於水井抽水引致地下水位洩降之理論與數值分析研究

Theoretical and numerical analysis of groundwater drawdown by pumping in wells

林姿沂(Tzu-Yi Lin)

指導教授 ： 馮道偉 ； 王藝峰

中原大學/工學院/土木工程研究所/碩士(2015年)

https://doi.org/10.6840/cycu201500757

摘要

由於單井抽水形成地下水位洩降的量測資料很少，可見過去對洩降曲線的相關研究極為有限，因此本研究探討單井抽水引起的地下水位洩降曲線的特性，期望所得成果可作為分析水井抽水造成土壤壓密沉陷量之參考資料。
本研究採用Theis公式、Thiem公式以及PMWIN數值程式分析於單井抽水造成之水位洩降現象，考慮的影響因子包括抽水量、抽水時間、滲透係數、流通係數、儲水係數及滲漏係數，將此等因子之值輸入上述三種分析模，試以計算其對地下水位洩降之影響。研究中以單層土層和多層土層兩種地盤進行參數分析，並分析三個現地抽水試驗案例。
依據研究結果，當抽水量愈大，則水力坡降也愈大，且距離抽水井愈近，水力坡降愈大，利用PMWIN計算之水力坡降比Theis公式小。初始水頭隨土層深度遞減時，阻水層井邊洩降量較少，洩降曲線影響範圍較大，初始水頭隨土層深度遞增時，阻水層井邊洩降量較大，洩降曲線影響範圍較小。阻水層對於完全貫入井井邊洩降比部分貫入井小。利用Theis公式在拘限含水層中，含水層厚度為30 m、滲透係數為7.2 m/d ，儲水係數為 0.0005、抽水量Q為1440 cmd及抽水時間t為 1440 mins，洩降量大於1 m的水平範圍在距離抽水井400 m以內，或是洩降量大於0.5 m的水平範圍則在距離抽水井712 m以內。這對分析地下水位下降造成地層下陷問題的意義是，抽水井鄰近土層的孔隙水壓減少較多(即有效應力增加較多)，因此土壤壓密沉陷量會較大。將PMWIN 在塔里木盆地與台中案例分析所得之洩降曲線與觀測值相近，在南投案例對滲透係數和抽水量做擬合分析，所得之洩降曲線與觀測值相近。

關鍵字

洩降曲線 ； 抽水試驗 ； 三維地下水模式

並列摘要

Since the formation of single-well pumping groundwater level drawdown of measuring little information, so in the past for drawdown curve related research is extremely limited. This study investigated the characteristics of the groundwater level drawdown curve caused by single-well pumping. This study investigated the characteristics of the groundwater level drawdown curve caused by single-well pumping. Hope can analyze pumping wells causing soil compaction settlement amount of reference material.
In this study, Theis and Thiem equation and single-well pumping water PMWIN analysis result of the drawdown phenomenon. Impact factors considered include pumping, pumping time, coefficient of permeability, transmissibility, coefficient of storage and coefficient of leakage. Impact of these factors on the groundwater level drawdown shall be calculated. Article use two kinds of single and multi-site soil parameter analysis, and analysis of three pumping test cases.
Based on the results, the greater the amount of pumping, the hydraulic gradient is also larger, and the closer from the pumping wells, the greater the hydraulic gradient. Calculation of hydraulic gradient use PMWIN smaller than Theis equation. When the initial head decreasing with soil depth, the well drawdown less aquitard, and a larger drawdown curve of influence. When the initial head with soil depth increasing, a large amount of aquitard the well drawdown and drawdown curve smaller sphere of influence. Aquitard for fully penetrating well the well drawdown than partially penetrating well little. Theis equation use in confined aquifer, aquifer thickness is 30 m, coefficient of permeability is 7.2 m/d 、coefficient of storage is 0.0005、pumping is 1440 cmd and pumping time is 1440 mins. Where drawdown more than 1 m at a distance of pumping wells within 400 m, or greater than 0.5 m drawdown place at a distance of pumping wells within 712 m. This analysis of groundwater drawdown caused by the subsidence problem in the sense that the pumping wells near the soil pore water pressure to reduce large (ie. large increase in effective stress), soil compaction settlement amount will be larger. The PMWIN in the Tarim Basin and Taichung case drawdown curve similar to that obtained with the observed value. In the case of Nantou coefficient of permeability and pumping do fit analysis, drawdown curve similar to that obtained with the observed value.

並列關鍵字

Drawdown curve ； Pumping test ； PMWIN

參考文獻

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