水泥攪拌樁對連續壁的外擠影響案例評估

Case Study of The Effect of Cement Jet Grouting on the Outward Displacement of Diaphragm Wall

甘道良(Daw-Liang Kan)

指導教授 ： 張達德

中原大學/工學院/土木工程研究所/碩士(2006年)

https://doi.org/10.6840/cycu200600033

摘要

摘 要
關鍵字：水泥攪拌樁工法、軟弱土層、壁體變位
水泥攪拌樁工法常用於軟弱土層之深開挖工程，其目的在地質改良，提高開挖區內土壤強度及被動土壓力，改善地層抗液化之潛能、增加開挖面土壤的穩定性及抑制壁體變位量。本文之工程案例採擴張式水泥攪拌樁工法，即是於樁體內直接以水泥漿攪拌改良，樁體外土壤間接滲透改良，同時提高土壤之承載力與抗剪力，有效改良土壤抗液化之潛能與抑制壁體變位量。但水泥攪拌樁工法在灌漿的施作過程常發生對連續壁產生外擠與鄰近地表隆起之現象，其位移量可能高達十公分以上，嚴重時甚至導致壁體破裂，影響工程品質與安全。綜觀諸多文獻記載，基本上導致壁體外擠之主要原因並非灌漿所使用之壓力過大，而是因基地內土壤之體積因灌漿過程中無法順利迴漿排土或過度擾動周圍軟弱土壤，導致基地內土壤之體積及土水壓力因水泥漿之注入而持續增加，造成連續壁體與鄰近地表過度變位或壁體破裂。故施工品質監管與控制、施工的程序、施工機具的選擇，均非常重要。
本文之工程案例鄰近台北市捷運淡水線，對於工程品質之要求與安全上的考慮，尤其特別嚴謹。由工程案例上的監測結果與改良成效，顯示為一施工品質良好之案例。故本文作者針對此工程案例歷經多方面努力的訪察、蒐集資料與彙整，並參考國內外文獻與諸多工程案例之經驗，文中除詳細陳述現場觀測結果外，並以理論說明壁體外擠的機制，分析、評估與建議，提供諸位大地工程先進對類似工程案例之參考。

關鍵字

水泥攪拌樁工法 ； 壁體變位 ； 軟弱土層

並列摘要

ABSTRACT
Key words： Chemical Churning Pile、soft ground、diaphragm wall displacement
Chemical Churning Pile is often used in deep excavation projects on soft ground. The purpose is to modify the geotechnical properties, to increases the strength of soil and passive soil pressure in the district, and to improve the liquefaction resistance of in-situ soil. It not only increases the stability of excavation, but also limits the lateral displacement of retaining walls. The case of this paper applies the expansive model of Chemical Churning Pile to modify soil properties directly inside the pile, and indirectly by permeating the soil mass outside the pile. It not only modifies the liquefaction resistant potential and limits the amount of diaphragm wall displacement effectively, but also increases the bearing force and the shear resistance of soil. However, it is frequently found that may induce the lateral outward displacement of diaphragm walls and the heave of the surrounding ground. Its displacement degree may exceed 10 cm, even cause the wall body to crack and seriously affect the project quality and security. Consider a great deal of documents and record, the outward movement of diaphragm walls is not induced by the seemingly high grouting pressure in fact, difficulties in expelling waste disposal from the grout hole or disturbing the soft surrounding ground excessively that leads to expansion of the soil mass is perhaps the governing mechanism. It causes the wall body to crack and the surrounding ground to shift excessively. So the supervision of constructional quality and procedure, and the choice of construction machinery are of utmost importance. The project case of this paper is near the Tamsui Line of Taipei Rapid Transit System. The demand of quality and the consideration of security are especially very rigorous. By the monitoring result and the effect of improving on the case, shows the case of a construction with good quality. So the author of this paper makes great efforts in many aspects to collect the materials and gather together whole to this project case, consult the domestic and the foreign papers and a great deal of experiences of project case. The mechanism that leads to the outward movements of diaphragm wall is also delineated via a theoretical approach. Analysis, assess and propose, and offer to the advanced persons of geotechnical engineering be the reference for the similar project case.

並列關鍵字

soft ground ； Chemical Churning Pile ； diaphragm wall displacement

參考文獻

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