臺灣山岳隧道受震脆弱性曲線之建立

Abstract

台灣的山岳隧道工程在設計階段時，通常僅會依據工程沿線所預估會遭遇的地質狀態進行支撐種類的設計，有關於地震對隧道的影響則不一定會加以考慮。也因為隧道或維生管線等線型構造與傳統的建築物形式大相逕庭，特別是台灣的地質狀態相對年輕且複雜，導致山岳隧道沿線的地層變化經常相當劇烈。近年更因為隧道結構逐漸老化或是圍岩風化等原因，地震對於隧道的影響有可能加劇。 本研究利用FLAC 2D軟體進行山岳隧道受震反應的數值模擬，以嘉寶隧道周圍岩體的地質與材料性質作為分析參數，建立貼近現場條件的模型。模擬過程考量覆土深度、剪力波速等重要影響因子，並施加具有特定回歸期之設計地震，以全面評估隧道於地震作用下之動態行為。最終，從分析輸出的隧道襯砌彎矩結果中提取損傷指標，據此繪製脆弱性曲線，以量化並評估山岳隧道在各種地震強度條件下之損傷潛勢與耐震性能

In Taiwan, mountain tunnels are typically designed based solely on anticipated geological conditions encountered along the tunnel alignment, and seismic impacts on tunnels are often overlooked at the design stage. Unlike conventional buildings, long tube-like structures such as tunnels or lifelines differ significantly in their structural behavior. Particularly, Taiwan's relatively young and complex geological settings cause abrupt variations in geological conditions along tunnel routes. Furthermore, due to progressive structural aging and surrounding rock weathering, tunnels may become increasingly vulnerable to seismic risks. This study employs FLAC 2D software to numerically simulate the seismic response of mountain tunnels. Lining properties and geotechnical properties from the rock mass surrounding the Jiabao Tunnel were incorporated into the numerical model, ensuring realistic and representative conditions. Critical influencing factors, including overburden depth and shear wave velocity, were considered. On the other hand, seismic input motions with different ground motion attributes were used to comprehensively evaluate the dynamic tunnel response. Finally, the bending moment results of the tunnel linings served as damage indicators, facilitating the development of fragility curves to quantify and evaluate the seismic vulnerability and resilience of mountain tunnels under various seismic intensity scenarios.