Buried pipe installation structure and buried pipe installation method

Abstract

To provide a burying technology for a buried pipe that effectively utilizes a weight of a burying material as a counterweight for a buried pipe.SOLUTION: A buried structure of a buried pipe is configured to: mount an earth clod weight structure 20 made of an earth clod structure, which is constructed by filling a plurality of cell structures 30 with a filler material 33 while stacking them on site, over a buried pipe 10; and make a total weight of the earth clod weight structure 20 and a total weight of a backfilling material 43 function as a counterweight for the buried pipe 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a buried pipe installation structure and a buried pipe installation method that use a cell structure to prevent large-diameter buried pipes from floating up. [Background technology]

[0002] Generally, when laying various types of large-diameter buried pipes such as pipelines underground, it is necessary to excavate the ground extensively and bury the pipes deep underground. In particular, at sites with high groundwater levels or where liquefaction of backfill soil is expected, it is necessary to bury the buried pipes deeper and increase the earth covering load.

[0003] A conventional burying method will be described with reference to FIG. 8. Retaining plates 61 are driven into the ground G so as to face each other, and a laying trench 62 is excavated between the retaining plates 61. After constructing a layered support base 63 at the bottom of the laying trench 62, the buried pipe 60 is laid on the support base 63. Backfill material 64 is poured into the entire trench 62 and compacted, and finally the retaining plate 61 is removed.

[0004] The excavation width of the trench 62 is larger than the diameter of the buried pipe 60, and the depth of the trench 62 must be the diameter of the buried pipe 60 plus a predetermined soil cover. The excavated cross-sectional dimensions of the trench 62 increase in accordance with the diameter of the buried pipe 60 . If the buried pipe 60 has a large diameter, such as a pipeline, the depth and width of the trench 62 will become very large. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-101369 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-120721 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-170678 [Patent Document 4] Japanese Patent Application Laid-Open No. 2008-267567 Summary of the Invention [Problem to be solved by the invention]

[0006] The above-mentioned conventional technology for installing buried pipes 60 involves the following problems. <1> As shown in Figure 8(A), of all the backfill material 64, only the central vertical weight w5 of the backfill material 64 located directly above the buried pipe 60 acts as a weight to prevent the buried pipe 60 from floating up, and the lateral vertical weights w6 of the backfill material 64 located on both the left and right sides of the buried pipe 60 are not fully utilized as a weight to prevent the buried pipe 60 from floating up. <2> As described above, the weight of the backfill material 64 that functions to prevent the buried pipe 60 from floating up is only the central vertical weight w5. Therefore, when the buried pipe 60 is a large diameter pipe or in the ground where the groundwater level is high, in order to increase the central vertical weight w5 of the backfill material 64, it is necessary to excavate the trench 62 deeper than the normal excavation depth and use a large amount of backfill material 64. Therefore, at such a site, the construction work for laying the buried pipe 60 becomes large-scale, and the burden of construction costs and construction time increases. <3> As shown in FIG. 8(B), when the retaining plate 61 is removed after covering with backfill material 64, the adjacent backfill material 64 expands into the space left by the retaining plate 61 and becomes loose. If the backfilling material 64 becomes loose, the buried pipe 60 will be deformed horizontally, and if the amount of deformation exceeds the allowable strain, not only will the buried pipe 60 be damaged, but the loosening of the backfilling material 64 will also cause problems such as the buried pipe 60 not being able to transmit its original load, reducing its ability to prevent the buried pipe 60 from floating up.

