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第45期 |
工程案例探討 |
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王劍虹 |
1994/03/01 |
90 |
無庫存
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| A THOUGHT FROM A SOFT GROUND EXCAVATION CASE |
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| 蔡錦松 |
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| 軟弱地盤、深開挖、新生地 |
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| 台北基河路災變提供深開挖工程檢討反省的機會。本文目的在於從此單一事件中記取教訓，累積經驗。文內將災變可能相關之因素歸結成專業技術、工程規劃以及地層本質三個方面來討論。其中，在專業技術方面，強調以安全監測來輔助工程進行。工程規劃方面，則認為地質調查應以適當之方法，取得可靠的數據資料。至於軟弱地盤狹長型基地，則在長邊擋土部份，建議地盤改良措施。地層本質方面，則認為軟弱新生地地質的特性乃是造成深開挖困擾的主要原因。文章結論指出，經由案例檢討，萃取相關經驗，仍是軟弱地深開挖技術進步的原動力。 |
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| A great ground subsidence which caused by a deep excavation within soft soil is described in this paper. Experience learning from this case is the major concern. Discussion extends to design and construction skills, planning and insitu geological conditions. The importance of construction monitoring is first mentioned for the safety of excavation. Secondly, proper insitu tests such as cone penetration test and wine shear test which are suitable for soft ground exploration are proposed. Thirdly, ground improvement is recommended for slender site especially with soft soil beneath. Finally, the paper indicates that the unstable characteristic of newly filled land on weak formation is the major concern for the current case and thus needed to be further studied. The conclusion is that the useful experience obtained will not only help similar works in the future but also raise the desire to understand the deep excavation within soft ground. |
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| A POST-STUDY ON THE STABILITY ANALYSIS OF AN EXCAVATION WITHIN SOFT GROUND |
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| 蔡錦松 |
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| 穩定分析、深開挖、不排水剪力強度、地盤改良 |
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| 新生地軟弱地盤深開挖之隆起穩定分析是本文討論重點。內容以討論民國八十二年九月二十六日於台北市基河路所發生的工程案例為主。該案例具有典型軟弱地盤深開挖隆起破壞之潛在條件。本文暫且不論及施工方面之可能因素，單就原設計穩定安全因數2.29前提下，重新檢討現地軟弱層土壤強度。首先指出原先以摩耳－庫倫型式所表示者應予以修正，接著推論舊基隆河道新生地，地表下10至35公尺間沈泥質黏土之不排水剪力強度應為：Su＝3.0＋0.16（D－10）t／m2。式中D為地表深度，單位為公尺。依據日本建築學會1974年修正公式重新驗算，得原設計之穩定安全因數為0.99。另外，由新的強度值來分析，欲滿足安全因數1.2之要求，連續壁貫入深度須達34公尺，較原先之24公尺，多10公尺。建議另以適當之地盤改良技術，來減少所需之貫入深度。 |
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| The stability of deep excavation within soft ground is the major concern in this paper. A case study describing a great ground subsidence happened in Taipei is presented. This case mentions a deep excavation in a soft soil site which was once an old river bed. A stability safety factor 2.29 was perviously proposed; but somehow was not proven in real construction. Important factors which influence analytical results are thus studied for this particular case. The new in-situ undrained shear strength, Su=3.0+0.16（D-10）t／m2, is then proposed for the soft soil between 10 and 35 meters in depth（D）. The stability analyses first indicate a different safety factor 0.99. Secondly, instead of the original 24-meter diaphragm wall, a new one with 34 meters in length is found to fullfill the requirement of safety factor 1.20. Ground improvement is thus recommended to reduce the required length for the new diaphragm wall. |
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| BUILDING PROTEVTION AND INSTRUMANTATION FOR EXCAVATION-A CASE STUDY |
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| 陳柏序、蘇鼎鈞、陳明山 |
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| 鄰房保護、地質改良、監測系統 |
