Wetting-induced collapse behavior associated with infiltration: A case study

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Limited information is available in the literature for interpreting the influence of water infiltration process that contributes to in-situ collapse in loess deposits. For this reason, the focus of the present investigation has been directed to studying the collapse deformation with respect to time in Heifangtai, China, where significant wetting-induced collapse deformation is widespread due to multiple years of irrigation activities. A method that is based on easy-to-obtain parameters from constant water content oedometer tests and the wetting soil-water characteristic curve is used for predicting the long-term wetting-induced collapse deformation. The proposed method is validated using a field infiltration test. The wetting-induced collapse behavior in Heifangtai is interpreted using the proposed method. Results of the study suggest that there is a significant difference in total subsidence between the irrigation and non-irrigation areas. The collapse in the irrigation area occurs during the period when the wetting front advances and the groundwater table (GWT) forms and rises until the formation of a new hydraulic equilibrium state, which is significantly different from its initial condition. However, the collapse in the non-irrigation area is mainly related to the GWT variation. The difference in the total subsidence between the irrigation and non-irrigation areas is predominantly associated with the propagation of the wetting front. The proposed method is simple and can be extended in practical applications for reliably estimating the in-situ collapse deformation associated with the water infiltration process.