[0007] On the other hand, as shown in Figure 9, Patent Documents 1 to 4 propose wrapping side backfill materials 64a, 64a with geotextile 65 on both the left and right sides of the buried pipe 60, and using the weight of the side backfill materials 64a, 64a as a reaction force source to prevent the buried pipe 60 from floating up. The technology for preventing the buried pipe 60 from floating up involves the following problems. <1> Theoretically, this is possible if the geotextile 65 can be tensioned to encase the side backfilling materials 64a, 64a and be firmly compacted. In actual construction, it is technically difficult to enclose the side backfilling materials 64a, 64a while applying tension to the geotextile 65, and to firmly compact the side backfilling materials 64a, 64a. If the geotextile 65 becomes loose or the lateral backfilling materials 64a, 64a are not compacted sufficiently, the ability of the backfilling materials 64a, 64a to prevent the buried pipe 60 from floating up is reduced, and the original weight of the lateral backfilling materials 64a, 64a is not fully utilized. <2> It is technically difficult to firmly compact the side backfill materials 64 a, 64 a over the entire length of the buried pipe 60 . If there is variation in the compaction of the side backfilling materials 64a, 64a, the effectiveness of utilizing the weight of the side backfilling materials 64a, 64a will be significantly reduced. <3> Since the weight of the side backfilling materials 64a, 64a cannot be fully utilized, in order to prevent the buried pipe 60 from floating up, it is necessary to bury the buried pipe 60 deeper and backfill it with a large amount of upper backfilling material 64b.

[0008] The present invention has been made in view of the above points, and its object is to provide a buried pipe installation structure and a buried pipe installation method that can solve the above problems. [Means for solving the problem]

[0009] The present invention is a buried pipe construction for burying a buried pipe underground, in which a soil mass weight structure made of a highly rigid soil mass structure fabricated on-site and having a gate-shaped or hook-shaped cross section is placed across the buried pipe, and the total weight of the soil mass weight structure functions as a counterweight for the buried pipe. Furthermore, the present invention provides a method for burying a buried pipe in the ground through a first step of excavating a trench between the ground into which retaining walls have been cast, a second step of laying the buried pipe in the trench, and a third step of backfilling the trench, in which the third step backfills the trench by placing a highly rigid earthen structure having a gate-shaped or hook-shaped cross section across the buried pipe, with the total weight of the earthen structure functioning as a counterweight for the buried pipe. In another embodiment of the present invention, the upper surface of the soil mass weight structure may be covered with backfill material, and the total weight of the backfill material may be supported by the soil mass weight structure. In another embodiment of the present invention, the mass weight structure may be placed across the buried pipe continuously or intermittently over the entire length of the buried pipe. In another embodiment of the present invention, the buried pipe has a bent portion, and the soil A mass structure may be placed on it. In another aspect of the invention, soil The mass weight structure may be symmetrical with respect to the buried pipe, or may be asymmetrical with respect to the buried pipe. In another form of the present invention, the soil mass and weight structure comprises a saddle section that can be hung horizontally across the top of the buried pipe to cover it, and side legs that hang down integrally with the end of the saddle section to cover the side of the buried pipe, and is composed of a plurality of cell structures in which the saddle sections and side legs are stacked on site, and filler material that is filled into the cell spaces of the cell structures and compacted on site. In another embodiment of the present invention, the saddle portion and the side leg portion may be integrally connected so as to be capable of transmitting loads via a connecting member that passes vertically or horizontally between the saddle portion and the side leg portion. [Effects of the Invention]

