目前的地下水整治方法多以垂直井進行，但因鑽設垂直井會破壞建築物，所以要解決建築物下的地下水污染問題，可在建築物周邊鑽設斜井，深入建築物下的污染含水層來進行相關的整治工作。含水層本身若存在一使地下水流動的區域性水流，當抽水試驗進行時，區域性水流會在抽水井周圍形成捕集區，捕集區內的地下水會被抽水井抽出。目前尚未有研究非受壓含水層中的斜井，在不同的井管設置和水文地質條件下，其捕集區變化的問題。本研究的目的是(1)分析斜井捕集區受斜井傾角、方位角、井篩段長度、定抽水率、含水層水力傳導係數垂直異向比和區域性水流梯度的影響。(2)利用線性疊加法，決定斜井的多井捕集區，並與垂直井的多井捕集區進行比較。假設斜井為一線源，本研究推導出捕集區的穩態解析解，得到以下五結論：(1)斜井傾角或是含水層垂直異向比越小，斜井捕集區的形狀在水平方向會向外延伸，垂直方向則會被壓縮。(2)斜井的方位角與區域性水流方向相同時，產生最大的捕集區範圍；方位角與區域性水流方向正交時，捕集區範圍最小。(3)斜井的方位角與區域性水流方向相反時，捕集區停滯點隨著區域性水流梯度增強，會越往上並朝井篩段的方向移動。(4)斜井捕集區的範圍與開篩段長度和定抽水率的大小成正比，與區域性水流梯度的大小則成反比。(5)利用斜井的多井捕集區解析解，決定在不同的斜井數量和井管設置下所產生的多井捕集區。相較於垂直井的多井捕集區，斜井可用少量的井數，以及較長的井篩段，深入建築物下的含水層，進行大範圍的整治工作，所以在解決建築物下之地下水污染問題的能力上，斜井比垂直井高。;It is rather impractical to install vertical wells inside a building for the sake of dealing with groundwater contamination under the building. Slanted wells, however, provide an alternative because they can be drilled with an inclination angle (with respect to the horizontal surface) from the edge of the building foundation to the target aquifer. The purposes of this study are (1) to investigate the influence of different hydrogeological conditions and well locations on the capture zone of the slanted well and (2) to determine the capture zone of the multiple slanted wells by using the linear superposition principle. A steady-state, analytical solution is developed for the three- dimensional (3D) capture zone created by a slanted well pumping under the influence of a uniform regional flow field of a constant hydraulic gradient. The aquifer is assumed to be unconfined, homogeneous with a vertical anisotropy ratio. Decreasing inclination angle of the slanted well or vertical anisotropy ratio compresses the 3D capture zone in the vertical direction while elongates its horizontal extent. The 3D capture zone is the largest when the slanted well is in the same direction of the regional flow, and the smallest when the slanted well is in the direction at a right angle to the regional flow. The stagnation point moves upward and closer to the slanted well screen when regional hydraulic gradient increases. The area of the capture zone is directly proportional to the well screen and the constant pumping rate, inversely proportional to the regional hydraulic gradient. A solution for multiple slanted wells is obtained which can be used to deal with practical conditions using more than one well to withdraw the contaminated groundwater below buildings that cannot be done using the conventional vertical wells.
