由於臺灣西部平原地質多為砂性土壤且部分地區水位分佈較高,且位處環太平洋地震帶,地震發生機率頻繁,橋梁隨時有可能遭受地震的威脅。由近年所發生的地震可觀察到,其多具有延時長、振幅大的特性,而此類型的地震可能導致砂性土壤產生液化的現象,致使橋梁樁身失去摩擦力,基樁所承受側向力遽增導致破壞。不論橋梁結構本身是因地震作用的損毀或是受到土壤液化行為的影響,都會對橋梁的安全性產生極大的傷害。有鑑於此,本研究擬針對樁基礎位於飽和砂土中且承受地震力之作用下影響與評估。 先前由蔡雨呈使用MIDAS GTS建立三維分析模型模擬橋梁與乾砂土壤間的互制行為,且配合國家地震中心振動台試驗,模擬橋梁受沖刷,導致樁基礎裸露時耐震行為,並進行實驗與數值分析比對。 本文進一步探討橋梁位於飽和砂土壤之互制關係,使用有限元素軟體OpenSEES建立三維分析模型,模擬樁基礎位於乾砂土壤與飽和砂土壤,並配合於國家地震工程研究中心縮尺橋梁單樁試體振動台試驗,模擬橋梁位於乾砂土壤與飽和砂土壤中的耐震行為,再將實驗數據與模擬分析結果進行比對。
This thesis intends to study the interaction of dynamic response between bridge pile and soil surrounding. The experimental dynamic responses of the bridge pier with pile located at dry sand and saturated sand, respectively, were obtained through shaking table test of an experiment including mass block, bridge column and pile embed in sandbox conducted by National Center of Earthquake Engineering (NCREE). The experimental results were served as the database for investigation. In additional to a deeper discussions on the differences between experimental results of dry sand and saturated sand, this thesis used software of OpenSEES to establish a three dimensional finite element model for nonlinear time history analysis. Through comparing the analytical results and experimental results, the accuracy of the model established was able to be assured so that the soil structure interaction between pile and soil (dry sand / saturated sand) can be better understood and served as prediction for the similar cases in practical engineering application.