下加载面修正剑桥模型在ABAQUS中的二次开发及应用

发布时间：2018-03-04 08:30

本文选题：下加载面修正剑桥模型　切入点：ABAQUS　出处：《哈尔滨工业大学》2014年硕士论文　论文类型：学位论文

【摘要】：通用有限元软件ABAQUS以其强大的非线性计算功能在岩土工程领域得到了广泛的应用。在其自带的弹塑性模型中，修正剑桥模型通常用于描述正常固结土的力学特性，在理论上比较合理并且在工程上得到了应用。然而，修正剑桥模型并不能合理描述超固结土体的力学特性。下加载面修正剑桥模型在理论上弥补了这一缺陷，它具有两个屈服面，通过下加载面位置的变化反映超固结土的应力应变特性，可以弥补ABAQUS自带本构模型的不足。本文主要工作及研究内容如下： 1、基于下加载面修正剑桥模型的基本理论，推导出其弹塑性本构关系的表达式和二次开发所需的应力应变更新公式。利用ABAQUS提供的用户材料子程序接口UMAT，，采用FORTRAN语言和显式的向前Euler积分算法针对下加载面修正剑桥模型开发出了子程序，扩充了ABAQUS软件的材料库。 2、利用所编的UMAT子程序对单个单元模型进行不同增量加载步数的排水条件下的三轴压缩测试，并与ABAQUS自带的修正剑桥模型进行对比，证明UMAT子程序具有较高的精度和较好的稳定性。应用子程序对单个单元模型模拟不同的围压和排水条件的三轴压缩试验，并将结果与用FORTRAN编程计算得到的理论解进行对比，结果表明子程序能充分反映不同超固结比、不同排水条件下超固结土体的性质，如应变软化和剪缩、剪胀等，说明了子程序的适用性。 3、在ABAQUS中模拟超固结土的三轴压缩试验和三轴加卸载试验，下加载面修正剑桥模型的UMAT子程序能更好地描述土体连续渐进的变形过程，相比于修正剑桥模型有较大的优势。 4、建立多个单元的超固结土三轴压缩试验和地基固结沉降的模型，分别与试验数据和ABAQUS自带的修正剑桥模型进行了对比，证明了下加载面修正剑桥模型对于超固结土的力学性质能进行较为准确的描述，而且适用于超固结土的地基的固结沉降问题。
[Abstract]:The universal finite element software ABAQUS has been widely used in geotechnical engineering for its powerful nonlinear computing function. In its own elastic-plastic model, the modified Cambridge model is usually used to describe the mechanical properties of normal consolidated soil. It is reasonable in theory and has been applied in engineering. However, the modified Cambridge model can not reasonably describe the mechanical properties of overconsolidated soil. It has two yield surfaces, which reflect the stress-strain characteristics of the overconsolidated soil by the change of the position of the lower loading surface, which can make up for the deficiency of the constitutive model of ABAQUS. The main work and research contents of this paper are as follows:. 1. Based on the basic theory of modifying Cambridge model with lower loading surface, The expression of the elastoplastic constitutive relation and the stress-strain updating formula for secondary development are derived. Using the user material subroutine interface provided by ABAQUS, the FORTRAN language and the explicit forward Euler integral algorithm are used to solve the problem of the lower loading surface. The modified Cambridge model developed a subroutine, The material library of ABAQUS software is expanded. 2. The UMAT subroutine is used to test the triaxial compression of a single unit model under the drainage condition with different incremental loading steps, and compared with the modified Cambridge model of ABAQUS. It is proved that the UMAT subroutine has higher precision and better stability. A single unit model is used to simulate the triaxial compression test of different confining pressure and drainage conditions, and the results are compared with the theoretical solution obtained by FORTRAN programming. The results show that the subroutine can fully reflect the properties of the overconsolidated soil under different overconsolidation ratios and drainage conditions, such as strain softening and shearing shrinkage, shear expansion, etc., which shows the applicability of the subroutine. 3. By simulating triaxial compression test and triaxial loading and unloading test of overconsolidated soil in ABAQUS, the UMAT subroutine of the lower loading surface modified Cambridge model can better describe the continuous progressive deformation process of soil, which is superior to the modified Cambridge model. 4. The triaxial compression test of overconsolidated soil and the model of foundation consolidation settlement were established, and the results were compared with the test data and the modified Cambridge model brought by ABAQUS. It is proved that the modified Cambridge model of the lower loading surface can accurately describe the mechanical properties of the overconsolidated soil and is suitable for the consolidation and settlement of the foundation of the overconsolidated soil.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU43

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