区分毛细和吸附作用的非饱和土抗剪强度模型

基于对非饱和土中孔隙水毛细和吸附作用的区分，得到了一种机制明确的非饱和土抗剪强度模型。首先，假定两种非饱和土的特殊状态，即只存在毛细作用的理想毛细状态和只存在吸附作用的理想吸附状态。分别给出了这两种理想状态的抗剪强度模型，其中毛细作用的影响可表示为考虑气化过程的有效饱和度和吸力的乘积，吸附作用的影响可初步简化表示为表观黏聚力的最大值。其次，利用二元介质模型，认为非饱和土中土-水作用是由这两种理想状态的不同权重组合而成。通过气化概率分布函数，表示了实际非饱和土中两种理想状态的参与比重，建立了适用于较广吸力变化范围的非饱和土抗剪强度模型。最后，通过与试验结果及当前流行的模型拟合结果的对比，验证了所建立的模型的合理性。研究表明，在考虑吸力对非饱和土力学性质的影响时，应该区分吸力的不同作用。

Shear strength of unsaturated soils considering capillary and adsorptive mechanisms

A new shear strength model is proposed for unsaturated soils to consider the capillary and adsorptive mechanisms. Firstly, two ideal states are defined for unsaturated soils, i.e., the ideal capillarity and adsorption states, which are only affected by capillary or adsorptive mechanisms, respectively. Then the shear strength expressions of the two ideal states are proposed respectively. The product of the effective degree of saturation and the suction considering the cavitation of water under the tension is selected as variable for the ideal capillarity part, and the maximum apparent cohesion is selected as variable for the ideal adsorption part preliminarily. Secondly, based on the concept of the binary-medium model, the unsaturated soil is regarded as a media combined with the two ideal parts by a participation function. The weight of each ideal part represented by participation function is dependent of a cavitation probability variable. Then the new unsaturated soil shear strength with capillary and adsorptive mechanisms is established for unsaturated soils, and applicable to a wide range of suction. Finally, the comparisons between the published experimental data and the predicted results of the proposed and current popular models are carried out, which illustrates the superiority of the proposed model. Thus, the results have shown that the capillary and adsorptive mechanisms should be distinguished when considering the effect of suction on the mechanical property for unsaturated soils.