大圆筒结构倾覆稳定分析的有限元法

大直径圆筒结构的倾覆稳定性是设计中考虑的一个重要问题。采用弹塑性有限元法，求解大圆筒结构在指定波浪条件下的荷载-位移关系曲线；通过荷载-位移关系的上限，确定结构的极限承载力；定义极限承载力与设计荷载的比值为结构的倾覆稳定安全系数，从而判断结构的倾覆稳定安全裕度。该方法避免了现行极限平衡分析方法确定土压力和转动中心的困难，可以考虑土与结构的相互作用和复杂的边界条件。通过对某工程实例的分析，初步验证了该方法的可行性。

Finite element method for analyzing overturn stability of large cylindrical structures

It is important to evaluate the safety of large cylinderical structures against overturn under possible conditions. Elastoplastic FEM is employed to solve this problem. First, a load-displacement curve of a cylindrical structure under certain condition is obtained by varying the load amplitude in the finite element analysis. Then the ultimate load that the cylindrical structure can bear, can be obtained, which is the upper bound load value at the load-displacement curve. Finally, a factor defined as the ratio of the ultimate load to design load is used to estimate the safety against overturn. The proposed method can avoid the difficulty existing in the current limit equilibrium analysis method, in which the earth pressure on the cylinder surface and the center of rotation must be determined. Furthermore, FEM can consider the interaction between the cylinderical structure and soil around. A practical case is analyzed to validate the applicability of the method.