JP5723569B2 - Sediment throwing method and sand throwing device using treme tube - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a method and apparatus for depositing earth and sand using a tremy pipe, and more particularly, to throwing earth and sand using a tremy pipe that can prevent the diffusion of pollution while preventing the tremmy pipe from being blocked by the loaded earth and sand. The present invention relates to a method and an apparatus for introducing earth and sand.

  A method of using a tremy tube when putting earth and sand into a water bottom such as the sea is known (for example, FIG. 1 to FIG. 4 of Patent Document 1). When throwing earth and sand into the seabed through the tremy pipe, in order to prevent clogging and blockage in the pipe, for example, sea water pumped up from the vicinity of the sea surface (water depth of about 1m to 2m) is injected from the upper end of the tremy pipe. Yes. In addition, various proposals have been made in order to suppress the diffusion of pollution caused by the input soil. In Patent Document 1, a muddy water suction port is provided around the spray port at the lower end of the tremy tube, and the generated muddy water is sucked from the muddy water suction port and ejected from the middle through the nozzle (FIG. 5 to FIG. 5). (See FIG. 8 etc.)

  By the way, it has been reported that when sand and sand are put back into a depression in the bottom of the water, pollution is more likely to diffuse in the autumn than in the summer. Therefore, the inventors of the present application focused on this phenomenon and analyzed the influence of the water density in the water area on the pollution diffusion. Based on the knowledge gained from this analysis, various studies have been made to create a technique for preventing the diffusion of pollution caused by the input soil while preventing the tremmy tube from being blocked by the input soil.

JP 56-1119035 A

  An object of the present invention is to provide an earth and sand charging method and an earth and sand charging apparatus using a tremy pipe that can suppress the diffusion of pollution while preventing the tremy pipe from being blocked by the charged earth and sand.

In order to achieve the above-mentioned object, the earth and sand throwing method using the tremy pipe of the present invention includes a suction pipe extending to the upper side of the tremy pipe at a position outside the tremy pipe at a site where the earth and sand are poured. The water is pumped up from a position deeper than 50% of the water depth of the site through the suction pipe from the lower end of the suction tube installed at a position outside the tremy tube, and the water depth of 50% of the site is water dense than water present in, while injecting from the upper end of the tremie tube, by injecting sediment into the sea bed in water depths 5m~30m through the tremie pipe, suppress the diffusion of contamination caused by the charged sediment It is characterized by doing.

The earth and sand injection device of the present invention has a density higher than that of water existing at a water depth of 50% of the water depth of this site and a tremy pipe standing on the water from the vicinity of the bottom of the site where the water depth is 5 to 30 m. Water injection means for injecting high water from the upper end of the tremmy pipe, and the water injection means is disposed away from the tremy pipe at a position outside the tremy pipe so that the water depth is more than 50% of the water depth of the site. A suction pipe extending from a deep position to above the tremy pipe and a suction pump connected to the suction pipe, and a lower end of the suction pipe through which the high-density water is sucked is located outside the tremy pipe. The water is pumped from the lower end of the suction pipe through the suction pipe from a position deeper than the depth of 50% of the water depth of the site, and has a density higher than that of water existing at the depth of 50% of the depth of the site. high , Said while injecting from the upper end of the tremie tube, by injecting sediment into the sea bed in water depths 5m~30m through the tremie pipe, characterized in that the inhibiting arrangement the diffusion of contamination caused by the charged sediment.

  ADVANTAGE OF THE INVENTION According to this invention, blockage | closure of the earth and sand in a tremy pipe | tube can be prevented by throwing in earth and sand, injecting water from the upper end of a treme pipe | tube. Moreover, since water with a higher density than the water existing near the water surface at the site where soil is introduced is used, the water density is higher than when water near the water surface is used. When it is done, the pollution becomes difficult to diffuse.

In the earth and sand injection method of the present invention, water is drawn up from a position deeper than 50% of the water depth at the site, and the water is injected from the upper end of the tremy tube. In the earth and sand injection device of the present invention, the water injection means is disposed away from the tremy pipe at a position outside the tremy pipe, and is located above the tremy pipe from a position deeper than 50% of the water depth of the site water. And a suction pump connected to the suction pipe. Thereby, the water whose density is higher than the water which exists in the vicinity of the water surface of the field where earth and sand are thrown in can be secured easily.

