Paper Title
Impact Force Assessment of Flexible Debris-Flow Barriers using Small-Scale Model Test

The impact forces applied on a closed-type erosion control dam and a ring-net were assessed using a small-scale model test. The experimental results demonstrated that the debris-flow behaved similar to fluids. The debris-flow impact force applied on the back of the closed-type erosion control dam was measured to be the largest at 4.14 kN on the lower part, followed by 3.66 kN on the middle part, and 1.66 kN on the upper part. The ring-net test results also demonstrated that the impact force was the largest on the lower part and decreased toward the upper part (from 2.28 kN to 1.95 kN and then, to 1.49 kN), similar to the results of the closed-type erosion control dam. When the mechanism of absorption of the debris-flow impact force by the flexible debris-flow barrier was analyzed using numerical analysis results, the actual horizontal force acting on the structure was equal to that obtained by the theoretical formula. This is because the closed-type erosion control dam resists the horizontal force using the stiffness of the structure similar to a concrete retaining wall. However, in the case of the ring-net, which utilizes the elastic stretching of the strand and particle transmission to the net front, the impact force was lower by up to 45% than the result of the erosion control dam. Index Terms—Debris-flow, flexible debris-flow barrier, erosion control dam, ring-net, debris-flow impact force