[0010] The present invention has at least one of the following effects. <1> By placing the soil mass weight structure across the buried pipe, not only the central vertical weight of the soil mass weight structure located directly above the buried pipe, but also the lateral vertical weight of the soil mass weight structure located to the side of the buried pipe can be used as a counterweight for the buried pipe. <2> When the top surface of the soil mass weight structure is covered with backfill material, the total weight of the backfill material located directly above the soil mass weight structure can also be used as a counterweight for the buried pipe. <3> Since the total weight of the earth mass structures that make up the earth mass weight structure and the total weight of the covering soil made up of backfill material can be used as counterweights, the buried pipe can be buried to a shallower depth than before. As a result, not only can the amount of excavation required for trench construction be reduced, but the amount of soil and sand used for backfilling can also be significantly reduced, improving construction costs and time, and significantly shortening the operating hours of construction machinery. This makes this technology an important one in line with Japan's SDGs (Sustainable Development Goals). <4> Even if the retaining plate used to retain the soil in the laying trench is removed, the soil mass weight structure placed across the buried pipe does not lose its shape, and the function of protecting the buried pipe by the soil mass weight structure is maintained. Therefore, compressive deformation of the buried pipe and damage to the buried pipe can be reliably prevented. <5> The saddle and side legs that make up the soil mass weight structure are made up of a plurality of cell structures stacked on-site, and the fill material is filled into the cell spaces of the cell structures on-site and compacted by rolling, thereby eliminating variations in compaction of the fill material and enabling the fill material to be compacted firmly and uniformly. <6> When a soil mass weight structure is placed on the bent portion of the buried pipe, the vertical weight of the soil mass weight structure can also counteract the thrust force acting on the bent portion of the buried pipe. <7> soil Since the lump weight structure can be formed asymmetrically with respect to the buried pipe, it is possible to apply vertical loads to each part of the lump weight structure according to the buried environment at the site, which not only increases the freedom of design but also enables the design of economical counterweights. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a partially cutaway perspective view of a buried pipe structure according to a first embodiment of the present invention; [Figure 2]1A is an explanatory diagram of a cell structure that constitutes a soil mass / weight structure; FIG. 1B is an explanatory diagram of a cell structure that has a rectangular cell space; and FIG. 1B is an explanatory diagram of a cell structure that has a honeycomb-shaped cell space. [Figure 3] An explanatory diagram of an example of the connection between the saddle and side legs that make up the soil mass weight structure. (A) is an explanatory diagram of a form in which side legs are connected to the underside of both ends of the saddle, and (B) is an explanatory diagram of a form in which side legs are connected to both sides of the saddle. [Figure 4A] An explanatory diagram of the buried pipe installation method. (A) is an explanatory diagram from the excavation process of the installation trench to the installation process of the buried pipe. (B) is an explanatory diagram of the construction process of the saddle part of the soil mass and weight structure. [Figure 4B] (C) is an explanatory diagram of the construction process of the saddle of the earth mass weight structure, and (D) is an explanatory diagram of the backfilling process of the earth mass weight structure. [Figure 5] Illustration of the effect of the soil mass and weight structure on preventing buoyancy of buried pipes [Figure 6] 1A and 1B are explanatory diagrams of a gate-shaped soil mass weight structure according to a second embodiment of the present invention, and FIG. 1B is an explanatory diagram of a hook-shaped soil mass weight structure according to a second embodiment of the present invention. [Figure 7] 1A is a longitudinal cross-sectional view of the bent portion of the buried pipe; FIG. 1B is a plan view of the bent portion of the buried pipe; and FIG. 1C is a plan view of the bent portion of the buried pipe sheathed with the soil mass weight structure. [Figure 8] An explanatory diagram of the conventional buried pipe installation structure. (A) is a cross-sectional view of the installation trench in which the buried pipe was installed, and (B) is a cross-sectional view of the installation trench in which the buried pipe was installed after the retaining plate was removed. [Figure 9] An explanatory diagram of a conventional buried structure in which buried pipes are buried using geotextiles DETAILED DESCRIPTION OF THE INVENTION

[0012] [Example 1] <1> Buried pipes The buried structure of the buried pipe 10 will be explained with reference to FIG. 1. The buried pipe 10 is a conduit capable of transporting various liquids or gases, and its cross section may be rectangular as well as circular. The buried pipe 10 includes a large-diameter pipe such as a pipeline, and the cross-sectional diameter thereof can be selected appropriately.

[0013] <2> Soil mass and weight structure (a means of preventing buried pipes from floating up) In the present invention, as a means for preventing the buried pipe 10 from floating up, a soil mass and weight structure 20 having a gate-shaped or hook-shaped cross section that can be placed across the buried pipe 10 is used. The soil mass weight structure 20 is a highly rigid soil mass structure that functions as a counterweight (balance weight) for the buried pipe 10, and the total weight of the soil mass weight structure 20 is utilized as a counterweight for the buried pipe 10.

[0014] The soil mass weight structure 20 comprises a saddle part 21 that can horizontally span and cover the upper part of the buried pipe 10, and a side leg part 22 that hangs down integrally with the end of the saddle part 21 and can cover the side part of the buried pipe 10. The soil lump and weight structure 20 is formed continuously along the longitudinal direction of the buried pipe 10, or is formed intermittently (discontinuously) along the longitudinal direction of the buried pipe 10. In this example, a configuration in which the soil lump weight structure 20 is formed symmetrically on both sides of the center of the soil lump weight structure 20 will be described.

