摘要
結構物基礎設計中兩種最基本之設計項目為極限承載力與沉陷量分析，極限承載力已經在一般均質土層中有明確之理論分析，但是一般地層皆為層狀土壤所組成，並且在水平層狀土壤中之極限承載力分析也尚未有所定論，故仍然有探討研究之必要。本研究將以有限元素分析程式PLAXIS作為分析工具，研究各種水平層狀土壤中之極限承載力。 本研究以PLAXIS當中的莫爾庫倫模式做為主要分析方法，首先分別對單一砂土與黏土探討出其個別的極限承載力，接著針對不同的砂土φ角分類出疏鬆砂(30°~35°)、緊密砂(36°~40°)兩種的沙土土壤，再對不同的黏土C值分類出軟弱黏土(30 kN/m2~50 kN/m2)、堅硬黏土(60 kN/m2~150 kN/m2)兩種的黏土土壤，最後以PLAXIS對互層的土壤做分析求得層狀砂土與黏土個別之極限承載力。 在本研究中，需探討互層土壤個具有不同厚度、不同之不排水剪力強度與摩擦角等設計參數，經過整理分析後可以得到層狀土壤之極限承載力與單一土壤極限承載力之關係(互層承載力參數β)，如此可幫助我們對層狀土壤之極限承載力有更完整的瞭解。
並列摘要
Two of the most important design items in the foundation design of structure are ultimate bearing capacity and settlement analysis. The theory for ultimate bearing capacity in homogenious soils is very clear. However, the ultimate bearing capacity theory in the layered soils has not been to a definite conclusion. As a consequence, an investigating and discussing the research. More research effort could be entered in this research is the ultimate bearing capacity of the layered soils. Finite to obtain the ultimate bearing capacity for varions kinds of layered soils. In this research, the main analytical method is The Mohr-Coulomb model in the PLAXIS software. First, the ultimate bearing capacity for single sand and clay was studied respectively. Second, single sand was categorised into loose sand (30°~35°) and dense sand (36°~40°) by different φ of sand. On the contrary, caly was catedorised into soft clay (30 kN/m2~50 kN/m2) and stiff clay (60 kN/m2~150 kN/m2) by different C of clay. Finally, the respective ultimate bearing capacity of layered sand and clay were obtained from the analysis of interlayer soils by the PLAXIS software. In this reserch, interlayer soils were with different stratum thickness, undrained shear strength and friction angle etc. Consequently, the ultimate bearing capacity for layered soils could be obtained in terms of ultimate bearing capacity of single soils respectively. As a result, we can reach the complete understanding for ultimate bearing capacity of layered soils.