英文篇名
INTRODUCTION TO THE “ON-GOING DESIGN” PRACTICE OF NEW AUSTRIAN TUNNELING METHOD
作者
林真在
關鍵字
新奧隧道工法、現地設計、岩體分類、大地行為、計測、坑內觀察、施工過程
摘要
本文針對新奧隧道工法在山岳隧道的工程實務,嘗試做整體性的簡要介紹,內容包括岩體分類、計測、坑內觀察、及施工中之現地設計等四項。岩體分類方面,強調岩體類別的判定是以大地行為來分類,而不是以隧道全線的地質情況來分類,此與國內目前的作法大不相同。計測及坑內觀察項目上,說明計測資料及坑內觀察記錄,可用以觀察隧道開挖後,隧道周圍地層及支撐的力學行為,以及確定隧道是否已達穩定狀態。至於施工中之現地設計方面,則介紹現地設計工作的施行過程,強調隧道的結構行為,除了與隧道全線地質情況、覆蓋厚度、隧道斷面大小、隧道斷面形狀有關外,亦跟輪進長度、輪進時間、開挖面分割掘進方式、開挖施工品質、仰拱閉合時間、仰拱閉合距離、支撐構件的種類與數量、以及支撐構件的按裝時間與順序等等施工條件息息相關,施工期間,任何施工條件的調整,都是設計作業的延伸,都屬於現地設計的工作範圍。最後強調,有經驗的隧道專業人員在充分的支持及授權下,瞭解隧道施工過程的隧道行為,掌握隧道的穩定性,藉由施工條件的調整,可消除潛在的可能災害因素,使得隧道工程更安全、更經濟。
英文摘要
This paper briefly presents the “on-going design” practice of NATM (New Austrian Tunneling Method) for the mountain tunnels. “On-going design” process during construction, rock mass classification, in-situ observation and geomechanical measurements are the topics used to illustrate the way of NATM practice. All the four topics have one thing in common.: they are dealing with ground behavior.
Some high lights of these four topics are presented in the paper such as:
1. Ground behavior instead of geologic conditions is the basis of NATM rock mass classification. This is quite different from other current classification schemes such as RMR system(Bieniawski) or Q system (Barton,Lien and Lunde). 2. Geomechanical measurements and in-situ observations provide very useful daily information for an experienced site engineer to evaluate the tunnel behavior. With the help of daily construction process records, the site engineer is generally able to control the tunnel stability by means of the construction process adjustment on a daily basis. Consequently the site tunnel engineer can get rid of tunnel disasters or minimize tunnel failures provided he is authorized to do so. 3. The construction process adjustments include changes in round length, cycle time, quantities of support elements, sequence of excavation and installation of support elements, time and distance of invert closure after bench excavation … etc. For the time being, it has to be emphasized that experienced site tunnel engineers and skilled labors are needed in order to construct tunnel safely and economically.