鄰近水庫泥岩夾砂岩隧道之施工

The Tunnel Construction in the Mudstone Intercalated with Sandstone Stratum near the Reservoir Area

王文禮(Wen-Li Wang) ； 蘇灼謹(Jow-Jiin Su) ； 吳富豐(Fuh-Feng Wu)

《地工技術》 59期 (1997/02) Pp. 69-80

https://doi.org/10.30140/SG.199702.0006

摘要

本省西南部山麓地區約一千餘平方公里範圍為泥岩地層所覆蓋，佔台灣島土地面積約百分之三，其中有幾個重要水庫位於該區，隧道施工經過水庫附近時，常因其獨特的水文與地質性質造成大小不一的災害。此類泥岩地層在乾燥未風化狀況下，具有相當程度之強度，但臨近水庫之泥岩地層則因為長期受到水庫蓄水浸潤與風化之影響，易消散成類似土壤之岩體，其單壓強度甚低，僅有5至23kg/c㎡。尤其是泥岩間所夾之疏鬆砂岩容易形成水流通路，隧道施工時常因為砂岩湧水及泥岩遇水軟化之特性造成崩坍及抽心等災害，帶來極大的困擾。本文即針對上述現象，以烏山頭水庫送水隧道之工程施工為例，探討在此種特殊地質與水文條件中，隧道設計與施工所應考量之因素及因應之對策。

關鍵字

泥岩夾砂岩 ； 鄰近水庫 ； 湧水 ； 抽心

並列摘要

More than 1000 k㎡ mountain area in southwestern Taiwan (approximately 3% of the total land area) is covered by massive mudstone stratum. There are several important reservoirs in this region which make the conditions more difficult for tunnel construction. The adverse hydrological and geological conditions have caused many tunnel collapses during excavation.The mudstone has a certain degree of strength if it is fresh and dry. However, the water in the reservoirs will infiltrate into the mudstone by the intercalated sandstone which is highly permeable. Consequently, the mudstone will disperse into soil-like soft material with very low uniaxial compressive strength varing from 5 to 23 kg/c㎡. During tunnel construction, the excavation face will become unstable due to the water inflow from the sandstone layer and the softened mudstone will deteriorate causing serious collapses. This paper describes the lessons learned from the Wu-Shan-Tou reservoir water intake tunnel. The effects of water in this special geological formation are discussed. The appropriate methods for overcoming this adverse condition are suggested for tunnel design and construction.

並列關鍵字

mudstone intercalated with sandstone ； near the reservoir ； water inflow ； collapse