Abstract: Wetting deformation of soft rockfill materials caused by external rainfall events is significant and often brings about challenges to engineering deformation control and operation safety. This paper presents an analysis of the basic law of material wetting strain under rainfall conditions, and reveals that the wetting strain caused by early rainfall accounts for a relatively big proportion and its time variation is well described using hyperbolic curves; For the case of a single rainfall event, we examine strain development during rainfall and demonstrate that its time variation in the early stage is also hyperbolic; Analysis on the influence of rainfall intensity on the overall wetting process shows that as rainfall intensifies, the rate of change in the strain increases but its magnitude decreases to a certain extent. To understand the variation in wetting strain with rainfall intensity in this case, we develop a model for calculating unsaturated infiltration wetting deformation in rainfall conditions based on the hyperbolic curve, and verify its applicability to prediction of the rainfall wetting deformation laws of soft rockfill materials.

Key words: geotechnics, wetting deformation, wetting model, infiltration in unsaturated condition, rainfall intensity