Dilatancy of granular materials in a strain space multiple mechanism model
Dilatancy of granular materials in a strain space multiple mechanism model
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DOI：
10.1002/nag.899
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发表时间：
2011-02
影响因子：
4
通讯作者：
S. Iai;T. Tobita;O. Ozutsumi;K. Ueda
中科院分区：
文献类型：
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作者：
S. Iai;T. Tobita;O. Ozutsumi;K. Ueda
颗粒材料是由新形成或消失接触的颗粒组成的集合体，在宏观变形过程中改变微观机械结构。这些结构通过应变空间多机构模型被理想化为由多个虚拟二维机构组成的双重结构，每个虚拟二维机构由多个一维性质的虚拟简单剪切机构组成。其中，二阶组构张量描述直接宏观应力应变关系，四阶组构张量描述增量关系。在这个模型框架中，连锁机制被定义为宏观应变的能量较少的分量，在微观力学和宏观膨胀分量之间提供了适当的桥梁。通过一个明显的假设，即微观力学对应与虚拟简单剪切应变有关，为膨胀收缩分量提供了另一座桥梁。我们还假定，在相变线稍上方的一条线以外的应力路径上的扩容只是由于连锁和扩容增加的机制，因为这种连锁最终在大的剪切应变下消失。这些经典假设构成了建立应变空间多机制模型中剪胀的基础。通过模拟砂土在单调荷载和循环荷载作用下的不排水特性，验证了该模型的有效性。版权所有©2010 John Wiley&Sons，Ltd.
A granular material consists of an assemblage of particles with contacts newly formed or disappeared, changing the micromechanical structures during macroscopic deformation. These structures are idealized through a strain space multiple mechanism model as a twofold structure consisting of a multitude of virtual two‐dimensional mechanisms, each of which consists of a multitude of virtual simple shear mechanisms of one‐dimensional nature. In particular, a second‐order fabric tensor describes direct macroscopic stress–strain relationship, and a fourth‐order fabric tensor describes incremental relationship. In this framework of modeling, the mechanism of interlocking defined as the energy less component of macroscopic strain provides an appropriate bridge between micromechanical and macroscopic dilative component of dilatancy. Another bridge for contractive component of dilatancy is provided through an obvious hypothesis on micromechanical counterparts being associated with virtual simple shear strain. It is also postulated that the dilatancy along the stress path beyond a line slightly above the phase transformation line is only due to the mechanism of interlocking and increment in dilatancy due to this interlocking eventually vanishing for a large shear strain. These classic postulates form the basis for formulating the dilatancy in the strain space multiple mechanism model. The performance of the proposed model is demonstrated through simulation of undrained behavior of sand under monotonic and cyclic loading. Copyright © 2010 John Wiley & Sons, Ltd.