediment thickness and profiling electrical properties. The measurement will take advantages of time domain reflectometry (TDR) technique to simultaneously provide apparent dielectric constant and electrical conductivity estimation by time domain analysis. Wide‐band dielectric spectroscopy method will also be developed based on TDR measurement. Penetrometer measurements developed in this study will serve the basis for quantitative interpretation of electrical geophysical method and facilitate fast investigation of sediment coverage, thickness, and pollution potential. According to the experience gaining during field examination, the developed TDR penetrometer can easily provide high space resolution data even in highly conductive environment. However, 4 limitations should be considered in this prototype. First, 5cm blind zone would be in the bottom if the hard‐to‐penetrated bedrock existing. Second, un‐proper penetrating control would influence the results because of the small sampling volume. Third, sensitivity would be lower for measuring apparent dielectric below 35. Last, in case of buckling, the clear section for extending rods should be less than 2m. Further modification is suggested to optimize the TDR penetrometer

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