山岳隧道軟弱地層開挖之個案分析

A Case Study of Tunnel Excavation in Soft Rock Ground

張文城(Wen-Cherng Chang)

《地工技術》 59期 (1997/02) Pp. 27-36

https://doi.org/10.30140/SG.199702.0002

摘要

北宜高速公路坪林隧道全長約12.9公里，共分為三條坑道，其中兩主坑直徑約13m，導坑直徑約5m。坪林隧道係由頭城端先以鑽炸法開挖約850m，爾後再以全斷面隧道鑽掘機開挖以貫通隧道。在以鑽炸法開挖的路段中，最重要的地質構造為寬約60m之金盈斷層，該斷層泥材料經挖開、解壓及吸水後極易膨脹瓦解，並可能有高膨脹壓力產生，因此隧道開挖時，其開挖順序與支撐便需有特殊之考量，並輔以灌漿補強工作及提高預估變形量，以避免開挖後開挖面入侵設計線。此外有系統之監測作業，亦為開挖過程重要工作項目之一。由監測結果顯示，開挖後仰拱噴凝土的儘速施作，以閉合隧道之支撐系統，為抑制隧道變形較經濟而有效之措施。

關鍵字

坪林隧道 ； 金盈斷層

並列摘要

The Pinglin tunnel of Taipei-Ilan expressway, including two main tubes and one pilot tube, is approximately 12.9 km in length. The diameter of the main tubes and pilot tube are approximately 13 m and 5 m respectively. The Pinglin tunnel was excavated approximately 850 m with drilling and blasting method from the Tou-Cheng portal firstly. Tunnel boring machine method will be adopted to complete the remaining section of the tunnel. The Chinyin fault with 60 m wide is the most important geological structure in the drilling and blasting section. The dialation behavior of the fault gouge material is very sensitive to the water, therefore the excavation sequence and support systems should be carefully studied. Some reinforced measures and more anticipated rock deformation also have been considered in order to avoid the excavated section intruding into the designed section. Systematic monitoring is also a very important task during the excavation. According to the monitoring results, the placing of the invert shotcrete to close the support system is the most effective and economic method to reduce the deformation of the rock mass after excavation.

並列關鍵字

pinglin tunnel ； chinyin fault