於大台北都會地區進行大深度開挖工程時，往往需面對來自台北盆地下方景美礫石層的高水頭壓力，施工時常須採取抽降水措施，以免開挖工程遭受地下水壓的上舉破壞。而抽降水工法所需佈設的抽水井數量，受現地抽水參數(即儲水係數S和傳導係數T)之影響甚大。因此本研究以幾處台北捷運車站施工過程之抽水和景美層地下水位變化的現場數據，配合數值軟體(Processing Modflow Ver.11)進行車站抽水的數值模型建立和數值模擬工作，來探討以不同方式得到的水理參數，所算得的抽水量和地下水位升降量，與施工期間監測值之差異程度。再由變化水理參數數值的方式，率訂出最合乎該工地深開挖施工期間，地下水位變化監測值的水理參數，並與施工前的抽水試驗做具體的比較；同時，也可驗證現行模擬方式之可行性。未來若能再取得更多的抽水案例監測資料，就可以逐步地建構出台北盆地景美層之簡易抽水數值模型，為後續大深度開挖工程之抽水作業，提供一個較為可靠適用的設計參考資料。

As the nature of basin formation, the Taipei basin is basically filled with groundwater from a few meters below the ground level to the gravel layer at the depth. While doing a deep excavation in Taipei metropolitan area, it is necessary to lower the uplifting groundwater pressure coming from the underlying Jingmei gravel layer using the deep well pumping method. To design the deep well pumping, it needs to obtain the hydraulic parameters (T, transmissivity and S, storativity) as well as the subsoil profiles information of the site. But often, the values of hrydraulic parameters are not easily available for a certain site. Although these parameters can be obtained from well pumping test (single well or multiple wells), the test is seldom done due to high cost. Alternatively, the hydraulic parameters listed in the literature are usually used even though it is understood these parameters are site-specific. So the number of wells actually used on-site tends to vary greatly from project to project. This study uses Processing Modflow ver.11 numerical software to simulate the water pumping behavior of Taipei MRT underground station construction. The collected data of the pumping test (including the flow rate of the pumping well and the drawdown of observation wells etc.) were used to calibrate the input hydraulic parameters to the Modflow software. In addition, a parametric study was also carried out to evaluate the influence of varying hydraulic parameters on the number of pumping wells needed and the drawdown of groundwater level. It was found that the hydraulic parameters tend to vary among single-well pumping, multiple-well pumping, and numerical back-calculation. In general, the number of pumping wells calculated based on the single-well pumping test results is more than the other two methods. The back-calculated parameters from the monitored data can better fit the water level change during construction. If more well-pumping data can be available in the future, a more simplified numerical model can be gradually established for the Jingmei gravel layer; and used as a reference for the design of the deep well pumping in the Jingmei gravel layer.

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