垂直排水帶預壓密工法最佳化配置-以「北投士林科技園區填土整地工程(第一期)」為探討案例

The Optimal Setup for the Precompression Method Using Vertical Drains – A Case Study on the Land Filling and Grading Construction of Beitou Shilin Science Park (First Phase)

游百崧(Pai-Sung Yu)

指導教授 ： 何嘉浚

國立臺北科技大學/工程學院/土木與防災研究所/碩士(2014年)

https://doi.org/10.6841/NTUT.2014.00285

摘要

為因應E世代的來臨及世界產業結構的轉變，台北市政府繼內湖科技園區、南港軟體園區之後，於民國92年起將北投、士林地區廣達90公頃的洲美地區分兩期開發為北投士林科技園區，並於98年至101年間完成佔地32公頃之第一期整地工程，從鑽探資料顯示洲美地區土層中含有深厚之軟弱黏土，本園區採用預壓密垂直排水帶工法，以填土靜壓激發黏土層產生超額孔隙水壓後，再藉由排水帶縮短排水路徑排流之原理，來加速完成軟弱黏土層之先期壓密沉陷。
綜觀國內此類工法之研究僅對於壓密成效進行探討，至於排水帶配置之適宜性則付之闕如，本研究中將引用上述案例資料進行垂直排水帶最佳化配置之探討，首先，透過監測數據圖解分析、壓密理論推算沉陷量、經驗曲線預測沉陷法迴歸計算等，評估壓密度及反算壓密度，再與幾個類似的大型工程案例比較而獲致現場與理論相應之合理推論，顯示出排水帶工法受到塗抹效應與井阻效應影響壓密速率，同時也發現砂黏土互層與壓密理論計算所得相近，深厚黏土層則差異甚大。
本研究將上述分析推論結果，採用PLAXIS有限元素數值程式進行建模分析，以軸對稱方式模擬排水帶有效影響範圍圓柱體，藉由參數調整及敏感度分析以了解各參數與井阻、塗抹效應之影響程度，並透過程式分析與實際曲線之驗證，求得排水帶有效影響深度。最終，本研究設定在不增加土方量及公共工程限定預算條件下，得到以排水帶打設深度20公尺、間距130公分採三角形排列方式為最佳化配置結果，並依據研究過程提出結論與建議作為二期工程參考。

關鍵字

垂直排水帶 ； 軟弱黏土 ； 壓密 ； 最佳化配置

並列摘要

In response to the forthcoming Generation E and the worldwide transformation of industry structure, Taipei City Government has attempted to develop the broad 90- hectare Zhoumei Area in Beitou and Shilin into Beitou Shilin Science Park since 2003 after the establishment of Neihu Technology Park and Nankang Software Park. The first phase grading construction (32- hectare) had been completed from 2009 to 2012. The geologic drilling data showed that solum in Zhoumei consist of thick soft clays. Therefore, Beitou Shilin Science Park adopted the precompression method using vertical drains, the filling hydrostatic method for producing excessive pore pressures, and then speed up the pre-compression of soft clays based on the concept of using vertical drains to shorten the drainage paths.
In Taiwan, related literature of this method mostly pivoted on the effects of compression. However, studies on the optimal setup of vertical drains were none. The current study employed the Beitou Shilin Science Park data to investigate the optimal setup of vertical drains. First of all, we presented graphical analyses of monitoring data, utilized compression theory, experience curve and regression analysis to predict subsidence amount, evaluated and reversely calculated the degree of consolidation, and then compared this case with other large constructions and achieved reasonable conclusions where facts complied with theory. The results showed that the compression speed of vertical drains method was affected by smear effect and well resistance effect and that interbedded sand clays were similar to the calculation results of compression theory but varied greatly with thick clays.
According to the aforementioned results, the current study adopted the finite element numerical software PLAXIS for modeling analysis and used an axial symmetric method to simulate the effective boundary of vertical drains. Parameter adjustment and sensibility analysis were provided to understand the impacts of each parameter, the smear effect and well resistance effect. We then employed software to analyze and verify the actual curve and obtained the effective influence depth of vertical drains. Eventually, with the attempt of not to increase the earth volume and public construction budgets, the current study came to a conclusion that the optimal setup of vertical drains is with 20-meter installation depth, 130-cm spacing in triangular placement. The results and suggestions concluded from the study may serve as a reference for the second phase construction.

並列關鍵字

Vertical Drains ； Soft clays ； Compression ； Optimal Setup

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