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基于连续介质土力学的本构模型框架,提出了一个三轴应力状态下的非饱和土本构模型。与非饱和土中的双应力变量不同,根据非饱和土功的表达式,选择广义有效应力、修正吸力和气体压力作为模型的应力状态变量。模型中考虑了气相压力变化对土体变形的影响,给出了固-液-气三相耦合的本构方程。固相采用了非相关联流动法则,并在固相硬化方程中考虑了液相和气相的影响。液相方程利用土水特征曲线描述,并考虑了塑性体应变的影响。气相方程的建立利用了Boyle定律和Henry定律,给出了受固相和液相变形影响的气相方程。最后建立了非饱和土弹塑性增量方程。利用已有的试验数据对模型进行了验证,并将考虑气相影响与未考虑气相影响的预测结果进行了对比。
Based on the constitutive model framework of continuum mechanics, a constitutive model of unsaturated soil under triaxial stress was proposed. Different from the bi-stress variables in unsaturated soil, the generalized effective stress, suction and gas pressure are selected as the stress state variables according to the expression of unsaturated earthwork. In the model, the influence of gas phase pressure on soil deformation is taken into account, and the constitutive equation of solid-liquid-gas three-phase coupling is given. The solid phase uses the non-associated flow rule and takes into account the influence of the liquid and gas phases in the solid-phase hardening equation. The liquid phase equation is described using the soil-water characteristic curve and takes into account the influence of the plastomer strain. The gas phase equation was established using Boyle’s law and Henry’s law, and the gas phase equation influenced by the solid and liquid phase deformation was given. Finally, the elasto-plastic incremental equations of unsaturated soil are established. The model has been validated by using the existing experimental data and the gas-phase effects are compared with those without gas-phase effects.