JP2001153262A - Structure for preventing float of buried conduit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a conduit from floating by ground water when a conduit is buried shallowly in the ground. SOLUTION: Side portions of a buried conduit 3 are joined with edges of geosynthetics 10, and the geosyntehtics 10 are enclosed by backfilling soil 5 around the buried conduit 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a buried conduit floating prevention structure.

[0002]

2. Description of the Related Art In recent years, so-called shallow burial methods for reducing the burial depth of pipes have been increasing for the purpose of simplifying the laying method of buried pipelines and shortening the construction period. If such a shallow burial method is adopted on the ground with a high groundwater level, there is a problem that the buried pipes float up due to the groundwater, which is inconvenient. In particular, the larger the diameter of the pipe, the greater the buoyancy.

[0003] That is, in the case of the ordinary deep burial method, the weight of the soil at the top of the pipe opposes the floating, but in the case of the shallow burying method, the weight of the soil at the top of the pipe is insufficient, so It will emerge.

[0004]

As a structure for preventing the floating of a pipe buried in the ground, as shown in FIG. 10, the area around the bottom 3a of the buried pipe 3 wrapped with the civil engineering sheet 2 is an intermediate height of the cross section of the pipe. After backfilling with the backfill soil 4, another civil engineering sheet 7 is laid from the pipe top 3 b, and is laid in the excavation groove 1 so as to overlap with a surplus portion of the civil engineering sheet 2 supporting the lower surface of the embedded pipe 3. By burying the backfill soil 5 and 6 above, the civil engineering sheet 2 prevents the pipeline from sinking, and the civil engineering sheet 7 allows the weight of the backfill soil 5 and 6 to be wider than the burial pipe 3. A structure in which the floating of the pipeline is prevented by adding to the structure of Patent No. 3 is disclosed (for example, Japanese Patent No. 2776695).

In the case of this construction method, two civil engineering sheets 2, 7 must be developed and laid along the curved upper and lower surfaces of the pipe according to the progress of the construction, so that the work becomes very complicated. was there. In addition, two civil engineering sheets 2, 7
There was a problem that the materials to be prepared increased.

The present invention has been made to solve the above problems, and to provide a buried pipeline floating prevention structure capable of reliably preventing the floating of a pipe due to a groundwater level by a simple construction when a shallow burying method is employed. This was done as an issue.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a floating prevention structure for a buried pipe according to the present invention connects an end of a geosynthetics to a side of a buried pipe and attaches the geosynthetics to the side. The buried pipe is wrapped around the backfill soil. Here, geosynthetics is a sheet-like material used with soil,
For example, geotextiles, geonets, geogrids, etc., refer to geotextiles, which are high-strength, low-elongation, low-creep deformation, physical properties with excellent impact resistance during construction, weather resistance, chemical resistance, Knitted fabric, woven fabric, non-woven fabric made of a fiber material that has excellent cold resistance, heat resistance, and chemical properties with good friction with soil, such as aramid fiber combined with high-density polyethylene resin or polyester fiber Say Further, a geonet and a geogrid refer to a net-like body made of the fiber material.

Therefore, according to the present invention, the geosynthetics are integrally connected to the pipe side surface, the backfill soil is backfilled on the developed geosynthetics, and the backfill soil is used as surplus of the geosynthetics. If it is wrapped in a part and then the whole is backfilled, the weight of the backfill soil with a larger area than the buried pipe is transmitted to the buried pipe via the geogrid, so that the floating of the pipe by groundwater can be prevented.

Further, since it is not necessary to develop two sheets along the curved upper and lower surfaces of the tube as in the prior art, the backfilling operation is facilitated. In addition, since only one sheet is required, the amount of materials can be reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a buried pipeline floating prevention structure according to the present invention will be described. Embodiment 1 FIG. 1 is a perspective view of a buried pipe used for a floating prevention structure of a buried pipe according to Embodiment 1 of the present invention, FIG.
FIG. 3 is a sectional view of a main part of another example of the configuration of the buried pipe 3, and FIG.
FIG. 5 is a cross-sectional view of a structure for preventing floating of a buried conduit according to Embodiment 1 of the present invention.

In FIG. 1, a buried pipe 3 is provided with locking portions 31... 31 for fastening a net-like geosynthetics (hereinafter referred to as a geogrid) 10 at an intermediate height position in the cross section of the pipe. A large number are protruded along the axial direction.
31 are integrally attached to the side surface of the buried pipe 3, and when the buried pipe 3 is a metal pipe such as a cast iron pipe, U
It is attached by welding a letter-shaped metal piece.