[0015] The saddle portion 21 and side leg portions 22 that make up the soil mass weight structure 20 are made up of a plurality of cell structures 30 stacked on-site and filler material 33 that is filled into the cell structures 30 on-site. The reason why a plurality of cell structures 30 are used in the soil lump and weight structure 20 is to enhance the compaction effect of the filler material 33 and to make the compaction of the filler material 33 uniform.

[0016] <2.1> Cell structure The cell structure 30 is a three-dimensional structure in which a plurality of strips 31 are arranged in a row in a vertical direction, and a plurality of cell spaces 32 that are open at the top and bottom are defined between the strips 31. The strip 31 is a flexible plate made of a weather-resistant and durable resin or metal material, and may have either a perforated or non-perforated structure. The height of the strip 31 is, for example, 75 to 300 mm, and the length (inner dimension) of one side defining the cell space 32 is, for example, 200 to 500 mm. The cell structure 30 is heavy enough to be transported manually, and is transported to the site in a folded state and then unfolded for use.

[0017] The soil lump and weight structure 20 is constructed from an assembly of cell structures 30 in order to allow the width and height of the saddle portion 21 and side leg portions 22 to be freely set, to make it easier to compact the filler material 33 and to compact it firmly, and to minimize leakage of the filler material 33 if part of the cell structure 30 is damaged.

[0018] <2.1.1> Example of cell structure Regarding the cell structure 30 illustrated in Figure 2, Figure 2(A) shows a cell structure 30 in which a plurality of linearly formed strips 31 are orthogonalized to define rectangular cell spaces 32, and Figure 2(B) shows a cell structure 30 in which portions of corrugated strips 31 are joined by heat fusion or the like to define honeycomb-shaped cell spaces 32. There are no particular restrictions on the planar shape of the cell space 32, and it may be a polygonal planar shape other than that exemplified in FIG.

[0019] <2.2> Filling material The filler material 33 is not particularly limited, but may be, for example, hard particles such as earth and sand, crushed stone, gravel, slag, or the like. It is also possible to use a fluidized solidification material such as liquefied treated soil as the filling material 33. The filling work with the filling material 33 is carried out for each layer of the cell structures 30 stacked in multiple stages, thereby achieving strong compaction.

[0020] <2.3> Integration of the saddle and lateral legs The saddle portion 21 and the side leg portion 22 that constitute the soil lump and weight structure 20 are made up of the above-mentioned plurality of cell structures 30 and filler material 33.

[0021] Referring to FIG. 3, a description will be given of a form in which the saddle portion 21 and the side leg portion 22 that constitute the soil lump and weight structure 20 are joined together.

[0022] <2.3.1> Joint morphology of the saddle and lateral crura (1) FIG. 3(A) shows a soil lump and weight structure 20 in which upper surfaces 22a of side legs 22 are joined to lower surfaces 21b of both ends of a saddle portion 21 to form an integrated structure.

[0023] In this embodiment, in order to integrate the saddle portion 21 and the side leg portion 22, a plate-shaped or sheet-shaped support material 23 is placed on the upper surface 21a of the saddle portion 21 and the lower surface 22b of the side leg portion 22, and one or more connecting bodies 24 are placed vertically between the saddle portion 21 and the side leg portion 22, penetrating the support material 23, and both ends of the connecting body 24 that has penetrated the support material 23 are fixed with fixing devices 25. The connector 24 has a length that allows it to extend through the saddle portion 21 and the side leg portion 22, and both ends thereof are structured to allow attachment of a fixing device 25 thereto. The weight of the side leg 22 can be transmitted to the saddle 21 via the connector 24 . Although not shown in the figures, one or more connectors 24 may be additionally installed vertically between the top and bottom of the saddle portion 21 located directly above the buried pipe 10 to rigidly connect the center of the saddle portion 21.

[0024] In order to make the present invention easier to understand, the side legs 22 are conveniently shown in the drawings with the same width dimension, but in actual construction, since the cell structure 30 is flexible, it is possible to construct the side legs 22 by bringing the inner surface of each cell structure 30 into contact with the outer surface of the buried pipe 10, and no large gaps will occur between the inner surface of the side legs 22 and the outer periphery of the buried pipe 10.