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| 大地工程師對於在軟弱粘土層進行之深開挖工程？應綜合考量開挖穩定性、支撐系統安全及鄰房保護等問題，必要時則需進行地質改良工程以減少擋土結構之變位量，及其衍生之地表沈陷和鄰房傾斜情形。本文主要介紹位於台北市天母地區某深開挖工程案例，因該基地土層極為軟弱，影響基礎開挖工程甚鉅，經評估連續壁變位量可能達19公分左右，故進行地質改良工程以減少連續壁變位量，其改變方法包括水泥高壓噴射樁，扶壁式改良（SMW工法）及土釘等施工方式。監測結果顯示實際連續壁變位量僅在l至2.5公分左右。另由於本工程施工中採用深井之強制抽水方式，導致粘性土層之壓密沈陷，惟大部份呈均勻沈陷現象，並未有鄰房損壞之間題發生。 |
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| For deep excavation in soft clay, the geotechnical engineer has to consider the stability of excavation, the safety of bracing system, the protection of adjacent structures, and so on. In certain cases, soil improvement techniques may be required in order to reduce lateral displacement of the retaining structure, subsequent ground settlement and tilt of adjacent structures. This paper describes a case history of deep excavation in very soft clay in Tien-Mu, Taipei. Soil improvement methods including jet grouting, soil mixed wall as well as soil nail have been employed to reduce lateral displacement of the diaphragm wall. The maximum lateral displacement of the diaphragm wall was estimated to be 19em if no soil improvement were employed. With soil improvement, lateral displacements less than 1 to 2.5cm were monitored. However, pumping from the artesian layer existing below the excavation level induced
consolidation of the soft claylayer. Fortunately, because of the uniform settlement, no damage to adjacent buildings was observed. |
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| A CASE STUDY OF 90M DEEP CYLINDER SHAPE SLURRY WALL CONSTRUCTION |
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| 鍾毓東、陳福成、余明山、柯允華 |
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| 連續壁、端版、穩定液、脫水機械、廢液處理、強塑劑、特密管、完整性試驗、混凝土側壓、施工管理、混凝土強度 |
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| 本文整理國內極特殊之90m深圓筒型連續壁案例，特別針對施工方法、工率及品質管理，加以紀錄分析。連續壁之混凝土強度，依深度由上而下依次為300kg／cm2、450kg／cm2及300kg／cm2三種強度，以承受隨壁體深度變化之彎矩，此設計觀念在國內極為罕見。分割單元中，公單元長度長達10m，仍能維持壁溝穩定，為本工程特色之一。開挖作業採用抓斗式MHL及鑽掘式BW兩種開挖機並用，對於開挖方法、接頭清洗及底泥清除方式，開挖效率與垂直精度，文中均詳加介紹；其中開挖垂直精度在千分之一以內，水準極高。穩定液在開挖過程中，扮演極重要角色，文中針對穩定液之配比、處理流程、品質檢驗、如何調整穩定液以節省成本、及如何處理廢液以達環保要求，均詳加闡述。同時，有關穩定液生產量及廢液處理使用之材料量相對於開挖土方量之比值，亦作整理，可做為成本分析之參考。其次，對於鋼筋籠吊裝及混凝土澆灌作業之方法及工率，亦加以詳實紀錄並統計。最後，探討混凝土之強度及其特性，發現現場鑽心取樣強度遠高於標準試體強度，平均比值約為125％～145％。 |
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| A case study of 90m-deep cylinder shape slurry wall construction, which break many local records of slurry wall construction, is illustrated in this article. The contents focus on the construction method, construction efficiency and quality control. The concrete strength along the depth of slurry wall, is designed to be 300kg/cm2, 450kg/cm2 and 300kg/cm2 corresponding to the variation of moment distribution. Such design concept is rare in local practice. Also an outstanding record of the construction is when the B element reaches 10m, the longest element ever used in local construction, the excavation trench remains stable.
Both clam-shell type MHL machine and drilling type BW machine are utilized to excavate the same element at the different depths. The excavation sequence, joint cleaning, slime treatment, excavation efficiency and the vertical accuracy are described in detail.
As commonly known, slurry always an important role in slurry wall construction, therefore part of this article is contributed to full discussion of the production procedure of slurry, which includes mixing proportion, quality control, quantity adjustment, and waste treatment. Mean while, the production of slurry, the material consumed for slurry and waste slurry treatment and the excavated soil volume of slurry wall are compared, so that the cost analysis and quality control can be refered in future projects related to slurry wall construction.