The buried pipe 3 is an FRP pipe, an FRPM pipe,
In the case of a vinyl chloride tube or the like, a U-shaped piece is integrally attached at the time of manufacture by hand lay-up or the like, and in the case of a synthetic resin tube, a piece of a similar material is attached by an adhesive or welding. In addition, the geogrid 10 has annular fitting portions 10a.
a is provided.

Then, fitting portions 10a...
Are arranged on the same line of sight as shown by dotted lines, and are connected by inserting connecting rods 32 as shown by imaginary lines in FIG. 1 and as shown in cross section in FIG. The structure for mounting the geogrid 10 is the same as that shown in FIGS.
The band member 33 is wound around the outer periphery of the tube 3 as shown in FIG. 3 and an engaging portion 34a of the connecting rod 32 is formed in an ear 34 to which the band member 33 is fastened. 10a can be inserted through the connecting rod 32.

Next, a structure for preventing the buried pipe from floating by the buried pipe will be described. As shown in FIG. 5, the excavation groove 1 is dug down to a required width, and the base floor material 1c is formed on the bottom surface 1b as necessary.
Has been put in and has been consolidated. A buried pipe 3 is installed on the bottom surface 1b of the excavation groove 1, and a side surface of the buried pipe 3 is provided with locking portions 31.
It is backfilled with the backfill soil 4 up to the position 31 and compacted.

Then, the geogrid 10 is connected to the locking portions 31, 31 by connecting rods 32, and extends from both sides of the buried pipe 3 to the inner side surfaces 1d, 1d of the digging groove 1 along the backfilled soil 4 of the digging groove 1. It is deployed and laid. Then, the inner surface of the excavation trench 1 surrounded by the geogrid 10 is backfilled with the backfill soil 5 to a height reaching the pipe top 3b on the outer surface of the buried pipe 3,
The weight of the backfill soil 5 is added to the geogrid 10.

The surplus part 10b of the geogrid 10 is folded over the backfill soil 5 so as to cover the backfill soil 5. Then, the backfill soil 6 is backfilled with the backfill soil 6 to the upper part of the opening of the excavation trench 1 on the geogrid 10 surrounding the backfill soil 5. Therefore, Geogrid 1
0, the weight of the backfill soil 5 and 6 is added. As a result, the weight of the buried pipe 3 is larger than the projected area of the buried pipe 3 from the geogrid 10 via the locking portion 31. It is reportedly being designed to counter the buoyancy of groundwater.

Next, the construction procedure of the first embodiment will be described. As shown in FIG. 6, the excavation trench 1 is excavated and both sides 1d, 1d
The sheet piles 11 and 11 are driven into the soil to stop the soil, and if necessary, the base floor material 1c is charged to consolidate the ground. Next, the buried pipe 3 is installed, and backfilled with the backfill soil 4 from the pipe bottom 3a to the height of the locking portion 31. In particular, the pipe is sufficiently sunk so as not to form a cavity in the pipe bottom 3a.

Then, if it is back-filled to the height of the locking portion 31,
The geogrid 10 is fixed to the locking portions 31, 31, and the geogrid 10 is temporarily supported along the upper surface of the buried backfill 4 and both side surfaces 1 d, 1 d of the groove 1. In this temporary support, the geogrid 10 is simply flattened on the bottom of the groove, and hooks (not shown) are protruded from the side of the groove, for example, on the sheet piles 11, 11, and the geogrid 10 is hooked or long. A rod (not shown) is hung horizontally from the upper surface of the sheet pile, and the long rod is supported by locking the other end of the geogrid 10 or the like.

Then, the space in the excavation trench 1 is backfilled with the backfill soil 5 to the height of the top of the buried pipe 3 and compacted again. After the backfilling, the temporary support of the geogrid 10 is released as shown in FIG. 7, and the surplus portions 10 b and 10 b are laid on the backfilling soil 5, and from the top to the opening surface of the groove 1. Backfill with backfill soil 6. Finally, the sheet pile 11 is pulled out, and the backfill soil 6 is compacted well as shown in FIG.

