Modelling unsaturated soil-structure interfacial behavior by using DEM

The interface between unsaturated soil and structure plays an important role in various geotechnical structures in natural environment. In this study, a series of three-dimensional numerical direct shear tests are conducted on a soil-structure interface under various suctions and normal stresses by using the discrete element method (DEM). The simulated macro-mechanical results match reasonably well with experimental data reported in the literature. During the shearing process, the micro-mechanical shearing properties between unsaturated soil and structure are investigated, including particle displacement, the magnitude and orientation of the contact force, and the magnitude and orientation of the capillary force. The influence of capillary cohesion on the macro- and micromechanical behavior of the interface changes non-monotonically with the suction increase. Samples with the suction (or degree of saturation) in the funicular regime usually show more distinct capillary cohesion effect compared with that in either capillary or pendular regimes. The capillary cohesion effect on unsaturated soilstructure interfacial behavior is weakened with increasing normal stress.

Automated summary

The interface between unsaturated soil and structure is crucial in geotechnical structures, with the capillary cohesion effect changing non-monotonically with suction increase. As suction increases, capillary cohesion has a significant impact on the interface behavior, but this effect weakens with increasing normal stress.