台灣隧道工程老問題之新探討－軟岩之力學特性

New Exploration to Old Problems of Tunneling In Taiwan-The Mechanical Characteristcs of Weak Rock

鄭富書(Fu-Shu Jeng) ； 黃燦輝(Tsan-Hwei Huang) ； 林銘郎(Ming-Lang Lin)

《地工技術》 79期 (2000/06) Pp. 81-90

https://doi.org/10.30140/SG.200006.0007

摘要

台灣之隧道施工，常遭遇嚴重擠壓、抽心及剝落等災害，造成不必要之工程經費耗費及施工時間大幅拖延。針對隧道擠壓之工程災害，本文共蒐集4座國內隧道擠壓相關案例，對於擠壓段之主要岩性、覆蓋厚度、施工概況與處理方式等加以介紹。由於造成隧道擠壓問題之因素，可能係軟弱岩石之不良力學性質所致。因此本文整理歸納近年來軟弱岩石之力學研究結果，推斷軟弱岩石的遇水弱化行為、剪應力引致體積膨脹行為及顯著潛變行為，可能為導致岩石強度降低及大量的膨脹變形的主要因素。本文最後將實驗結果代入有限元素法中，進行隧道案例分析。由分析結果中可看出，當考慮此三種力學特性時，隧道變形量遠大於一般彈性或彈塑性之分析結果。由此可知，日後隧道設計、施工時，應對此三項力學特性仔細評估，以減少擠壓災害之產生。

關鍵字

隧道擠壓 ； 軟岩 ； 弱化 ； 剪脹 ； 潛變

並列摘要

In Taiwan, squeezing condition is encountered from time to time, especially while tunneling through weak rocks or faulted zone. This problem lasts over three decades, Based on experience of four squeezing tunnels in Taiwan, this paper investigates the phenomena and mechanism associated with tunnel squeezing with emphasis on the mechanical properties of rocks.Based on Jeng (1998), rocks with the following characteristics are most vulnerable to squeezing condition: wetting deterioration, shear dilation and creep of rock as well. These three mechanical characteristics of weak rock are presented in this paper. According to the experimental results, obvious strength reduction and excess deformation are observed. When these behaviors of rocks are incorporated into the analysis of tunneling, much more deformation is obtained, compared to the conventional elastic or elasto-plastic models.

並列關鍵字

squeezing tunnel ； weak rock ； wetting deterioration ； shear dilation ； creep