JP2008253201A - Pipeline structure and complex thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pipeline structure stably keeping the environment suitable for propagation of benthic organisms and heightening the variety of species living in a coastal zone, and to provide a complex thereof. <P>SOLUTION: The pipeline structure 10 is installed in the coastal zone, having a water area in which the water level changes vertically and forms a habitat for the benthic organisms by utilizing the water level change, and is equipped with a granule-storing part 1 which is equipped with a pipe line, having one terminal that communicates with an upper opening 10a, positioned in between the maximum water level and the minimum water level of the coastal zone, and having a shape directed downward from the one terminal to a prescribed position, and thereafter, being directed upward from the position; and a communicating pipeline 8 for communicating the other terminal of the granule-storing part 1 with a lower-side opening 10b formed at a position lower than the upper-side opening. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pipeline structure and a complex thereof, which are installed in a coastal area having a water area where the water level fluctuates up and down to form a benthic habitat using the water level fluctuation.

  Some coastal areas such as seas and rivers have revetments built to prevent erosion by waves and to prevent disasters. The revetment is generally constructed by artificial structures such as concrete. Various proposals have been made so far about means for inhabiting living things in the artificial structures constituting the revetment.

  For example, Patent Document 1 describes a method of building a revetment with a block provided with a hole for a fish nest. Patent Document 2 describes a method of building a revetment using a block wall structure that can accommodate stones and earth and is provided with a concave portion that becomes a habitat for living organisms. Furthermore, Patent Document 3 describes a method of building a revetment using a revetment panel material having holes through which small animals can go in and out.

  The revetments described in Patent Documents 1 to 3 are mainly intended for fish, crustaceans, amphibians, etc. among living organisms inhabiting waters. In other words, the revetment described in the above document is intended to artificially form a void in which these organisms can inhabit and to fix the organisms.

  By the way, various creatures inhabit coastal areas such as tidal flats and sandy beaches. For example, various organisms called benthic organisms live in tidal flats that repeat flooding and drying due to sea level changes caused by tides. The benthic organisms inhabit the sandy mud in the coastal area, and are organisms that crawl on the sandy mud or make holes in the sandy mud to form burrows. Specific examples of benthic organisms include sea bream, clams and crabs. In particular, in recent years, gokai and clams are attracting attention for their ability to purify mud and seawater in tidal flats.

As one of the environmental conditions inhabited by such benthic organisms, it is known that the change in the degree of saturation of sand and mud due to changes in tide level is important. The degree of saturation is the volume percentage of the liquid part occupying the part (gap) other than the solid of the soil, and can also be referred to as the water content of the habitat. For example, Non-Patent Document 1 describes that suction that occurs in sand mud due to fluctuations in the tide level is indispensable for the click crabs to form burrows. Rice crabs have the property of forming sand mud in the form of dumplings and discharging them to form nest holes. In sand mud with 100% saturation or dry sand mud, the particles of sand mud do not bind together to form sand dumplings, so for sand crabs, saturated sand mud suitable for forming sand dumplings appears. An environment that can be said to be desirable.
Japanese Patent Laid-Open No. 10-25727 JP 2004-324373 A Japanese Patent Laid-Open No. 11-293646 Masashi Sasa and Yoichi Watanabe, “Elucidation of Critical Phenomena and Living Environment of Sediment Environment in Living Activity of Tidal Flats”, Journal of Coastal Engineering, Japan Society of Civil Engineers, 2006, Vol. 53, p. 1061-1065

  In actual tidal flats and sandy beaches, the movement and replenishment of sand and mud is repeated by tides. Therefore, sand mud is maintained in good condition as a habitat for benthic organisms. On the other hand, it can be said that it is difficult to maintain the habitat of benthic organisms in a good state continuously with the conventional revetments according to Patent Documents 1 to 3 described above. These revetments are provided with voids to allow fish and other organisms to settle, but they have the function of retaining sand mud, which is a habitat for benthic organisms, and maintaining it in good condition. This is because there is not.