[0025] <2.3.2> Joint form of the saddle and lateral crura (2) FIG. 3(B) shows a soil lump and weight structure 20 in which a side surface 22c of a side leg 22 is joined to a side surface 21c of a saddle portion 21 to form an integrated structure.

[0026] In this embodiment, in order to integrate the saddle portion 21 and the side leg portion 22, one or more connecting bodies 24 are placed horizontally between the saddle portion 21 and the side leg portion 22, and both ends of the connecting body 24 are fixed with fixing devices 25. The weight of the side legs 22 can be transmitted to the saddle 21 via a plurality of connectors 24 .

[0027] In the connecting structure shown in FIG. 3(B), the vertically oriented connecting body 24 shown in FIG. 3(A) may be additionally installed on the side leg portion 22.

[0028] <2.3.3> Means of connecting the saddle and side legs In this example, the means for connecting the saddle portion 21 and the side leg portion 22 can be a combination of a connecting body 24 that is, for example, belt-shaped, rod-shaped, or string-shaped, and a fixing device 25 that can be attached to the end of the connecting body 24 and fixed. As the means for connecting the saddle portion 21 and the side leg portion 22, various known connecting means can be applied as long as the load can be transmitted between the saddle portion 21 and the side leg portion 22.

[0029] [Method of burying underground pipes] A method for burying the buried pipe 10 will be described with reference to FIGS. 4A and 4B.

[0030] 1. Excavation process of the laying trench (Figure 4A(A)) Retaining plates 41 such as sheet piles are driven into the ground G facing each other, and a trench 40 having dimensions that allow the buried pipe 10 to be laid is excavated while the retaining plates 41 prevent the soil from collapsing. A support base 42 is constructed by spreading sand, good quality soil, etc. in layers over the entire bottom of the laying trench 40.

[0031] 2. Buried pipe laying process (Figure 4A(A)) After the buried pipe 10 is hung horizontally inside the laying trench 40, the buried pipe 10 is laid on the upper surface of the support foundation 42.

[0032] 3. Backfilling process of the construction trench (Figure 4A(B) to Figure 4B(D)) The buried pipe 10 is laid inside the trench 40 in the following manner.

[0033] <1> Construction of soil mass and weight structure The side legs 22 are constructed first, and then the saddle 21 is constructed, and a gate-shaped earthen mass structure 20 is constructed so as to straddle the buried pipe 10.

[0034] <1.1> Construction of the lateral limb (Figure 4A(B)) The steps of laying the aforementioned cell structure 30 on the upper surface of the support foundation 42 exposed on both sides of the buried pipe 10, filling the cell spaces 32 of the cell structure 30 with filler material 33, and compacting the filler material 33 are repeated until a predetermined height is reached, thereby forming side legs 22, 22 on both sides of the cell structure 30. The compaction of the filler material 33 can be efficiently carried out using a known rolling machine such as a roller type, a vibrating type, or a tamping type.

[0035] When constructing the side legs 22, the filler material 33 is constrained in each cell space 32, and compaction is performed on a unitary basis for each cell structure 30. This eliminates variation in the compaction of the filler material 33 throughout the entire side legs 22, and allows the filler material 33 to be compacted uniformly and firmly over the entire length of the soil mass weight structure 20 (laying trench 40).

[0036] <1.2> Construction of the saddle (Figure 4B(C)) A saddle portion 21 is constructed across both leg portions 22, 22 provided on both sides of the cell structure 30. The method of constructing the saddle section 21 is similar to that of the side leg section 22, and involves repeating the steps of laying the cell structure 30, filling the cell spaces 32 of the cell structure 30 with filler material 33, and compacting the filler material 33 by rolling it down until it reaches a predetermined height.

[0037] When constructing the saddle section 21, the filler material 33 is compacted for each individual cell structure 30, and the filler material 33 is compacted in a constrained state in each cell space 32 of the cell structure 30. This eliminates variation in the compaction of the filler material 33 throughout the entire saddle section 21, and allows the filler material 33 to be firmly and uniformly compacted over the entire length of the soil mass weight structure 20 (laying trench 40).

