Abstract
An increasing demand for exploitation of ocean space creates a need for artificial low cost protection of marinas and nurseries. So far floating breakwaters are frequently chosen to provide this protection, particularly in location where large tide is considered, and water depth is large. Recently a breakwater which consists of submerged horizontal plate has attracted much of attention, because this breakwater has several advantages such as a low construction cost, an easy exchange of seawater behind the breakwater, no obstruction of sea scenery etc.
It is, however, of importance to keep the submerged plate with a constant depth from a free surface irrespective of tide, in order to get its good performance fully. Thereby we can not apply the existing mooring system such as a catenary type mooring and tension leg type mooring to it, and it has been a great problem of long standing to moor this type of floating breakwater at seas. A new mooring system has been developed lately. This mooring system consists of sliding double-piles which can follow tide and can prevent the floating body from oscillating in waves.
We have carried out the extensive forced oscillation tests to make clear the hydrodynamic forces in the sliding double-piles. In this paper, we derive the practical formula from the experimental results which is useful for estimation of hydrodynamic forces in various conditions of double-piles.