  For example, even if a recess is provided on a conventional revetment and it is filled with sand mud, if the depth of the recess is shallow, sand mud is likely to be washed away by the flow of water, and the habitat for benthic organisms is lost. There is a risk that. On the other hand, if the depth of the recess is deep, water permeability inside the sand mud tends to be insufficient. If the water permeability is insufficient, fresh water containing dissolved oxygen will not be supplied to the inside, and the mud will rot and the environment will not allow benthic organisms to live.

  Thus, in the conventional revetment, living organism species are limited, and benthic organisms that use sand and mud as their habitat cannot be stably inhabited.

  The present invention has been made in view of such circumstances, can stably maintain an environment suitable for benthic habitat, and enhances the diversity of species living in the coastal area. An object of the present invention is to provide a pipe structure and a composite thereof.

  The present invention is installed in a coastal area having a water area where the water level fluctuates up and down, and uses the water level fluctuation to form a habitat for benthic organisms. A first granular material storage section having one end communicating with the upper opening located between the lowest water level and a pipe line shaped downward from this one end and then upward; and a first granular material storage And a communication conduit that communicates the other end of the portion with a lower opening provided at a position lower than the upper opening.

  When the water level in the coastal area rises, the air in the communication pipe of the pipe structure according to the present invention is compressed and the pressure rises. The mechanism by which the pressure of air in the communication pipe rises is as follows. That is, when the water level in the coastal area rises, the water level introduced through the lower opening also rises in the communication pipeline. Then, the air in the communication conduit is pushed toward the upper opening by the water surface, but the flow of air is hindered by the particulate matter filled in the particulate matter reservoir. As a result, the pressure of the air in the communication pipe increases. However, when the differential pressure generated at both ends of the granular material storage section filled with the granular material increases, air flows through the granular material. In this case, the pressure distribution in the granular material reservoir is high on the lower opening side and low on the upper opening side.

  When the water level in the coastal area further rises and reaches the position of the upper opening, water flows from the upper opening into the pipeline, and fresh fresh water is supplied to the granular material reservoir. Thereby, the decay of the granular material in a granular material storage part is suppressed.

  On the other hand, when the water level in the coastal area is lowered, negative pressure is generated in the communication pipe, contrary to the case where the water level is raised. When the water level in the coastal area falls, the water level introduced through the lower opening also falls in the communication pipe. However, the inflow of air from the upper opening into the pipe line is prevented by the granular material filled in the granular material storage unit. As a result, negative pressure is generated in the pipeline. However, when the differential pressure generated at both ends of the granular material storage section filled with the granular material increases, air flows through the granular material. In this case, the pressure distribution in the granular material reservoir is high on the upper opening side and low on the lower opening side.

  In the pipe structure according to the present invention, an air pressure difference is generated at both ends of the granular material storage portion as described above in accordance with the fluctuation of the water level in the coastal area. Due to this pressure difference, a part of the pore water in the granular material reservoir is replaced with air, so that the saturation of the granular material (water content ratio of the granular material reservoir) can be changed over time. That is, according to the pipe structure of the present invention, an actual tidal flat or sandy beach environment can be reproduced in that the degree of saturation changes with time. Moreover, the decay of the granular material in a granular material storage part can fully be suppressed because air distribute | circulates the inside of a granular material storage part. As described above, according to the present invention, an environment suitable as a habitat for benthic organisms can be formed in the granular material stored in the granular material storage unit, and this environment can be maintained sufficiently stably. .

  In the present invention, it is preferable that the communication pipe has a pipe having a shape that extends upward from the other end of the first granular material reservoir and then downward. When the communication pipe has such a shape, the volume of the space in the pipe can be sufficiently secured while the entire pipe structure is made compact.

  In the present invention, the lower opening is preferably provided at a position higher than the lowest water level in the coastal area. When the water level in the coastal region is lowered to a position lower than the lower opening, the space in the communication pipe line is released to the atmosphere through the lower opening, so that the air therein is replaced with fresh fresh air. Therefore, when the water level rises again, fresh air is supplied to the particulate matter in the particulate matter storage unit, so that the decay of the particulate matter in the particulate matter storage unit is further effectively suppressed.