It is explanatory drawing which illustrates embodiment of the earth and sand injection | throwing-in apparatus of this invention. It is explanatory drawing which illustrates the reference form of the earth and sand injection | throwing-in apparatus. It is explanatory drawing which shows an experimental apparatus. It is explanatory drawing which showed the pollution diffusion state of Example 1 based on numerical calculation. It is explanatory drawing which showed the pollution diffusion state of Example 2 based on numerical calculation. It is explanatory drawing which showed the pollution diffusion state of the comparative example 1 based on numerical calculation. It is explanatory drawing which showed the pollution diffusion state of the comparative example 2 based on numerical calculation.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method and apparatus for introducing earth and sand using a tremy tube of the present invention will be described based on the embodiments shown in the drawings.

  As illustrated in FIG. 1, the earth and sand injection device 1 according to the present invention includes a tremely pipe 2, and a water injection system including a suction pipe 4 and a suction pump 5 that allow water W to flow into the tremy pipe 2 from the upper end of the tremy pipe 2. Means.

  The tremy pipe 2 is held by a holding member 7 provided on the work boat 9 and is erected on the water from the vicinity of the water bottom at the site where the earth and sand S is introduced. A hopper 3 is installed at the upper end of the tremy tube 2. The size of the tremy tube 2 is, for example, an inner diameter of about 1 m to 5 m, a total length of about 7 m to 25 m, and a wall thickness of about 10 mm to 15 mm.

  In this embodiment, the tremy tube 2 is a straight cylindrical steel tube, but is not limited to a straight shape, and may have a shape in which the lower diameter is further expanded. Moreover, the tremey tube 2 can use both an expansion-contraction type and a non-expansion type. In the case of the expansion / contraction type, for example, a structure in which a plurality of tubular bodies are connected in a telescopic manner is used. In the case of the non-expandable type, a simple single pipe or a structure in which a plurality of pipes are added is used. The tremy tube 2 is not limited to a single tube, and a double tube composed of an inner tube and an outer tube can also be used.

The lower end of the suction pipe 4 is disposed at a position deeper than the vicinity of the water surface at the site and not in contact with the water bottom. The vicinity of the water surface of the present invention is a position of about 1 to 2 m from the water surface. Specifically, the lower end of the suction pipe 4 is disposed at a position that is deeper than the water depth h (= H × 50% ) 50% of the water depth H and does not contact the water bottom, and the upper end is disposed at the upper opening of the hopper 3. Yes. Thus, the suction pipe 4 is extended from the predetermined water depth position to the upper part of the tremy pipe 2. The suction pump 5 is installed on the work boat 9 and is provided in the middle of the suction pipe 4. As the suction pipe 4, for example, a flexible pipe made of resin is used.

  A conveyor belt 8 is installed adjacent to the hopper 3 and serves as earth and sand charging means. The conveyor belt 8 puts the earth and sand S loaded on the work ship 9 through the hopper 3 into the tremy pipe 2. In addition, a backhoe bucket or the like can be used as the earth and sand charging means.

  The method of throwing earth and sand S into the bottom of the water using the earth and sand throwing device 1 is as follows.

  First, the earth and sand S are put into the hopper 3 using the conveyor belt 8. At this time, the suction pump 5 is operated to inject water W into the hopper 3 through the suction pipe 4. That is, water W having a higher density than water existing in the vicinity of the water surface at the site where the earth and sand S is introduced is injected into the pipe from the upper end of the tremy pipe 2 by the water injection means. In this way, a high amount of water W (water W having a small density difference from the water present at the bottom of the water) is injected from the upper end of the tremy tube 2 and a predetermined amount of earth and sand S is introduced into the bottom of the water through the tremy tube 2. To do. In the construction at sea, the earth and sand S is thrown into the bottom of the water while injecting water W having a higher salinity than seawater present near the sea surface at the site into the tremy pipe 2.

