- 學位論文
利用PLAXIS中的UBC3D-PLM組成律模擬土壤液化
Simulation of Soil Liquefaction by Using UBC3D-PLM Model in PLAXIS
摘要
台灣地處菲律賓海板塊與歐亞大陸板塊的交界處，是由兩板塊不斷的碰撞擠壓形成的，屬於非常年輕大陸。特殊的地理位置導致了台灣地區發生地震的機率極為頻繁，再加上獨特的地質條件，土壤液化等地震災害事件也隨之而來。近年來，隨著人們安全意識的提升，土壤液化所引起的災害較少直接造成人員傷亡，但往往會導致大範圍的建築及地下管線系統的損壞不僅造成了大量的經濟損失而且還對民生帶來了極大的影響。因此，對土壤液化的相關研究就顯得極為重要。 本研究主要針對PLAXIS 中的UBC3D-PLM液化組成律模式作討論。首先，通過模擬不排水CDSS 試驗，對該組成律中的參數對模型的影響做初步的評估。然後，通過模擬和比對大量的離心機試驗，對該組成律模擬液化行為時的性能作出總結。希望能對使用該組成律模擬液化行為的學者提供參考。 通過一系列的比對發現，用不排水CDSS 試驗擬合參數時，應該優先考量應力路徑和抗液化曲線而不是應力應變曲線，並且需要同時擬合多組不同CSR條件下的試驗而不是單一擬合一種CSR下的試驗結果。 在模擬離心機的液化試驗時普遍能得到與試驗行為較為一致的超額孔隙水壓歷時。但在模擬前需要注意該組成律模式不適用於計算初期大地應力且需注意輸入的地震加速度資料的基線是否有偏移，所偏移量較大，需要先做基線修正再做數值模擬。
並列摘要
Taiwan is located at the junction of the Philippine Sea Plate and the Eurasia Plate. It is a young continent formed by constant collision and pressure of two plates. Special geographical location increases the probability of earthquake in Taiwan. Coupled with unique geological conditions, soil liquefaction and other earthquake disaster events follows. With the improvement of people's safety awareness, disasters caused by soil liquefaction become less baleful. However, it has caused not only large-scale economic losses, but extensive damage to buildings and underground pipeline systems, and brought great impact on people's livelihood as well. Therefore, it is of great significance to research on soil liquefaction. This study focuses on the UBC3D-PLM liquefaction constitutive model in PLAXIS. Firstly, preliminarily evaluate the effect of the parameters in the constitutive ratio on the model through simulating the Cyclic Direct Simple Shear experiment. Then, conclude the performance of the constitutive ratio in simulating liquefaction behavior, through imitation and comparison of a numerous centrifuge tests. It is hoped to provide a reference for the scholars who use the constitutive ratio to simulate liquefaction behavior. Through a series of comparisons, it is found that when fitting parameters in Cyclic Direct Simple Shear tests, priority should be given to Stress paths and anti-liquefaction curves rather than stress strain curves. In addition, it is necessary to fit multiple tests under different conditions of cyclic stress ratio at the same time, rather than only fit the test results under one cyclic stress ratio. In the liquefaction test of centrifuge, excess pore water can be obtained which is more consistent with the test behavior. But it should be noted that the mode of constitutive ratio is not applicable for calculation of initial tectonic stress before simulation. Besides it also pay attention to whether the baseline of the input seismic acceleration data is offset. The baseline correction should be done before taking a numerical simulation.