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第42期 |
特殊地質之地工技術 |
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謝旭昇 |
1993/06/01 |
90 |
無庫存
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| DESIGN AND APPLICATION OF SOIL NAILING AS EXCAVATION RETAINING STRUCTURE |
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| 呂芳熾、周安之、謝旭昇、林永光 |
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| 土釘（Soil Nailing）為歐美最近二、三十年來所發展之現場土壤加勁技術（In-Situ Soil Reinforcement Technique），藉由密間距之加勁材（Inclusion）配合面版（facing），將現場土壤加勁形成一穩定之現場重力結構，如圖一所示，並增加土壤之抗剪強度，以抵擋因施工或其他因素改變土壤內之力系所造成之作用力。依Bruce，Jewell（1986）之描述，現場土壤加勁技術可區分為（1）土釘、（2）微型樁（Micropile）、（3）土釘筍（Soil dowel）三種，其使用之範圍隨土壤之坡度由陡至平緩而漸從土釘轉變為土釘筍，其間三種加勁材隨滑動面與加勁材之夾角不同而影響其受力行為，由土釘之拉力，至微型樁之剪力及彎矩，最後之土釘筍之剪力作用（Schlosser，1982）。而由圖二更可比較此三種現場土壤加勁技術異同之處。土釘雖是最近發展之工法，但已被廣泛運用於各種土木工程上，包括邊坡穩定、基礎開挖、橋台（Abutments）及隧道出入口處及其週邊之護坡工程，圖三即為土釘被運用於各種土木工程上之示意圖，其實國外亦有施工案例，將士釘運用瀕臨破壞或變形過大之擋土結構之修補（Remediation）加強工程上。本文將淺略介紹土釘之施工方式，土釘擋土措施之設計與行為，並簡略介紹一施工實例，將土釘配合噴漿運用於安山岩塊層之基地開挖，達到安全性與經濟性之要求。 |
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| Conventional excavation retaining structures such as diaphragm walls, sheet pile walls, soldier piles, etc., were found to be unsuitable for use in dense ground. In Taiwan area, andesite debris in northern Taipei and gravel in Taoyuan/Chungli may be regarded as dense ground, and soil nailing appears to be a viable alternative in these subsoil conditions. Soil nailing can be categorized as in-situ soil reinforcement technique, which utilizes closely spaced inclusions and facings to strengthen in-situ ground. This technique has found wide acceptance in such areas as slope stabilization, fuondation excavation, etc. Mechanism and design principles of soil nailing are addressed in this Paper, a deep excavation project with the application of soil nails is also presented. |
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| PLANNING AND CONSTRUCTION OF A DEEP EXCAVATION IN TIEN-MOU AREA |
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| 郭鵬志、蔡國基、郭晉榮 |
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| 台北市天母地區之深開挖工程為業主及施工者之最怕。中山北路七段附近地質為緊密安山岩塊堆積層，且基地皆位於狹小巷道內，動線極差，擋土結構施作困難。忠誠路一帶地質則為台北市最軟弱之黏土，擋土結構雖容易施作，但開挖時每因擋土結構變形過大造成鄰房損害。本案例之地層狀況兼具極軟及極硬之特質，基礎之規劃施工對工程參與者為一極大之挑戰，本文即記述其過程以供類似工程之參考。 |
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| Tien-Mou is located on the northern fringe of Taipei basin, and this area is notorious for its very soft clay and very dense andesite debris. Excavation in very soft clay inevitably induces large deformation of retaining structure, and adjacent buildings are often damaged as a consequence. If dense andesite debris were encountered, it would be very difficult to construct the required foundation or retaining structure. In either case, long delay of schedule is quite common. As for this particular project, soft clay and hard andesite were both encountered. Detailed site investigation and pile load tests were carried out in advance. Diaphragm wall was constructed with guide wall erected above ground surface to achieve trench stability. Dense andesite debris was trenched through with skill and patience. Soil improvement was also adopted to limit diaphragm wall displacement. |
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| A DEEP EXCAVATION NEAR HILL SLOPE |
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| 周建國 |
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| 本文旨在檢討及報告一個深開挖工程實際案例，而本工程案例的特點包括：
（a）基地座落於坡地邊緣，具有坡地地質之特性，如土質疏鬆，地下水豐富具流動性，岩層構造對工程安全造成重大影響等。
（b）本工程歷經失敗，善後處理至復工完成，其完整而坎坷之過程，值得工程界人士引為前車之鑑。
（c）深開挖工程已積極朝坡地發展，類似地工問題將不斷考驗工程界人士，已有之失敗及成功之經驗均同等珍貴。本工程第一次開挖之失敗原因，值得警惕，善後之果斷處理及復工方式則可供類似案例參考。
（d）本工程防治地下水上舉力，採用基礎底部消壓措施，費用最經濟且效果良好，其處理方式可供參考。 |
