JP2021181706A - Liquefaction countermeasure construction method and liquefaction countermeasure structure - Google Patents

Abstract

To provide an underground pipe protected against liquefaction.SOLUTION: A liquefaction countermeasure method for an underground pipe 10 having a straight pipe part 11 and a deformation part 12 to which a thrust force generated due to the difference of a flow of water flowing therein from that of the straight pipe part 11 is applied includes the injection step of injecting an injection material which causes reduction of flowability into a foundation material 15 introduced around the deformation part 12 laid in a groove formed by drilling the foundation.SELECTED DRAWING: Figure 1

Description

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

Patent Documents 1 to 1 as a technique for preventing the buried pipe buried in the ground from moving due to the liquefaction of the ground material around the buried pipe due to the earthquake and the disconnection of the connection portion of the buried pipe caused by the movement. The technique described in 5 is known. Patent Documents 1 and 2 describe that in order to prevent the connection portion of the buried pipe from coming off, a buried pipe whose part that is easily detached is reinforced in advance is used. Patent Documents 3 to 5 describe techniques for injecting a reinforcing material around the buried pipe in order to prevent the buried pipe from rising or sinking due to liquefaction of the ground.

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

In a pipe through which water flows, such as an agricultural pipeline, a thrust force generated by the change in water flow acts on a part where the water flow changes, such as a bent part. When the pipe is stretched and buried in a substantially horizontal direction, the thrust force is generated in the substantially horizontal direction, which is different from the force for ascending or sinking the pipe. In a buried pipe buried in the ground, earth pressure and frictional force between the soil and the pipe become reaction forces, so that the deformed part of the buried pipe does not move even if a thrust force acts.

However, when the circumference of the buried pipe is liquefied due to an earthquake, the earth pressure and the frictional force between the soil and the pipe are reduced, and it becomes impossible to resist the thrust force, and the deformed portion becomes easy to move. If the deformed part moves, it will lead to disconnection of the connection part of the buried pipe and damage to the pipe. Detachment of the connection part of the buried pipe or damage to the pipe in the ground not only hinders the supply of agricultural water, but may also lead to secondary damage such as ground runoff and traffic obstruction due to water leakage. Therefore, there is a demand for a technique for preventing the movement of the buried pipe and the disconnection of the connection portion due to the decrease in earth pressure.

Since the techniques described in Patent Documents 1 and 2 are techniques for burying a pipe after reinforcing a deformed portion that is easily detached, they cannot be applied to an existing pipe already buried in the ground. Further, the techniques described in Patent Documents 3 to 5 are techniques for preventing the floating or subsidence of the buried pipe due to the liquefaction of the ground, and cannot prevent the influence of the thrust force acting in a substantially horizontal direction. ..

One aspect of the present invention is to prevent the buried pipe from moving due to the influence of the thrust force by taking measures against liquefaction in the buried pipe, and to prevent the connection portion of the buried pipe from coming off.

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

According to one aspect of the present invention, by taking measures against liquefaction in the buried pipe, it is possible to prevent the buried pipe from moving due to the influence of the thrust force and prevent the connection portion of the buried pipe from coming off.

It is a top view which shows the buried pipe which applied the liquefaction measures construction method which concerns on one Embodiment of this invention. It is sectional drawing explaining the buried pipe buried in the soil. It is sectional drawing explaining the liquefaction measures construction method which concerns on one Embodiment of this invention. It is a schematic diagram explaining another example of the thrust force generated in the buried pipe. It is a schematic diagram explaining another example of the thrust force generated in the buried pipe. It is a schematic diagram explaining another example of the thrust force generated in the buried pipe. It is a top view explaining another example of the liquefaction measures construction method which concerns on one Embodiment of this invention.

[Liquefaction countermeasure method]
Hereinafter, an 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. In the coordinate axes shown in each figure, the Z axis is extended in the vertical direction, and the X axis and the Y axis are extended in the horizontal direction. Therefore, FIG. 1 is a top view of the buried pipe 10 as viewed from the ground side when the buried pipe 10 is buried in the soil.
As shown in FIG. 1, the buried pipe 10 to be liquefied by the liquefaction countermeasure method has a straight pipe portion 11 and a deformed portion 12 in which the flow of water flowing inside is different from that of the straight pipe portion 11. The straight pipe portion 11 and the deformed portion 12 are connected so that water can flow inside. A thrust force W generated by the flow of water flowing inside the deformed portion 12 being different from that of the straight pipe portion 11 is applied to the deformed portion 12. The buried pipe 10 is buried in a groove 13 formed by excavating the ground. The groove 13 in which the buried pipe 10 is embedded is filled with the base material 15.
In the example shown in FIG. 1, the deformed portion 12 is a bent portion bent with respect to the straight pipe portion 11. A reinforcing portion 14 is located outside the arc of the deformed portion 12, and a liquefaction countermeasure structure 100 is constructed by the buried pipe 10 and the reinforcing portion 14. In the liquefaction countermeasure construction method, the liquefaction countermeasure is applied to the buried pipe 10 by forming the 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 reach several tens of kilometers.