  In the present invention, when the water level in the coastal area rises from the lowest water level to the highest water level, the volume of air in the communication pipe that is pushed up toward the first granular material storage part is the first granular material storage. It is preferably larger than the volume of the part. According to the pipe structure having such a configuration, a sufficient amount of air can be supplied to the particulate matter in the particulate matter storage unit due to the fluctuation of the water level in the water area.

  In this invention, it is preferable that the granular material with which a 1st granular material storage part is filled is sand mud with an average particle diameter of 0.01-20 mm. In addition, when benthic organisms live in the granular material filled in the granular material reservoir, the granular material (sand mud) has an average particle size on the lower limit side of the above range (for example, average particle size) However, it is easy to ensure air permeability and water permeability in the granular material reservoir. This is because when benthic organisms inhabit in the granular material, nest holes and holes formed by movement of the benthic organisms can become air or water flow paths.

  Further, the present invention is a composite of pipeline structures in which a plurality of pipeline structures having the above-described configuration are provided in parallel in the coastal area, and the first granular material storage portions of adjacent pipeline structures are connected to each other. Provided is a composite comprising a second granular material reservoir having a communicating pipe line.

  According to the composite of the pipe structure having such a configuration, air and water are supplied to the granular material filled in the second granular material storage unit as the water level in the water area fluctuates. Suction occurs. Therefore, an aerobic region is formed in the first granular material storage unit, while a microaerobic region is formed in the second granular material storage unit. That is, various aerobic conditions can exist in a mosaic pattern in the first and second granular material reservoirs. As a result, it is possible to further promote the diversification of biological species, the improvement of the abundance and the expansion of the habitat, and the effect of further improving the purification action by the organism can be expected.

  ADVANTAGE OF THE INVENTION According to this invention, the pipe line structure which can maintain the environment suitable for habitat of benthic organisms stably, and can raise the diversity of the species inhabiting a coastal area, and its composite_body | complex are provided. can do.

  Hereinafter, a preferred embodiment of a pipe structure according to the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a perspective view showing a pipeline structure according to this embodiment. A conduit structure 10 shown in the figure is formed by connecting a first U-shaped tube 1, a second U-shaped tube 2 and an L-shaped tube 3 in this order. In the present embodiment, the second U-shaped tube 2 and the L-shaped tube 3 form a communication conduit 8 therein. Further, the first U-shaped tube 1 forms a first granular material reservoir, and the first U-shaped tube 1 is filled with the granular material 5.

  An upper opening 10a is formed at one end 1a of the first U-shaped tube 1, and the first U-shaped tube 1 has a shape that extends downward from the one end 1a and then upwards. The other end 1b of the first U-shaped tube 1 and one end 2a of the second U-shaped tube 2 are connected. The second U-shaped tube 2 has such a shape that it goes upward from one end 2a and then goes downward. The first U-shaped tube 1 and the second U-shaped tube 2 form an S-shaped conduit.

  The other end 2b of the second U-shaped tube 2 and one end 3a of the L-shaped tube 3 are connected. The L-shaped tube 3 has a shape that is bent downward from one end 3a thereof and then bent at a right angle in the horizontal direction. The end of the pipe line extending in the horizontal direction of the L-shaped tube 3 forms the other end 3b of the L-shaped tube 3, and a lower opening 10b is formed at the other end 3b. The horizontal pipe line of the L-shaped tube 3 passes below the first U-shaped tube 1 and extends to a position below the upper opening 10a.

  In the pipe structure 10 having the above-described configuration, the granular material 5 filled in the first U-shaped tube 1 serves as a habitat for benthic organisms. As the granular material for the habitat of benthic organisms, those mainly composed of sand and mud are preferable. When sand mud is used, depending on the species to be inhabited, those having an average particle diameter of 0.01 to 20 mm can be used. From the viewpoint of ensuring air permeability and water permeability, the lower limit of the average particle size of the sand mud is more preferably 0.05 mm, and still more preferably 0.1 mm. Further, the upper limit of the average particle size of the sand mud is more preferably 15 mm, and still more preferably 10 mm.