Even if the buried pipe 3 attempts to settle, the settlement of the geogrid 10 is suppressed by the backfill soil 4, so that the geogrid 10 can be settled without laying the civil engineering sheet 2 as shown in FIG. It becomes prevention. Further, since the geogrid 10 has a mesh shape, drainage is good, and there is no possibility that groundwater stays on the surface on which the geogrid 10 is deployed or the geogrid floats in the groundwater with the buried pipe 3 wrapped. Embodiment 2 In Embodiment 1 described above, the case where the geogrid 10 is connected to the middle height of the tube side surface of the buried tube 3 is shown.
As shown in FIG.

In this case, the geogrid 10 is connected to the tube bottom 3a.
It is arranged along the inner wall surface of the excavation groove 1 from the base floor material 1c of the excavation groove 1 bottom surface 1b, and is buried with the backfill soil 5 from the tube bottom 3a to the tube side, and the surplus part is extended to the tube top 3b. 1
0b and 10b are superimposed, and furthermore, backfilled with the backfill soil 6 up to the upper part of the trench excavation groove 1. Since the configuration other than the above is the same as that of the first embodiment, the same portions are denoted by the same reference numerals and detailed description will be omitted.

In the case of the second embodiment, the backfill soil 5 at the bottom 3a also functions as a weight for preventing floating, which is advantageous for a large-diameter pipe having a large buoyancy or a shallowly buried pipe. Also, compaction of the backfill soil 5a, 5a on both sides of the pipe bottom 3a,
In the conventional case, as shown in FIG. 11, both sides of the pipe bottom are tamped, and when the backfill portion is covered with the civil engineering sheets 7, 7, the vertical wall portions 5b, 5b of the backfill soil 5a, 5a may collapse. However, in the second embodiment, the backfill soils 5a and 5a on both sides can be easily tamped, and the backfill state is improved.

The geosynthetics used in the first and second embodiments have been described in the case of a geogrid in the form of a mesh. However, knitted fabrics, woven fabrics, and nonwoven fabrics can be used if the filterability and the in-plane water permeability are good. So-called geotextiles may be used. Also, as shown in FIG. 8 (b), the buried pipe 3 can be buried in the same procedure when the digging groove 1 is a plain digging groove without using a sheet pile, and the same effect is obtained by the geogrid 10. Can be FIG. 8 (b)
In FIG. 8, the same members as those in FIG.

[0024]

As described above, according to the present invention, the weight of the backfill soil having an area larger than that of the buried pipe is added to the buried pipe via the cloth-like and net-like geosynthetics, so that the groundwater level can be changed. Even in the case where buoyancy acts on the buried pipe, a sufficient mass of backfill soil is added to prevent buoyancy.

Further, even when buoyancy is generated due to liquefaction during an earthquake, a floating prevention effect is exhibited. Also, when installing, it is only necessary to fasten the geosynthetics to the side of the pipe, the required number is reduced by half compared to the conventional civil engineering sheet, and there is no need to lay along the curved surface through the pipe bottom or pipe top. This has the effect of simplifying construction.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a buried pipe and a geogrid according to Embodiment 1 of the present invention.

FIG. 2 is a cross-sectional view of a main part showing a connection state between a buried pipe and a geogrid.

FIG. 3 is a cross-sectional view of a main part showing another configuration example of a connection state between a buried pipe and a geogrid.

FIG. 4 is a perspective view of the connected state shown in FIG. 3;

FIG. 5 is a cross-sectional view of a buried structure for preventing floating of a pipeline according to the first embodiment;

FIG. 6 is a cross-sectional view illustrating a construction state according to the first embodiment.

FIG. 7 is a sectional view showing a construction state of the first embodiment.

FIG. 8 is a sectional view showing a construction state of the first embodiment;
(A) shows the case of a digging groove using a sheet pile, and (b) shows the case of a plain digging groove without a sheet pile.

FIG. 9 is a cross-sectional view of a buried structure for preventing floating of a pipeline according to a second embodiment.

FIG. 10 is a sectional view showing a conventional embedded structure.

FIG. 11 is a sectional view showing another conventional buried structure.

[Explanation of symbols]

 Reference Signs List 1 excavation groove 2 civil engineering sheet 3 buried pipe 4 backfilled soil 5 backfilled soil 6 backfilled soil 10 geogrid (geosynthetics) 10b fitting part 31 locking part

Claims (1)

[Claims] 1. A floating prevention structure for a buried pipeline, wherein an end of the geosynthetics is connected to a side portion of the buried pipe, and the geosynthetics wraps backfill soil around the buried pipe. .