JP7406307B2 - Liquefaction countermeasure construction method using drainage pipes and drainage pipes - Google Patents

Description

The present invention relates to a drainage pipe and a liquefaction countermeasure construction method using the drainage pipe.

As a countermeasure against ground liquefaction, a method is known to penetrate permeable drainage pipes into the ground that is at risk of liquefaction and allow pressurized groundwater in the ground to flow into the drainage pipes to release excess pore water pressure. It is being Moreover, Patent Document 1 describes a pull-out strainer for a well, Patent Document 2 describes a method for constructing foundation piles, and Patent Document 3 describes a pile foundation for ground that is easily liquefied.

Japanese Patent Application Publication No. 11-256625 Japanese Patent Application Publication No. 10-37170 Publication No. 51-62203

When a drainage pipe penetrates into ground that is at risk of liquefaction, it may penetrate deep underground. Therefore, a long drainage pipe is required. In order to penetrate long drainage pipes into the ground, large construction machinery is required.

When a drainage pipe is penetrated deep underground, penetration resistance increases. For this reason, normal drainage pipes require thick steel pipes, which increases the manufacturing cost of the drainage pipe.

Furthermore, it is also necessary to consider the deformation of drainage pipes due to impact during penetration. For this reason, the parts of the drain pipe that are hit must have enough strength to withstand even strong hits.

This invention was made in view of the above circumstances, and its purpose is to provide a drainage pipe that is strong enough to withstand strong blows and that can be penetrated deeply into the ground with a small construction machine. .

A drainage pipe according to a first aspect of the present invention is a drainage pipe that includes a plurality of pipe bodies and is expandable and retractable by the plurality of pipe bodies, and includes a main pipe part having a tip part, and a tip engaging part provided at the tip part. a first pipe body having a stop part, a main pipe part having a rear end part, and a main pipe part provided at the rear end part, when pressed or hit by an extrusion jig, the rear end part of the other pipe body substantially a second pipe body having a rear end locking part that can be pressed or hit by an extrusion jig by being on the same plane, and the front end locking part is connected to the main pipe part of the first pipe body. is a separate body, the inner diameter of which is smaller than the inner diameter of the main tube portion of the first tube body, and the outer diameter of the main tube portion of the second tube body is less than or equal to the inner diameter of the tip locking portion. The rear end locking part is inserted into the front end locking part, is separate from the main pipe part of the second pipe body, and has an outer diameter smaller than or equal to an inner diameter of the main pipe part of the first pipe body, and the inner diameter of the tip locking portion is larger than that of the second tube, and the outer diameter is larger than the inner diameter of the second tube. The rear end locking part is characterized by having a depression or a protrusion provided on the side surface of the rear end locking part, which is larger than the outer diameter of the main pipe part .

In the drainage pipe according to a second aspect of the invention, in the first aspect, the length of the rear end locking portion along the tube axis direction of the second pipe body is the length of the rear end locking portion of the tube axis. The thickness is longer than the thickness along the direction perpendicular to the direction.

In the drainage pipe according to a third aspect of the invention, in the first aspect, the depression suppresses rotation of the rear end locking part provided on a contact surface with the rear end locking part of the extrusion plate of the extrusion jig to extrude. or the protrusion is fitted with a recess that is provided on a contact surface of the extrusion plate with the rear end locking part and suppresses rotation of the rear end locking part. shall be.

A drainage pipe according to a fourth aspect of the present invention is characterized in that, in the first aspect, the depression or the protrusion fits into a protrusion or a depression provided on the inner circumferential surface of the first pipe body.

A liquefaction countermeasure construction method using a drainage pipe according to a fifth invention is a liquefaction countermeasure construction method using a drainage pipe according to any one of claims 1 to 4 , wherein The stop part is pushed out into the ground by applying pressure or impact with a pressing jig, and the second pipe body is made to reach below the groundwater level or soft ground, and the groundwater in the ground flows into the pipe of the second pipe body into the drainage pipe. It is characterized by releasing excess pore water pressure.

