營運中岩石隧道三維變位與襯砌裂縫型態之數值探討

Lining Crack Patterns Corresponding with 3D Displacements for Rock Tunnels in Operation Revealed by Numerical Simulation

黃士庭(Shih-Ting Huang)

指導教授 ： 黃燦輝

共同指導教授 ： 王泰典

國立臺灣大學/工學院/土木工程學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201602667

摘要

現代隧道的分析主要奠基於「彈塑性介質中孔洞周圍應力應變組成關係之探討」與「閉合收斂曲線概念」之上，這些地下岩體開挖理論大多是由歐美國家所提出，由於該地區地質年代久遠，岩體強度高且膠結良好，經開挖後的圍岩穩定性高，故隧道竣工後便能穩定營運。然而我國與日本，因地質年輕，許多隧道在完工後開始營運數年內，便出現種種異狀，顯示前述理論的基本假設並不適用於我國，而如何延長營運中隧道之服務年限就成為當今台灣隧道工程的重要議題。
在營運中隧道內出現的各種異狀中，以襯砌裂縫所佔的比例最高，而其呈現之型態與其肇因往往有一定的關聯性，故普遍認為紀錄裂縫的型態及發展情形可作為營運中隧道維護工作之反饋。
本研究建立一同時有圍岩與隧道之數值模型，將6種剛體運動與2種斷面變形施加於圍岩模型，間接使襯砌發生變位後，觀察襯砌上出現之裂縫型態，進而探討隧道斷面幾何、隧道長度、施工縫數量與圍岩勁度等因子對裂縫型態之影響，最後以台灣東南部某隧道之監測變位進行模擬，其結果與實際觀察到之裂縫紀錄進行比對，以測試本研究所建置模型之實用性。研究結果指出，本研究所探討的8種變位情況會引致隧道襯砌不同的裂縫樣貌，然裂縫型態幾乎不受各因素影響；在現地案例討論中，數值模型之襯砌的裂縫型態與出現位置與現地紀錄一致，此皆顯示裂縫判釋可做為探究異狀肇因之法。

關鍵字

營運中隧道 ； 圍岩變位 ； 襯砌變位 ； 裂縫型態 ； 數值模擬

並列摘要

In this stage, the analysis of tunnels is based on the study of “stress-strain relationship around a hole in an elasto-plasticity media” and “closed convergence curve concept”. These theories of underground excavation are mostly proposed by European and American countries. Because of their old geological ages and high strength and excellent cement of rock mass, the tunnels there can be operated stably as long as the construction is fully completed. However, the tunnels constructed in Japan and Taiwan, are deformed to give some impacts to their operation, due to the young geological ages of Japan and Taiwan. Thus, the theories above cannot be fully applied in the cases in Taiwan, and how to keep the operation of tunnels stable becomes one important issue in tunnel engineering of Taiwan.
In the tunnel, there are different kinds of defect can be observed on the lining, for the reason that there are various kinds of way to detect the tunnel. The most common issue in the operation of tunnels is how to deal with cracks on the linings. Since the patterns of cracks seem related to the relevant causes, it is generally viewed as an effective way to deal with the cracks for maintaining tunnels in operation by observing, recording and explaining the pattern and development of cracks.
In this study, one finite element model with one tunnel and the surrounding rock mass is proposed to survey the relationship between the patterns of cracks and different conditions of displacements of lining induced by the movements of surrounding rock mass. Besides, the impacts of different cross-section geometry and length of tunnels, different number of construction joints and stiffness of surrounding rock mass to the development of cracks are investigated, and one case study is demonstrated. The results show that the different conditions of displacements of surrounding rock mass would induce distinct patterns of cracks of linings, and the crack patterns would not alter caused by different condition of tunnels. The case study also shows that the patterns and the positions of cracks on the model in this study are consistent with the in-situ record.

並列關鍵字

tunnel in operation ； displacement of rock mass ； lining displacement ； crack patterns ； numerical simulation

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