JP4332878B2 - Artificial tidal flat structure with subsidence repair function - Google Patents

Description

The present invention relates to an artificial tidal flat constructed by creating a landfill soil layer using earth and sand such as dredged soil on a soft ground with a bottom, and laying a sand-covering layer in a desired thickness on the landfill soil layer. Is related to the structure of

  In recent years, due to the increasing awareness of the environment, the conservation of the waterfront environment has attracted attention, and artificial tidal flats have been developed in the beach area. Artificial tidal flats are attracting attention because they can make effective use of dredged dredged sand and are being planned and implemented in various places.

  As shown in Fig. 9 (a), a conventional artificial tidal flat has a submerged dike 2 built on the bottom of the water in front of the revetment 1 and is placed on the soft clay layer 3 on the bottom of the water between the submerged dike 2 and the revetment 1. The landfill sand layer 4 is formed so that the revetment side becomes higher by putting in the soil, and the sand cover layer 5 having a thickness of about 1 m is formed thereon, and the surface of the sand cover layer 5 is submerged by the tides. It is constructed to be an intertidal zone that is exposed.

  In such artificial tidal flats, the submarine ground 3 to be created is often soft, and the landfill sand layer 4 using dredged soil is also often soft, so that the sand-covering layer 5 is loaded thereon. In addition, as shown in FIG. 9 (b), there is a problem that consolidation settlement occurs over time, and there are many portions where the artificial tidal flat is constantly submerged, and the tidal flat area decreases.

In order to repair such a decrease in tidal flats due to ground subsidence, conventionally, a lightweight raising material 6 or a raised layer 6 made of sand is formed on the sand-carrying layer 5 of the subsidized portion as shown in FIG. The method is taken (for example, patent document 1).
Japanese Patent Laid-Open No. 11-336043

  In the above-mentioned conventional technology, sand and other materials for raising the bulk of the artificial tidal flats that have subsided are raised to restore the artificial tidal flats to their original height. Because it is necessary, it is necessary to purchase new high-quality sand, and thin layer sand covering work for shallow water requires a lot of labor. Furthermore, since the thickness of the sand covering layer increases, there is a problem that consolidation settlement occurs again. Furthermore, when new sand is laid on the old sand-covering layer, the organisms that inhabit the old sand-covering layer are killed, and there is a problem that the biological environment generated in the tidal flat is destroyed.

In view of such a conventional problem, the present invention efficiently raises and repairs an artificial tidal flat that has been sunk using waste such as dredged soil that is difficult to process without using new high-quality sand. It was made for the purpose of providing an artificial tidal flat structure with a settlement repair function that can be performed without destroying the biological environment that has already occurred.

The feature of the invention relating to the artificial tidal flat structure with subsidence repair function according to claim 1 for solving the conventional problems as described above and achieving the intended purpose is a landfill sediment layer appropriately built up on the submarine ground. An artificial tidal flat in which a sand-covering layer is installed, and a bag-like sheet is laid on the upper surface of the landfill soil-and-sand layer, the sand-covering layer is laid on the upper surface, and the sand-covering layer is laid in the state In the artificial tidal flat structure with subsidence repair function that makes it possible to fill the filling material in the bag-like sheet, a large number of rectangular bag-like sheets formed with a water-permeable sheet-like material are laid on the upper surface of the landfill soil layer. In addition, one end side of the filling material injecting hose is inserted into each bag-like sheet, and the other end side of the hose can be connected to the filling material supply path from the filling material pressure pump, The bag-like sheet is directed from the land side toward the underwater side. The hose for filling the filling material is installed continuously from the underwater side end portion of the bag-like sheet to the outside of the land side end portion, and is inserted through the land side end portion so that it can be pulled out.

  A feature of the invention described in claim 2 is that, in addition to the configuration of claim 1, a plurality of filling hoses for injecting filling material are provided for each bag-like sheet.

