边界面模型在ABAQUS的开发应用

Implementation and application of bounding surface model in ABAQUS

目前岩土动力分析中,土体的本构模型大多采用等效线性粘弹性模型,其仅是通过迭代的手段来近似地反映土体的剪切模量与阻尼比随应变水平的非线性关系,不能反应孔压的增长和永久变形的发展,与土体的真实特性尚有较大差距。因此采用能反映土体动力特性的弹塑性模型是十分有必要的。给出了边界面模型的Eu ler向后本构积分算法和的一致切线模量矩阵的推导,介绍了利用UMAT子程序在ABAQU S中开发了边界面模型的具体过程。对三轴不排水静、动力试验进行了数值模拟。结果表明,所开发的边界面用户材料子程序具有较好的稳定性和较高的计算精度,从而可利用ABAQU S前后处理方便、计算精度高和模拟复杂问题能力强的优点,为岩土动力分析提供了一种可供选择的手段。

In most dynamic analyses of geotechnical problems, an iterative equivalent linear approach is usually used to model the nonlinear strain dependent modulus and damping properties of the soils. However, the computed seismic response can not reflect the effects of the induced pore pressure during earthquake shaking and the permanent deformations can not be predicted directly. So it is important to adopt an appropriate elastic-plastic model to simulate soil behaviors under the cyclic loading conditions. The integration algorithm of bounding surface model and the consistent tangent matrix were derived first, and then the procedure to write a UMAT subroutine in ABAQUS for bounding surface model was described in detail. Finally, the undrained triaxial shear tests were simulated using ABAQUS with the developed model, and the computed results were found to be reasonable and reliable. The developed user subroutine can make use of the advantages of ABAQUS such as convenient preprocessor and postprocessor, high solution precision and high ability to handle complex problems. Therefore it provides an alternative method for dynamic analysis of geotechnical problems.