摘要
　　本文針對預製式垂直排水帶改良地盤之行為，提出了一套二維有限元素法的數值模擬程序，此模擬程序並考慮了垂直排水帶的塗抹效應與井阻效應的影響，而SAGE CRISP乃為本研究所採用之數值模擬程式。所提出的有限元素法之數值模擬程序分別實行應用在垂直排水帶改良之圓形土柱單元 (unit cell) 的分析上以及現地全尺寸之地盤改良行為的分析上，以此來驗證所提出之數值模擬程序的有效性。經由數值預測的結果顯示，對於Hansbo所提出之圓形土柱單元的理論解(Hansbo, 1981)與數值預測作比較，其趨勢結果相當的吻合。接下來，再進一步針對第二曼谷國際機場之參考區域實行全尺寸地盤改良行為之模擬分析，並將數值預測之結果與現地監測資料作比較，其比較項目包含地表沉陷、側向變形及超額孔隙水壓，比較結果顯示出良好的數值預測能力。
　　此外，根據本研究所提出之數值模擬程序來進行一系列的參數研究，包括排水帶安裝參數(例如: 排水帶施打間距及排水帶打設深度)、排水帶排水能力和土堤之填土高度。最後將上述一系列參數研究製作成排水帶改良地盤之設計圖表，以提供排水帶改良工程之參考。

ABSTRACT
　　A two-dimensional (2-D) Finite Element Method (FEM) simulation with a simulation scheme for smear effect and well resistance in Prefabricated Vertical Drain (PVD) improved ground was proposed and the computer program, SAGE CRISP, is employed through this study. The FEM analysis incorporated with the proposed matching schemes was performed on unit cell and full-scale PVD improved ground and to validate the effectiveness of numerical prediction. It was found that the numerical result appears good agreement with the theoretical solution of unit cell and field measurement that included the settlement rate, lateral movement and excess pore pressure of PVD improved ground of the Second Bangkok International Airport (SBIA) at reference section.
　　In addition, according to the posed numerical procedure, a series of parameter studies were performed on PVD installation parameters (such as PVD spacing, PVD installation depth), specific discharge capacity of PVD and specific fill height. Eventually, the parameter studies were analyzed to establish the design charts and to provide the reference for PVD improved ground.

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