According to the first to fifth aspects of the invention, it is possible to provide a drainage pipe that is strong enough to withstand strong blows and that can be penetrated deeply into the ground using a small construction machine.

FIG. 1 is a schematic sectional view schematically showing a state in which a drainage pipe according to an embodiment of the present invention is driven into the ground. FIG. 2 is a diagram showing the appearance within circle II in FIG. 1. FIG. 3(a) is a schematic cross-sectional view showing an example of the first tube. FIG. 3(b) is a schematic cross-sectional view showing an example of the intermediate tube. FIG. 3(c) is a schematic cross-sectional view showing an example of the second tube. FIG. 4 is a schematic cross-sectional view showing an exploded view of the first tube. FIG. 5A is a schematic cross-sectional view showing an example of a state in which the intermediate tube and the second tube are accommodated in the first tube. FIG. 5(b) is a schematic cross-sectional view showing an example of a state in which the intermediate tube and the second tube protrude from the first tube. FIGS. 6A and 6B are schematic cross-sectional views schematically showing how a drainage pipe according to an embodiment is driven into the ground. FIGS. 7A and 7B are schematic cross-sectional views schematically showing how a drainage pipe according to an embodiment is driven into the ground. FIGS. 8A and 8B are schematic cross-sectional views schematically showing how a drainage pipe according to an embodiment is driven into the ground. FIG. 9 is a schematic sectional view schematically showing a state in which the drainage pipe according to the first modification is driven into the ground. FIGS. 10(a) to 10(c) are schematic plan views schematically showing a rear end locking portion of a drainage pipe according to a second modification. FIGS. 11(a) to 11(c) are schematic cross-sectional views schematically showing a rear end locking portion of a drainage pipe according to a third modification. FIG. 12 is a schematic sectional view schematically showing an example of a state in which a drainage pipe is driven into the ground. FIG. 13 is a schematic cross-sectional view schematically showing an example of a state in which a drainage pipe is driven into the ground. FIG. 14 is a schematic sectional view schematically showing an example of a state in which a drainage pipe is driven into the ground.

An example of a drainage pipe according to an embodiment of the present invention will be described below with reference to the drawings.

(One embodiment)
<Drain pipe>
FIG. 1 is a schematic sectional view schematically showing a state in which a drainage pipe according to an embodiment of the present invention is driven into the ground. FIG. 2 is a diagram showing the appearance within circle II in FIG. 1.

As shown in FIGS. 1 and 2, the drainage pipe 10 according to the first embodiment is a multistage drainage pipe that includes a plurality of pipe bodies and is expandable and contractible by the plurality of pipe bodies. The drain pipe 10 is, for example, a highly corrosion-resistant plated steel pipe with a plate thickness of about 2.3 mm, and includes three first pipe bodies 11 of different diameters, large, medium, and small, each having a length of about 2 m, and a second pipe body. 12 and an intermediate tube body 13. A convex lid 14 is attached to the tip of the second tube 12.

Each of the first tube body 11, the second tube body 12, and the intermediate tube body 13 is driven into the ground 100, for example, vertically from the ground surface 101 or vertically diagonally downward. The drainage pipe 10 collects groundwater in the ground 100 through the water collection hole H1, suppresses a rise in the groundwater level 102, and allows pressurized groundwater in the ground 100 to flow into the drainage pipe 10. Release excess pore water pressure. This will take measures against ground liquefaction. The drainage pipe 10 can be applied not only to artificial ground such as reclaimed land, but also to natural ground such as along river coasts and around old river channels, and to cut and fill constructed land such as hilly areas. It can also be applied to slopes and can be used to suppress the rise in groundwater levels during rainfall.

