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  • 學位論文

基於有限元素法之邊坡穩定分析的模型不確定性

Model Uncertainty in FEM-based Slope Stability Analysis

指導教授 : 卿建業

摘要


基於有限元素法之強度折減法被認為是計算安全係數最正確的方法,其優點為滿足力平衡及力矩平衡、真實考慮到變形量、不需先行假設臨界滑動面。 本研究基於蒐集世界各地之43個已破壞黏土邊坡案例的文獻,參考其中記載的邊坡相關資料進行邊坡模型的模擬,過程中利用不同土壤參數之文獻回顧等將其誤差降至最低。再利用基於有限元素法之強度折減法,於不同破壞準則中分析其安全係數,同時也將其結果與極限平衡法分析的結果作比較與探討。 另一方面,利用可靠度分析建立起利用基於有限元素法之強度折減法計算出來的安全係數與可靠度指標和破壞機率之間的轉換關係,利用此轉換關係可以分析出一未知邊坡之安全性,以期未來可以作為邊坡整治的一個參考依據。 基於有限元素法之強度折減法分析其邊坡模型之安全係數對於穩定性分析是有貢獻的,相對於極限平衡法的分析模式中,以有限元素法為分析背景下,其中不僅滿足了所有力平衡與力矩平衡方面的應力問題,同時也參考了楊氏模數值進行整體變形量的計算,其分析結果的誤差程度也比其他穩定性分析方法更好。 未來希望於邊坡模型當中可以加入土壤參數的空間變異性以及更多可能誤差項目校正,再者於一些外部力量因素影響的模擬,如可能發生的動態因素像降雨、地震等,在未來也希望邊坡模型中能加入這些模擬元素,以期盼這個分析模式能更趨於完整。

並列摘要


FEM-based strength reduction method is considered to be the most correct way to calculate the factor of safety, the advantages are that satisfy the force equilibrium and moment equilibrium, take into account the deformation factually and do not need to assume the critical slip surface at first. In this study, we collect references which include 43 numbers of collapsed clay slope examples around the world to simulate the slope model and also minimize the biases in literatures review of different soil parameters. Use FEM-based strength reduction method to analyze the factor of safety in different failure criteria and also compare and discuss with the results of the limit equilibrium metod. On the other hand, use reliability analysis to establish the transformation relation between the factort of safety calculated by using FEM-based strength reduction method, reliability index and failure probability. Use this transformation relation can be able to analyze the safety of an unknown slope, we hope this can be used as a reference for the remediation of slope. Use FEM-based strength reduction method to analyze the factor of safety of slope models is a great contribution to stability analysis. Relative to the limit equilibrium method, the finite element method satisfies not only force but also moment equilibrium and considers Young's modulus, this method is better than others. In the future, we hope that can consider the spatial variability of soil parameters in the slope model. Moreover, simulate the external force factors like rainfall, earthquakes, etc. to make this analytical model more complete.

參考文獻


Bjerrum, L. and Kjaernsli, B. (1957). Analysis of the stability of some norwegian natural clay slopes. Geotechnique, Vol. 7, No. 1, pp. 1-16.
Chai, J-C., Miura, N., Shen, S-L. (2002). Performance of embankment with and without reinforcement on soft subsoil. Canadian Geotechnical Journal, Vol 39,
Chang, Y.L. and Huang, T. K. (2005). Slope stability analysis using strength reduction technique. Journal of the Chinese Institute of Engineers, Vol. 28, No. 2, pp. 231-240.
Chen, Y.J. and Kulhawy, F.H. (1993). Undrained strength interrelationships among CIUC, UU, and UC Tests. Journal of Geotechnical Engineering, ASCE,119(11), 1732-1750.
of Earth and Earth Supported Structures, 1(1), 129-158.

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