JP7394344B2 - Liquefaction countermeasure construction method and liquefaction countermeasure structure - Google Patents

Description

The present invention relates to a liquefaction countermeasure construction method and a liquefaction countermeasure structure.

Patent Documents 1 to 3 disclose techniques for preventing movement of buried pipes buried underground due to liquefaction of ground materials around the buried pipes due to earthquakes, and for preventing separation of joints of buried pipes caused by such movement. The technique described in No. 5 is known. Patent Documents 1 and 2 describe the use of a buried pipe whose parts that are likely to come off are reinforced in advance in order to prevent the connection portion of the buried pipe from separating. Patent Documents 3 to 5 describe techniques for injecting reinforcing material around a buried pipe in order to prevent the buried pipe from floating or sinking due to liquefaction of the ground.

Japanese Patent Application Publication No. 2002-276853 Japanese Patent Application Publication No. 2005-163897 Japanese Patent Application Publication No. 2016-17341 Japanese Patent Application Publication No. 7-286356 Japanese Patent Application Publication No. 2013-164103

In pipes in which water flows, such as agricultural pipelines, thrust forces generated by changes in water flow act at locations where water flow changes, such as at bent portions. When the pipe is buried extending in a substantially horizontal direction, the thrust force is generated in the substantially horizontal direction and is different from the force that causes the pipe to float or sink. In a buried pipe buried underground, the earth pressure and the frictional force between the soil and the pipe serve as reaction forces, so that the deformed part of the buried pipe does not move even if a thrust force acts on it.

However, when the area around a buried pipe becomes liquefied due to an earthquake, the earth pressure and the frictional force between the soil and the pipe decrease, making it impossible to resist thrust force, making the deformed part easier to move. If the deformed part moves, it may lead to disconnection of the connection part of the buried pipe or damage to the pipe. Separation of underground pipe connections or damage to pipes not only disrupts the supply of agricultural water, but can also lead to secondary damage such as ground erosion and traffic disruption due to water leakage. Therefore, there is a need for technology that prevents the movement of buried pipes and the separation of connections due to a decrease in earth pressure.

The techniques described in Patent Documents 1 and 2 are techniques for burying a pipe after reinforcing deformed parts that are likely to come off, and therefore cannot be applied to existing pipes that are already buried underground. Furthermore, the technologies described in Patent Documents 3 to 5 are technologies for preventing buried pipes from rising or sinking due to liquefaction of the ground, and cannot prevent the effects of thrust forces that act in a substantially horizontal direction. .

One aspect of the present invention aims to prevent movement of the buried pipe due to the influence of thrust force by applying liquefaction countermeasures to the buried pipe, and to prevent separation of the connection portion of the buried pipe.

In order to solve the above problems, the present invention includes the following aspects.
1) A liquefaction countermeasure construction method for buried pipes, wherein the buried pipe has a straight pipe section and a deformed section to which a thrust force is applied due to the flow of water flowing inside the pipe being different from the straight pipe section. It includes an injection step of injecting an injection material that reduces the fluidity of the foundation material into the foundation material introduced around the deformed part laid in a trench formed by excavating the ground. liquefaction countermeasure construction method.
2) The liquefaction countermeasure construction method according to 1), wherein in the injection step, the injection material is injected into the foundation material on the downstream side in the direction in which the thrust force is applied.
3) The periphery of the deformed part is covered with a protective material, and in the injection step, the injection material is injected into the base material introduced around the protective material, according to 1) or 2). Liquefaction countermeasure construction method.
4) Any one of 1) to 3), further including, before the injection step, a step of burying the buried pipe in which the buried pipe is laid in the trench and the foundation material is introduced around the buried pipe. Liquefaction countermeasure construction method described in.
5) The liquefaction countermeasure method according to any one of 1) to 4), wherein the injection material includes one or more selected from the group consisting of silica solution, clay, cement, slag, bubbles, and gas. .
6) A buried pipe that has a straight pipe section and a deformed section to which a thrust force is applied due to the flow of water flowing inside the pipe being different from the straight pipe section, and a trench formed by excavating the ground. A liquefaction countermeasure structure comprising: a reinforcing portion that is provided in a foundation material introduced around the laid deformed portion and has lower fluidity than the foundation material.