In this embodiment, each peripheral wall of the first tube 11, the second tube 12, and the intermediate tube 13 is a perforated peripheral wall having, for example, a plurality of water collection holes H1. An example of the diameter of the water collection hole H1 is 5 mm. A large number of water collection holes H1 are formed in each of the peripheral wall of the first tube 11, the second tube 12, and the intermediate tube 13 at a pitch of 10 mm, for example. An example of the appearance of the water collection hole H1 is shown in FIG. 2. An example of the open area ratio of each of the peripheral wall of the first tube 11, the second tube 12, and the intermediate tube 13 is 5% or more and 15% or less.

Note that the water collection hole H1 allows groundwater or excess pore water to permeate therethrough, and the water collection hole H1 may reach, for example, the groundwater level 102 or soft ground within the ground 100. Therefore, the water collection hole H1 only needs to be provided at least in the second pipe body 12.

Further, the drain pipe 10 only needs to have at least two stages, the first pipe body 11 and the second pipe body 12, and the intermediate pipe body 13 can be omitted. Furthermore, it is also possible to provide two or more stages of intermediate pipe bodies 13 to form a multistage drainage pipe with four or more stages.

FIG. 3(a) is a schematic cross-sectional view showing an example of the first tube. FIG. 3(b) is a schematic cross-sectional view showing an example of the intermediate tube. FIG. 3(c) is a schematic cross-sectional view showing an example of the second tube. FIG. 4 is a schematic cross-sectional view showing an exploded view of the first tube. FIG. 5(a) is a schematic cross-sectional view showing an example of a state in which the intermediate tube and the second tube are accommodated in the first tube. FIG. 5(b) is a schematic cross-sectional view showing an example of a state in which the intermediate tube and the second tube protrude from the first tube.

<First pipe body>
As shown in FIG. 3(a), the first tube body 11 includes a main tube portion 11c having a tip portion 11a and a rear end portion 11b, a first rear end locking portion 21, and a first tip locking portion 31. and has.

The first rear end locking portion 21 is provided at the rear end portion 11b of the main pipe portion 11c. As shown in FIG. 4, the first rear end locking part 21 is separate from the main pipe part 11c. The first rear end locking portion 21 is fixed to the rear end portion 11b of the main pipe portion 11c by, for example, welding. The first rear end locking portion 21 can be hit by, for example, a pressing jig to be described later.

The outer diameter φ21o of the first rear end locking portion 21 is larger than the outer diameter φ11o of the main pipe portion 11c (φ21o>φ11o). Further, the inner diameter φ21i of the first rear end locking portion 21 is greater than or equal to the inner diameter φ11i of the main pipe portion 11c (φ21o≧φ11o). In this example, the inner diameter φ21i of the first rear end locking portion 21 is, for example, approximately equal to the inner diameter φ11i of the main pipe portion 11c (φ21i≈φ11i).

The length L21 of the first rear end locking part 21 along the tube axis direction Z is longer than the thickness T21 of the first rear end locking part 21 along the direction perpendicular to the tube axis direction Z (L21> T21). As a result, the cross-sectional shape of the first rear end locking portion 21 along the tube axis direction Z becomes longer along the tube axis direction Z. Moreover, the thickness T21 of the first rear end locking part 21 is thicker than the wall thickness of the main pipe part 11c.

The first tip locking portion 31 is provided at the tip portion 11a of the main tube portion 11c. The first front end locking portion 31 is separate from the main tube portion 11c, similar to the first rear end locking portion 21 (FIG. 4). The first tip locking portion 31 is fixed to the tip portion 11a of the main tube portion 11c by, for example, welding. The inner diameter φ31i of the first tip locking portion 31 is smaller than the inner diameter φ11i of the main pipe portion 11c (φ31i<φ11i).

<Intermediate pipe body>
As shown in FIG. 3(b), the intermediate tube body 13 includes a main tube portion 13c having a tip portion 13a and a rear end portion 13b, a third rear end locking portion 23, and a second tip locking portion 32. , has.

