Mesoscale analysis of the suction stress characteristic curve for unsaturated granular materials

There is still no theoretical framework accounting for linkage between seepage and deformation of unsaturated granular materials. Using a mesoscale liquid bridge model, we propose the first approach for deriving the suction stress characteristic curve (SSCC). Then, we verify the method by obtaining both the soil–water characteristic curve and SSCC for cubic and tetrahedral granular packing. The approach is further validated by generating the SSCCs of granular packings with different particle size distributions. On this basis, a new two-parameter model is suggested that satisfactorily predicts the SSCCs of various real granular materials. The nonlinear variation of strength versus suction is also properly described by a new formula for three kinds of soil. We believe that this SSCC model can help resolve solid–fluid coupling in seepage and deformation problems in unsaturated granular engineering.