The artificial tidal flat structure with subsidence repair function according to the present invention described above is constructed by laying a bag-like sheet between the landfill soil layer and the covering sand layer and filling the bag-like sheet with a filling material. When subsidence occurs due to consolidation of the landfill soil layer, materials that need to be disposed of, such as dredged material, are used without purchasing new high-quality sand material, and the sand-covering layer can be raised at low cost. It can be raised while maintaining the biological environment that has already occurred. Moreover, since the raising work can be performed by the filling work of the filling material, it can be easily performed with less labor, and the bag-like sheet can be raised more than once by providing a sufficient capacity.

  In addition, the filling material is made by using earth and sand such as clay as the filling material, inserting a filling material injecting hose into the bag-like sheet, and mixing and stirring water in the filling material and sand. By filling the slurry with a pump through the filling material injecting hose, the filling operation of the filling material is mechanically easily and reliably performed.

  Furthermore, by using a water-permeable sheet material for the bag-like sheet, even when earth and sand having a high silt component such as dredged soil are used, the silt component is filtered by the sheet-like material, and the dredged soil is contained in the sand covering layer. Does not permeate, and can be raised without degrading the quality of the sand-capping layer, so that it is possible to effectively use the clay that needs to be disposed of separately.

  Further, the filling material injecting hose is continuously inserted from the inside of one end side to the outside of the other end side of the bag-like sheet, and the filling material slurry is drawn while the inside filling material injecting hose is pulled out of the other end side. By filling the bag-like sheet with the filling material, it is possible to sequentially fill the filling material into several sections from the end of the bag-like sheet, and to adjust the filling amount for each section with respect to the variation in subsidence. Thus, unevenness on the surface of the sand-capping layer after raising the height can be reduced.

  Furthermore, by inserting a plurality of filling materials injecting hoses into the bag-like sheet, the above-described raising operation by filling the filling materials for each section can be performed by the number of filling hoses. , Can respond to unexpected settlement.

  Next, embodiments of the present invention will be described based on examples shown in the drawings.

  1 and 2 show a schematic configuration of an example of an artificial tidal flat structure with a settlement repair function according to the present invention. In the figure, reference numeral 1 is a revetment, 2 is a submerged dam built on the bottom of the water in front of the revetment, 4 is a buried earth and sand layer built up on a soft clay layer 3 on the surface of the bottom of the seabed between the submerged levee 2 and the revetment 1 It is. The upper surface of the landfill soil layer 4 is inclined so that the land side, that is, the revetment side 1 side becomes higher. These structures are the same as those of the conventional artificial tidal flat described above, and the dredged soil with the bottom of the water nearby can be used for the landfill sand layer 3. In the figure, reference numeral 7 denotes a support layer under the water bottom ground.

  In this artificial tidal flat, a sand-covering layer 5 for forming a sandy beach is formed on the surface layer, and a bag-like sheet 10 is laid between the sand-covering sand layer 5 and the landfill soil sand layer 3.

  As shown in FIG. 3 (a), the bag-like sheet 10 uses sheet-like materials 11 and 11 having water permeability such as geotextile, which are doubled. The sheet-like material preferably has a water permeability that does not allow the silt component contained in the clay to permeate. Such a sheet-like material is sewn around as shown in the same figure (b), and is formed into a rectangular bag shape that can be filled with a filling material such as earth and sand between the front and back sheet-like materials 11, 11. The filling material inlet cylinder 12 is fixed to the side upper surface in communication with the inside. Then, the bag-like sheet 10 is rolled up and conveyed to the site as shown in FIG. 3C, and is spread and laid in order from the land side toward the bottom of the water at the construction site.

  When laying, a large number of bag-like sheets 10 directed from the land side toward the bottom of the water, that is, toward the submerged dike 2 are arranged in parallel and laid on one surface without any gap. Each bag-like sheet 10 is formed corresponding to the width of the artificial tidal flat at a predetermined installation position, and is laid in a continuous arrangement on one side by laying in a predetermined place. In addition, although not shown in the drawing, a plurality of bag-like sheets 10 may be laid side by side in a continuous arrangement in the longitudinal direction, and the direction is parallel to the revetment 1 in addition to being directed from the land side to the bottom of the water. Alternatively, it may be laid in any direction such as an oblique direction.

