土体循环塑性模型的动力有限元分析

Dynamic analysis of soil cyclic plastic model by finite element method

在简要介绍基于广义塑性力学的土体次加载面循环塑性模型与土体动力有限元分析原理与计算方法的基础上,将循环塑性模型的本构方程结合进土体的动力平衡方程中,用无条件稳定的隐式积分(Newmark)法求解动力方程,建立了基于循环塑性模型的土体有限元动力分析方法;编制了相应的弹塑性动力有限元程序,程序用FORTRAN语言编写,采用模块结构,可求解连续介质在平面应力、平面应变和轴对称情况下的动力反应问题;最后利用所编程序对水平自由场地的饱和沙层在基岩加速度作用下的动力响应问题进行计算分析.通过对孔隙水压力发展时程、加速度响应时程与剪应力响应时程等计算结果的分析比较,初步验证了模型与程序用于实际计算的可行性和可靠性.

The subloading surface cyclic plastic model for soil based on the generalized plastic mechanics and the principle and method of elastic - plastic dynamic analysis by finite element method (FEM) are introduced briefly in the paper. The constitutive equation of the model is integrated into the dynamic equation, and the Newmark method is adopted to solve the dynamic equation, then the FEM dynamic analysis method based on the cyclic plastic model is established. The corresponding elastic - plastic dynamic finite element program is worked out. The program is compiled in FORTRAN language, and the module structure is adopted in the program. The program can be applied to solve the dynamic response problem of plane stress, plane strain and axial symmetry of continuous medium. Finally, the program is applied to calculate the dynamic response of a free horizontal field of saturated sands under seismic acceleration. The validity and reliability of the model and program are verified from the analysis of the time-curve of pore-water pressure, acceleration and shear stress.