According to one aspect of the present invention, by applying liquefaction countermeasures to the buried pipe, movement of the buried pipe due to the influence of thrust force can be prevented, and separation of the connection portion of the buried pipe can be prevented.

FIG. 2 is a top view showing a buried pipe to which a liquefaction countermeasure construction method according to an embodiment of the present invention has been applied. It is a sectional view explaining a buried pipe buried in soil. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view illustrating a liquefaction countermeasure construction method according to an embodiment of the present invention. It is a schematic diagram explaining another example of the thrust force produced in a buried pipe. It is a schematic diagram explaining another example of the thrust force produced in a buried pipe. It is a schematic diagram explaining another example of the thrust force produced in a buried pipe. It is a top view explaining other examples of the liquefaction countermeasure construction method concerning one embodiment of the present invention.

[Liquefaction countermeasure construction method]
Hereinafter, one embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited to this embodiment.

FIG. 1 is a top view showing a buried pipe 10 to which a liquefaction countermeasure construction method according to an embodiment of the present invention is applied. Note that in the coordinate axes shown in each figure, the Z axis extends in the vertical direction, and the X and Y axes extend in the horizontal direction. Therefore, FIG. 1 is a top view of the buried pipe 10 viewed from the ground side when the buried pipe 10 is buried in soil.
As shown in FIG. 1, a buried pipe 10 that is subjected to liquefaction countermeasures using a liquefaction countermeasure construction method has a straight pipe section 11 and a deformed section 12 in which the flow of water flowing inside the pipe section 11 is different from that of the straight pipe section 11. The straight pipe portion 11 and the deformable portion 12 are connected so that water can flow therein. A thrust force W is applied to the deformed portion 12 due to the flow of water flowing inside the portion being different from that of the straight pipe portion 11 . The buried pipe 10 is buried in a trench 13 formed by excavating the ground. The groove 13 in which the buried pipe 10 is buried is filled with a foundation material 15.
In the example shown in FIG. 1 , the deformed portion 12 is a bent portion that is bent relative to the straight tube portion 11 . A reinforcing part 14 is located outside the arc of the deformed part 12, and a liquefaction prevention structure 100 is constructed by the buried pipe 10 and the reinforcing part 14. The liquefaction countermeasure construction method takes liquefaction countermeasures to the buried pipe 10 by forming a reinforcing portion 14 .

The buried pipe 10 is, for example, an agricultural pipeline through which agricultural water flows for irrigation, but is not limited thereto. The diameter of the buried pipe 10 is, for example, 50 mm or more and 4000 mm or less. The total length of the buried pipe 10 may extend to several tens of kilometers.

The liquefaction countermeasure construction method involves injecting an injection material that reduces the fluidity of the foundation material 15 into the foundation material 15 introduced around the deformed part 12 laid in a trench 13 formed by excavating the ground. Includes an injection process. The injection step is a step of forming the reinforcing portion 14 by injecting an injection material into the base material 15. The reinforcing part 14 is composed of the injection material and the base material 15 in the area into which the injection material is injected, and may be a portion where the fluidity of the base material 15 is reduced due to the inclusion of the injection material.

The injection process will be explained with reference to FIG. 2. FIG. 2 is a cross-sectional view taken along line AA' in FIG. 1, and is a diagram illustrating a liquefaction countermeasure construction method according to an embodiment of the present invention. As shown in FIG. 2, the buried pipe 10 is buried under the ground G.

When burying the buried pipe 10, first, the ground G is excavated to form the groove 13. Then, the base material 15 is laid on the bottom of the groove 13, and the buried pipe 10 is laid on the base material 15. Then, the foundation material 15 is introduced and compacted until the top of the buried pipe 10 is buried. As a result, the periphery of the buried pipe 10 within the groove 13 is covered with the base material 15. Then, the buried pipe 10 is buried by introducing the backfilling material 17 onto the foundation material 15 and compacting it. The base material 15 is a material mainly containing sand, gravel, crushed stone, etc. The backfilling material 17 is usually excavated ground material, but it may also be ground material brought from outside. In this way, the liquefaction countermeasure construction method may further include a step of burying the buried pipe 10 in which the buried pipe 10 is laid in the trench 13 and the foundation material 15 is introduced around the buried pipe 10.