The third rear end locking portion 23 is provided at the rear end portion 13b of the main pipe portion 13c. The third rear end locking part 23 is separate from the main pipe part 13c. The third rear end locking portion 23 is fixed to the rear end portion 13b of the main pipe portion 13c by, for example, welding. The third rear end locking portion 23 can be hit by, for example, a pressing jig to be described later.

The outer diameter φ23o of the third rear end locking portion 23 is larger than the outer diameter φ13o of the main pipe portion 13c (φ23o>φ13o). Further, the outer diameter 23o of the third rear end locking portion 23 is set to be smaller than or equal to the inner diameter φ11i of the main tube portion 11c of the first tube body 11 and larger than the inner diameter φ31i of the first tip locking portion 31 (φ23o≦ φ11i, and φ23o>φ31i). As a result, the third rear end locking portion 23 is inserted into the main tube portion 11c of the first tube body 11, and can be locked to the first tip locking portion 31 (see FIG. 5(a) and Figure 5(b)). Further, the outer diameter φ13o of the main pipe portion 13c is equal to or less than the inner diameter φ31i of the first tip locking portion 31 (φ13i≦φ31i). Thereby, the main tube portion 13c can be inserted into the first tip locking portion 31.

The inner diameter φ23i of the third rear end locking portion 23 is greater than or equal to the inner diameter φ13i of the main pipe portion 13c (φ23o≧φ13o). In this example, the inner diameter φ23i of the third rear end locking portion 23 is, for example, approximately equal to the inner diameter φ13i of the main pipe portion 13c (φ23i≈φ13i).

The length L23 of the third rear end locking portion 23 along the tube axis direction Z is longer than the thickness T23 of the third rear end locking portion 23 along the direction perpendicular to the tube axis direction Z (L23> T23). As a result, the cross-sectional shape of the first rear end locking portion 21 along the tube axis direction Z becomes longer along the tube axis direction Z. Further, the thickness T23 of the third rear end locking portion 23 is thicker than that of the main pipe portion 13c.

The second tip locking portion 32 is provided at the tip portion 13a of the main tube portion 13c. Like the third rear end locking portion 23, the second tip locking portion 32 is separate from the main tube portion 13c. The second tip locking portion 32 is fixed to the tip portion 13a of the main tube portion 13c by, for example, welding. The inner diameter φ32i of the second tip locking portion 32 is smaller than the inner diameter φ13i of the main pipe portion 13c (φ32i<φ13i).
Further, the outer diameter φ32o of the second tip locking portion 32 is equal to or less than the inner diameter φ31i of the first tip locking portion 31 (φ32o≦φ31i). Thereby, the second tip locking part 32 can be inserted into the first tip locking part 31.

<Second pipe body>
As shown in FIG. 3(c), the second tube body 12 includes a main tube portion 12c having a front end portion 12a and a rear end portion 12b, a second rear end locking portion 22, and a lid body 14. .

The second rear end locking portion 22 is provided at the rear end portion 12b of the main pipe portion 12c. The second rear end locking part 22 is separate from the main pipe part 12c. The second rear end locking portion 22 is fixed to the rear end portion 12b of the main pipe portion 12c by, for example, welding. The second rear end locking portion 22 can be hit by, for example, a pressing jig to be described later.

The outer diameter φ22o of the second rear end locking portion 22 is larger than the outer diameter φ12o of the main pipe portion 12c (φ22o>φ12o). Further, the outer diameter 22o of the second rear end locking portion 22 is set to be smaller than or equal to the inner diameter φ13i of the main pipe portion 13c of the intermediate tube body 13 and larger than the inner diameter φ32i of the second tip locking portion 32 (φ22o≦φ13i , and φ22o>φ32i). Thereby, the second rear end locking part 22 is inserted into the main pipe part 13c of the intermediate tube body 13, and can be locked to the second front end locking part 32 (FIG. 5(a) and FIG. 5(b)). Further, the outer diameter φ12o of the main pipe portion 12c is equal to or less than the inner diameter φ32i of the second tip locking portion 32 (φ12i≦φ32i). Thereby, the main pipe portion 12c can be inserted into the second tip locking portion 32.