  Since the water W is injected into the tremy pipe 2, in the case of the earth and sand S having a high viscosity, the water W prevents the earth and sand S from adhering to the inner wall of the tremy pipe 2. Moreover, even if the amount of the earth and sand S to be charged at one time is excessive, the flow of the earth and sand S is smoothed by the water W without being disturbed by friction with the inner wall of the tremy pipe 2. Therefore, the injection of the water W makes it difficult for the earth and sand S to be clogged in the tremy tube 2, thereby preventing the tremmy tube 2 from being blocked.

  Furthermore, the water W to be injected into the tremy tube 2 has a higher density than the water near the water surface, and the density difference from the water at the bottom is small. Therefore, even if the earth and sand S introduced with the water W is released from the lower end of the tremy pipe 2, it becomes difficult to float in the water, and the diffusion of pollution is suppressed. In particular, the upward spread of pollution is reduced. The higher the density of water, the more advantageous it is to suppress the diffusion of pollution.

In the sea, the deeper the water, the higher the density of the seawater (salt concentration). In addition, the difference in water density in the depth direction increases as the water temperature increases, such as in summer. Therefore, in order to make the density of the water W injected into the pipe of the tremy pipe 2 close to the density of the water existing in the bottom of the water into which the earth and sand S is introduced, the lower end of the suction pipe 4 is 50% of the water depth H , more preferably 70. %, more preferably disposed at a position deeper than 90%.

  By disposing the suction pipe 4 in this way, water W having a smaller density difference from the water present at the bottom of the water can be injected into the tremy pipe 2. That is, in construction at sea, water W having a smaller salinity difference from seawater existing at the bottom of the water can be injected into the tremy tube 2. Thereby, it becomes possible to further suppress the diffusion of the contamination due to the introduced earth and sand S.

  If water having a density higher than the water existing at the depth H at the site is used, there is a risk that the ecosystem will be adversely affected. Therefore, ideally, the water W having the same density as the water existing at the bottom of the earth and sand S is poured from the upper end of the tremy pipe 2 into the pipe.

The reference form of the earth and sand throwing-in apparatus 1 illustrated in FIG. 2 is obtained by changing only the water injection means of the previous embodiment. This water injection means is constituted by a suction pipe 4, a suction pump 5 and a storage tank 6. One end of the suction pipe 4 is disposed inside the storage tank 6, and the other end is disposed in the upper end opening of the hopper 3. The installation location of the storage tank 6 is not limited to the inside of the ship but can be on the ship.

The storage tank 6 stores water W having a higher density than water existing in the vicinity of the water surface at the site where the earth and sand S is introduced. In the case of this reference form, the density of water existing in the vicinity of the water surface at the site where the earth and sand S is introduced is grasped in advance, and water W having a density higher than that density is stored in the storage tank 6. Then, the water S stored in the storage tank 6 is injected into the pipe from the upper end of the tremy pipe 2 through the suction pipe 4, and the earth and sand S is poured into the water bottom through the tremy pipe 2.

In this reference form, it becomes possible to inject water W having a higher density than the water existing at the depth H of the site where the earth and sand S is introduced into the tremy tube 2. That is, in construction at sea, water W having a higher salinity concentration than seawater existing at the depth H can be used.

Water W having a higher density than water existing at a water depth of 50% , more preferably 70%, and even more preferably 90% of the water depth H is stored in the storage tank 6, and the earth and sand S is stored in the same manner as in the above-described embodiment. The water W having a smaller density difference from the water present at the bottom of the water to be introduced is configured to be injected into the tube of the tremy tube 2.

The present invention can be applied when the water depth H is 5 m to 30 m. In addition, it can be applied not only to construction at sea but also to construction in rivers and lakes.

  A hydraulic experiment was conducted using an experimental apparatus 10 that can simulate the density structure of the upper and lower two layers (upper layer UL and lower layer DL) shown in FIG. The experimental apparatus 10 has a vertical pipe 11 standing on a water tank 12 containing water, and a reserve tank 13 is connected to an upper end of the vertical pipe 11 via an open / close valve 14. And the muddy water MW of the reserve tank 13 was thrown into the bottom face of the water tank 12, and the diffusion state of pollution was confirmed. As shown in Table 1, the experiment conditions were varied for the four types (Examples 1 and 2 and Comparative Examples 1 and 2) with only the presence or absence of stratification of the water stored in the water tank 12 and the solvent density of the turbid water MW. I did it.