  In this way, each of the bag-like sheets 10, 10... Is laid, and at the same time, one end side of the press-fitting hose 13 is connected to each filling material inlet cylinder 12. Thereafter, the sand covering layer 5 is formed, and the other end of the press-fitting hose 13 is extended to the upper surface of the sand covering layer 5. The press-fitting hose 13 is normally buried in the sand-covering layer 5 or covered with a cover.

  The artificial tidal flat constructed as described above sinks due to the consolidation of the landfill sand layer 4 and the soft clay layer 3 of the submerged ground. When repairing the artificial tidal flat, each bag is made by using a pump as a slurry of dredged soil as shown in FIG. The sheet 13 is filled.

  That is, the branch path 16 of the slurry transport path 15 is connected to each press-fitting hose 13, and the medium filler slurry obtained by slurrying the medium filler a by the slurrying device 17 is sent to the slurry transport path 15 by the pressure pump 18. This is press-fitted into the bag-like sheet 13. Each branch passage 16 is provided with an opening / closing valve 16a. When the filling material slurry is press-fitted, the opening / closing valve 16a is appropriately opened / closed to select and press-fit one or more bag-like sheets 10. .

  Thus, when the filling material slurry is press-fitted into each of the bag-like sheets 10, 10,..., The water constituting the slurry permeates the bag-like sheet 10 and flows into the sand-covering layer 5, but from the silt component. The filler a made of a solid component having a large particle size does not permeate the bag-like sheet 10 and is filled inside. As shown in FIG. 5, the covering sand layer 5 is raised by the thickness of the expanded bag-like sheet 10. And subsidence is repaired.

  A hose or a steel pipe can be used for the slurry transport path 15, and a concrete transport pump such as a squeeze pump or a piston pump can be used for the pressure feed pump 18.

  Various kinds of earth and sand can be used as the filling material a. When dredged soil is used, for example, as shown in FIG. This is transferred to a slurrying tank 23 of a slurrying device 17 mounted on the pumping ship 21 by a cargo handling machine such as a backhoe 22 mounted on the pumping ship 21, where it is stirred and added to the clay. Is made into a slurry and is pumped by a pump 18. When the water content ratio of the dredged soil itself is high, or when it is slurried in the earth transport ship 20, it can be pumped as a slurry without adding water.

  As the pumping pump 18, a hydraulic pump can be used when the water content ratio of the slurry is small, and a spiral pump can be used when the water content ratio is high.

  In addition, when the filling material a is made into a slurry by adding water, it is also possible to use land and sand such as construction residual soil having a low water content in addition to the above-mentioned dredged soil. Further, by adding a weight reducing material such as a lightweight aggregate to reduce the weight, it is possible to reduce the consolidation settlement due to the weight of the filling material being loaded on the ground below.

  In the above-described embodiment, the case where the filling material slurry is directly injected from the filling material inlet cylinder 12 of each bag-like sheet 10 and is put into the bag-like sheet at once is shown. It is also possible to inject the filling material sequentially from the 10 water bottom side ends. In that case, as shown in FIG. 6, after each bag-like sheet 10 is laid in parallel from the land side to the water bottom side on the landfill layer 4 in the same manner as described above, each filling material inlet The hose 25 for filling the filling material is inserted into the bag-like sheet 10 from the cylinder 12. The tip of the filling material injecting hose 25 is brought to the inside of the bottom of the bag-like sheet 10, and the other end is led out to the ground side through the filling material injection port 12.

  In this way, the filling material injecting hose 25 is led out from the inside of one end of each bag-like sheet 10 to the outside of the other end, and then the sand covering layer 5 is laid and the filling material injecting hose is formed on the surface. It installs so that the front-end | tip of 25 can be exposed.

  In the subsidence repair of the artificial tidal flat constructed in this way, as shown in FIGS. 7 and 8, the end of the filling material injecting hose 25 is connected to the branch passage 16 of the slurry transport passage 15 described above, and a pressure pump 18 inject the filling material slurry. As a result, the filling material slurry is discharged from the inner end 25a of the bag-like sheet of the filling material injecting hose 25, and the inner filling material is filled in the bottom end of the bag-like sheet 10.

