Insight into Consolidation and Wetting Deformation Behaviors of Unsaturated Loess from a Novel Discrete-Element Model

Unique physical and mechanical characteristics of unsaturated loess in the northwest region of China, including high compression and wetting behaviors, challenge the construction of engineering structures. To investigate the effect of microscopic interaction force during consolidation and wetting, we established a novel contact model considering van der Waals force and capillary force by the secondary development and discrete-element method. After the effectiveness of the proposed contact model was assessed based on single contact model tests, wetting and loading tests were conducted to investigate the effect of multiple factors on consolidation and wetting deformation. The results present that the proposed contact model is suitable for capturing the consolidation and wetting deformation properties of unsaturated loess. With the increase of water content from 3% to 11.6%, the capillary forces between loess particles decrease, finally leading to maximum wetting deformation of 2.7%. Furthermore, a lower relative compaction in simulated loess samples causes more significant consolidation deformation. Besides, the van der Waals force has a slight effect on the deformation characteristics, and the relative difference is about 1%. These results help to stimulate more in-depth studies on the relationship between the microscopic and macroscopic properties of unsaturated loess and reduce the engineering risks.