The water tank 12 is a rectangular parallelepiped having a side of 300 mm, and the vertical pipe 11 is a model of a tremmy pipe. The size is 300 mm long, the inner diameter is 24 mm, and the lower end is 50 mm above the bottom of the water tank 12 as shown in FIG. Arranged to be located. The maximum density difference in the density stratification was 2 kg / m ^3, and the water temperature change during the experiment was minute, and the density of the water stored in the water tank 12 was adjusted with salinity. Moreover, since the amount of turbidity generated varies greatly depending on subtle conditions when earth and sand are directly introduced into the water in the water tank 12, the turbid water MW with high reproducibility of the experiment is introduced. Kaolin (maximum particle size 0.0750 mm, clay content 77.6%, silt content 22.4%, soil particle density ρ = 2690 kg / m ³ ) is used for the turbid particles, and the solvent in the water tank 12 is used as the solvent. A density of 1010 kg / m ³ was prepared using the same water.

In the experiment, 100 cm ³ of turbid water MW was continuously added in 4 seconds by opening the on-off valve 14 instantaneously. FIGS. 4 to 7 show the diffusion state of the contamination 38 minutes and 50 seconds after the turbid water is charged (corresponding to 300 seconds in the experiment). 4 to 7 show the diffusion state of the contamination based on numerical calculation, but since it is confirmed that it is consistent with the experimental result, the data can be regarded as the experimental result. 4 to 7 show that the darker the color, the more muddy water MW is distributed.

  In all cases of Examples 1 and 2 and Comparative Examples 1 and 2, the turbidity spread so as to crawl the bottom surface of the water tank 12 at the beginning of the turbid water injection. Thereafter, in Examples 1 and 2, as shown in FIGS. 4 and 5, the diffusion of the contamination was limited to the bottom surface. On the other hand, in Comparative Examples 1 and 2, as shown in FIGS. 6 and 7, the contamination gradually diffused upward as time passed. From these results, it can be seen that the diffusion state of the pollution differs depending on the density difference between the solvent of the turbid water and the water mass at the charging point, and the diffusion of the pollution can be suppressed in Examples 1 and 2 using the solvent having a small density difference.

DESCRIPTION OF SYMBOLS 1 Input device 2 Tremy pipe 2a Holding member 3 Hopper 4 Suction pipe 5 Suction pump 6 Storage tank 7 Inflow pipe 8 Conveyor belt 9 Work ship 10 Experimental apparatus 11 Vertical pipe 12 Water tank 13 Reserve tank 14 Opening and shutting valve S Earth and sand W Water MW Turbid water UL Upper DL Lower layer

Claims (2)

At the site where the earth and sand are thrown in , a suction pipe that extends to the upper side of the tremy pipe is arranged at a position outside of the tremy pipe, and the lower end of the suction pipe installed at a position outside the tremy pipe. through the suction pipe, and pumped water from deeper than 50 percent of the depth of the water depth of the field, the high water density than water present in 50% of the depth of the site, is injected from the upper end of the tremie tube On the other hand, a method for introducing earth and sand using a tremy pipe, wherein the earth and sand are introduced into the bottom of the water at a depth of 5 to 30 m through the tremy pipe to suppress the diffusion of pollution caused by the introduced earth and sand. From the top of the Tremy pipe, the Tremy pipe standing on the water from near the bottom of the 5 to 30 m depth where the earth and sand is thrown in, and the water having a higher density than the water existing at 50% of the water depth of the spot. Water injection means for injecting, and the water injection means is arranged at a position outside the tremy pipe and spaced apart from the tremy pipe and from a position deeper than 50% of the water depth of the site to above the tremy pipe The suction pipe is formed by an extending suction pipe and a suction pump connected to the suction pipe, and a lower end of the suction pipe through which the high-density water is sucked is installed at a position outside the tremy pipe. Water is drawn from a position deeper than 50% of the water depth of the site through the suction pipe from the lower end, and water having a higher density than water existing at the depth of 50% of the site is drawn into the upper end of the tremy pipe. While al injected by injecting sediment into the sea bed in water depths 5m~30m through the tremie pipe, dosing device sediment, characterized in that the inhibiting arrangement the diffusion of contamination caused by the charged sediment.