Abstract: A bag material has a tubular shape and can be folded back at an intermediate position in a longitudinal direction. Crushed stones can be stored in a folded part of the back material. An opening on one side of the bag material can be moved to a position close to an opening on the other side of the bag material. A one-side closing rope that closes the opening on the one side of the bag material is provided near this opening. An other-side closing rope that closes the opening on the other side of the bag material is provided near this opening. The other of the one-side closing rope and the other-side closing ropes can be released with the opening closed by one closing rope.

Abstract: A scour prevention unit includes a bag body housing block objects in a bag material, and a cloth integrated with the bag body, wherein the cloth is housed in the bag material and is laid below the block objects, or is fixed below the bag body outside the bag body by fixing means.

Abstract: A bag material has a tubular shape and can be folded back at an intermediate position in a longitudinal direction. Crushed stones can be stored in a folded part of the back material. An opening on one side of the bag material can be moved to a position close to an opening on the other side of the bag material. A one-side closing rope that closes the opening on the one side of the bag material is provided near this opening. An other-side closing rope that closes the opening on the other side of the bag material is provided near this opening. The other of the one-side closing rope and the other-side closing ropes can be released with the opening closed by one closing rope.

Abstract: A scour prevention unit includes a bag body housing block objects in a bag material, and a cloth integrated with the bag body, wherein the cloth is housed in the bag material and is laid below the block objects, or is fixed below the bag body outside the bag body by fixing means.

Abstract: The condition of a seabed 200 and the condition of tidal currents near the seabed 200 are investigated in advance to examine the number of filter units (FUs) 50 and the position where the FUs 50 are to be installed. Then, piles 12b as a base of a foundation are provided so as to be supported by a bearing layer. A plurality of FUs 50 are installed in close contact with each other between the seabed 200 and each pile 12b. Then, a formwork 12e for a base slab portion 12a is installed on the upper ends of the piles 12b. Concrete is placed in the formwork 12e to form the base slab portion 12a. Then, a tower 11 is fixed to the upper end of the base slab portion 12a.

Abstract: At a location where unevenness 1000 is present, the condition of a seabed 200 is investigated in advance to examine the respective numbers of large filter units 51 and small filter units 52 to be used, and the position where the large filter units 51 and the small filter units 52 are to be installed. Based on the investigation result, the small filter units 52 are installed on the bottom of the unevenness 1000. The large filter units 51 are installed on the upper surface formed by the installed small filter units 52, and are leveled so that the upper surface formed by the installed large filter units 51 becomes flush with the seabed 200.

Abstract: At a location where a submarine cable 20 is to be installed, the condition of a seabed 200 and the condition of tidal currents near the seabed 200 are investigated in advance to examine the number of filter units 50 and the position where the filter units 50 are to be installed. First, the submarine cable 20 is installed on the seabed 200. Then, the filter units 50 are installed so as to cover the submarine cable 20 installed on the seabed 200.

Abstract: The condition of a seabed 200 and the condition of tidal currents near the seabed 200 are investigated in advance to examine the number of filter units (FUs) 50 and the position where the FUs 50 are to be installed. Then, piles 12b as a base of a foundation are provided so as to be supported by a bearing layer. A plurality of FUs 50 are installed in close contact with each other between the seabed 200 and each pile 12b. Then, a formwork 12e for a base slab portion 12a is installed on the upper ends of the piles 12b. Concrete is placed in the formwork 12e to form the base slab portion 12a. Then, a tower 11 is fixed to the upper end of the base slab portion 12a.

Abstract: At a location where a submarine cable 20 is to be installed, the condition of a seabed 200 and the condition of tidal currents near the seabed 200 are investigated in advance to examine the number of filter units 50 and the position where the filter units 50 are to be installed. First, the submarine cable 20 is installed on the seabed 200. Then, the filter units 50 are installed so as to cover the submarine cable 20 installed on the seabed 200.

Abstract: At a location where unevenness 1000 is present, the condition of a seabed 200 is investigated in advance to examine the respective numbers of large filter units 51 and small filter units 52 to be used, and the position where the large filter units 51 and the small filter units 52 are to be installed. Based on the investigation result, the small filter units 52 are installed on the bottom of the unevenness 1000. The large filter units 51 are installed on the upper surface formed by the installed small filter units 52, and are leveled so that the upper surface formed by the installed large filter units 51 becomes flush with the seabed 200.