边界面模型在ABAQUS的开发应用

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Euler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ABAQUS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ABAQUS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.

Implementation and application of bounding surface model in ABAQUS

In most dynamic analy ses of geotechnical problems, an iterat ive equiv alent linear approach isusual ly used to model the nonl inear st rain dependent modulus and damping proper ties o f the soils. How ever, the computed seismic response can not ref lect the ef fect s of the induced por e pressur e during ear thquakeshaking and the permanent deformatio ns can not be predicted direct ly. So it is impor tant to adopt anappropriate elast ic-plast ic mo del to simulate soil behaviors under the cyclic loading condit ions. T he integration alg orithm of bounding sur face model and the consistent tang ent mat rix w ere derived f irst , and thenthe pro cedure to w rite a UMAT subro ut ine in ABAQU S for bounding surface model w as descr ibed in detail.Finally , the undr ained t riax ial shear tests w ere simulated using ABAQU S w ith the developed mo del,and the computed r esult s w ere found to be reaso nable and reliable. T he developed user subroutine canmake use o f the advantag es of ABAQUS such as convenient prepro cessor and postprocesso r, high solutionpr ecision and hig h ability to handle complex problems. T herefo re it prov ides an alter nat ive method for dynamicanalysis of geotechnical problems