Two-phase CFD investigation of the flow-barrier interaction for slit barriers

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4. Two-phase CFD investigation of the flow-barrier interaction for slit barriers

Debris flows are highly mobile and destructive geophysical flows that cause substantial devastation and casualties to infrastructures downstream. To mitigate these side effects, obstacles of various types, such as slit barriers, are constructed alongside the predicted flow channels. The successful implementation of slit barriers is imperative to determine the optimal dimensions and arrangement. However, the complicated process of interaction between the debris flow and the slit barriers is not yet fully understood, and a unified procedure for the design is still lacking. Thus, the aim of this study is to explore the impact of transverse blockage on the dynamic properties of two-phase debris flows and to analyze the effects of the presence of a second row of taller barriers compared to the first one, using FLOW-3D software. The findings indicate that increasing the transverse blockage in a single row of slit barriers can effectively reduce the downstream depth-averaged velocity up to a certain threshold. Beyond this threshold, the effectiveness is only marginally improved compared to lower blockage percentages. Moreover, insufficient barrier height, together with high transverse blockage values, causes a significant overflow volume of debris flow, making the barriers less efficient. In conclusion, increasing the number of rows to two, where the height of the second row is set at 1.5 times the depth of the flow after landing from the overflow of the first row, effectively attenuates flow velocity and furthermore reduces the flow influx volume per unit time.

4th Asia-Pacific Conference on Physical Modelling in Geotechnics (ACPMG2024)

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