隨著城市的快速發展，地下空間的使用率逐漸增加。而淺層的地下隧道多使用明挖覆蓋法 (cut-and-cover) 並以矩形隧道形式建造，其優點在於方便施工且相關設施可最大化利用開挖空間，不同的土層會對隧道產生不同的影響，在高地下水位設置明挖覆蓋隧道時，應考慮上浮的影響。本研究以離心模型探討地下水位高程對矩形隧道動態反應的影響，並比較不同地下水位面時其加速度反應、孔隙水壓反應、地表沉陷量、隧道位移及旋轉角之變化。
本研究在80 g進行四組動態離心模型試驗，透過改變地下水位面高程，探討相對於隧道具有不同高度地下水位時，土壤液化程度與隧道動態反應的互制行為。試驗結果表示 (1) 隧道周圍受震激發的超額孔隙水壓會較自由場的超額孔隙水壓小；(2) 地下水位面高於隧道底部時，基盤震動造成隧道周圍土壤液化程度不同，引致隧道受震時的擺動(rocking)及旋轉(rotation) ；(3) 當地下水位高於隧道頂部時，地震會使隧道上浮且正上方地表隆起，然而越遠離隧道則地表高程變化則相對為向下沉陷。未來可以更進一步討論，當地下水位高於隧道時，在隧道旁的支撐開挖與隧道間的相互影響行為。

The shallow underground tunnels mostly use cut-and-cover and are constructed in the form of rectangular (box-shaped) tunnels, which have the advantage of being convenient for construction and related facilities can maximize the use of excavation space. Different soil layers will have different effects on the tunnel. When setting cut-and-cover tunnels with high groundwater levels, the effect of floating should be considered. This study investigates the impact of earthquakes on existing tunnels at different groundwater levels, and compares the changes in acceleration response, water pressure response, surface subsidence, tunnel displacement and rotation angle at different groundwater levels.

In this study, four sets of dynamic centrifugal model tests were conducted to explore the relationship between the earthquake and the tunnel by changing the depth of the groundwater table. The test results show (1) The soil pore water pressure around the tunnel is smaller than that of the free field (2) When the water level is higher than the tunnel , earthquakes can cause the tunnel to rocking and rotate (3) When the groundwater level is higher than the tunnel, the earthquake will cause the tunnel to uplift and the surface above it to heaving, but the further away from the tunnel, the greater the surface subsidence . Further discussions can be made in the future as to what the impact of supporting excavation next to the tunnel will be when the water level is higher than the tunnel.