  However, when the pipeline structure 10 is installed in a coastal region in a state where benthic organisms are pre-inhabited in the first U-shaped tube 1, sand mud (for example, an average particle size) whose average particle diameter is lower than the above range. Even if sand mud having a particle size of 0.01 to 0.05 mm is used, air permeability and water permeability of the portion filled with the granular material 5 are easily secured. This is because when benthic organisms inhabit the part, a nest hole or a hole formed by movement of the benthic organism can be a flow path of air or water.

  Note that a plurality of sand muds having different average particle diameters may be used in combination as the granular material 5 filled in the first U-shaped tube 1. Moreover, gravel and nutrients may be added to sand mud to prepare a bottom sediment, which may be filled in the first U-shaped tube 1.

  FIG. 2A to FIG. 2D are cross-sectional views of a revetment structure including the pipe structure 10 having the above-described configuration. The revetment structure 15 shown in the figure is constructed on the coast, and a plurality of pipeline structures 10 are installed in parallel along the coastline inside the revetment structure 15. FIG. 2A to FIG. 2D continuously show the state from the lowest water level state through the highest water level state to the lowest water level state again.

  The “highest water level” here means an average high water level (MHW), and the “lowest water level” means an average low water level (MLW). However, hereinafter, the highest water level and its time zone are simply referred to as high tide level and high tide, respectively, and the lowest water level and its time zone are simply referred to as low tide level and low tide time, respectively. 2A shows a state at low tide, FIG. 2B shows a state at high tide, FIG. 2C shows a state at high tide, and FIG. 2D shows a state at low tide. It is.

  First, the relationship between the positions of the upper opening 10a and the lower opening 10b of the pipe structure 10 and the tide level will be described with reference to FIG. As shown in FIG. 2A, the lower opening 10b is provided at a position higher than the low tide level. By providing the lower opening 10b in such a position, the lower opening 10b is exposed on the sea surface at low tide, and external air is introduced into the second U-shaped tube 2 and the L-shaped tube 3 through the lower opening 10b. Is supplied.

  On the other hand, as shown in FIG.2 (c), the upper side opening 10a is provided in the position lower than a high tide level. By providing the upper opening 10a at such a position, the upper opening 10a is submerged in the sea at high tide, and external seawater is supplied to the granular material 5 through the upper opening 10a. Therefore, for example, when the tide level is in the state shown in FIG. 2A, the granular material 5 is in a state of being submerged by seawater supplied at high tide, as shown in FIG. That is, in this state, the inside of the first U-shaped tube 1 is filled with the granular material 5 and the pore water.

  In addition, when it is desired to set a small amount of seawater that floods the granular material 5, if the space on the upper opening 10a side (the one end 1a side) of the first U-shaped tube 1 that is not filled with the granular material 5 is decreased. Good. That is, the granular material 5 may be filled in the vicinity of the peripheral edge of the upper opening 10a and further to the height of one end 1a.

  Moreover, the height of the granular material 5 on the other end 1b side of the first U-shaped tube 1 is not necessarily the same height as the one end 1a side. For example, the granular material 5 may be filled on the other end 1b side up to a position higher than the one end 1a side. By doing so, the granular material 5 on the other end 1b side can be prevented from being submerged. In this way, by appropriately setting the height at which the granular material 5 is filled, it is possible to form environments with different water content ratios and aerobic conditions on the one end 1a side and the other end 1b side, and further improve the diversification of biological species. Can contribute.

  Next, with reference to FIG. 2 and FIG. 3, how the state in the pipe structure 10 changes in accordance with the fluctuation of the tide level will be described. FIG. 3 (A) is a graph schematically showing a change in tide level, and FIG. 3 (B) is a graph schematically showing a change in air pressure in the communication pipe line 8 accompanying a change in tide level.

  When the tide level gradually rises from the low tide state shown in FIG. 2 (a) and the tide level reaches the tide level L1 shown in FIG. 2, the pressure in the communication line 8 increases as shown in FIG. 3 (B). start. The tide level L1 is a tide level in which the lower opening 10b is completely submerged and air conduction between the communication pipe 8 and the outside is interrupted.