Thrust force occurs where the flow of water inside the pipe changes, and can cause separation of the connected portion of the pipe or breakage of the pipe. The thrust force W generated in the deformed portion 12 in which the water flow inside is different from that in the straight pipe portion 11 is propagated to the ground outside the groove 13 by the foundation material 15 around the deformed portion 12. Normally, the earth pressure of the ground acts as a reaction force to this thrust force, so movement of the deformed portion 12 due to the thrust force W is suppressed.

Here, in the event of an earthquake, the ground outside the trench 13 formed by excavation may not liquefy, but only the portion of the foundation material 15 backfilled into the trench 13 may liquefy. In this way, when the foundation material 15 liquefies due to an earthquake, the thrust force W applied to the deformed portion 12 does not propagate to the ground, and the earth pressure of the ground does not act as a reaction force to the thrust force W. As a result, the deformed portion 12 is displaced within the range where the base material 15 is introduced in the groove 13, and the connecting portion between the straight pipe portion 11 and the deformed portion 12 is separated, leading to water leakage. Furthermore, in the case of a pipe material such as a hard vinyl chloride pipe in which the straight pipe section 11 and the deformed section 12 are joined with adhesive, there is a possibility that the pipe will be damaged.

In the injection process, an injection material that reduces the fluidity of the base material 15 is injected into the base material 15 introduced around the deformed part 12 to which the thrust force W is applied, and the reinforcing part 14 is injected into the base material 15. Form. Since the reinforcement portion 14 suppresses the movement of soil particles during an earthquake, even if the foundation material 15 liquefies due to an earthquake, the thrust force W is propagated to the ground by the reinforcement portion 14. As a result, the earth pressure of the ground becomes a reaction force, and the movement of the deformed portion 12 due to the thrust force W is suppressed. In this manner, the strength of the base material 15 can be made less likely to decrease through the injection process.

In the injection step, an injection material is injected into the base material 15 around the deformed portion 12 . That is, the injection material is injected between the deformed portion 12 within the groove 13 and the ground outside the groove 13. Thereby, a reinforcing portion 14 is formed between the deformed portion 12 and the ground. The reinforcing portion 14 is preferably in contact with the deformed portion 12 and the ground, but may be separate from the deformed portion 12 or the ground.

As a method of injecting the injection material in the injection process, for example, an opening is formed in a part of the ground G at a position corresponding to the position above where the base material 15 is introduced, and an injection pipe is inserted into the opening. Examples include, but are not limited to, a method of injecting an injection material. When the diameter of the buried pipe 10 is large, a person enters the buried pipe 10, forms an opening in the pipe from the inside, and inserts the injection pipe 16 into the opening, as shown in FIG. An injection material may be injected into the base material 15.

Further, in the injection step, the injection material may be injected into the base material 15 on the downstream side in the direction in which the thrust force W is applied. By injecting the injection material into the base material 15 on the downstream side in the direction in which the thrust force W is applied, movement of the deformed portion 12 due to the influence of the thrust force W can be effectively suppressed. In the example shown in FIGS. 1 and 2, since the deformable portion 12 is a bent portion, the thrust force W is applied in a direction from the inside to the outside of the arc of the deformed portion 12 (Y-axis direction in FIG. 2). Therefore, in the injection process, the reinforcing part 14 is formed by injecting the injection material into the base material 15 outside the arc of the deformed part 12. Also in the example shown in FIG. 5, which will be described later, the reinforcing portion 54 is formed by injecting the injection material into the base material 55 on the downstream side in the direction in which the thrust force W is applied.

In addition, as shown in FIGS. 1 and 2, when the buried pipe 10 is provided so as to extend in a substantially horizontal direction, the direction in which the thrust force W is applied is the substantially horizontal direction. On the other hand, as shown in FIG. 3, when the buried pipe includes a portion extending approximately vertically, the direction in which the thrust force W is applied is the diagonally upward or diagonally downward direction depending on the bending angle of the deformed portion 12. becomes. FIG. 3 is a sectional view illustrating a liquefaction countermeasure construction method according to an embodiment of the present invention.

The injection material reduces the fluidity of the base material used to backfill buried pipes. Examples of the injection material may include one or more selected from the group consisting of silica solution, clay, cement, slag, bubbles, and gas as an active ingredient. The injection material may be, for example, a fluid liquid that solidifies and becomes gel-like over time, thereby reducing the fluidity of the base material. Such an injection material may further contain a gelling accelerator, thereby making it possible to adjust the gelling time of the injection material. As the injection material, for example, a known grout material can be used.