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

The injection process will be described with reference to FIG. FIG. 2 is a cross-sectional view taken along the line AA'of FIG. 1, and is a diagram illustrating a liquefaction countermeasure 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 foundation material 15 is laid on the bottom of the groove 13, and the buried pipe 10 is laid on the foundation material 15. Then, the base material 15 is introduced and compacted until the top of the buried pipe 10 is filled. As a result, the periphery of the buried pipe 10 is covered with the foundation material 15 in the groove 13. Then, the buried pipe 10 is buried by introducing the backfilling material 17 onto the foundation material 15 and compacting it. The foundation material 15 is a material mainly containing sand, gravel, crushed stone and the like. The backfill material 17 is usually excavated ground material, but may be ground material brought from the outside. As described above, the liquefaction countermeasure method may further include the burying step of the buried pipe 10 in which the buried pipe 10 is laid in the groove 13 and the foundation material 15 is introduced around the buried pipe 10.

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

Here, at the time of an earthquake, the ground outside the groove 13 formed by excavation may not be liquefied, and only the portion 15 of the foundation material backfilled in the groove 13 may be liquefied. As described above, when the foundation material 15 is liquefied by the 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 become the reaction force of the thrust force W. As a result, the deformed portion 12 is displaced within the range in which 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 the occurrence of water leakage. Further, in the case of a pipe material such as a rigid vinyl chloride pipe in which the straight pipe portion 11 and the deformed portion 12 are joined by an adhesive, the pipe may be damaged.

In the injection step, the injection material that reduces the fluidity of the foundation material 15 is injected into the foundation material 15 introduced around the deformed portion 12 to which the thrust force W is applied, and the reinforcing portion 14 is placed in the foundation material 15. Form. Since the movement of soil particles is suppressed in the reinforcing portion 14, even if the foundation material 15 is liquefied due to the earthquake, the thrust force W is propagated to the ground by the reinforcing 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 way, the injection step makes it difficult for the base material 15 to lose its strength.

In the injection step, the injection material is injected into the foundation material 15 around the deformed portion 12. That is, the injection material is injected between the deformed portion 12 in the groove 13 and the ground outside the groove 13. As a result, the 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 separated from the deformed portion 12 or the ground.

As a method of injecting the injection material in the injection step, for example, an opening is formed in a part of the ground G at a position corresponding to above the position where the foundation material 15 is introduced, and an opening is formed through an injection pipe 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 to form an opening in the pipe from the inside as shown in FIG. 2, and the injection pipe 16 inserted into the opening is used to form an opening. The injection material may be injected into the base material 15.

Further, in the injection step, the injection material may be injected into the foundation material 15 on the downstream side in the direction in which the thrust force W is applied. By injecting the injection material into the foundation material 15 on the downstream side in the direction in which the thrust force W is applied, the movement of the deformed portion 12 due to the influence of the thrust force W can be effectively suppressed. In the examples shown in FIGS. 1 and 2, since the deformed portion 12 is a bent portion, the thrust force W is applied in the 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 step, the reinforcing portion 14 is formed by injecting the injection material into the foundation material 15 outside the arc of the deformed portion 12. Further, also in the example shown in FIG. 5 described later, the injection material is injected into the foundation material 55 on the downstream side in the direction in which the thrust force W is applied to form the reinforcing portion 54.

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 in a substantially vertical direction, the direction in which the thrust force W is applied is an obliquely upward or diagonally downward direction depending on the bending angle of the deformed portion 12. Will be. FIG. 3 is a cross-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 for backfilling the buried pipe. As an example of the injection material, one or more selected from the group consisting of silica solution, clay, cement, slag, air bubbles, and gas may be contained as an active ingredient. The injection material is, for example, a fluid liquid, and may be a material that solidifies with the passage of time into a gel to reduce the fluidity of the base material. Such an injectable material may further contain a gelation accelerator, whereby the gelation time of the injectable material can be adjusted. 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 adopt it according to the properties of the ground around the buried pipe 10. For example, the grout material used as an injection material includes a one-component type and a two-component type. The one-component grout material includes cement milk, and the two-component grout material includes a water glass-based solution type grout material, a suspension type grout material, and the like.

