應用無網格廣義有限差分法於礦場地下水抽水洩降數值模式之不確定性量化

Quantifying Uncertainty of Subsurface Flow Model for Mine Dewatering Well using Meshless Generalized Finite Difference Method

陳尚潁(S.Y. Chen) ； 徐國錦(K.C. Hsu)

《鑛冶：中國鑛冶工程學會會刊》 66卷1期 (2022/03) Pp. 7-28

https://doi.org/10.30069/MM.202203_66(1).01

摘要

採礦工程與地下水息息相關，利用抽水井降低礦場區域地下水壓能夠增進採礦之效益。抽水洩降情形通常可以透過數值模式模擬，然而地下孔隙介質具有異質性，數值模型之參數採樣量測資料具有稀缺性，礦場管理者為評估效益與風險，應量化地下水流模式抽水洩降計算結果之不確定性。本研究提出使用無網格廣義有限差分法，結合序率地下水文學動差方程式法，以數值計算量化模式不確定性。並利用地質統計學克利金法實現動差方程法中的參數條件化。本研究設計八組情境以驗證提出之工具的準確度、並討論參數條件化對於穩態水流或暫態抽水洩降之模式不確定性減量效果。研究結果顯示串聯廣義有限差分法與動差方程式法，可以準確評估地下水流模式不確定性，參數條件化能有效降低地下水流模式不確定性，且在抽水洩降情境中減量效果尤其顯著。本研究提出之工具可應用於礦場排水管理、地下水資源保育、地熱能源或油氣資源開採。

關鍵字

礦場排水 ； 無網格法 ； 地下水 ； 不確定性

並列摘要

Mining projects are closely related to groundwater field. The use of pumping wells for mine dewatering can increase the efficiency of mining. The drawdown of pumping can usually be simulated by numerical models. However, the subsurface porous medium is heterogeneous. The parameter measurement data are scarce. Mine managers should quantify the uncertainty of subsurface drawdown models in order to evaluate economical and enviromental risks. This study proposed to use the meshless generalized finite difference method, combined with the moment equation method, to numerically compute the uncertainty of the subsurface flow model. Kriging method is utilized for conditioning sampled parameter in the moment equation method. In this study, eight scenarios are designed to verify the accuracy of the proposed tool, and to discuss the effect of parameter conditioning on the model uncertainty reduction of steady-state water flow or transient pumping drawdown. The research results show that the coupling generalized finite difference method and the moment equation method can accurately quantify the uncertainty of simulated hydraulic head. Parameter conditioning can effectively reduce the uncertainty of the model, and the reduction effect is particularly significant in the scenarios of pumping drawdown. The proposed approach can be applied to mine dewatering management, groundwater conservation, geothermal energy or oil and gas resource extraction.

並列關鍵字

mine dewatering ； meshless method ； groundwater ； uncertainty

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