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| The booming land development industry had used up most of the good construction sites in recent years, new projects had little choice but to build upon marginal sites. This Paper documented a construction project situated near hill slope, where unfavorable subsurface and ground water conditions led to the total failure of basement excavation. In fear of damaging adjacent buildings, the excavation was swiftly backfilled, leaving steel struts and other equipments buried within. Extensive meetings were held between developers, designers, consultants and contractors to devise a remedial plan. The excavation was resumed and safely completed as a result of careful planning and tight construction control. |
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| DIAPHRAGM WALL CONSTRUCTION IN A VERY SMALL SITE |
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| 劉泉枝、謝昆璋、林永光 |
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| 近年來，國內都會區超高層建築蓬勃發展，緊鄰既有建築物新建大樓之情形幾已不可避免，大樓地下室之開挖危及鄰近建築物之問題遂接腫而至。為保護鄰房之安全，勁度高及擁有良好水密性之地下連續壁已成為國內目前最普遍之擋土結構方式。尤其最近正進行之捷運系統及鐵路地下化深開挖主體工程，均亦使用地下連續壁作為擋土結構。另國內都會區建築工程有一特色，即是將老舊之建築物拆除改建大樓。然因協調中無法達成利益上之共識，拆除建築物後之基地面積往往不大，而旁邊依然留有老舊房子，為求取更高之經濟效益之條件下又必須作深開挖工程構築地下室，旁邊之老舊鄰房依舊存在而必須在工程進行中加以保護，使之不致因開挖而產生太大之沈陷量及避免不必要之鄰房損壞糾紛，導致整個地下工程施工之困難度大幅增高。本文藉由一實際之工程案例，探討在一狹窄之基地範圍內，於不影響施工品質之條件下，如何分析及設計連續壁結構體，並在分析之過程中探討最佳之開挖工法，另外並介紹考慮在連續壁施作期間及基地開挖時，如何保護鄰房之措施，最後再由現場監測結果加以證實。 |
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| New construction sites in Taipei City are often acquired by demolishing old buildings. In most cases, the construction site is surrounded by fragile building. In order not to damage adjacent buildings, diaphragm wall is often selected as the retaining structure. The authors encountered a very small site in downtown Taipei, the traffic and site dimension made the construction of diaphragm wall very difficult, standard design and construction procedures were doomed to failure under such circumstances. Special measures including soil nailing and soil improvement were taken to ensure the safety of diaphragm wall construction and subsequent basement excavation. Layout of the construction site also required detailed planning, otherwise a jammed-up site would make the construction of diaphragm wall virtually impossible. |
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| PILING CONSTRUCTION OF DOWN-THE-HOLE HAMMER IN ANDESITE FORMATION |
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| 石 強 |
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| 台灣北部大屯火山羣地層中之堅硬安山岩塊，不但堆積緊密且其粒徑常在2、3公尺以上，而岩心單壓強度更高達1000公斤／平方公分以上，令土木建築工程中之一般基礎施工機械鍛羽而歸。在今日寸土寸金，工程不但必須進行且將愈挖愈深時，採用氣動潛孔錘（DOWN-THE-HOLE HAMMER）工法施工，不失為一解決方法。
目前國內針對堅硬地層之基樁鑽孔施工方式共計有人工挖掘及機械鑽掘兩方式。人工挖掘方式已行之久遠，惟自民國七十七年國內興起較廉價之機械鑽掘方式，以及逐年來之個人生命價值觀提昇導致從業人數銳減之影響，此一方式已逐漸式微。機械鑽掘方式國內常見的為油壓式或電動式全套管工法，即借搖管機，旋管機或震動機進尺套管，並另使用各類取土設備清除套管中之土石岩塊，兩相配合完成基樁鑽孔作業，或亦有於地層無崩孔現象時逕用取土設備鑽孔施工者。而另一種普遍見於美日歐等國之機械鑽掘方式即此氣動潛孔錘工法。以下章節介紹民國七十九年自美引進施工之SILVERDRIL氣動潛孔鑼，及其使用於台北縣淡水鎮兩處工地之安山岩地層基樁與排樁工程之施工情況及應用心得，提供工程界之參考。 |
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| As we know, large size down-the-hole hammer is one of the useful methods to solve piling construction problem in hard rock formation. Since 1990, the Silverdril's down-the-hole hammer has been imported form America and successfully used in two cases in andesite formation in Tamshui. This paper gives a brief introduction of the hammer and records the construction and application experience of the two case examples. |
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| THE APPLICATION OF STEEL FIBER REINFORCED SHOTCRETE IN MINGTAN UNDERGROUND POWER CAVERN |
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| 高呈毅、陳新火、李鴻洲 |