For example, when the soil around the buried pipe 10 has a small permeability coefficient (poor permeability), a water glass-based solution type grout material is preferably used. As a water glass solution type grout material, a water glass solution classified in "Durable grout injection method construction guideline" (publisher; Japan Grout Association, published; March 2012, the same applies hereinafter). There are alkaline grout materials, neutral / acidic grout materials, special neutral / acidic grout materials, special silica (silica colloid) grout materials, and alkaline grout materials belonging to organic grout materials, all of which belong to the type of inorganic grout material. It can be used. In particular, in the case of a special neutral / acidic grout material or a special silica (silica colloid) grout material, it can be preferably used as a grout material capable of maintaining durability for a long period of time.

Further, when the permeability coefficient of the soil around the buried pipe 10 is large (good permeability), a suspension type grout material is preferably used. Examples of the suspension type grout material include ultrafine grout materials and special slag grout materials belonging to non-water glass grout materials, alkaline grout materials belonging to water glass grout materials, and neutral / acidic grout materials. In particular, when considering the permeability to soil having a small permeability coefficient, even a special slag system belonging to a suspension type non-water glass system can be used.

The liquefaction countermeasure construction method can be executed in an existing pipe in which the buried pipe 10 is already buried under the ground G in a buried state. As a result, it is not necessary to dig up the existing pipe or replace the existing pipe with a new one as a measure against liquefaction. When burying the buried pipe 10, the injection material may be injected into the foundation material 15. That is, the liquefaction countermeasure method may be executed when a buried pipe is newly installed, or may be executed for an existing pipe.

The range in which the injection material is injected into the foundation material 15 in the injection step is not particularly limited, and the diameter of the buried pipe 10, the internal pressure, the distance between the buried pipe 10 and the ground, and the porosity of the foundation material 15 (soil particles, air). And an index showing the ratio of non-soil particles in the ground consisting of water), etc., may be appropriately selected.

The injection amount of the injection material to be injected in the injection step is not particularly limited, but it is necessary to replace the air and water parts with the injection material by assuming the porosity of the foundation material 15 in the injection range by soil survey or the like. You may choose the amount.

The range and amount of the injection material to be injected in the injection step 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 portion 12 and the ground outside the groove 13, 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 portion 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 foundation material 15 in the gap is 40%, the injection amount of the injection material is L = 4.6m ³ × 0.4 = 1.8m ³ .

As described above, according to the liquefaction countermeasure construction method, even when the foundation material 15 used for backfilling the buried pipe 10 is liquefied due to the influence of the earthquake, the thrust force W can be propagated to the ground by the reinforcing 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. According to the liquefaction countermeasure method, it is possible to prevent the strength of the foundation material 15 around the deformed portion 12 from decreasing.

The buried pipe 10 to which the liquefaction countermeasure method is applied has a straight pipe portion 11 and a deformed portion 12, so that a thrust force is applied to the deformed portion 12 when water is flowed inside. The thrust force applied to the deformed portion 12 will be described with reference to FIGS. 4 to 6. 4 to 6 are schematic views illustrating an example of a thrust force generated in a buried pipe.

As shown in FIG. 4, an internal pressure P is applied to the buried pipe 10 having a straight pipe portion 11 and a bent deformed portion 12, and a thrust force W is applied to the deformed portion 12. The thrust force W is generated at a place where the flow of water changes, and is proportional to the internal pressure of the pipe and the cross-sectional area (square of the diameter). Further, since the deformed portion 12 is bent, the applied thrust force is affected 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 by the following equation (1):
W = 2PAsin (Θ / 2) ... (1)

The earth pressure, which is the reaction force of the thrust force W applied to the deformed portion 12, is the unit volume weight of the ground soil, the outer width of the arc of the deformed portion 12 (the length between both ends of the deformed portion 12), and the earth pressure. It is proportional to the depth at which the deformed portion 12 is embedded.

As described above, even if the foundation material 15 is liquefied, in the buried pipe 10, the propagation of the thrust force to the ground is not hindered by the reinforcing portion 14 formed between the deformed portion 12 and the ground. As a result, the earth pressure of the ground, which is the reaction force of the thrust force, does not decrease, and the movement of the deformed portion 12 is suppressed. In this way, it is possible to prevent the deformed portion 12 from coming off.

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 the buried pipe having the shape shown in FIGS. 5 and 6. That is, the structure of the deformed portion included in the buried pipe includes a branch structure shown in FIG. 5, a single drop pipe structure shown in FIG. 6, and the like, in addition to the bent structure as shown in FIG.

The buried pipe 50 shown in FIG. 5 includes a straight pipe portion 51 and a deformed portion 52 branched from the straight pipe portion 51, and is laid in the groove 53. In the buried pipe 50, the internal pressure P is applied substantially vertically to the pipe wall as shown by the arrow. Then, while the opposing components of the internal pressure P are offset, the components added to the pipe wall of the portion where the straight pipe portion 51 and the deformed portion 52 branch are not canceled, and a thrust force W is generated. In this way, the thrust force W is applied to the deformed portion 52 in which the flow of water changes from the straight pipe portion 51 side to the side facing the straight pipe portion 51.

