EFFECTS OF DROP WEIGHT SHAPE ON SURFACE DAMAGE OF CONCRETE UNDER REPEAT COLLISION OF DROP WEIGHT

Abstract

Collision of rock pellets mixed in waterflows causes surface damage to concrete of the dams and the soil saving dams, and causes problems on the maintenance of these structures. Some experimental researches had been tried to grasp this phenomena up to now, but shapes of the rock pellets have not been considered in these past researches using with only ball shaped drop weights in the repeat collision tests. In this paper, repeat collison tests using with drop weights shaped in polyhedron with vertexes are carried out to estimate the effects of vertexes of rock pellets on the surface damages of the concrete by the impact loading. The cuboctahedron which is one kind of polyhedron with regular polygons is employed to shape the drop weights with vertexes to compare with the ball shaped drop weights. Ratio of loss volume per the kinetic energy increased by the vertexes of drop weight are discussed from the experimental results. In addition, effects of the drop weight mass and the dropweight height are discussed from a view point of the relationship between the loss volume on concrete surface and the kinetic energy of drop weights.