英文篇名
Route Selection and Countermeasures to Difficult Geological Conditions for the Construction of Dongao Tunnel
作者
邵厚潔、李民政、李怡德、林敬智
關鍵字
斷層、抽坍、湧水、灌漿
摘要
東澳隧道位於宜蘭縣蘇澳鎮及南澳鄉,為「台9線蘇花公路山區路段改善計畫」蘇澳東澳段之要徑工程,屬雙孔公路隧道。隧道全長約3.32公里,淨寬11.52m,其貫穿猴猗山及東澳嶺,自北而南沿途穿越蘇澳層、小帽山斷層、南蘇澳層、猴猗山斷層及東澳片岩層,沿線最高覆蓋515m。本工程於2012年12月15日開工,隧道開挖施工期間曾遭遇多次抽坍及湧水等問題,工程難度堪稱本路段之最,設計階段即參酌兩個鄰近鐵路隧道案例所遭遇困難研擬施工中地質探查、先撐、止排水工法等因應對策,針對部分軟弱地盤則配合採用開挖面預加固工法,終於2016年4月26日及2016年7月7日貫通北上線及南下線,爾後本路段於2018年2月5日通車。本隧道案例通過複雜變質岩區且位處地下水豐沛區域,相關經驗可供後續相關工程參考。
英文摘要
As the critical path along the Suao-Dongao section of the Suhua Highway Improvement Project, Dongao tunnel is a twin-tube highway tunnel located between Suao and Nanao of Yilan county. The tunnel, which is 3.32 km in length and 11.52m in net width, traverses Mt. Houi and Dongao Ridge. The tunnel passes through Suao Formation, Xiaomaoshan Fault, Nansuao Formation, Houishan Fault and Dongao Schist. The largest overburden subjected to the tunnel is 515 m. The construction, which is the most difficult one along the Suao-Dongao section, was started on Dec 15th, 2012. Serious cave-ins and groundwater inflow were encountered during the construction. At the design stage of Dongao tunnel, difficulties encountered during the construction of two nearby railway tunnels were carefully studied. Countermeasures to the construction problems, which were anticipated to occur during the construction of Dongao tunnel, were drawn up. Such countermeasures include geological exploration, forepoling, hindrance of groundwater flow. Besides, pre-reinforcement of tunnel heading was used when there was poor ground. The northbound and southbound of Dongao tunnel were broken through on April 26th and Jul 7th, 2016, respectively, while the tunnels started service on Feb. 5th, 2018. Since the tunnel passes through an area with complex metamorphic rock system and abundant groundwater, the experience presented in this paper serves as a great reference for future tunnel construction in difficult ground.