Therefore, also for the buried pipe 50, the reinforcing portion 54 is formed between the deformed portion 52 and the ground by injecting the injection material into the foundation material 15 introduced around the deformed portion 52. As a result, even if liquefaction occurs in the foundation material 55, the propagation of the thrust force to the ground is not hindered. As a result, the earth pressure of the ground, which is the reaction force of the thrust force, does not decrease, and the movement of the deformed portion 52 is suppressed. In this way, it is possible to prevent the deformed portion 52 from coming off.

Further, the buried pipe 60 shown in FIG. 6 includes a straight pipe portion 61a and a straight pipe portion 61b. The straight pipe portion 61a and the straight pipe portion 61b have different diameters and are connected by the deformed portion 62. The buried pipe 60 is a one-sided pipe whose diameter changes. The buried pipe 60 is laid on the foundation material 65b laid in the groove formed by excavating the ground to the excavation line 63b. The buried pipe 60 is filled with the foundation material 65a up to the foundation material backfilling line 63a, and is filled with the backfilling material from the foundation material 65a to the ground G.

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

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

As a result, even if the foundation material 65a or the foundation material 65b is liquefied, the thrust force W is propagated to the ground above and below the buried pipe 60 by the reinforcing portion 64a or the reinforcing portion 64b, and the propagation of the thrust force W to the ground is hindered. Not done. As a result, the earth pressure of the ground, which is the reaction force of the thrust force W, does not decrease, and the movement of the deformed portion 62 is suppressed. In this way, it is possible to prevent the deformed portion 62 from coming off.

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

The liquefaction countermeasure structure 70 includes a reinforcing portion 14 together with the buried pipe 10 and the thrust block 71. In the injection step, the reinforcing portion 14 is formed by injecting the injection material around the thrust block 71, that is, into the foundation material 15 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 the 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 according to the internal pressure, diameter, bending angle, etc. of the buried pipe 10.

When the foundation material is liquefied due to an earthquake, the deformed portion may be displaced together with the thrust block due to the thrust force applied to the deformed portion. In the configuration of FIG. 7, since the reinforcing portion 14 is formed around the thrust block 71 around the deformed portion 12, even if the foundation material 15 is liquefied, the thrust force W is propagated to the ground by the reinforcing portion 74. The propagation of the thrust force W to the ground is not hindered. As a result, the earth pressure of the ground, which is the reaction force of the thrust force, does not decrease, and the movement of the deformed portion 12 and the thrust block 71 is suppressed. In this way, it is possible to prevent the deformed portion 12 from coming off.

[Liquefaction countermeasure structure]
The liquefaction countermeasure structure according to the embodiment of the present invention includes a straight pipe portion and a buried pipe having a deformed portion to which a thrust force generated by the flow of water flowing inside is different from that of the straight pipe portion. It is provided in a foundation material introduced around the deformed portion laid in a groove formed by excavating the ground, and has a reinforcing portion having a lower fluidity than the foundation material.
That is, the liquefaction countermeasure structure 100 constructed by the liquefaction countermeasure construction method according to the above-described embodiment of the present invention 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 are based on the above-mentioned description of the liquefaction countermeasure construction method according to the embodiment of the present invention.

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

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

Claims (6)

It is a liquefaction countermeasure construction method for buried pipes.
The buried pipe has a straight pipe portion and a deformed portion to which a thrust force generated by the flow of water flowing inside is different from that of the straight pipe portion.
Liquefaction, which comprises an injection step of injecting an injection material that reduces the fluidity of the foundation material into the foundation material introduced around the deformed portion laid in the groove formed by excavating the ground. Countermeasure construction method. The liquefaction countermeasure 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 circumference of the deformed part is covered with a protective material, and the circumference is covered with a protective material.
The liquefaction countermeasure method according to claim 1 or 2, wherein in the injection step, the injection material is injected into the foundation material introduced around the protective material. Any one of claims 1 to 3, further comprising an burying step of the buried pipe in which the buried pipe is laid in the groove and the foundation material is introduced around the buried pipe before the injection step. Liquefaction countermeasure construction method described in. The liquefaction countermeasure method according to any one of claims 1 to 4, wherein the injection material contains one or more selected from the group consisting of silica solution, clay, cement, slag, air bubbles, and gas. .. A buried pipe having a straight pipe portion and a deformed portion to which a thrust force generated by the flow of water flowing inside is different from that of the straight pipe portion.
Liquefaction countermeasures provided in the foundation material introduced around the deformed portion laid in the groove formed by excavating the ground and provided with a reinforcing portion having a lower fluidity than the foundation material. structure.

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