[0038] <1.3> Connection between the lateral leg and the saddle The side legs 22 and the saddle 21 are integrally connected by connecting members 24 as shown in FIG. 3 to construct a gate-shaped soil mass structure 20. The layout of the side legs 22 and the saddle portion 21 and the connection between the side legs 22 and the saddle portion 21 are appropriately selected from either the form shown in FIG. 3(A) or 3(B).

[0039] The soil mass and weight structure 20 constructed on site so as to straddle the buried pipe 10 has its side legs 22, 22 positioned adjacent to both the left and right sides of the buried pipe 10, and the saddle portion 21 positioned adjacent to the upper part of the buried pipe 10.

[0040] 4. Backfill soil covering process (Figure 4B(D)) The top surface of the soil mass and weight structure 20 is covered with soil by repeatedly spreading and compacting backfill material 43 such as soil and sand. The backfill material 43 not only functions as a simple soil covering material, but also functions as a counterweight for the buried pipe 10 by having the total weight of the backfill material 43 supported by the soil mass and weight structure 20 .

[0041] It should be noted that covering the soil with the backfill material 43 is not essential, and the soil lump and weight structure 20 itself may be configured to serve as the soil cover without covering the soil with the backfill material 43.

[0042] 5. Removal of the retaining wall (Figure 4B(D)) After the backfill material 43 has been covered up to the height of the ground G, the retaining plate 41 is removed. The top surface of the soil mass and weight structure 20 is covered with soil by repeatedly spreading and compacting backfill material 43 such as soil and sand. Covering the soil with backfill material 43 is not essential, and the soil lump and weight structure 20 may also serve as the soil cover without covering the soil with backfill material 43.

[0043] Since the side legs 22, 22 of the soil mass and weight structure 20 are located on both the left and right sides of the buried pipe 10 close to the outer circumferential surface of the buried pipe 10, the side legs 22, 22 do not displace in the width direction even when the retaining plate 41 is removed. More specifically, even if the retaining plate 41 is removed, the soil mass weight structure 20 does not lose its shape. Since the filler material 33 is restrained by the cell structure 30 constituting the side leg portion 22, the filler material 33 does not loosen or fall out, and is kept in a tightly compacted state. Since the function of protecting the buried pipe 10 by the soil mass and weight structure 20 is maintained, even if the retaining plate 41 is removed, compressive deformation and damage to the buried pipe 10 in the horizontal direction can be reliably prevented.

[0044] In addition, it is advisable to fill the space left by removing the retaining plate 41 with part of the backfill material 43.

[0045] [Prevents buried pipes from floating up] The function of preventing the buried pipe 10 from floating up during an earthquake or the like will be described with reference to FIG.

[0046] <1> Relationship between vertical weight acting on soil mass and backfill material FIG. 5 shows the relationship between the buoyancy U acting on the buried pipe 10 and the downward vertical weight acting on the soil mass and weight structure 20 and the backfill material 43.

[0047] Regarding the vertical weight of the soil mass and weight structure 20, the central vertical weight of the part (saddle part 21) located directly above the buried pipe 10 is w1, and the lateral vertical weight of the part (side leg part 22) located directly above the side of the buried pipe 10 is w2. Similarly, the vertical weight of the backfill material 43 is defined as w3, where w3 is the central vertical weight of the part located directly above the buried pipe 10, and w4 is the lateral vertical weight of the part located directly above the side of the buried pipe 10.

[0048] <2> Vertical weight of the soil mass and weight structure In the present invention, the saddle portion 21 and the side leg portions 22 that constitute the soil mass weight structure 20 are integrated so as to be able to transmit the load, so that the vertical weight that can counteract the buoyancy U of the buried pipe 10 is not only the central vertical weight w1, but also the left and right lateral vertical weights w2, w2, which function as weights that counteract the buoyancy U of the buried pipe 10. That is, since the soil mass weight structure 20 is a highly rigid soil mass structure, the entire weight (w1+w2+w2) functions as a counterweight for the buried pipe 10.

[0049] <3> Vertical weight of backfill material Furthermore, the backfill material 64 positioned above the soil mass and weight structure 20 also counters the buoyancy U of the buried pipe 10 with a weight obtained by adding the central vertical weight w3 and the side vertical weights w4, w4. That is, the weight (w3+w4+w4) of all the backfill material 64 functions as a counterweight via the highly rigid earth mass structure.