In addition, a detailed record and statistics on the methods and efficiency of rebar cage insertion and concrete placing are also discussed in the article. In the end, the concrete strength and its characteristics are studied and it is found that the strength of the in-situ cored sample is higher than that of the cylinder sample with a mean ratio of 125%~145%. |
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| PIPE JACKING FOR A PIPE-ROOF PROJECT CONSTRUCTED BELOW GROUND WATER TABLE |
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| 廖洪鈞 |
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| 推管作業、管幕工程、粉土質砂土、地下水 |
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| 本文將以地下水位下管幕工程之推管施工作業為例，比較地箭工法，土壓平衡式推管工法，和泥水加壓式推管工法等三種推管方式在高地下水位下（水實約在4.5m～9m之間）粉土質砂土層中施工之適用性，同時，對於不同推管方式，在施工過程中所遭遇之困難及排除方式，也將於文中加以討論。 |
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| A Pipe-roof project was constructed within the silty sand layer of Tapei Basin and under a water head ranging from 4.5m to 9m. Totally, three types of pipe jacking methods, namely, the earth arrow method, the earth pressure-balanced type shield method, and the slurry-balanced type shield method, were adopted for this project. This paper will compare the suitability of these three methods for this particular project. The difficulties encountered during the pipe jacking process will be highlighted and the measures taken to deal with the problems will be discussed also. |
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| THE DESIGN AND CONSTRUCTION OF THE PING, LIN PILOT TUNNEL IN TAIWAN |
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| 劉弘祥、張龍均 |
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| 導坑、隧道鑽掘機、鑽炸法、地下支撐、隧道計測、地工試驗 |
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| 坪林隧道導坑為坪林主隧道施工前之地質探查隧道，其目的在於探查沿線地質構造及地質弱帶、辦理地工計測及試驗、瞭解隧道鑽掘機（TBM）對不同岩體之鑽進行為、提前排除主隧道周圍之地下水、預先處理主隧道之地質弱帶及提供主隧道施工期間之輔助通道等。本文首將敘述本工程之內容與地質之概況。續對於工程設計之考量將詳加敘述，諸如洞口佈置與邊坡保護、斷面佈置、支撐設計、隧道計測、地工試驗及地質調查等。由於本工程是國內首次採用TBM開挖隧道，針對此工法選擇及機具規格之擬訂亦加以說明。最後將記錄本工程於鑽炸階段與TBM階段之施工成果，並探討特殊問題發生之原因與處理經過，以供工程同好參考。 |
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| The Pinglin Tunnel of Taipei-Ilan Expressway Project in Taiwan, at 12.9km, will be the longest 2-lane vehicle tunnel in Southeast Asia and the third longest one in the world. The Pinglin Pilot Tunnel（φ=4.8m）, which is located between and slightly below the two main tunnels（φ=11.8m）.
The functions of pilot tunnel are subjected to obtain parameters on geological conditions, to pretreat poor strata and predrainage groundwater, to experience the TBM in difficult ground and to serve as auxiliary tunnel during and after construction of the two main tunnels. The pilot tunnel was commenced in August 1991 by drill & blast method from the east portal, while the TBM was under manufactured. The TBM was transported to the job site in September 1992. After erecting was slided to the face, the TBM started to bore in November 1992. It is expected to go quite ahead the main tunnel. In this paper, the contents and geological condition of this project will be introduced briefly first, then will describe about the design of this project in details such as the slop protection and structure design for the portal area, the design of cross connection of the tunnels and the choice of ground support, tunnelling measurement, and geotechnical tests. In addition, it will express the primary specification of TBM and merit of construction especially in encountering the fractured and water contented ground. |
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| SOIL AND WATER CONTAMINATION DUE TO OIL LEAKAGE - A CASE HISTORY |
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| 陶正綱 |
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| 土壤污染、浮油回收、污染整治 |
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| 地下油槽及油管洩漏造成的土壤及地下水污染，已成為環工及地工的重要問題。本文主要就污染調查與整治之背景與作法作觀念性的說明，並介紹一個土壤與地下水同時進行整治的工程案例，以供工程界參考。 |
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| The contamination of soil and ground water resulting from the leakage of underground oil tank or pipe have become a major problem both in environmental and geotechnical aspect. This paper explains conceptually the method for the investigation and treatment of the contamination A case history is also presented herein for the reference. |
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