地錨拉拔試驗聲訊反應之有限元素分析

Accoustic Response of Ground Anchor under Pullout Test from Finite Element Analysis

楊智麟(Chih-Lin Yang)

指導教授 ： 張德文

淡江大學/工學院/土木工程學系碩士班/碩士(2010年)

https://doi.org/10.6846/TKU.2010.00149

摘要

本研究以有限元素分析軟體ABAQUS建立背拉式地錨之二維和三維模型，以瞭解地錨結構系統的聲訊波傳特性、傳播規律和衰減機制。研究項目分為兩部份，第一部份為地錨拉拔試驗模擬，吾人藉由二維和三維模型及參考前期一維分析模式所提出的材料組構模式進行模擬，並與現地實驗及理論模式做比較。第二部份為聲訊反應模擬，吾人採用一維模式所建議之脈衝載重及初始條件進行二維及三維模擬，並針對各聲訊時間差進行回饋分析。
　　研究結果顯示：(1)由分析域大小探討結果顯示，分析域的深度對拉拔試驗模擬結果沒有明顯影響；分析域的寬度則對拉拔試驗模擬結果具有顯著影響，寬度二十米既可得合理的拉拔曲線模擬結果。(2)由舊有地錨拉拔試驗模擬之結果顯示，二維模型所得拉拔曲線與現地試驗結果相似，而三維模型所得之結果則有較高的承載容量。(3)二維及三維模型可模擬卸載歷程之拉拔曲線並改善一維模型缺點，地錨之承載力明顯取決於固定端之長度 (4)在聲訊反應模擬中，二維模型所得之聲訊歷時與試驗聲訊結果相似，但舊有地錨之三維模型聲訊歷時與現地試驗結果差距較大。(5)在回饋分析中，吾人藉由前人所建議之二維及三維時間差定位法進行分析。由時間差定位法回饋得到結果顯示，淺層損傷時(破壞位置在深度3m處)，所回算得破壞位置與實際破壞位置相差約為2m內；而深層損傷時(破壞位置在深度在10m以上)，所回算得破壞位置與實際破壞位置相差約為1m內。淺層回算結果會有較大的誤差，其因在於回算過程中，些微的時間誤差既對結果會產生顯著的變化。

關鍵字

地錨 ； 聲波監測 ； 有限元素法 ； 回饋分析

並列摘要

In this study, using the FEM software ABAQUS to establish 2D and 3D anchor model to study the singal propagation characteristics and attenuation mechanisms. Research project is divided into two parts, first, anchor pullout test simulation by 2D and 3D model refer to the analytical model proposed material model and to compare experimental and theoretical models. Second, simulation for the signal using by theoretical model suggested the impulse load and the initial conditions for 2D and 3D simulation, and using the signal time difference for feed-back analysis.
The observation are summarized as follows: (1) From the analysis domain size discussion result show that, depth change didn’t affect anchor pullout test simulation results; width change affect anchor pullout test simulation results. Width of 20 meters can get reasonable results. (2)From the old anchor pullout test simulation results show that 2D model from drawing curves and the test results were similar, while 3D model of the results obtained have high load-carrying capacity. (3) 2D and 3D model can simulate the uninstall process of drawing curves and improve the shortcomings of one-dimensional model, clearly depends on the capacity of anchors in the length of the fixed side. (4) In the signal simulation, 2D model of the signal similar to the test result, but old anchor 3D model of the signal significantly different between the test result. (5)In the feed-back analysis, using the 2D and 3D analysis of the time difference location method proposed by others. The result show that, surface damage (damage location in the depth 3m) , the result varies with the actual location within about 2m. Deep damage (damage location in depth of 10m or more), the result varies with the actual location within about 1m. The result has large errors because of calculation process, the small error will be significant changes in the result.

並列關鍵字

Anchor ； Acoustic Monitoring System ； Finite Element Method ； Feed-back analysis

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