軟岩河床における洗掘機構に関する実験的検討

抄録

There are many rivers which the degradation of river bed is caused and soft rock under gravel layer has exposed in these rivers. Combination of soft rock is weak and it is scoured easily. The stability of the bridge pier and the revetment which is constructed on the soft rocks is decreased when these structures are constructed on the soft rocks when the soft rock bed is exposed. Therefore it is necessary to clarify the scouring mechanism in the soft rock riverbed. The expose of soft rock is caused at the upstream of the Ishikari River. In the research in 2008,the cause of the scouring was examined by the assumption which of impact of gravel. However, the results of hydraulic experiments in 2009 were not able to be explained by the assumption. In addition to the collision of gravels, friction with gravels and soft rock was taken into consideration as a cause of scouring. This friction effect is focused in this paper. It became clear from the result of hydraulics experiments that the collision of gravels and friction of gravels have influenced scouring of soft rock bed.