EVALUATION OF HYDRODYNAMIC FORCE ON CONNECTED STONE BED PROTECTION WORKS AT THE DOWNSTREAM OF A WEIR

Nature oriented hydraulic structures made of natural stones such as ripraps have been used in Japan considering river environment. Negative aspect of these structures is easy to collapse under intense flow. Therefore, a connect stone is proposed to increase its stability against the intense flow. In this study, stability of two types connected stones, one is non-porous and the other is porous type, was investigated under rapidly varied flow conditions such as supercritical flow and hydraulic jump. Stability analysis using uplift and drag force acting on the connected stone shows that the non-porous type connected stone may collapse turn up and lift up mode. Furthermore, it is clarified that the porous type connected stone is more stable than the non-porous type.