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| 為因應明潭地下廠房區特殊地質條件下之支撐需求，並迎合大地工程最新之設計與施工趨勢，明潭廠房首次在國內採用鋼纖維噴凝土（Steel Fiber Reinforced Shotcrete）做為廠房及變壓器室頂拱及上部側壁之永久性支撐，與傳統習慣採用剛性混凝土頂拱支撐之設計方式實有甚大之差異。由於國內缺乏這方面實際之施工經驗，加上明潭工程之工期十分緊迫，是以，由鋼纖維噴凝土最佳配比之探討、各項相關試驗之進行、施工規範之訂定乃至現場之施作，均由工地工程師在甚為有限之時間內一一克服並完成。本文將針對鋼纖維噴凝土之特性、使用材料、有關試驗及其實際施工之情形做一概略之介紹。 |
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| In order to cope with the geological conditions at the Mingtan power cavern, which needs a flexible support, for the first time in Taiwan, steel fiber reinforced shotcrete（SFRS）was formally introduced. Steel fiber reinforced shotcrete, prestressed tendons and rock bolts, form the permanent support of the roof and upper sidewalls of the Mingtan power cavern, which is of great contrast to the traditionally adopted rigid roof support design concept. This paper briefly describes the characteristics of SFRS, the materials used, the test results from both laboratory and field before and during the excavation of the power cavern. The stability of power cavern after the application of SFRS was indicated by the reading of monitoring instruments. |
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| DETERMINATION OF AQUIFER ANISOTROPY FROM PUMPING TEST DATA |
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| 余進利、李振誥、程繼民、費道格 |
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| 含水層導水係數之異向性可由現場抽水試驗資料分析得知，利用此方法至少需有四口井，一口為抽水井，另三口為觀測井，有時三口觀測井仍無法求得含水層導水係數張量，因此，需要有更多口之觀測井，當觀測井數超過三口時，則可用最小二乘法迴歸分析之。本文解析方法是以泰斯方程式與井函數為基礎，並利用Bear於1972年所提出之導水係數張量觀念。現場抽水試驗是於台灣中部某地區進行，該區共設有抽水井一口，觀測井五口。由抽水試驗所獲得之洩降與時間資料，經本文分析結果顯示，此五口觀測井經不同組配分析時，平均異向比（主要導水係數／次要導水係數）會有些許之政變，但主要導水方向則變化不大。為比較起見，也提出由傳統方法所算出之導水係數與貯水係數。 |
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| The horizontal anisortopy was determined from field test which requires at least four wells; one pumping well and three observation wells. However, three observation wells are not always sufficient to obtain the principal direction transmissivity. If more than four observation wells are used, the least squares method can be used to analyze the data. The analytical method which based on the Theis and well function equations, utilizes the transmissivity tensor concept introduced by Bear（1972）. The case study presented here is from a pumping test using six wells at a site near Central Taiwan. Our results show that, when analyzing different combinations of the five observation wells, the average anisotropic ratio（the ratio of principal transmissivity）varies somewhat, but the direction of the principal transmissivity remains virtually unchanged. For comparison, the transmissivity and storage coefficient, as determined by traditional method are also presented. |
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| DEW DEVELOPMENTS IN SOIL IMPROVEMENT TECHNIQUES FOR BUILDING FOUNDATIONS IN MAINLAND CHINA |
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| 唐業清 |
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| 由於大陸建設事業的迅速發展，建築地基處理新技術有了很大進展。在繼承、引進和吸收國外先進經驗的基礎上，開創了許多具有特色的新技術、新成果，本文將概括的介紹這些新進展。 |
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| To cope with the rapid growth of building industry in Mainland China, there are new developments and achievements in the techniques of foundation soil improvement. This Paper describes these techniques, namely: reinforeing soil system, dynamic compaction, construction-debris-pile, stone column, grouting, micropiling, preconsolidation with fabric drains and retaining structures for deep excavation. For each technique, the background and history of development are introduced. Discussion is based on results of research and practical experience of field applications of the various soil improvement methods. Some cases studies are also cited. |
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