JP2015212486A - Dredging/soil throwing-away method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dredging/soil throwing-away method without diffusing a pollutant in a small range from the inside of a work area.SOLUTION: In a dredging/soil throwing-away method, an upper end part of a water permeable suspension membrane-like body of providing a functional object on a surface, is fixed to a quadrangular grab frame on the periphery for executing dredging or soil throwing-away work, and next, a float is provided in the grab frame, and surrounds the periphery of the dredging or soil throwing-away work, and next, a grab bucket 3 is dropped from a high place to a place surrounded by a functional water permeable suspension membrane-like body, and is sunk in soil of the water bottom in its force, and the grab bucket 3 is pulled up from a water surface, and sediment is loaded on a barge.

Description

The present invention relates to a dredging / soil disposal method in the ocean, harbor, dam, river, lake and the like.

Conventionally, mining of earth and sand such as the seabed and riverbed has been performed using a grab ship. The grab boat has a winch mechanism that can turn 360 ° like the upper revolving body of a power shovel, hangs a grab bucket from the tip of the boom, and excavates earth and sand with this grab bucket. In the actual excavation work, the grab bucket was dropped from a high place, and by the momentum, it was submerged in the sediment at the bottom of the water, grabbed the sand and pulled it up and loaded it onto the ship. However, this dredging method has the disadvantage that the water in the dredging work area is polluted and diffused.
In recent years, environmental awareness has increased, and it is no longer allowed to diffuse polluted water to the surrounding area when dredging and dumping.

Therefore, in recent years, the dredging / soil disposal work area has been surrounded by curtains so that polluted water does not diffuse around. For the purpose of preventing the spread of polluted water, the curtain used was exclusively canvas. When dredging work was done by using curtains made of canvas, the diffusion of polluted water could be prevented, but it was not perfect. That is, if the grab bucket is dropped from a high place in the place surrounded by the curtain, a high water pressure is generated in the curtain surrounded by the drop, and this water pressure causes the disadvantage that polluted water diffuses from the lower end of the curtain to the outside. there were.

  Therefore, the present inventor has completed various studies on the construction method for preventing the polluted water in the curtain surrounded by the water pressure generated when the grab bucket is dropped or thrown away during dredging, and to complete the present invention. It came.

  That is, the present invention is a dredging / soil disposal method characterized in that it is carried out by enclosing the periphery of a dredging or earth dumping work with a water-permeable hanging membrane-like body provided with a functional object on the surface.

  According to the method of the present invention, it is possible to effectively prevent the diffusion of contaminated water during dredging or earth disposal.

Sectional drawing which shows the state of the conventional dredging method Front view showing water-permeable drooping membrane Front view showing another water-permeable drooping membrane Front view of a functional water-permeable drooping membrane with functional objects Sectional drawing which shows the state of the dredging method of this invention Sectional view showing the flow of water that permeates through the mesh

FIG. 1 is a cross-sectional view showing a conventional dredging method. A float 2 is provided on the upper part of a curtain 1 made of canvas (water impervious) to surround the periphery of the dredging work.
In this way, when the grab bucket 3 is dropped from a high place into the dredging work area surrounded by the curtain 1 made of canvas, the water pressure inside the curtain 1 generated at that time is the canvas that is impermeable to water around it. Since it is surrounded by water, water cannot pass therethrough, and therefore, vigorously from the open portion of the lower end 4 of the curtain 1, the polluted water in the go of the curtain 1 diffuses outside and pollutes the surrounding water area with the polluted water.
Further, the partial expansion and contraction in the curtain 1 due to a series of operations of dropping and pulling up the grab bucket 3 disturbs the water area in the curtain 1 and erupts in the water area from the open portion of the lower end 4 of the curtain 1 to the bottom of the water. As a result, the pollution was diffused.

The present invention uses a water-permeable drooping membrane 5 provided with a functional object on the surface in place of a conventional canvas. The water-permeable drooping membrane 5 used in the method of the present invention comprises: A net-like shape 6 as shown in FIG. 2 or a rope-like shape 7 as shown in FIG. 3 can be used. The functional object 8 provided on the surface of the water-permeable hanging membrane 5 includes, for example, a braid obtained by forming a plurality of loop fibers diagonally around the rope core, and a plurality of ropes around the rope core. A braid obtained by molding a small loop fiber into a spiral shape, a braid obtained by processing the rope core into a brush shape with a fiber, and the like are used.

