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大量的非饱和土干湿循环试验表明,当土体处于吸湿过程直至吸力降低为0 k Pa时,土体并不能达到完全饱和状态,还存在一定的残余气体。在高饱和度时,由于残余气体以封闭气泡的形式分布在土体中,土体呈现较大的压缩性,使其与饱和土的性质不同。在这种状态下,现有的非饱和土本构模型预测到的土饱和度为100%,与试验结果存在一定的偏差。为了使本构模型在高饱和度状态时具有较高的精度,对非饱和土的毛细滞回和塑性变形耦合本构模型进行了修正,使其能够考虑残余含气量的影响。通过预测与实测结果比较,证明了新模型能够有效地模拟残余含气量对非饱和土力学特性的影响。
A large number of unsaturated soils wet-dry cycle tests show that when the soil is in the process of absorbing moisture until the suction decreases to 0 kPa, the soil does not reach full saturation and some residual gas exists. At high saturation, due to the residual gas in the form of closed bubbles distributed in the soil, the soil shows greater compressibility, making it different from the nature of saturated soil. Under this condition, the unsaturated soil constitutive model predicts the soil saturation to be 100%, and there is some deviation from the test results. In order to make the constitutive model with high accuracy in high saturation state, the capillary hysteresis and plastic deformation coupling constitutive model of unsaturated soil is modified to consider the influence of residual gas content. The comparison between the predicted and measured results proves that the new model can effectively simulate the influence of residual gas content on the mechanical properties of unsaturated soils.