STUDY ON A PRACTICAL USE OF A NATURE MADE TYPE GROYNE (TRI-PYRA GROYNE)

Abstract

This paper deals with a nature made type groyne which can be called laid triangular sharp pyramid type groyne(Tri-Pyra groyne). Original nature made groyne can be seen at some gravel and stone bed river channels. On the other hand, man-made old groynes of similar shape, called arako groyne, are still functioning at ash-mud bed channels in Kyushu, some are for more than 300 years. Here, considering the rationality of these groynes, stability and function of the groyne were evaluated by field consideration, and 2D calculation. Comparison was also made with another similar groynes. As conclusion, adaptation of this type of groynes, especially Tri-Pyra groyne, is proposed for practical application and the direction of its further development is also suggested.