新型光纖光柵高解析監測技術於污染場址水文地質參數異質場調查

Application of Novel Fiber Bragg Grating Multilevel Monitoring System on Characterizing Hydrogeological Heterogeneity for a Contaminated Site

葉欣瑋(SIN-WEI YEH) ； 何彥德(YEN-TE HO) ； 王子賓(TZU-BIN WANG) ； 張良正(LIANG-CHENG CHANG) ； 董天行(TIEN-HSING TUNG) ； 王昱力(YU-LI WANG) ； 蔡瑞彬(JUI-PIN TSAI)

《台灣水利》 70卷1期 (2022/03) Pp. 33-45

https://doi.org/10.6937/TWC.202203_70(1).0003

摘要

求得整治場址高解析度的三維含水層參數場，以預測藥劑與污染團在含水層的移動路徑是非常重要的。傳統的水力試驗因均質參數場的假設，往往無法反映現地土壤之異質性。為了求得污染場址之水文地質參數異質場（水力傳導係數K與比儲水係數Ss場），本研究以水力掃描為基礎，發展新型三維參數場調查技術，此技術包含兩大部分：（1）光纖光柵（FBG）多深度觀測系統：此部分包含橡皮膜封層阻隔器與光纖光柵水溫水壓感測器（2）循序迭代推估器（Successive linear estimator，SLE）結合奇異值分解（Singular value decomposition，SVD）：本研究以SVD降低原SLE演算法中之參數共變異矩陣維度，以降低現地案例分析時之大量計算資源需求。本技術透過現地試驗驗證，以光纖光柵多深度測器搭配現地整治藥劑灌注進行水壓變化量測（水力掃描），再將量測水壓變化以SLE轉化為三維水文地質參數場，所得K場再與跨孔井下電阻率剖面比較，結果顯示兩者趨勢一致，可支持本研究方法之可行性。最後，本研究以推估參數場模擬藥劑灌注後的流向與無法抵達之區域，分析結果將可作為污染整治之重要參考，最終達到精準整治之目標。

關鍵字

水力掃描 ； 光纖光柵 ； 精準整治 ； 多深度觀測井

並列摘要

To access and predict the movement of the plume and remediation agent in the aquifers, it is essential to understand the detailed hydrogeological parameters fields. However, the unrealistic homogenous assumptions in traditional pumping and slug tests hardly convey these three-dimensional parameter fields accurately. To characterize the aquifer heterogeneity of contaminated site (hydraulic conductivity K and specific storage Ss), a new technology is investigated on the basis of Hydraulic Tomography (HT). The newly developed technology consists of two parts: (1) A multilevel observation well consists of rubber packers and fiber Bragg grating (FBG) piezometer and thermometer. (2) Integrating singular value decomposition (SVD) into successive linear estimator (SLE). This method reduces the dimension of covariance matrix of the parameters that need to be estimated. Thus, the SLE's computational loading could be reduced effectively. The proposed method is verified by conducting an HT field test through agent injection during a site remediation event. Besides the FBG experiments, a cross-hole electrical resistivity survey (CHERT) was conducted to understand the sediment structure of the study site, and the CHERT profiles are used to validate the estimated K fields. The results show that the obtained resistivity image profiles are consistent with the estimated K fields. Finally, we utilized the estimated K and Ss fields to simulate the movement of remediation agent. Once the spatial distribution of the remediation agent is obtained, the area where the agent is unable to reach could be observed, we can thus adjust the remediation agent injection strategy to guarantee the agent contact the plume.

並列關鍵字

Hydraulic Tomography (HT) ； Fiber Bragg Grating (FBG) ； Surgical Remediation ； Multi-Level Observation Well

參考文獻

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