Many analytical approaches for capture mechanism of woody debris were proposed by using Distinct Element Method with spherical assembled element, as well as cylindrical element or cylindrical assembled element. This paper presents an analytical approach of influence of surface shapes on the analysis for capture mechanism of woody debris. When the woody debris was modeled by spherical assembled element, larger amount of woody debris were captured than that of experimental results. It was caused that the debris was caught each other by the uneven surface made by connection of sphere elements. On the other hand, when the woody debris was modeled by cylindrical element or cylindrical assembled element, the experimental result of capture mechanism and capture probability were simulated well. It is pointed out that the smooth surface of cylindrical element can express the frictional effect between woody debris and structural member in the capture process very well.

Key wordsFinfluence of shape property, woody debris, cylindrical element, cylindrical assembled element