This study performed three-dimensional finite element stress and deformation analyses on a grid-type steel check dam (i.e., grid-type dam) in Hua-Shan Creek and an enhanced B-type steel check dam (i.e., B-type dam) in Tseng-Wen Reservoir through debris flow loading. For the grid-type dam, two horizontal connection members were connected on the top run. The connection members stringed together the unit structures of the dam and penetrated the dam wing at fixed ends, which provided a restraint effect on the entire dam structure. The grid-type design could effectively transfer the loading from the unit structures at the dam center to those of the dam wing and prevent higher maximum stress ratios (e.g., shear, bending, and combined stress ratios). The maximum horizontal displacement of the unit structure gradually decreased from the dam center to the wing. For the B-type dam, all the unit structures only bore their own loading because no horizontal connection member was present to transfer the loading between structures.Consequently, each unit structure demonstrated similar maximum stress ratios and maximum horizontal displacement.Additionally, the maximum tensile stress occurred at the vertical upstream member and horizontal downstream member,whereas the maximum compressive stress occurred at the vertical downstream member and horizontal upstream member.In both cases, the maximum horizontal displacements occurred when the boulder impact force of debris flows was smaller than 2% of the effective dam height, which satisfied standard international inspection requirements. Moreover,the maximum combined stress ratio was sensitive to the diameter-to-thickness ratio of the steel-pipe member, which significantly decreased as the maximum combined stress ratio increased.
Key Words: Steel check dam, unit structure, steel-pipe member, maximum combined tensile-to-compressive stress
ratios, maximum horizontal displacement, diameter-to-thickness ratio