考虑气相硬化的准饱和黏土弹塑性模型

假定准饱和黏土由饱和基质（土骨架和水）和封闭气体组成，采用饱和基质塑性体应变和气体塑性体应变作为硬化参数以反映准饱和黏土的塑性硬化行为，在综合考虑气体溶解系数随温度和水中含盐量变化、预固结应力随封闭气体的变化等关键因素的基础上，基于临界状态土力学理论提出了可以反映封闭气体气压变化对准饱和黏土力学影响的弹塑性本构模型。模型共计10个材料参数，均可通过等向压缩试验和三轴剪切试验获得。通过与已有试验数据对比分析，结果显示本模型可以较好地模拟准饱和黏土在不排水应力路径下的应力-应变关系、孔隙水压力发展以及饱和度的演变规律；所建立模型形式简单，参数易于确定，为准饱和黏土地基中岩土工程问题的设计、计算及灾变控制提供了重要的理论基础。

Elastoplastic model of quasi-saturated clay considering gas phase hardening

Quasi-saturated clay is assumed to consist of saturated matrix (soil skeleton and water) and occluded gas. Plastic volumetric strain of saturated matrix and gas is used as hardening parameter to reflect the plastic hardening behavior of quasi-saturated clay. The variation of gas solubility coefficient with temperature and salinity in water and the variation of pre-consolidation stress with occluded gas are used as key factors. Based on the theory of critical state mechanics, an elastoplastic model is proposed to reflect the influence of the pressure change of the occluded gas on the mechanical characteristics of quasi-saturated clay. There are 10 material parameters in the proposed model, all of which can be obtained from compression test and triaxial shear test. By comparing against existing experimental data, the results show that the model can well simulate the stress-strain relationship, pore water pressure development and saturation evolution under undrained stress path. The proposed elastoplastic model is simple in form and its parameters can be easily determined, and it provides an important theoretical basis for the design, calculation and disaster control of geotechnical engineering problems in quasi-saturated clay foundations.