岩石隧道受震反應：現地監測資料解析與三維數值模擬

Seismic Response of Rock Tunnels:In-situ Monitoring Data Analysis and Three-dimensional Numerical Simulation

蘇仁偉(Jen-Wei Su)

指導教授 ： 王泰典

國立臺灣大學/工學院/土木工程學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202103080

摘要

隧道，廣泛運用於輸水、輸電、排淤、運輸及交通等民生相關用途，串連起受阻隔的區域，隧道在過去被認為耐震性較地上結構物佳。然而在幾次地震事件中均發生隧道破壞的情形，如：1999年集集地震後在台灣中部地區調查發現，有49座隧道受地震影響發生不同程度之破壞，2008年汶川地震中也有許多隧道破壞的案例，這些岩石隧道的破壞案例顯示隧道受震分析及隧道耐震設計議題之重要性。然而現有發展成熟之潛盾隧道二維受震分析方法難以應用於須考慮三維地形或地質條件下之山岳隧道，並且也鮮少有隧道受震現地監測資料的應用，岩石隧道受震分析之研究仍有許多議題需要突破。
本研究旨在將現地監測資料應用於岩石隧道三維數值分析，探討岩石隧道在三維地形條件下之受震反應，藉此建立一套系統性之分析方法。並釐清其適用範圍與限制，最後對岩石隧道受震數值分析方法及受震反應提出建議。
文獻回顧部分，首先回顧了隧道震害事件，梳理隧道受震分析方法，評述差異。現地監測部分，取得南橫公路嘉寶隧道之受震監測資料，包括隧道襯砌內三軸加速度計及鄰近兩地震測之地震站歷時，透過加速度資料處理與解析整理出隧道內受震行為及隧道與鄰近地震站之關係。數值模擬部分首先以簡單模型建立分析模式，探討模型適用性，接著建立案例隧道之現地地形三維數值模型。並以前述監測資料歸納出之結論為依據，得到數值模型的震動輸入，將分析結果與現地監測資料比較，以驗證現地監測資料作為數值模型震動激發之可行性與三維數值模擬之正確性，最後進一步探隧道之受震反應。
監測資料之分析結果顯示，隧道受震行為受隧道斷面左右兩側不對稱之地形影響甚大，使每次地震事件之受震行為趨勢相同。並且歸納出，當震央離案例隧道及鄰近地震測站大於60公里且平均差小於3公里時，會使隧道與地震站加速度紀錄表現出較相似特徵。基於此結論，可藉由鄰近地震站地震紀錄得到輸入至現地隧道數值模型之震動輸入，由此而得之數值模擬結果也與現地隧道受震紀錄相符。數值模擬結果顯示，對於淺覆蓋區域，震動時會有特定頻率特別顯著，且同斷面上最大加速度通常發生於離地表較近處。隧道在離洞口越近，其受震時之最大加速度越大、訊號能量也越大，因此建議進行耐震設計時應特別注意隧道洞口之受震反應。

關鍵字

岩石隧道 ； 現地監測資料 ； 希爾伯特-黃轉換 ； 三維數值模擬 ； 受震反應

並列摘要

Abstract
Tunnels are widely used for water, power transmission, silt drainage, transportation and traffic and other livelihood-related purpose, connecting blocked areas in series. In the past, tunnels were considered to have better earthquake resistance than above-ground structures. However, there are still cases of tunnel damage in several earthquake events. For example, a investigation in central Taiwan after the Chichi earthquake in 1999 found that 49 tunnels were damaged by the earthquake to varying degrees. There were also many tunnel damage cases in the Wenchuan earthquake in 2008. The damage cases of these rock tunnels show the importance of tunnel seismic analysis and tunnel seismic design issues. However, the existing well-developed two-dimensional seismic analysis methods for shield tunnels are difficult to apply to mountain tunnels under which three-dimensional terrain or geological conditions must be considered. And there are few applications of in-situ monitoring data for tunnel earthquakes. There are still many issues in the study of seismic analysis of rock tunnels that need to be broken through.
The purpose of this research is to apply in-situ monitoring data to the 3D numerical analysis of rock tunnels. Discuss the seismic response of rock tunnels under three-dimensional terrain conditions. To establish a systematic analysis method and clarify its scope and limitations. Finally, suggestions are made for the numerical analysis method and seismic response of rock tunnels. In the literature review, the tunnel seismic damage cases were reviewed. Sort out the tunnel seismic analysis methods and comment on the differences. In-situ monitoring part. This study obtained the seismic monitoring data of the Jiabao Tunnel of Tai-20 Highway, including the three-axis accelerometer in the tunnel lining and the seismic record of the two stations nearby. Through acceleration signal processing and analysis, the seismic behavior in the tunnel and the relationship between the tunnel and the nearby seismic station are discussed. In the numerical simulation part, a simple model is used to establish an analysis model to discuss the applicability of the model, and then a three-dimensional numerical model of the site terrain of the case tunnel is established. And based on the conclusion of the monitoring data, the input excitation of the numerical model can be obtained. The analysis results are compared with the o in-situ monitoring data to verify the feasibility of the in-situ monitoring data as an input excitation of numerical model and the correctness of the 3D numerical simulation. Finally, further discuss the seismic response of the tunnel.
The analysis results of the monitoring data show that the seismic behavior of the tunnel is greatly affected by the asymmetrical topography on the left and right sides of the tunnel section, so that the seismic behavior trend of each seismic event is the same. And it can be concluded that when the epicenter is more than 60 km away from the case tunnel and the nearby seismic station and the mean deviation is less than 3, the acceleration records of the tunnel and the seismic station will show more similar characteristics. Based on this conclusion, the input excitation to the numerical model of the in-situ tunnel can be obtained from the seismic records of the nearby seismic station, and the numerical simulation results obtained from this are also consistent with the seismic records of the in-site tunnel. Numerical simulation results show that for shallow overburden section, certain frequencies are particularly significant during seismic, and the maximum acceleration on the same section usually occurs closer to the ground surface. The closer the section is to the portal, the greater the maximum acceleration and the greater the signal energy. Therefore, it is recommended that special attention should be paid to the seismic response of the tunnel portal when conducting seismic design.

並列關鍵字

Rock tunnel ； In-situ monitoring data ； Hilbert Huang Transform ； Three-dimensional numerical simulation ； Seismic response

參考文獻

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