The length L22 of the second rear end locking portion 22 along the tube axis direction Z is longer than the thickness T22 of the second rear end locking portion 22 along the direction perpendicular to the tube axis direction Z (L22> T22). As a result, the cross-sectional shape of the second rear end locking portion 22 along the tube axis direction Z becomes longer along the tube axis direction Z. Further, the thickness T22 of the second rear end locking portion 22 is thicker than the main pipe portion 12c.

A lid 14 is locked to the tip 12a of the main pipe portion 12c. The tip of the lid 14 is convex. This reduces earth pressure resistance during driving. The lid body 14 is made of, for example, resin such as polypropylene or metal such as ductile cast iron.

<Liquefaction countermeasure construction method>
Next, a liquefaction countermeasure construction method using the drainage pipe 10 according to one embodiment will be explained.

FIGS. 6(a) to 8(b) are schematic cross-sectional views schematically showing how the drainage pipe according to the first embodiment is driven into the ground.

<Preparation of extrusion jig>
When driving the drainage pipe 10 into the ground 100, an extrusion jig is used. An example of the extrusion jig 1 is shown in FIG. 5(a).

As shown in FIG. 6(a), the extrusion jig 1 includes a rod 2, a first locking nut 3, a second locking nut 4, and a first extrusion plate 5a. The rod 2 is made of, for example, a steel bar with threads formed on its outer peripheral surface. Each of the first locking nut 3 and the second locking nut 4 is threaded onto the thread of the rod 2 . The first locking nut 3 is attached to the tip of the rod 2. The first extrusion plate 5a is fixed on the rod 2 by being sandwiched between the first locking nut 3 and the second locking nut 4 before the drain pipe 10 is driven in.

When driving the drainage pipe 10, the rear end of the rod 2 is pushed by a hydraulic pile driver 7 or a breaker. Thereby, the drainage pipe 10 is driven into the ground 100 vertically from the ground surface 101 or vertically diagonally downward. At this time, for example, a rod cap 6 may be attached to the rear end of the rod 2, if necessary.

<Installing the extrusion jig>
As shown in FIG. 6(b), the extrusion jig 1 is inserted into the drain pipe 10. In the extrusion jig 1, a first locking nut 3, a first extrusion plate 5a, and a second locking nut 4 are attached to the rod 2 in this order from its tip. The diameter of the first extrusion plate 5a is, for example, larger than the inner diameter (φ21i) of the first rear end locking portion 21. Thereby, the first extrusion plate 5a comes into contact with the first rear end locking part 21, the second rear end locking part 22, and the third rear end locking part 23.

<Drive the first tube body 11>
As shown in FIG. 7(a), with the second tube 12 and the intermediate tube 13 accommodated in the first tube 11, the first tube 11 is placed against the ground 100. Drive it vertically from the surface 101 or diagonally downward. The driving depth D1 at this time is approximately from the tip of the lid 14 to the rear end of the first to third rear end locking parts 21 to 23.

<Extrusion of intermediate tube body 13>
Next, the first extrusion plate 5a is removed from the rod 2 from the extrusion jig 1, and the second extrusion plate 5b is newly attached to the rod 2. Next, the first addition rod 2a is added to the rod 2 by the first coupler 8a. The diameter of the second extrusion plate 5b is, for example, larger than the inner diameter (φ23i) of the third rear end locking portion 23 and smaller than the inner diameter (φ11i) of the main pipe portion 11c. Thereby, the second extrusion plate 5b comes into contact with the second rear end locking portion 22 and the third rear end locking portion 23 through the main pipe portion 11c. Then, as shown in FIG. 7(b), with the first tube 11 fixed in the ground 100 and the second tube 12 accommodated in the intermediate tube 13, the intermediate tube 13 is pushed out, and the intermediate tube 13 is pushed out. The tubular body 13 is driven deeper into the ground 100 than the first tubular body 11 vertically from the ground surface 101 or vertically diagonally downward. The driving depth D2 at this time is approximately from the tip of the lid 14 after driving the first tube 11 to the tip of the lid 14 when the intermediate tube 13 is pushed out.