  When the tide level further rises and the pressure of air in the communication pipe 8 rises to some extent, air enters the gap between the granular materials 5 in the first U-shaped pipe 1 from the second U-shaped pipe 2 side, and the pore water Is replaced by air. Therefore, while the degree of saturation of the granular material 5 on the second U-shaped tube 2 side is partially lowered, the upper opening 10a side is in a flooded state (see FIG. 2B). When the pressure in the communication pipe 8 further rises and the air comes out to the upper opening 10a side, the pressure fluctuates little by little as shown in FIG.

  Thereafter, when the tide level reaches the tide level L2 shown in FIG. 2, the pressure in the communication pipe 8 rises again as shown in FIG. 3 (B). The tide level L2 is a tide level in which the upper opening 10a is completely submerged and air conduction between the U-tube 1 and the outside is interrupted.

  When the tide level starts to decrease after the high tide, the pressure of the air in the communication line 8 starts to decrease accordingly. When the pressure in the communication pipe line 8 decreases to a certain negative pressure, air enters the gap between the granular materials 5 in the first U-shaped pipe 1 from the upper opening 10a side, and the gap water is replaced with air. Therefore, while the degree of saturation of the granular material 5 on the upper opening 10a side is partially reduced, the second U-shaped tube 2 side is submerged (see FIG. 2D). When the pressure of the air in the communication pipe 8 further decreases and the air from the upper opening 10a side comes out to the second U-shaped pipe 2 side, the pressure fluctuates little by little as shown in FIG. . Thereafter, when the level becomes lower than the tide level L1, the communication line 8 is opened to the atmosphere through the lower opening 10b, so that the pressure of the air in the communication line 8 becomes atmospheric pressure.

  From the viewpoint of allowing a sufficient amount of air to flow through the granular material 5 using the above-described series of tide level fluctuations, it is preferable that the space inside the pipe structure 10 has the following structure. That is, while the tide level rises from the low tide level to the high tide level, the volume of the communication pipe 8 pushed up in the direction of the first U-shaped pipe 1 is larger than the internal volume of the first U-shaped pipe 1. It is preferable. More specifically, the volume of the space between the tide level L1 and the tide level L2 in the communication conduit 8 is preferably larger than the internal volume of the first U-shaped tube 1.

  According to the pipe structure of the present embodiment, seawater is periodically supplied from the upper opening 10a to the granular material 5 in the first U-shaped pipe 1 due to the fluctuation of the tide level as described above, Air is supplied to the granular material 5 by the differential pressure generated at both ends. Thereby, the decay of the granular material 5 can fully be suppressed. Further, the pore water of the granular material 5 is periodically replaced with air, and suction is generated each time. Thus, a suitable environment for benthic organisms can be formed in the portion filled with the granular material 5 in the first U-shaped tube, and the environment can be stably maintained.

(Second Embodiment)
FIG. 4 is a cross-sectional view showing a second embodiment of the present invention. The revetment structure 25 shown in the figure is the same as the revetment structure 15 according to the first embodiment except that the shape of the pipe connected to the second U-shaped pipe 2 is different from that of the L-shaped pipe 3. It is the same composition. In the pipe structure 20 provided in the revetment structure 25, a bent pipe 23 having the following shape is connected to the second U-shaped pipe 2. The bent tube 23 has a shape that is bent downward from the connecting portion with the second U-shaped tube 2 and then bent obliquely downward. The end of the pipe line extending in the obliquely downward direction of the bent tube 23 forms the other end 23b of the bent tube 23, and a lower opening 10b is formed. The conduit in the direction obliquely below the bent tube 23 passes below the first U-shaped tube 1 and extends to a position below the upper opening 10a. In the present embodiment, a communication pipe 28 is formed inside the second U-shaped pipe 2 and the bent pipe 23.

  The communication conduit 28 having the above configuration has an advantage that a sufficient amount of air can be ventilated by the granular material 5 while the tide level changes from the low tide level to the high tide level. That is, in the pipe structure 10 of the first embodiment, the air in the horizontal pipe line of the L-shaped pipe 3 escapes to the outside before the tide level reaches the tide level L1. According to the road structure 20, the air in the pipe line obliquely below the bent pipe 23 can also be effectively used as the air pushed up to the granular material 5 side. FIG. 4 shows a state where the tide level rises to the tide level L1 and the lower opening 10b is submerged.

