JPS61282507A - Sand covering work for bottom under water - Google Patents

Abstract

PURPOSE:To uniformly spread sand over the bottom under water by a method in which while raising air bubbles upwards in water by jetting air from many air nozzles in an air jet tool set near the bottom under water, sand is spread over the rising place of air bubbles from the water surface. CONSTITUTION:While towing an air jet tool 12 and a sand spreader 3 by a ship etc. sand 8 is spread from the sand spreading holes 5 of a sand spreading tube 4 into water and air is jetted from the air nozzles 14 of an air jet tube 13. The air so jetted goes up in the form of air bubbles 18 and the settling speed of the sand 8 is reduced by the ascending stream of the air bubbles 18, thereby swirling and dispersing the sand 8. The sand 8 is then slowly deposited on floating sludge 17 to form a sand deposit layer 19.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is an underwater bottom covering suitable for use, for example, when spreading sand on soft underwater floating mud and covering the surface with a sand layer of uniform thickness. It concerns the sand method.

(Prior Art) There are cases where the bottom surface of a beach where sludge is deposited is covered with a sand layer, or as a drainage layer between layers when sludge is reclaimed.

In such cases, conventionally the sand spreading section of the sand spreading boat was used.

They simply dropped sand into the water and spread it.

(Problem to be solved by the invention) However, with this method of dispersing sand, the sand falls in a concentrated manner, and the falling speed is high, causing it to sink into the mud surface and almost spread over the water bottom. There was a problem that it was not possible to form a sand layer of uniform thickness.

An object of the present invention is to provide an underwater sand covering method that allows sand to be spread almost uniformly.

(Means for Solving the Problems) The underwater bottom encrusting method according to the present invention involves injecting air from a large number of air outlets of an air injection tool disposed near the underwater bottom to raise air bubbles in the water. This method is characterized in that sand is spread from a sand spreader on the water surface to the location where the air bubbles rise.

(Effect) When sand is sprinkled from above the water surface to a place where air bubbles are rising, the air bubbles slow down the sedimentation speed of the sand, and the sand is lifted up and dispersed, very slowly coming together. It will accumulate like this.

(Example) Examples of the present invention will be described in detail below with reference to FIGS. 1 to 4. As shown in the figure, there is a floater 2 on the water surface 1.
Sand spreader 3 is floating. Sand spreader 3 is
A sand distribution pipe 4 is provided, and a large number of sand distribution holes 5 are provided in two rows on the lower surface of the sand distribution pipe 4. An angle member 6 is provided in the pipe between the rows, and sand is supplied from a sand supply pipe 7. 8 is supplied in the form of a slurry together with water, and is configured to be discharged from each sand dispersion hole 5 to perform the dispersion.

A winch 9 is mounted on the floater 2, and a wire row 110 pulled out from the winch 9 is attached to a roller 11.
The air injection device 12 is suspended and supported at the lower end of the air injection device.

The air injection device 12 has a structure in which air injection pipes 13 are connected and communicated with each other in a grid pattern, and a large number of air discharge ports 14 are provided in two rows on the lower surface of each air injection pipe 13. Near compressor 1 on floater 2
5 through an air hose 16, and the air is discharged from each air outlet 14.

As shown, the air injection device 12 is positioned near the floating mud 17 on the bottom of the water, and the sand spreader 3 is positioned on the water surface 1 correspondingly. In such a state, sand 8 is scattered into the water from the sand dispersion hole 5 of the sand dispersion pipe 4 while being appropriately towed by a ship or the like so that both move in conjunction with each other, and from the air discharge port 14 of the air injection pipe 13. causes air to be expelled. The exhaled air is bubble 1
8 and rises through the water. Due to the upward flow of the bubbles 18,
The sand 8 spread from the water has a lower settling speed,
Moreover, it is lifted up and dispersed. As a result, the sand 8 is dispersed and deposited very slowly, making it possible to cover the floating mud 17, which has almost no supporting force, as a thin volumetric sand layer 19. The volumetric sand [119] can be increased or decreased by increasing or decreasing the amount of sand spreading from the sand spreader 3 or by increasing or decreasing the moving speed of the sand spreader 3 and the air injection tool 12.

(Effects of the Invention) As explained above, in the present invention, sand is spread where air bubbles are rising from the water, so the upward flow of air bubbles slows down the sedimentation speed of the sand, and the sand is lifted up and dispersed. However, the sand can be deposited very slowly and evenly. Therefore, it is possible to thinly cover the floating mud with almost no supporting force.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of the implementation state of the underwater sand covering method according to the present invention, FIGS. 2 and 3 are a side view and a vertical sectional view of a part of the sand dispersion pipe, and FIG. 4 is an air injection Bottom view of an example of the tool,
FIG. 5 is a longitudinal sectional view showing an example of an air injection pipe. 1...Water surface, 2...Floater 13.
...Sand spreader, 4...Sand spreader pipe, 5...
...Sand distribution hole, 8...Sand, 10...
・Wire rope, 12... Air injection device, 13
... Air injection pipe, 14 ... Air discharge port, 17 ... Floating mud, 18 ... Air bubbles, 19
...volume sand layer.

Claims (1)

[Claims] The feature is that air is injected from a number of air outlets of an air injection device disposed near the bottom of the water to cause air bubbles to rise in the water, and sand is spread from a sand spreader on the water surface to the location where the air bubbles rise. Underwater bottom covering method.