The material of the grout material used as the injection material is not particularly limited, and it is preferable to select and employ it in accordance with the properties of the ground around the buried pipe 10. For example, grouting materials used as injection materials include one-component types and two-component types. One-component grouting materials include cement milk, and two-component grouting materials include water glass solution grouting materials, suspension grouting materials, and the like.

For example, if the buried pipe 10 is surrounded by soil with a low hydraulic conductivity (poor permeability), a water glass solution type grout material is preferably used. Water glass-based solution type grout materials are classified into the "Durable Grout Injection Method Construction Guidelines" (Publisher: Japan Grout Association, Published: March 2012, hereinafter the same). There are alkaline grout materials and neutral/acid grout materials that belong to inorganic grout materials, special neutral/acid grout materials, special silica (silica colloid) grout materials, and alkaline grout materials that belong to organic grout materials. It is possible to use In particular, special neutral/acid grout materials and special silica (silica colloid) grout materials can be preferably used as grout materials that can maintain durability for a long period of time.

Furthermore, when the soil around the buried pipe 10 has a high hydraulic conductivity (good permeability), a suspension type grout material is preferably used. Suspension type grout materials include ultrafine particle grout materials and special slag grout materials that belong to non-water glass grout materials, and alkaline grout materials and neutral/acid grout materials that belong to water glass grout materials. In particular, when considering permeability to soil with a low hydraulic permeability coefficient, even a special slag type that belongs to a suspension type non-aqueous glass type can be used.

The liquefaction countermeasure construction method can be performed on an existing pipe in which the buried pipe 10 is already buried under the ground G while the pipe is still buried. This eliminates the need to dig out existing pipes or replace existing pipes with new ones to prevent liquefaction. Incidentally, when burying the buried pipe 10, an injection material may be injected into the base material 15. That is, the liquefaction countermeasure construction method may be performed when newly installing a buried pipe, or may be performed on an existing pipe.

In the injection process, the range in which the injection material is injected into the foundation material 15 is not particularly limited, and may vary depending on the diameter of the buried pipe 10, the internal pressure, the distance between the buried pipe 10 and the ground, the porosity of the foundation material 15 (soil particles, air and an index indicating the proportion of particles other than soil particles in the ground consisting of water).

In addition, the amount of injection material to be injected in the injection process is not particularly limited, but the porosity of the base material 15 in the injection range is estimated through soil surveys, etc., and the amount necessary to replace the air and water part with the injection material is determined. You can choose the amount.

The range and injection amount of the injection material in the injection process can be calculated as follows, for example. That is, since the range in which the injection material is injected is the gap between the deformed part 12 and the ground outside the groove 13, if the volume of the gap is V and the porosity of the foundation material 15 in the gap is n. , the injection amount L of the injection material is L=V×n. Therefore, for example, the length (l) of the gap is 7.04 m, the height (h) is 1.3 m, and the distance (d) between the deformed part 12 and the ground outside the groove 13 is 0.5 m. In this case, V=7.04×1.3×0.5=about 4.6 m ³ . If the porosity n of the base material 15 in the gap is 40%, the injection amount of the injection material will be L=4.6 m ³ ×0.4=1.8 m ³ .

In this way, according to the liquefaction countermeasure construction method, even if the foundation material 15 used for backfilling the buried pipe 10 liquefies due to the influence of an earthquake, the thrust force W can be propagated to the ground by the reinforcement part 14. . Thereby, the earth pressure of the ground becomes a reaction force, and movement of the deformed portion 12 due to the thrust force W is suppressed. According to the liquefaction countermeasure construction method, it is possible to prevent the strength of the base material 15 around the deformed portion 12 from decreasing.

The buried pipe 10 to which the liquefaction countermeasure construction method is applied has a straight pipe portion 11 and a deformed portion 12, so that when water flows inside, a thrust force is applied to the deformed portion 12. The thrust force applied to the deformable portion 12 will be explained with reference to FIGS. 4 to 6. 4 to 6 are schematic diagrams illustrating examples of thrust forces generated in buried pipes.