[0050] <4> Overall vertical weight Taking these factors into consideration, the total weight of the soil mass and weight structure 20 and the total weight of the backfill material 43 (w3+w4+w4) functions as a counterweight against the buried pipe 10 floating up. Therefore, even when the buried pipe 10 is a large-diameter pipe or the ground has a high groundwater level, the buried depth H of the buried pipe 10 can be made shallow. By making the buried depth H of the buried pipe 10 shallower, the amount of trench excavation and the amount of backfill material 43 used can be reduced, resulting in a significant reduction in construction costs and construction period.

[0051] [Example 2] Other embodiments will be described below, and in the description, the same parts as those in the above-described embodiment will be given the same reference numerals and detailed description thereof will be omitted.

[0052] <1> Other lump and weight structures The soil mass and weight structure 20 is not limited to the bilaterally symmetrical shape shown in the first embodiment. The asymmetrical soil lump and weight structure 20 will be described with reference to FIG.

[0053] FIG. 6(A) shows another soil lump and weight structure 20 in which the widths L1, L2 of the left and right side legs 22, 22 provided on both sides of the saddle portion 21 are different. Furthermore, the heights and widths H1 and H2 of the left and right side legs 22 may be different.

[0054] FIG. 6(B) shows a configuration in which a side leg 22 is provided on only one side of the saddle portion 21, either the left or the right, to form the soil lump weight structure 20 into a hook shape. The total weight of the saddle portion 21 is adjusted taking into consideration the buried environment of the buried pipe 10, the direction of buoyancy generated in the buried pipe 10, and the like.

[0055] <2> Effects of this example In this example, in addition to being able to obtain the same effects as in Example 1, it is possible to apply vertical loads to each part of the soil mass weight structure 20 according to the buried environment at the site, which not only increases the freedom of design but also makes it possible to design an economical counterweight. Furthermore, even at a site where there are existing underground obstacles, rocks, hard ground, etc. close to the buried pipe 10 and making excavation impossible, the left-right asymmetrical earth mass weight structure 20 buried in accordance with the burial conditions at the site can function as a counterweight for the buried pipe 10.

[0056] [Example 3] Referring to FIG. 7, the earth lump and weight structure 20 applied to the bent buried pipe 10 will be described. The buried pipe 10 is, for example, a pipe body such as an agricultural pipeline or a drainage pipe for a hydroelectric power plant, and may be buried in a bent state in a dogleg shape.

[0057] <1> Thrust force acting on the bent part of the buried pipe Referring to Figure 7(B), it is known that if a buried pipe 10 having a bent section is buried in the ground such as an embankment without any countermeasures being taken, when water flows inside the buried pipe 10, an outward centrifugal force is generated at the bent section of the buried pipe 10, generating a thrust force F that moves the buried pipe 10 diagonally upward. If the thrust force F of the buried pipe 10 is left unattended, there is a risk that it may cause deformation such as uplift or rupture in the road 44 located above, or that part of the buried pipe 10 may be destroyed.

[0058] As countermeasures for this, methods have been proposed, such as driving anchors into the ground and using the anchors as a reaction force source to fix the buried pipe 10 facing toward the inside of the curve, or burying the buried pipe 10 in hard ground such as natural rock, but these countermeasures are expensive in terms of construction costs and construction time, and there is room for improvement.

[0059] <2> Soil mass weight structure capable of resisting thrust forces Explaining with reference to FIG. 7(C), the soil mass and weight structure 20 having the gate or hook shape described above is provided at the bent portion of the buried pipe 10. By simply installing the aforementioned soil mass weight structure 20 across the bent portion of the buried pipe 10, the thrust force F acting on the bent portion of the buried pipe 10 can be countered by the vertical weight of the soil mass weight structure 20. In this example, it is desirable to employ an asymmetrical soil lump and weight structure 20 as shown in FIG.

