臺北都會區逆打開挖工程變形趨勢之研究

Taipei Urban Area Top-Down Excavation Project Deformation Trends

陳易一(Yi-Yi Chen)

指導教授 ： 陳水龍

國立臺北科技大學/工程學院/土木與防災研究所/碩士(2010年)

https://doi.org/10.6841/NTUT.2010.00416

摘要

由於都會區地狹人稠，寸土寸金，為有效利用有限的土地，都市建築遂有往天上及向地下發展的趨勢，超過地下30公尺以上的開挖也不斷地被挑戰。因應此地下發展的需求，地工技術也不斷地發展與挑戰傳統技術而往前邁進。地下開挖工法隨著使用目的與開挖深度演變，從早期淺開挖時採用的斜坡明挖或鋼版支撐開挖，到深開挖階段採用的連續壁工法，開挖施工方式也從順打工法發展到逆打（築）工法，甚或是雙順打工法等。為了爭取時效達到提早利用的經濟目的，工期已成為地下工法考量時的最大因素之一；另於都會區開發幾乎都與鄰房相距甚近或緊貼，進行地下施工時很難避免造成鄰損問題，故開挖施工及鄰房安全也是另一考量因素。基於工期及安全性考量，地下逆打工法已是都會區開發時被普遍採用的工法之ㄧ。
本研究以工程開挖深度，來探討施工時擋土壁體的變形狀況，及四周地面沉陷情形，以此判斷工程之安全性。若此兩項之最大變位皆能低於規範要求的標準，則可預言工程可滿足安全施工之基本要求。本研究蒐集了15個逆打深開挖的工程案例，以統計學的迴歸分析，來綜合探討最大側向變形量及最大沉陷量相對於開挖深度的關係。期望在以後的逆打深開挖工程，可以用此模式於擋土設施設計時簡便地事先來判斷出變形量，或研判施工現場壁體變形及地表沉陷量之安全監測數值的合理性。
本研究中之案例，其開挖深度介於6公尺至31.7公尺，故所得的迴歸分析式之應用，應在此範圍內為宜。對於開挖深度超過32公尺以上之工程，此迴歸分析式所推測之變位量應只可作為參考及趨勢預側之用。

關鍵字

逆打工程 ； 深開挖 ； 側向變形量 ； 沉陷量 ； 開挖深度

並列摘要

Urban areas are densely populated, and the cost of such lands tends to be very high. Skyscrapers and underground developments had become the trend for urban architecture. Underground excavations of over 30 meters are constantly being challenged. To meet the demands of underground development geotechnical engineering development had pioneered the way and constantly challenged traditional technologies. Underground excavation techniques had evolved with various project purposes and excavation depths, such as the slope open cut method or braced excavation utilized in earlier shallow excavations, and the diaghrams construction method used for deep excavations. Excavation implementation methods had also developed from bottom-up to top-down methods, or even dual bottom-up methods. In the interest of striving for swifter effectiveness of economical purposes, project schedule had become one of the main consideration factors for underground excavation methods. In addition, urban developments were often near or adjacent to neighboring buildings and were usually difficult to avoid the problems of causing neighboring damages. Therefore, the safety of neighboring buildings has also become a consideration factor. Due to considerations for project schedule and safety the underground top-down method had become one of the most prevalent methods for urban development.

The present study investigated diaghrams deformation conditions and settlement conditions of surrounding lands based on excavation depth, and evaluated the safety levels of the engineering projects. If the maximum deflection of these two items managed to be lower than regulation requirement standards, then it was predicted the project could satisfy basic engineering safety requirements. The present study gathered 15 top-down deep excavation case samples and used statistical regression analysis to jointly investigate the respective largest lateral deformation and the maximum settlement in relation to excavation depth. It was hoped that future top-down deep excavation projects can utilize this model during the diaghrams design stage to conveniently estimate deformation levels, or evaluate the justifiability of safety monitoring values of on-site wall deformation and ground settlements.

並列關鍵字

Top-down engineering, ； deep excavation ； lateral deformation ； settlement ； excavation depth ； monitoring management value

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