岩土工程中,土与结构的耦合作用通常导致土体产生极大变形,即大变形问题,如桩、桩靴和吸力锚的嵌入安装.传统有限元法在求解大变形问题时,网格将产生极大变形,导致计算误差很大,甚至不收敛.基于条形基础嵌入问题,对两种不同的大变形有限元法(网格重划分法和CEL法)进行对比分析.给出了两种大变形有限元法的实现流程,并分析了条形基础在均质各向同性和正常固结黏土中的嵌入问题,通过与条形基础承载力公式和RITSS大变形有限元法对比,验证了两种方法的有效性;通过用户子程序,模拟了正常固结黏土不排水抗剪强度随基础嵌入的变化规律;对比了条形基础嵌入过程中土体的流动机制.
In geotechnical engineering,soil-structure interactional problems always involve large deformations of soil,such as the penetration of piles,spudcans and suction caissons.Large mesh distortions can occur in the classical finite element analysis due to large deformations,which will induce a calculation error and even fail to get a convergent solution.A comparative study of two different large deformation finite element methods,i.e.,the rezoned meshes method and the CEL method,on the penetration of strip foundations was carried out.The two methods were elaborated and used to analyze the penetration of strip foundations in homogeneous and normally consolidated clays.In comparison with the bearing capacity formula and the results of the RITSS approach,the efficiency of the two methods is well verified.With a user defined subroutine,the undrained shear strength of the normally consolidated clay can be updated with the penetration of strip foundations.The soil flow mechanisms during the penetration of strip foundations are also presented.