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第53期 |
都會區之深開挖工程 |
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蔡錦松 |
1996/02/01 |
90 |
無庫存
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| 謝百鉤、歐辛煜 |
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| 地盤改良，雙栓塞 |
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| 都市的現代化發展，使得工程技術面臨巨大的挑戰。如何在擁擠的都市空間進行地下工程 ，並避免影響或損害鄰近結構物，為當今都市施工重要課題。本文將介紹台北捷運施工所採用之建物保護方法，並評估其成效。結果顯示，建物保護措施可減少因施工所造成之影響，然而若保護工作施作不當，將適得其反。 |
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| The modernization and development of metropolitan areas push construction technology facing great challenge. How to construct underground facilities in a congested city without influencing or damaging adjacent structures has become an important issue. This paper introduces and evaluates several building protection methods which were employed in the Taipei MRT constructions. The result of evaluation indicates that the protection methods have reduced the construction-induced settlement greatly. However, the protection methods may cause serious side effects if they are not carefully applied. |
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| 蔡錦松、周立德 |
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| 台北盆地、深開挖、地表沉陷、經驗公式 |
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| 本文整理現有的各種深開挖引致之地表沉陷的經驗預測方法，以四個觀測良好的實際開挖案例，利用各種經驗預測方法計算沉陷量，再與觀測結果進行比較，確立各經驗預測法之適用性。研究結果發現，無論是凹槽型或三角槽型沉陷型態，Hsieh和Ou的方法均可得到很好的類比。最後本文以有限元素法分析開挖區外地表下不同深度的沉陷情形，並與觀測結果比較，根據分析及比較的結果建議地表下沉陷的預估方法。 |
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| This paper summarizes the current empirical methods for estimating ground surface settlements caused by excavation. The different points among the current empirical methods are discussed. Four excavation cases with well documented measurements are used to compare the suitability of these methods. The present study indicates that Hsieh and Ou's method can give good concordance with field measurements for concave type as well as spandrel type of settlement troughs. Besides, ground settlements at various depths behind the wall are studied using finite element method. Based on the analysis results with the field observations,a tentative method for predicting settlement at various depths is then proposed. |
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| 黃南輝、廖建智、范陳柏 |
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| 舊地下室、深開挖工程、都會區 |
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| 都市更新情況下，經常遇到正常深開挖工程進行前，必須將原有建築物遺留下來之舊地下室先行拆除的工作。由於都會區建物緊鄰，拆除工作往往影響到鄰近地盤，甚至造成鄰產損傷。本文主旨在於提供有效的施工方法，並從土壤力學中解壓-再壓的觀念，說明土壤變形之難恢復特性，進而討論拆除工作中，外力支承轉換過程的重要性。文章中並以兩處工地實地完成的成功案例，作為往後工程之參考。 |
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| Removing the basement of old building before normal deep excavation is a commonly met situation today for the development of urban renewing. The disturbance caused by destorying the old basement may affect or even further damage the adjacent properties surrounding due to the congested allocation of buildings. The present paper is to describe useful procedures for construction. The importance of loading support transformation by a neat construction procedure based on the unloading-reloading concept of basic soil mechanics is also included. Two cases are also presented to give examples of successful work for the current concern, and therefore to provide typical procedure that engineers can follow hereafter. |
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| 謝旭昇、程日晟 |
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| 連續壁設計分析、彈性基礎樑 |
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| 連續壁之設計分析牽涉土壤力學理論、支撐及連續壁之結構行為。但分析之假設狀況常與現場實際情形有所出入，因而導致不合理之設計結果。本文針對連續壁之基本設計假設進行探討，包括分析模式、土壤強度、地盤反力係數、水壓力、超載壓力、支撐預壓等，現場施工控制對連續壁行為之影響亦有所提及。基本上連續壁之設計仍須倚賴經驗，純理論之分析結果易生錯誤。 |