  After injecting a certain amount of filling material a, the filling material injecting hose 25 is pulled out to the land side by a certain length, and the next filling operation is performed in the same manner. This is repeated sequentially, the inside of the bag-like sheet 10 is divided into several sections in the longitudinal direction, and filling is carried out sequentially from the bottom of the water, and the sand covering layer 5 is raised and repaired as shown in FIG. Also, if the subsidence is partially different, the filling amount of the filling material is adjusted according to the subsidence of each section, thereby reducing the unevenness of the cost of the sand-capping layer after raising. . In addition, it is the same as that of the above-mentioned Example that the on-off valve 16a is operated, the 1 or several bag-like sheet | seat 10 is selected, and a filling material filling operation | work is performed.

  In the detailed example, a case where one filling material injecting hose 25 is inserted into one bag-like sheet 10 is shown, but a plurality of filling materials are injected into one bag-like sheet 10. By inserting the hose 25 in the same manner and performing one raising repair with one of the hoses 25, the number of times of the raising repair can be repaired.

  Further, the filling material injecting hose 25 may be inserted into the bag-like sheet 10 in advance when the bag-like sheet 10 is manufactured, and the above-described filling material injection port cylinder 12 is used for the projecting end. You may penetrate the land side edge part of the bag-like sheet 10 without doing. Further, the filling material injecting hose 25 only needs to have flexibility so that it can be pulled out from the bag-like sheet 10, and it does not matter whether the hollow cross-sectional shape has shape retention.

It is a longitudinal cross-sectional view which shows an example of the artificial tidal flat structure with a settlement repair function which concerns on this invention. It is a top view which shows a bag-like sheet | seat laying state same as the above. FIG. 1 shows a bag-like sheet used in the artificial tidal flat structure shown in FIG. 1, (A) is a perspective view showing superposition of water-permeable sheet materials, (B) is a perspective view in a completed state, and (C). FIG. 4 is a perspective view showing a state during conveyance. It is a top view which shows the filler injection | pouring state for subsidence repair in the artificial tidal flat structure shown in FIG. It is a longitudinal cross-sectional view same as the above. It is sectional drawing which shows the other example of the artificial tidal flat structure with a settlement repair function which concerns on this invention. It is a top view which shows the filler injection | pouring state for subsidence repair same as the above. It is a longitudinal cross-sectional view same as the above. It shows a conventional artificial tidal flat structure, (A) is a longitudinal sectional view in a completed state, (B) is a longitudinal sectional view showing a subsidence state, and (C) is a longitudinal sectional view showing a raised repair state.

a Filling material 1 Revetment 2 Submarine 3 Soft clay layer 4 Landfill soil layer 5 Covering sand layer 7 Supporting layer 10 Bag-shaped sheet 11 Sheet-shaped material 12 Filling material injection port 13 Press-in hose 15 Slurry transporting path 16 Branching path 16a On-off valve 17 Slurry device 18 Pressure pump 19 Crane ship 20 Earth ship 21 Pump transport ship 22 Backhoe 23 Slurry tank 25 Filling material injection hose 25a Inner end of bag-like sheet

Claims (2)

An artificial tidal flat in which a sand-covering layer is installed on a landfill soil layer that is appropriately raised on the bottom of the ground, a bag-like sheet is laid on the top surface of the landfill soil layer, and the sand-covering layer is laid on the top surface In the artificial tidal flat structure with subsidence repair function that enables filling of the filling material in the bag-like sheet in a state where the sand covering layer is laid ,
A large number of rectangular bag-like sheets formed with a water-permeable sheet-like material are laid on the upper surface of the landfill soil layer,
One end side of the filling material injecting hose is inserted into each bag-like sheet, and the other end side of the hose can be connected to the filling material supply path from the filling material pressure pump. The sheet-like sheet is installed from the land side toward the underwater side, and the filling material injecting hose is continuous from the underwater side end of the bag-like sheet to the outside of the land side end, and outside the land side end. Artificial tidal flat structure with subsidence repair function, which is characterized by being able to be pulled out. The artificial tidal flat structure with a subsidence repair function according to claim 1, wherein a plurality of filling hoses for injection of filling material are installed for each bag-like sheet.

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