[0060] <3> Effects of this example In this example, in addition to obtaining the same effect as in Example 1, there is also the advantage that it is possible to resist thrust forces simply by applying the soil mass weight structure 20 to an buried pipe 10 having a bent portion. Furthermore, the soil mass weight structure 20 suppresses the behavior of the embankment in which the buried pipe 10 is buried, thereby serving as an earthquake-resistant reinforcement member for the embankment, and the load-dispersing effect of the soil mass weight structure 20 can reduce the wheel load acting on the buried pipe 10. In addition, even if the embankment slope is eroded by rainwater, tsunami, etc., the buried pipe 10 can be protected by the protective action of the soil mass and weight structure 20. [Explanation of symbols]

[0061] 10. Buried pipe 20...Earth clod weight structure 21. Saddle 22...Side leg 23... Bearing material 24... Consolidated body 25... Fixture 30. Cell structure 31. Belt 32 Cell space 33 Filling material 40.....Laying trench 41... Retaining wall 42...Support foundation 43...Backfilling material 44...road

Claims

1. A buried pipe structure for burying a buried pipe underground, A soil mass weight structure having a gate-shaped or hook-shaped cross section and made of a highly rigid soil mass structure fabricated on-site is placed across the buried pipe; The soil mass and weight structure comprises a saddle portion that can suspend and cover the upper portion of the buried pipe, and a side leg portion that hangs down integrally with the end of the saddle portion and can cover the side portion of the buried pipe, The saddle portion and the side leg portion are constructed by a plurality of cell structures stacked on-site, and a fill material filled and roll-compacted into the cell spaces of the cell structures on-site, The total weight of the soil mass and weight structure functions as a counterweight for the buried pipe. Buried pipe construction.

2. 2. The buried pipe structure according to claim 1, wherein the top surface of said soil mass weight structure is covered with backfill material, and the total weight of said backfill material is supported by said soil mass weight structure. Buried structure.

3. 3. The buried pipe structure according to claim 1, wherein the soil mass and weight structures are placed continuously or intermittently over the entire length of the buried pipe.

4. 3. The buried pipe structure according to claim 1, wherein the buried pipe has a bent portion, and the soil mass and weight structure is placed across the bent portion of the buried pipe.

5. 3. The buried pipe structure according to claim 1, wherein the soil mass and weight structure is asymmetrical with respect to the buried pipe.

6. 2. The buried pipe structure according to claim 1, characterized in that the saddle portion and the side leg portion are integrally connected so as to be able to transmit loads via a connecting member that penetrates vertically or horizontally between the saddle portion and the side leg portion.

7. A method for burying a buried pipe in the ground, comprising: a first step of excavating a trench between the ground and a retaining wall; a second step of laying a buried pipe in the trench; and a third step of placing a soil mass and weight structure across the buried pipe to backfill the trench, The soil mass and weight structure is provided with a saddle portion that can be hung horizontally over the top of the buried pipe to cover it, and side legs that hang down integrally with the end of the saddle portion and can cover the side of the buried pipe, and is composed of a plurality of cell structures in which the saddle portions and side legs are stacked on site, and a fill material that is filled into the cell spaces of the cell structures on site and compacted by rolling, The third step is characterized in that the soil mass weight structure, which has a gate-shaped or hook-shaped cross section and is made of a highly rigid soil mass structure fabricated on-site, is placed across the buried pipe to backfill the laying trench, and the total weight of the soil mass weight structure functions as a counterweight for the buried pipe. Burying pipe installation method.

8. 8. The buried pipe installation method according to claim 7, further comprising a fourth step of covering the upper surface of the soil mass structure with backfill material, the total weight of which is supported by the soil mass structure.

9. 9. The method for burying a buried pipe according to claim 7 or 8, wherein the soil mass and weight structures are placed continuously or intermittently over the entire length of the buried pipe.

10. 9. The method for burying a buried pipe according to claim 7, wherein the buried pipe has a bent portion, and the soil mass and weight structure is placed across the bent portion of the buried pipe.

11. 9. The method for burying a buried pipe according to claim 7 or 8, wherein the soil mass and weight structure is asymmetrical with respect to the buried pipe.

12. 9. The buried pipe installation method according to claim 7 or 8, characterized in that the saddle portion and the side leg portion are integrally connected so as to be able to transmit loads via a connecting body that penetrates vertically or horizontally between the saddle portion and the side leg portion.

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