(Third embodiment)
FIG. 5 is a cross-sectional view showing a third embodiment of the present invention. The revetment structure 35 shown in the figure has the same configuration as the revetment structure 15 according to the first embodiment, except that it has an L-shaped tube 33 having the following shape instead of the L-shaped tube 3. The L-shaped pipe 33 has a shape in which the diameter of a pipe line extending in the vertical direction is partially enlarged. In the present embodiment, the second U-shaped tube 2 and the L-shaped tube 33 constitute a communication conduit 38 therein.

  According to the communication pipe line 38 having the above configuration, there is an advantage that a sufficient amount of air can be ventilated by the particulate matter 5 while the tide level changes from the low tide level to the high tide level. FIG. 5 shows a state where the tide level rises to the tide level L1 and the lower opening 10b formed at the other end 33b of the L-shaped tube 33 is submerged.

(Fourth embodiment)
In said 1st-3rd embodiment, although the pipe line structure in which the pipe line was formed with pipes, such as a U-shaped pipe and an L-shaped pipe, was illustrated, the pipe line structure concerning this embodiment is a predetermined shape. A plurality of concrete blocks and plates having a combination are installed and a pipe line is formed by these facing surfaces.

  6 and 7 are exploded perspective views showing a process of constructing the pipeline structure 40 according to the present embodiment with a plurality of concrete blocks and concrete panels. First, as shown in FIG. 6, a substantially Y-shaped block 41 and a substantially U-shaped block 42 are respectively produced. The block 41 has a groove 41a formed on the upper surface. Further, the standing surface 41b and the bottom surface 41c of the block 41 facing the block 42 are flat surfaces.

  The block 42 has a substantially U-shape, and the concave portion 43 of the block 42 is for installing the block 41 in a state of being separated from the inside thereof. A convex portion 42 a extending downward is provided on the tip side of the upper portion 42 d of the block 42. Further, the standing surface 42b of the block 42 facing the block 41 and the bottom surface 42c of the recess 43 are flat surfaces that are orthogonal to each other. As shown in FIG. 7, the convex portion 42 a of the block 42 enters into the groove portion 41 a of the block 41 and constitutes the granular material storage portion 45. The communication pipe 48 is configured by cooperation of the standing surface 42b and the bottom surface 42c of the block 42 and the standing surface 41b and the bottom surface 41c of the block 41.

  The block structure 40 is constructed by sandwiching the block 41 and the block 42 from both sides with the panels 46 and 47. As shown in FIG. 7, the panels 46 and 47 are provided with convex portions 46a and 47a having the same shape as the gap formed between the block 41 and the block 42, respectively. These convex portions 46a and 47a are fitted into a gap formed between the block 41 and the block 42 to form a side wall surface of the pipe line, and the panels 46 and 47 are made of concrete or the like with respect to the blocks 41 and 42. Fixed with solidification material. When the pipeline structure 40 according to the present embodiment is used as a revetment structure, it is possible to assemble in the field, and a large amount of particles are used in the granular material storage unit 45 by using large blocks 41 and 42. The object 5 can be filled, and the abundance and type of the organisms that inhabit the object 5 can be remarkably improved.

(Fifth embodiment)
In said 1st-4th embodiment, although one pipe line structure is installed in the up-down direction, you may install a several pipe structure in the up-down direction. For example, FIG. 8 is a cross-sectional view of a revetment structure including a plurality of pipeline structures 10 according to the first embodiment. By arranging the conduit structure 10 in this way, it is possible to improve the abundance and type of living organisms and diversify environmental conditions.

(Sixth embodiment)
Further, the pipe structure of the present invention is not limited to being installed in a revetment structure, and may be installed, for example, on a pier column. FIG. 9 is a perspective view showing a state in which a plurality of pipeline structures 10 are installed on a pier post 60.

