MAT HOLED IN FORWARD END AND METHOD OF LAYING SAID MAT

PURPOSE:To prevent the forward end of a mat from being scoured off, by a method wherein scouring-preventing mats, each having a number of holes formed in a specified range of the mat, are laid in a manner that they are protruded from the foundation of a breakwater and the lower part of precast concrete armour nuits, and a flow of water and the like is produced at the forward end of the mat. CONSTITUTION:In order to prevent foundation rubble-mound 3 of a breakwater 4 and a sea bottom ground 1 from being scoured off, scouring preventing mats 7 and 10 are laid between the seat bottom ground 1 and the foundation rubble- mound or covering stones 3. The mat 10 has a number of holes 12 bored in a specified range at the forward end thereof to creat a flow of water therethrough. The range, where the holes 12 are formed, is sized to be about one half length of a portion which is protruded toward the sea side from the forward end of the precast concrete armour units 3, such as breakwater, or the foundation. Further, the hole is sized to be about 5-30cm in diameter, and the area rate of the holes is 15-30% of the forward end of the mat. This prevents are forward end of the mat from being scoured off due to the high waves during winter season.