<Extrusion of second tube 12>
Next, the second extrusion plate 5b is removed from the rod 2 from the extrusion jig 1, and the third extrusion plate 5c is newly attached to the rod 2. Next, the second addition rod 2b is added to the rod 2 by the second coupler 8b. The diameter of the third extrusion plate 5c is, for example, larger than the inner diameter (φ22i) of the second rear end locking portion 22 and smaller than the inner diameter (φ13i) of the main pipe portion 13c. Thereby, the third extrusion plate 5c comes into contact with the second rear end locking part 22 through the main pipe part 13c. Then, as shown in FIG. 8(a), the second tube 12 is pushed out with each of the first tube 11 and the intermediate tube 13 retained in the ground 100. It is driven deeper than the intermediate tube body 13 vertically from the ground surface 101 or vertically diagonally downward. The driving depth D3 at this time is approximately from the tip of the lid 14 after the intermediate tube 13 is extruded to the tip of the lid 14 when the second tube 12 is extruded.
Although not shown, the third extrusion plate 5 is not attached, and the first locking nut 3, which is larger than the inner diameter of the second rear end locking part 22, is attached to the rod 2, and the first locking nut 3 locks the second pipe. The body 12 may be pushed out.

<Removal of extrusion jig 1>
Next, as shown in FIG. 8(b), the extrusion jig 1 is pulled out from the drain pipe 10. In this way, the liquefaction countermeasure construction method using the drainage pipe 10 according to one embodiment is implemented.

According to such a drainage pipe 10, the first pipe body 11, the second pipe body 12, and the intermediate pipe body 13 have the first rear end locking part 21, the second rear end locking part 22, and the second pipe body 13, respectively. 3. It has three rear end locking parts 23.

The outer diameter φ21o of the first rear end locking portion 21 is made larger than the main pipe portion 11c of the first tube body 11, and similarly, the outer diameter φ22o of the second rear end locking portion 22 is made larger than the main tube portion 11c of the first tube body 11. It is larger than the main pipe part 12c, and the outer diameter φ23o of the third rear end locking part 23 is larger than the main pipe part 13c of the intermediate pipe body 13. Therefore, the strength of the first rear end locking part 21 can be made higher than the strength of the main pipe part 11c. Similarly, the strength of the second rear end locking part 22 can be made higher than the strength of the main pipe part 12c, and the strength of the third rear end locking part 23 can be made higher than the strength of the main pipe part 13c. Become.

Each of the first to third rear end locking portions 21 to 23 is a portion that is pressed or hit by the extrusion jig 1. That is, according to the drainage pipe 10, the strength of the part where pressure or impact is applied can be increased, and for example, when the drainage pipe 10 is penetrated deep underground, the penetration resistance given to the drainage pipe 10 is large. In this case, even if a strong blow is applied, the drain pipe 10 can have enough strength to withstand it.

In one embodiment, each of the first to third rear end locking parts 21 to 23 has a length along the tube axis direction Z that is longer than a thickness along the direction orthogonal to the tube axis direction Z. In this way, by making the cross-sectional shapes of the first to third rear end locking parts 21 to 23 longer along the tube axis direction Z, the first to third rear end locking parts 21 to 23 The strength of the locking parts 21 to 23 can be further increased.

Further, in one embodiment, the thicknesses T21 to T23 of the first to third rear end locking parts 21 to 23 are made thicker than the wall thicknesses of the main pipe parts 11c, 12c, and 13c. According to this, the contact surface between the press or impact area and the extrusion plates 5a to 5c of the extrusion jig 1 is compared with a drain pipe without the first to third rear end locking parts 21 to 23. , a large amount can be secured. Therefore, the force applied from the extrusion jig 1 can be more efficiently transmitted to each of the first pipe body 11, the second pipe body 12, and the intermediate pipe body of the drain pipe 10. If it becomes possible to transmit force efficiently, it is also possible to weaken the force applied from the extrusion jig 1 during penetration compared to a drain pipe that does not have the first to third rear end locking parts 21 to 23. becomes. This is advantageous in suppressing deformation of the drain pipe 10.