(Seventh embodiment)
When installing a plurality of pipeline structures in parallel along the coastline, the granular material reservoirs of adjacent pipeline structures are connected by a pipeline to form a composite of pipeline structures, You may fill a granular material into the pipe line which connects a granular material storage part. For example, in the composite structure 100 of the pipe structure shown in FIG. 10, the first U-shaped pipes 1 of the plurality of pipe structures 10 installed on the pier post 60 are connected by the connecting pipe 50. In the present embodiment, the connecting pipe 50 constitutes a second granular material reservoir, and the connecting pipe 50 is also filled with the granular material 5. In the present embodiment, the first U-shaped tube 1 is connected to the second U-shaped tube 2 at 90 in order to facilitate the connection of the first U-shaped tubes 1 of the adjacent pipe structure 10. The pipe structure 10 connected by rotating is installed on the post 60 of the jetty.

  In the pipe structure composite 100, air and seawater are supplied to the granular material 5 in the connecting pipe 50 as the tide level fluctuates. Therefore, an aerobic region is formed in the granular material 5 in the first U-shaped tube 1 of the pipe structure 10, while local suction occurs in the granular material 5 in the connecting pipe 50. A microaerobic region is formed. That is, various aerobic conditions can exist in a mosaic pattern in the composite 100 of pipe structures. As a result, it is possible to further promote the diversification of biological species, the improvement of the abundance and the expansion of the habitat, and the effect of further improving the purification action by the organism can be expected. In addition, the composite body 100 of a pipe line structure is good also as an aspect installed in a seawall structure similarly to said 1-5 embodiment.

  As mentioned above, although embodiment of the pipe line structure and its composite_body | complex concerning this invention was described in detail, the following forms may be sufficient as this invention.

  For example, in the first to third embodiments, the pipe has a circular cross-sectional shape, but the shape may be an ellipse or a rectangle. Moreover, although illustrated about the case where the lower side opening 10b is provided in a position higher than the low tide level, even if the lower side opening 10b is provided in a position lower than the low tide level, the granular material 5 in the granular material storage unit On the other hand, the effect by supplying seawater and air can be acquired.

  Furthermore, the pipe structure 10, 20, 30, 40 and the complex 100 thereof according to the present invention are not limited to the coast as long as the water level is a coastal area where the water level fluctuates up and down with a moderate frequency and height difference, Applicable. Such places include rivers and lakes.

<Evaluation experiment>
(Experimental example 1)
In order to evaluate the performance of the pipe structure according to the present invention, a pipe structure having the shape shown in FIG. 11 and a container that accommodates the pipe structure are prepared, and a water level fluctuation experiment in which water is poured into the container and water is reduced is repeated. It was. The conditions of this experimental example are summarized in Table 1.

  The bottom sediment is prepared by adding 0.5 part by mass of organic matter (peptone) to 100 parts by mass of sand mud collected from the tidal flat, and this sediment is placed in the pipeline (the hatched portion of the pipeline structure shown in FIG. 11). ). The experiment was conducted for 28 days while changing the water level in the container under the conditions shown in Table 1. Prior to the start of the experiment, 7 days, 14 days and 28 days after the start of the experiment, the redox potential of the sediment and the amount of sulfide were measured. The oxidation-reduction potential was measured using an ORP meter (manufactured by Toa DKK Corporation, trade name: RM-20P). The amount of sulfide was measured using a sulfide detector tube (manufactured by Gastec Co., Ltd.).

(Experimental example 2)
A water level fluctuation experiment was conducted in the same manner as in Experimental Example 1 except that a pipe structure (see Table 2) having a short pipe line extending downward was used. Further, the redox potential and the amount of sulfide were also measured in the same manner as in Experimental Example 1.

(Comparative Example 1)
A pipe structure that has a through hole at the top of the pipe structure and that does not supply air to the bottom sediment in the pipe even if the water level fluctuates. Got ready. A water level fluctuation experiment was conducted in the same manner as in Experimental Example 1 except that this pipe structure was used. Further, the redox potential and the amount of sulfide were also measured in the same manner as in Experimental Example 1.

The results of Experimental Examples 1 and 2 and Comparative Example 1 are shown in Table 3 and FIGS.