  As shown in FIG. 4, these functional objects 8 are integrally provided on a net-like 6 or rope-like water-permeable drooping membrane 5. Moreover, the water-permeable drooping membrane-like body 5 of the net | network 6 or the rope-like shape 7 can also be adjusted using the functional object 8 as another aspect. As the water-permeable drooping membrane 5 having such a functional object 8 provided on the surface, for example, Patrecia P-NR type (trade name, manufactured by Nippon Solid Co., Ltd.) is used.

Next, the method of the present invention will be described.
As shown in FIG. 5, a water-permeable drooping membrane body (hereinafter referred to as a functional water-permeable drooping membrane body) 6 having a functional object 8 provided on the surface in the vicinity of the dredging or earth disposal work. The upper end is fixed to a square grab frame. Next, a float is provided in the grab frame to surround the periphery of the dredging or dumping work.
Moreover, it is preferable to provide a weight 9 at the lower end of the functional water-permeable drooping membrane 5. The weight 9 can be a square of the same steel pipe as the shape of the grab frame using the steel pipe, and can be provided in the middle of the functional water-permeable drooping membrane 5 (not shown). When the functional water-permeable drooping membrane 5 is lifted up, the weight of the steel pipe provided in the middle is larger than the outer peripheral dimension of the grab frame of the steel pipe, and the weight of the steel pipe provided in the lower end is the weight of the steel pipe weight provided in the middle. It is desirable to make it larger than the outer dimension.

Next, the grab bucket 3 is dropped from a high place at the place surrounded by the functional water-permeable drooping membrane 5, and is submerged in the soil at the bottom of the water to grab the sand and lift the grab bucket 3 from the water surface. Load earth and sand on the ship.
As described above, when the grab bucket 3 is dropped from a high place, a high water pressure is generated on the inner side surrounded by the functional water-permeable hanging membrane-like body 5. However, according to the method of the present invention, since the functional water-permeable drooping membrane 5 is water-permeable, water flows out from the gap, so that partial expansion and contraction in the curtain 1 due to water pressure is reduced. The pollutant in the water comes into contact with the functional object 8 and is attached and captured. The pollutant adhered to and trapped on the functional object 8 gradually grows and enlarges, and eventually peels off from the functional object 8 and settles on the bottom of the water.
As shown in FIG. 6, when a high water pressure is applied to the inner side surrounded by the mesh body 6, this water flow is trickled by the section of the mesh body 6, so that the momentum of the water is increased as an ordered fluid. The flow 11 which is deenergized and tries to escape from the net string 10 becomes an inner vortex 12 behind the net string 10, and the flow to be drawn into the inner wrap entrains soil particles in the water and becomes contaminated while interfering with each other. It forms a soul (cloud soul) and becomes a sinking soul. A flow that sinks to a small extent in the polluted area is formed, which is effective for sinking the sinking soul to the bottom of the water.
On the other hand, on the inner side surrounded by the functional water-permeable drooping membrane 6, interference sedimentation occurs by large and small contaminant particles near the water surface, and then the interference sedimentation further progresses as a cloud soul and the contaminants settle to the bottom of the water. It becomes like this.

Also, in the soil disposal method according to the present invention, interference sedimentation is performed in the flow of trickling of the entire sedimentation without diffusing the pollutant at the initial stage of the mud discharge, and then the adherence / sedimentation of the particulate contaminants is performed. Furthermore, since the sedimentation slurry after sedimentation flows under the depth of the landfill (3 m or less) and reaches an equilibrium state, it is possible to prevent diffusion of pollutants out of the surrounding area.
Further, when the particles of the mud are fine particles such as clay and colloid, the solid aggregating agent is suspended from the water-permeable hanging membrane 5 and the dissolved solid aggregating agent is the water-permeable hanging membrane 5. It is possible to prevent the pollutant from diffusing out of the surroundings by the micro floc method in which the polluted fine particles that adhere to the water-permeable penetrating membrane 5 are aggregated.

6 ... Water-permeable drooping membrane 9 ... Functional object

Claims (1)

A dredging / soil disposal method characterized in that it is constructed by surrounding a fence or soil disposal work with a water-permeable drooping membrane on which a functional object is provided.

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