Further, the first tube body 11 and the intermediate tube body 13 each have a first tip locking portion 31 and a second tip locking portion 32. The third rear end locking portion 23 can be locked with the first tip locking portion 31, and the second rear end locking portion 22 can be locked with the second tip locking portion 32. For this reason, the drainage pipe 10 is a multi-stage drainage pipe that can be expanded and contracted by a plurality of pipe bodies, and for example, penetration resistance can be reduced, and a small construction machine can penetrate deeply into the ground 100.

As described above, according to one embodiment of the present invention, it is possible to provide a drainage pipe that has strength enough to withstand strong blows and can be penetrated deeply into the ground using a small construction machine.

(First modification)
Next, a modification of the drain pipe according to an embodiment of the present invention will be described.
FIG. 9 is a schematic sectional view schematically showing a state in which the drainage pipe according to the first modification is driven into the ground.

As shown in FIG. 9, the first modification of the drainage pipe 10 is an example in which the first pipe body 11 is not provided with the water collection hole H1. The drainage pipe 10 allows underground water or excess pore water to pass therethrough, and the water collection hole H1 may reach within the ground 100, for example, below the groundwater level 102 or to soft ground. The water collection hole H1 may be provided at least in the second pipe body 12.

(Second modification)
FIGS. 10(a) to 10(c) are schematic plan views schematically showing a rear end locking portion of a drainage pipe according to a second modification.

As shown in FIG. 10(a), at least one depression 41 may be provided on the side surface of the rear end locking portion (the third rear end locking portion 23 is shown as a representative in the figure). good. At least one or more depressions 41 fit into, for example, a protrusion provided on the extrusion plate 5b of the extrusion jig 1 in the third rear end locking part 23. Thereby, the load of the extrusion plate 5b can be reliably transmitted to the drain pipe 10, so rotation of the intermediate tube body 13 can be suppressed, and the drain pipe 10 can be extruded reliably and easily.

Furthermore, as shown in FIGS. 10(b) and 10(c), at least one protrusion 42 may be provided on the side surface of the third rear end locking portion 23. At least one or more protrusions 42 fit into a recess provided in the extrusion plate 5b of the extrusion jig 1, for example, in the third rear end locking part 23. Even in this case, the load of the extrusion plate 5b can be reliably transmitted to the third rear end locking part 23, so that the drain pipe 10 can be extruded reliably and easily.

Further, the recess 41 or protrusion 42 on the side surface of the third rear end locking portion 23 may be fitted with a protrusion or recess provided on the inner circumferential surface of the first tube body 11. Even in this case, the load of the extrusion plate 5b can be reliably transmitted to the third rear end locking part 23, so that the drain pipe 10 can be reliably and easily extruded.

It goes without saying that the configuration of such a modified example can also be applied to the first rear end locking part 21 and the second rear end locking part 22.

(Third modification)
FIGS. 11(a) to 11(c) are schematic cross-sectional views schematically showing a rear end locking portion of a drainage pipe according to a third modification.

As shown in FIG. 11(a), a step 51 may be provided on the surface of the rear end locking portion, for example, the third rear end locking portion 23 that is pressed or struck. The step 51 fits into a projection provided on the extrusion plate 5b of the extrusion jig 1.

Furthermore, as shown in FIG. 11(b), a projection 52 may be provided on the surface of the third rear end locking portion 23 that is pressed or struck. The protrusion 52 fits into a recess provided in the extrusion plate 5b of the extrusion jig 1.

Further, as shown in FIG. 11(c), a curved surface 53 may be provided on the surface of the third rear end locking portion 23 that is pressed or struck. The curved surface 53 fits into a recess provided in the extrusion plate 5b of the extrusion jig 1.