As shown in FIG. 4, the buried pipe 10 having a straight pipe part 11 and a bent deformed part 12 has an internal pressure P
is applied, and a thrust force W is applied to the deformed portion 12. The thrust force W is generated at a point where the flow of water changes, and is proportional to the internal pressure and cross-sectional area (square of the diameter) of the pipe. Further, since the deformed portion 12 is bent, the applied thrust force is influenced by the angle indicated by Θ in FIG .
Θ indicates the bending angle of the deformed portion 12.

Therefore, when the internal pressure is P and the cross-sectional area of the deformed portion 12 is A, the thrust force W can be calculated using the following formula (1):
W=2PAsin(Θ/2)...(1)

The earth pressure of the ground, which acts as a reaction force to the thrust force W applied to the deformed part 12, is determined by the unit volume weight of the soil in the ground, the outer width of the arc of the deformed part 12 (the length between both ends of the deformed part 12), It is proportional to the depth at which the deformed portion 12 is buried.

In this way, even if liquefaction occurs in the foundation material 15, the propagation of thrust force to the ground in the buried pipe 10 is not inhibited by the reinforcing part 14 formed between the deformed part 12 and the ground. As a result, the earth pressure in the ground, which acts as a reaction force to the thrust force, does not decrease, and the movement of the deformed portion 12 is suppressed. In this way, detachment of the deformed portion 12 can be prevented.

The thrust force is applied not only to the buried pipe 10 having the bent deformed portion 12 shown in FIG. 4 but also to buried pipes having shapes as shown in FIGS. 5 and 6. That is, the structure of the deformed portion of the buried pipe includes, in addition to the bent structure shown in FIG. 4, the branched structure shown in FIG. 5, the single-sided pipe structure shown in FIG. 6, and the like.

The buried pipe 50 shown in FIG. 5 includes a straight pipe part 51 and a deformed part 52 branched from the straight pipe part 51, and is laid in a groove 53. In the buried pipe 50, an internal pressure P is applied substantially perpendicularly to the pipe wall, as shown by the arrow. While the opposing components of the internal pressure P are canceled out, the component applied to the tube wall at the portion where the straight pipe section 51 and the deformed section 52 diverge is not canceled out, and a thrust force W is generated. In this way, the thrust force W is applied to the deformed portion 52 where the flow of water changes from the straight pipe portion 51 side to the side opposite thereto.

Therefore, for the buried pipe 50 as well, by injecting the injection material into the foundation material 15 introduced around the deformed part 52, a reinforcing part 54 is formed between the deformed part 52 and the ground. Thereby, even if liquefaction occurs in the foundation material 55, the propagation of the thrust force to the ground will not be inhibited. As a result, the earth pressure of the ground, which acts as a reaction force to the thrust force, does not decrease, and the movement of the deformed portion 52 is suppressed. In this way, detachment of the deformed portion 52 can be prevented.

Furthermore, the buried pipe 60 shown in FIG. 6 includes a straight pipe part 61a and a straight pipe part 61b. The straight pipe portion 61a and the straight pipe portion 61b have different diameters and are connected by a deformed portion 62. The buried pipe 60 is a drop pipe whose diameter changes. The buried pipe 60 is laid on a foundation material 65b laid in a trench formed by excavating the ground to an excavation line 63b. The top of the buried pipe 60 is filled with the foundation material 65a up to the foundation material backfill line 63a, and the area from the foundation material 65a to the ground G is filled with the backfill material.

In the buried pipe 60, an internal pressure P is applied to the deformed portion 62 substantially perpendicularly to the pipe wall, as shown by the arrow. Although the opposing vertical components of the internal pressure P are canceled out, a thrust force W is generated by other components. In this way, a thrust force W is applied to the deformed portion 62 where the flow of water changes in the direction of the straight pipe portion 61a having a small diameter.

In the injection step, an injection material is injected around the deformed portion 62 to form a reinforcing portion 64a and a reinforcing portion 64b. That is, an injection material is injected between the base material backfill line 63a around the deformed part 62 and the buried pipe 60 to form the reinforcing part 64a. Further, a reinforcing portion 64b is formed by injecting an injection material between the excavation line 63b around the deformed portion 62 and the buried pipe 60.

As a result, even if the foundation material 65a or the foundation material 65b liquefies, the thrust force W is propagated to the ground above and below the buried pipe 60 by the reinforcing portion 64a or 64b, and the propagation of the thrust force W to the ground is inhibited. Not done. As a result, the earth pressure of the ground, which acts as a reaction force to the thrust force W, does not decrease, and the movement of the deformed portion 62 is suppressed. In this way, detachment of the deformed portion 62 can be prevented.

