潛盾隧道中填充材料於大口徑輸水管線受震時之互制行為探討

Abstract

隧道配管工法常用在安裝新設之大口徑輸水管線於高灘地及過河段，該工法具體施作方式以潛盾工法完成隧道後佈設新管，並於隧道襯砌與管線間之空隙完整填充控制性低強度材料以固定管線。然而臺灣地震頻發，受震時隧道內固定管線所使用之填充方案於管線之影響仍不得仍知。本研究以有限元素法軟體ABAQUS進行二維動態分析及三維擬靜態分析，探討填充材料之強度與澆灌量對管線之影響。另外，在三維分析中，用勁度折減之方式以模擬管線間之接頭，以簡化模擬完整之分段管線，進行合理性驗證，驗證結果顯示簡化模型與分段管線之變位及轉角行為相似。 本研究以10 kgf/cm2、40 kgf/cm2及140 kgf/cm2三種填充材料強度及滿灌、3/4滿灌、半滿灌、1/4滿灌等四種澆灌量之組合。分析結果顯示滿灌澆灌量下，管線呈現較大之應變及管線間相對轉角，而半滿灌則為本研究較合適之澆灌情境。在填充材料強度方面，呈現材料強度越強管線應變越小之趨勢，故本研究接著探討彈塑性填充材料於及澆灌量對於管線之影響。 相較於彈性模型，使用彈塑性填充材料模型中，管線上之應變及相對轉角較大且材料強度於管線之影響較為明顯。同時，材料強度越強，管線應變則有越小之趨勢，半滿灌及滿灌澆灌量中，管線之應變分布趨勢相似，其中半滿灌澆灌量情境具較小之管線應變及管線間相對轉角。綜上所述，本研究在所有考量之填充情境組合中建議使用於管線影響最小之半滿灌澆灌量及140 kgf/cm2之材料強度作為填充情境組合。

Shield tunneling method is often used to install new pipelines in areas with high ground water levels or river crossings. The method involves laying underground pipes after completing the tunnel and filling the annular gap between the pipeline and the lining segments with backfill. Conventionally, the backfill uses controlled low-strength material (CLSM) and the gap is often filled entirely to secure the pipeline. However, due to the frequent earthquakes in Taiwan, the impact of the conventional filling schemes used for securing pipelines within tunnels during seismic events remains unknown. The main purpose of this study is to investigate the impact of filling scenarios on pipelines, 2D dynamic analysis and 3D pseudo-static analysis are conducted in ABAQUS. In the 3D model a simplified model of a continuous pipeline with stiffness reduction at the joints is used to simulate segmented pipeline. To validate the simplified model, a full-scale segmented pipeline test is construct as simplified model in ABAQUS to validate the use of the simplified method. The validation results indicate that the simplified model exhibits similar displacement and angular behavior to the segmented pipeline. In the parameter study, elastic material models were first established to investigate the impact of the filling scenarios including combinations of three filling material strengths which is 10 kgf/cm2, 40 kgf/cm2, and 140 kgf/cm2 and four filling scenarios including fully filled, 3/4 filled, half filled, and 1/4 filled on the pipeline. The analysis results of different filling scenarios show that the fully filled scenario results in the highest strain and relative rotational angle changes more drastically between pipeline segments, making it the least suitable filling scenario. On the other hand, the half filled scenario is the most suitable condition among the non-full filled scenarios. Additionally, the impact of filling material strength on the pipeline is relatively small, showing a trend where the stronger the material, the smaller the pipeline strain. Therefore, elastoplastic models with different material strengths were established for half filled and the fully filled scenarios to explore the impact of material strength and filling scenarios on the pipeline. Compared to the elastic model, the elastoplastic model shows greater strain and greater relative rotational angle on the pipeline, with the influence of material strength being more apparent, similarly showing a trend where stronger material results in smaller pipeline strain. The strain distribution trend in the half filled and fully filled scenarios is similar, with the half filled scenario showing smaller pipeline strain and smaller relative rotational angle between pipeline segments. In summary, among all the considered filling scenario combinations, this study recommends using the half filled scenario with a material strength of 140 kgf/cm2 as the filling scenario combination that minimizes the impact on the pipeline.