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| Design and analysis of diaphragm wall requires knowledge on soil mechanics as well as behaviors of strut and wall. The design is generally based upon assumptions that deviate a lot from practice, which may lead to erroneous results. This paper discusses the nature of a few design assumptions, including analysis model, soil strength, modulus of subgrade reaction, water pressure, surcharge loading, preload of struts,etc. The effects of construction control on the behavior of diaphragm wall are also addressed. Basically, the design must rely heavily on experience, or else it may be completely incorrect. |
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| 蘇信淵、彭嚴儒、朱 旭、陳鴻濤 |
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| 筏基、地盤反力係數 |
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| 目前大樓基礎大部份採用筏式基礎，而地盤反力係數為一重要之設計參數。基本上地盤反力係數並非純粹由土壤性質決定，設計上須同時考慮土壤及結構之勁度以為選擇之基準。本文列舉現行決定地盤反力係數之各種方法，並以案例顯示其間之差異。本文亦討論連續壁及結構勁度對整體分析之影響，作者並依本身之設計經驗提供一組地盤反力係數值以供參考。但在目前地盤反力係數值仍位有定論之狀況下，筆者建議筏基設計時進行必要之敏感度分析。 |
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| Most of the current high-rise buildings use raft foundation as their main foundation system, and the modulus of subgrade reaction (Ks) is considered as one of the essential design parameters. Basically, modulus of subgrade reaction is not just a soil parameter, it is affected by the structural stiffness as well. This paper lists various approaches for the selection of Ks；an example is provided for comparison purpose. The effects of diaphragm wall and structural stiffness is addressed, and the authors also recommend a set of Ks values for reference. For critical structural design, it is suggested that a sensitivity study on Ks be always carried out. |
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| 余明山、賴慶和、楊清源 |
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| 托底、地盤改良、荷種轉移 |
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| 台北市忠孝橋橋墩A15的基礎原係由16支直徑0.5公尺、長度35公尺之鋼管樁支撐，由於捷運隧道路線通過該橋墩下方，必須於潛盾隧道通過前對橋墩先進行托底工程及切除北側之6支鋼管樁。托底作業期間橋墩之容許沉陷量為10公厘。主要工程項目包括設置直徑1.2公尺、長度50公尺之基樁5支及深2公尺、寬1.5公尺之支承梁。並於新設之托底支承梁之樁及帽梁施作時，開挖深約8公尺。橋墩荷重轉移作業期間採用自動監測系統即時監控轉移過程。監測項目計有基樁、帽梁、千斤頂及橋墩之位移量，千斤頂荷重及以鋼筋計監測基樁荷重。觀測結果顯示轉移期間千斤頂最大總荷重達483噸，最大衝程約3公厘，基樁最大沉陷約0.2公厘。整個荷重轉移過程中，橋墩隆起約1.5公厘。而捷運南港線下行線潛盾通過期間，橋墩僅產生約1公厘之沉陷。 |
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| Pier A15 of Chunghsiao Bridge is founded on 16 steel pipe piles with a diameter of 500mm. Six of them blocked the way of two stacked tunnels of the Taipei Rapid Transit Systems and had to be removed before the shield machine passed under the pier. The bridge structure is a continuous prestressed beam. The settlement of the pier was limited to 10mm. A pit was made first to expose the pile cap and to provide sufficient headroom for subsequent operations. Five cast-in-place concrete bored piles were installed and cast into a load-transfer slab. The load from the bridge was transferred to these new piles by jacking the pile cap against this transfer slab before the cutting of the old piles. A total jacking force of 483 tones was applied. After all these six piles were cut, the transfer slab was structurally connected to the pile cap to form a composite cap and the operation was then completed. Instrument readings indicate that the pier heaved up by an insignificant amount of 1.5mm during underpinning. The settlements of new piles were only 0.2mm. The lower tunnel has been completed and the settlement of the pier during the passing of the shield machine was only 1mm. |
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