(Experimental example 3)
After preparing the same pipe structure and container as used in Experimental Example 1 and filling a predetermined portion with shell mold dredged sand (No. 8 dredged sand) having an average particle size of 0.05 mm in the duct, Four gokais were introduced from the opening. Such a pipe structure was installed in the container, and the water level in the container was changed under the conditions shown in Table 1. FIG. 14 shows fluctuations in pressure in the pipe line (top) during a period from when the water is full to the next full time.

  Prior to the start of water injection in this experimental example (around 6:00 in FIG. 14), it is considered that holes and burrows associated with the movement of sandworms are formed in portions filled with dredged sand. For this reason, it is assumed that the pressure in the pipeline fluctuated little by little and did not rise for a while even after water injection was started. Therefore, inhabiting benthic organisms such as sandworms in the sand, which is granular, compared to the case where sandworms do not inhabit, it is in the pipeline (particulate matter storage) filled with sand. It is considered that the air permeability of the air is easily secured.

It is a perspective view which shows the shape of the pipe line structure which concerns on this invention. (A)-(d) is sectional drawing which each shows the state in the pipe structure accompanying a water level fluctuation | variation. (A) And (B) is a graph which shows typically the change of the tidal level and the change of the pressure in a pipe line accompanying it, respectively. It is sectional drawing which shows 2nd Embodiment of the pipe line structure which concerns on this invention. It is sectional drawing which shows 3rd Embodiment of the pipe line structure which concerns on this invention. It is a disassembled perspective view which shows the process of constructing the structure based on 4th Embodiment of this invention. It is a disassembled perspective view which shows the process of constructing the structure based on 4th Embodiment of this invention. It is sectional drawing which shows 5th Embodiment of the pipe structure based on this invention. It is sectional drawing which shows 6th Embodiment of the pipe line structure which concerns on this invention. It is sectional drawing which shows 7th Embodiment of the pipe line structure which concerns on this invention. It is sectional drawing which shows the pipe line structure and container used for the water level fluctuation | variation experiment. It is a graph which shows the oxidation reduction potential of a granular material storage part. It is a graph which shows the amount of sulfur substances of a granular material storage part. It is a graph which shows the pressure fluctuation in the pipe line during a water level fluctuation | variation experiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 20, 30, 40 ... Pipe structure, 100 ... Composite, 1 ... 1st U-shaped pipe (1st granular material storage part), 45 ... 1st granular material storage part, 8, 28, 38, 48 ... communication pipe line, 5 ... granular material, 10a ... upper opening, 10b ... lower opening, 50 ... connection pipe (second granular material storage part), MHW ... high tide level (highest water level), MLW ... low tide Rank (lowest water level).

Claims (7)

A pipe structure that is installed in a coastal area having a water area where the water level fluctuates up and down, and forms a benthic habitat using the water level fluctuation,
A first granular material storage section having one end communicating with the upper opening located between the highest water level and the lowest water level of the coastal area, and having a pipe line shaped to go downward from the one end and then upward ,
A communication conduit that communicates the other end of the first granular material reservoir and a lower opening provided at a position lower than the upper opening;
A conduit structure characterized by comprising:   2. The pipe structure according to claim 1, wherein the communication pipe has a pipe having a shape that extends upward from the other end of the first granular material storage unit and then downwards. .   The pipe structure according to claim 1 or 2, wherein the lower opening is provided at a position higher than the lowest water level in the coastal area.   When the water level in the coastal area rises from the lowest water level to the highest water level, the volume of air in the communication pipe that is pushed up in the direction of the first granular material reservoir is the first granular material reservoir. The pipe structure according to any one of claims 1 to 3, wherein the pipe structure is larger than the volume of the pipe structure.   The pipeline structure according to any one of claims 1 to 4, wherein the granular material filled in the first granular material storage part is sand mud having an average particle diameter of 0.01 to 20 mm. object.   The conduit structure according to any one of claims 1 to 5, wherein benthic organisms inhabit the granular material filled in the first granular material storage unit. A composite pipe structure comprising a plurality of the pipe structures according to any one of claims 1 to 6 provided in parallel in the coastal area,
A composite comprising a second granular material storage part having a pipe line communicating the first granular material storage parts of the adjacent pipe structure.

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