Here, as shown in FIG. 7, a liquefaction countermeasure structure 70 in which the deformed portion 12 of the buried pipe 10 is surrounded by a thrust block 71 is also included in the scope of the present invention. That is, the periphery of the deformed portion 12 is covered with a thrust block (protective material) 71, and the injection material may be injected into the base material 15 introduced around the thrust block 71 in the injection process. FIG. 7 is a top view illustrating another example of the liquefaction countermeasure construction method according to an embodiment of the present invention.

The liquefaction countermeasure structure 70 includes the buried pipe 10 and the thrust block 71 as well as a reinforcing portion 14 . In the injection process, the reinforcing portion 14 is formed by injecting the injection material into the base material 15 around the thrust block 71, that is, between the thrust block 71 and the ground. That is, the injection material is injected around the deformed portion 12 via the thrust block 71 . Here, the thrust block 71 is a known protective material provided in a buried pipe as a measure against liquefaction, and may be, for example, a concrete block. The size of the thrust block 71 can be designed depending on the internal pressure, diameter, bending angle, etc. of the buried pipe 10.

When the foundation material liquefies due to an earthquake, the thrust force applied to the deformed portion may displace the deformed portion along with the thrust block. In the configuration of FIG. 7, the reinforcing part 14 is formed around the thrust block 71 around the deformed part 12, so even if the foundation material 15 liquefies, the thrust force W is propagated to the ground by the reinforcing part 74. The propagation of the thrust force W to the ground is not inhibited. As a result, the earth pressure of the ground, which acts as a reaction force to the thrust force, does not decrease, and the movement of the deformable portion 12 and the thrust block 71 is suppressed. In this way, detachment of the deformed portion 12 can be prevented.

[Liquefaction prevention structure]
A liquefaction countermeasure structure according to an embodiment of the present invention includes a buried pipe having a straight pipe portion and a deformed portion to which a thrust force is applied due to a flow of water flowing inside the straight pipe portion being different from that of the straight pipe portion. and a reinforcing part that is provided in a foundation material introduced around the deformed part laid in a trench formed by excavating the ground, and whose fluidity is lower than that of the foundation material.
That is, the liquefaction countermeasure structure 100 constructed by the liquefaction countermeasure construction method according to the embodiment of the present invention described above is one aspect of the liquefaction countermeasure structure according to the present invention. Therefore, the details of the liquefaction countermeasure structure according to the present invention conform to the explanation of the liquefaction countermeasure construction method according to the embodiment of the present invention described above.

The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. are also included within the technical scope of the present invention.

10 Buried pipe 11 Straight pipe section 12 Deformed section 13 Groove 14 Reinforcement section 15 Foundation material 100 Liquefaction countermeasure structure

Claims (6)

A liquefaction countermeasure construction method for buried pipes,
The buried pipe has a straight pipe part and a deformed part to which a thrust force is applied due to a flow of water flowing inside the pipe being different from that of the straight pipe part,
Liquefaction, which includes an injection step of injecting an injection material that reduces the fluidity of the foundation material into the foundation material introduced around the deformed part laid in a trench formed by excavating the ground. Countermeasure construction method. The liquefaction countermeasure construction method according to claim 1, wherein in the injection step, the injection material is injected into the foundation material on the downstream side in the direction in which the thrust force is applied. The periphery of the deformed part is covered with a protective material,
The liquefaction countermeasure construction method according to claim 1 or 2, wherein in the injection step, the injection material is injected into the base material introduced around the protective material. Any one of claims 1 to 3, further comprising a buried pipe burying step of laying the buried pipe in the groove and introducing the base material around the buried pipe before the injection step. Liquefaction countermeasure construction method described in. The liquefaction countermeasure construction method according to any one of claims 1 to 4, wherein the injection material includes one or more selected from the group consisting of silica solution, clay, cement, slag, bubbles, and gas. . A buried pipe having a straight pipe portion and a deformed portion to which a thrust force is applied due to the flow of water flowing inside the pipe being different from that of the straight pipe portion;
A liquefaction countermeasure, comprising: a reinforcing section that is installed in a foundation material introduced around the deformed section laid in a trench formed by excavating the ground, and whose fluidity is lower than that of the foundation material. structure.

Images