An unsaturated soil is a three-phase material that is ubiquitous on the earth’s surface. The fully saturated and completely dry states are just two limiting conditions of an unsaturated soil. The state and properties of unsaturated soils can change significantly with external loads, weather conditions and groundwater level. Proper modelling of the state-dependent behaviour of unsaturated soils is crucial for analysing the performance of almost all civil engineering structures. So far, there are many unsaturated soil models and several relevant review papers in the literature. None of the existing review papers, however, focused on the state dependency of unsaturated soil behaviour. Moreover, some aspects of soil behaviour have not been reviewed, including small strain stiffness, dilatancy and stress-dependence of water retention curve. In the current review paper, the state dependency of unsaturated soil behaviour is reviewed, with a particular attention to the three missing parts. The review is carried out in a unified and relatively simple constitutive framework, which adopts a three-by-three compliance matrix to link incremental volumetric strain, deviator strain and degree of saturation to incremental mean net stress, deviator stress and suction. All of the nine variables in the proposed three-by-three compliance matrix have clear physical meanings and can be measured through compression, shearing and water retention tests. Theoretical models based on other constitutive stress variables can be also converted to this framework by matrix transformation.

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非饱和土的状态相关性行为本构模型：概述

非饱和土壤是在地球表面无处不在的三相材料。完全饱和和完全干燥的状态只是非饱和土壤的两个限制条件。非饱和土壤的状态和性质会随着外部负荷，天气条件和地下水位的变化而显着变化。正确建模非饱和土壤的状态相关行为对于分析几乎所有土木工程结构的性能至关重要。到目前为止，文献中有许多非饱和土模型和一些相关的综述论文。然而，现有的评论论文都没有集中于非饱和土壤行为的状态依赖性。此外，还没有对土壤行为的某些方面进行回顾，包括较小的应变刚度，膨胀性和保水曲线的应力依赖性。在当前的综述文件中，对非饱和土行为的状态依赖性进行了综述，并特别注意了三个缺失部分。审查是在一个统一且相对简单的本构框架中进行的，该框架采用三乘三的柔度矩阵将增量体积应变，偏斜应变和饱和度与增量平均净应力，偏斜应力和吸力联系起来。提议的三乘三依从性矩阵中的所有九个变量都具有明确的物理含义，可以通过压缩，剪切和保水测试进行测量。也可以通过矩阵变换将基于其他本构应力变量的理论模型转换为该框架。特别注意三个缺失的部分。审查是在一个统一且相对简单的本构框架中进行的，该框架采用三乘三的柔度矩阵将增量体积应变，偏斜应变和饱和度与增量平均净应力，偏斜应力和吸力联系起来。提议的三乘三依从性矩阵中的所有九个变量都具有明确的物理含义，可以通过压缩，剪切和保水测试进行测量。也可以通过矩阵变换将基于其他本构应力变量的理论模型转换为该框架。特别要注意三个缺失的部分。审查是在一个统一且相对简单的本构框架中进行的，该框架采用三乘三的柔度矩阵将增量体积应变，偏斜应变和饱和度与增量平均净应力，偏斜应力和吸力联系起来。提议的三乘三依从性矩阵中的所有九个变量都具有明确的物理含义，可以通过压缩，剪切和保水测试进行测量。也可以通过矩阵变换将基于其他本构应力变量的理论模型转换为该框架。偏斜应变和饱和度到平均净应力，偏斜应力和吸力的增量。提议的三乘三依从性矩阵中的所有九个变量均具有明确的物理含义，可以通过压缩，剪切和保水测试进行测量。也可以通过矩阵变换将基于其他本构应力变量的理论模型转换为该框架。偏斜应变和饱和度到平均净应力，偏斜应力和吸力的增量。提议的三乘三依从性矩阵中的所有九个变量均具有明确的物理含义，可以通过压缩，剪切和保水测试进行测量。也可以通过矩阵变换将基于其他本构应力变量的理论模型转换为该框架。