AN ELASTO-PLASTIC DESCRIPTION OF TWO DISTINCT VOLUME CHANGE MECHANISMS OF SOILS
AN ELASTO-PLASTIC DESCRIPTION OF TWO DISTINCT VOLUME CHANGE MECHANISMS OF SOILS
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DOI：
10.3208/sandf.42.5_47
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发表时间：
2002-10
影响因子：
3.7
通讯作者：
A. Asaoka;T. Noda;E. Yamada;K. Kaneda;M. Nakano
中科院分区：
文献类型：
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作者：
A. Asaoka;T. Noda;E. Yamada;K. Kaneda;M. Nakano
摘要在临界状态土力学中，土的体积变化特性通常是根据传统的“e-log p”关系来分析的。然而，例如，即使平均有效应力没有任何显著增加，有时也会发生松散砂的压实/致密化。本研究提出了一个模型，它认为，体积变化可能会发生由于土壤结构的衰变/崩溃的事实。考虑到粘土和砂土之间的差异，本研究采用修正的剑桥模型模拟超次加载面和旋转硬化。土结构的衰减，超固结损失和各向异性的演变的影响相互讨论有关他们与正在进行的塑性变形的关系。基本本构模型的反应，特别是在本研究中的“压实”的沙子。在松散的砂土上反复施加低水平的剪应力会产生大量的体积压缩，这是由于初始土壤结构的快速坍塌。重复加载也会导致超固结比的快速增加。排水和不排水剪切行为的砂自然显着变化沿着这一致密化/压实过程，这也是一致的预测使用一组土壤参数。因此，在本研究中，基于与密度无关的土壤参数，在单一的理论框架中完全描述了不同密度下同一砂土的弹塑性行为。
ABSTRACT In critical state soil mechanics, the volume change behavior of soils has typically been analyzed based upon conventional “e—log p' relationships”. However, compaction/densification of loose sand, for example, can sometimes occur even without any significant increase of mean effective stresses. This study presents a model which considers the fact that volume change can occur due to decay/collapse of the structure of soils. Taking into consideration the differences between clay and sand, this study models super-subloading surfaces together with rotational hardening using the modified Cam-clay model. The effects of decay of the soil structure, loss of overconsolidation and evolution of anisotropy are mutually discussed concerning their relationship with ongoing plastic deformation. Fundamental constitutive model responses are illustrated in the present study particularly for “compaction” of sand. Repeated application of low-level shear stress upon loose sand yields a huge amount of volume compression, which is due to the rapid collapse of the initial soil structure. Repetition of the loading also results in a rapid increase of the overconsolidation ratio. Drained and undrained shear behavior of the sand naturally changes remarkably along this densification/compaction procedure, which is also consistently predicted using a single set of soil parameters. Elasto-plastic behavior of the same sand at various densities is thus totally described in the present study in a single theoretical framework based on soil parameters independent of density.