[1] Chen, Z.Y., Liang, S.B., Shen, H. , He, C., "Dynamic centrifuge tests on effects of isolation layer and cross-section dimensions on shield tunnels" Soil Dynamics and Earthquake Engineering,Vol. 109, pp. 173-187 (2018).
[2] Chou, J.C., Kutter, B.L., Travasarou, T., Chacko, J.M., "Centrifuge Modeling of Seismically Induced Uplift for the BART Transbay Tube" Geotechnical and Geoenvironmental Engineering, Vol. 137, pp. 754-765 (2011).
[3] Tsinidis, G., Pitilakis, K., Madabhushi, G., Heron, C., "Dynamic response of flexible square tunnels: centrifuge testing and validation of existing design methodologies" Geotechnique, Vol. 65, No. 5, pp. 401-417 (2015).
[4] Amorosi, A., Boldini, D., Falcone, G., "Numerical prediction of tunnel performance during centrifugedynamic tests" Springer-Verlag Berlin Heidelberg, Vol. 9, No. 4, pp. 581-596 (2014).
[5] Tsinidis, G., Pitilakis, K., Madabhushi, G., "On the dynamic response of square tunnels in sand" Engineering Structures, Vol. 125, pp. 419-437 (2015).
[6] Chen, Z.Y., Shen, H., "Dynamic centrifuge tests on isolation mechanism of tunnels subjected to seismic shaking" Tunnelling and Underground Space Technology, Vol. 42, pp.67-77 (2014).
[7] Abate, G., Massimino, M.R., Maugeri, M., "Numerical modelling of centrifuge tests on tunnel-soil systems" Bulletin Of Earthquake Engineering, Vol. 13, pp.1927-1951 (2015).
[8] Baziar, M.H., Moghadam, M.R., Kim, D.S., Choo, Y.W., "Effect of underground tunnel on the ground surface acceleration" Tunnelling and Underground Space Technology, Vol. 44, pp.10-22 (2014).
[9] Hung, W.Y., Lee, C.J., Chung, W.Y., Tsai, C.H., Chen, T., Huang, C.C., Wu, Y.C., "Seismic behavior of pile in liquefiable soil ground by centrifuge shaking table tests," Journal of Vibro engineering, Vol. 16, Issue 2, pp. 712-720 (2014).
[10] 李崇正，「離心機模型原理」，實驗土壤力學講義，桃園，臺灣 (1997)。
[11] 交通部公路工程部，「隧道設計標準」，市區道路及附屬工程設計規範 (2003)。
[12] Wang, W.L., Wang, T.T., Su, J.J., Lin, C.H., Seng, C.R., Huang, T.H., "Assessment of damage in mountain tunnels due to the Taiwan Chi-Chi earthquake" Tunnelling and Underground Space Technology, Vol. 16, No.3, pp. 133-150 (2001).
[13] Song, G.Y., Marshall, A.M.,"Centrifuge modelling of tunnelling induced ground displacements: pressure and displacement control tunnels" Tunnelling and Underground Space Technology, Vol. 103, pp. 1-16 (2020).
[14] Juneja, A., Hegde, A., Lee, F.H., Yeo, C.H.,"Centrifuge modelling of tunnel face reinforcement using forepoling" Tunnelling and Underground Space Technology, Vol. 25, No.4, pp. 377-381 (2010).
[15] Tsinidis, G., Pitilakis, K., Madabhushi, G., Heron, C., "Dynamic response of flexible square tunnels: centrifuge testing and validation of existing design methodologies" Geotechnique, Vol. 65, No.5, pp. 401-417 (2015).
[16] Meguid, M.A., Saada, O., Nunes, M.A., Mattar, J., " Physical modeling of tunnels in soft ground: A review " Tunnelling and Underground Space Technology, Vol. 23, pp.185-198 (2008).
[17] Chen, R.P., Li, J., Kong, L.G., Tang, L.J., " Experimental study on face instability of shield tunnel in sand " Tunnelling and Underground Space Technology, Vol. 33, pp.12-21 (2013).
[18] 黃俊學，「基盤土壤液化對上方土堤位移的影響」，碩士論文，國立中央大學土木工程學系，桃園，臺灣 (2016)。
[19] 梁友承，「以離心模型模擬不同粒徑分佈砂層於液化時之行為」，碩士論文，國立中央大學土木工程學系，桃園，臺灣 (2019)。
[20] 楊子霈，「以動態離心模型試驗模擬不同型式基礎建築物於液化地盤之受震反應」，碩士論文，國立中央大學土木工程學系，桃園，臺灣 (2013)。
[21] 張睿庭，「以離心模型試驗探討輸電鐵塔於不同地盤條件下之動態反應」，碩士論文，國立中央大學土木工程學系，桃園，臺灣 (2020)。
[22] 汪祐毅，「以離心模型試驗探討不同隧道與連續壁間距的動態反應」，碩士論文，國立中央大學土木工程學系，桃園，臺灣 (2021)。
[23] Taylor, R.N., “Centrifuge in modelling: principles and scale scale effects,” In: Geotechnical Centrifuge Technology, edited by Taylor, R.N., CRC Press, pp.19-33 (1994).
[24] Steedman, R.S., Zeng, X., “Dynamics,” In: Geotechnical Centrifuge Technology, edited by Taylor, R.N., CRC Press, pp.168-194 (1994).