中文摘要 本研究發展元素釋放法(Element Free Method, EFM)計算機程式來模擬地下水滲流的問題，並比較元素釋放法與Lagrange有限元素法程式SEEP在準確性與計算時間上之優劣。 Lagrange有限元素法在處理非侷限流時，需針對邊界條件作元素網格重建之處置，且初始狀況的網格與節點建立需花費較多時間。元素釋放法是基於移動式最小平方(Moving Least Squares, MLS)內差的觀念來處理定義域內節點資料之一種無網格(Meshless)的數值分析方法，只需離散節點的資料即可建立形狀函數，沒有節點與元素間關係之限制，因此可省下輸入資料的時間。 對於非滲透性結構物造成節點影響範圍的改變，本文採用通視原則修正節點搜尋的範圍，並採用權值調整法來處理積分網格非完全包含於定義域內之問題。對土壩滲流問題以不重新組立網格而改由增加節點的方式，依滲流線的邊界條件進行疊代計算。 ABSTRACT A computer code based on the element free method to simulate the seepage behavior is developed in this research. Comparisons, specifically on accuracy and efficiency, are made between the newly developed code and the Lagrange finite element program SEEP. In analyzing unconfined flow problems, remesh is general used in finite element code as is in the SEEP. Besides, construction of the initial element mesh for the input data file is more or less time consuming. Element free method is a meshless numerical technique based on the concept of Moving Least Squares, which interpolates the data of various nodal points within the domain to be analyzed. Shape functions, similar to those in the finite element method, are formed based on a base function and a weight function along with related nodal data for each reference point. Connectivity between nodes and elements is thus freed and saves efforts for the related input. The influence circle is sometimes obstructed by the boundary due to various geometry of analyzing domain and a rule of determining the nodal influence circle is developed. Gauss integration is used and its result is adjusted while the domain is not perfectly matched by the integration cell. An improved result is obtained by adding nodes on the line of seepage during iteration in simulating the seepage behavior of an earth dam.