Even in such a third modification, the load of the extrusion plate 5b can be reliably transmitted to the third rear end locking part 23, so that the drain pipe 10 can be reliably and easily extruded.

It goes without saying that the configuration of such a modified example can also be applied to the first rear end locking part 21 and the second rear end locking part 22. Moreover, the third modification can be combined with the second modification.

(Construction example)
Next, an example of construction of a drainage pipe according to an embodiment of the present invention will be described.
FIGS. 12 to 14 are schematic cross-sectional views schematically showing an example of a state in which a drainage pipe is driven into the ground.

As shown in FIG. 12, among the locations where liquefaction countermeasures are to be taken, there are locations subject to height restrictions, such as under the viaduct 200, for example. Drainage pipes for liquefaction countermeasures cannot be driven deeper than the limited height Hlimit.

However, according to the drainage pipe 10 according to one embodiment, it has the first pipe body 11, the second pipe body 12, and the intermediate pipe body 13, and these pipe bodies can be expanded and contracted. Therefore, by retracting the drainage pipe 10 before driving it and expanding it after driving it, it is possible to drive the drainage pipe 10 deeper than the height limit Hlimit into the ground 100 from the ground surface 101. Become. Thereby, according to the drainage pipe 10, it is possible to obtain the advantage that the construction site is less likely to be subject to height restrictions, and the number of locations where construction is impossible can be reduced. The total length L of the drain pipe 10 after driving can also be set to be equal to or greater than the height limit Hlimit. As a result, it becomes possible to further lower the groundwater level 102 and collect pressurized groundwater more effectively in locations subject to height restrictions. Of course, the drainage pipe 10 allows construction even at construction sites that cannot be reached without passing through places subject to height restrictions.

Further, as shown in FIG. 13, locations where liquefaction countermeasures are to be taken include, for example, narrow locations such as a gap G between buildings 300 and a narrow alley.

According to the drainage pipe 10 according to one embodiment, the total length L of the drainage pipe 10 after driving is deep, but as shown in FIGS. 6(a) to 8(b), the first pipe 11, the second The driving depth of the tubular body 12 and the intermediate tubular body 13 may be approximately the same as the length of the first tubular body 11 at the longest, for example. Therefore, although the total length L can be increased, a large construction machine is not required. Thereby, the drainage pipe 10 can be constructed even in a narrow place.

Moreover, as shown in FIG. 14, the drainage pipe 10 according to one embodiment can be applied to, for example, a slope. This makes it possible to suppress the rise in groundwater level during rainfall.

Above, the drainage pipe 10 and the liquefaction countermeasure construction method using the drainage pipe 10 according to the embodiment of the present invention have been described in detail. The technical scope of the present invention should not be construed as being limited by these examples.

1: Extrusion jig 2: Rod 2a: First addition rod 2b: Second addition rod 3: First locking nut 4: Second locking nut 5a: First extrusion plate (extrusion plate)
5b: Second extrusion plate (extrusion plate)
5c: Third extrusion plate (extrusion plate)
6: Rod cap 7: Hydraulic pile driver 8a: First coupler 8b: Second coupler 10: Drain pipe 11: First pipe body 11a: Tip part 11b: Rear end part 11c: Main pipe part 12: Second pipe body 12a: Tip part 12b: Rear end part 12c: Main pipe part 13: Intermediate pipe body 13a: Tip part 13b: Rear end part 13c: Main pipe part 14: Lid body 21: First rear end locking part (rear end locking part) stop)
22: Second rear end locking part (rear end locking part)
23: Third rear end locking part (rear end locking part)
31 : First tip locking part 32 : Second tip locking part 41 : Hollow 42 : Protrusion 51 : Step 52 : Protrusion 53 : Curved surface 100 : Ground 101 : Ground surface 102 : Groundwater level 200 : Viaduct 300 : Building H1 : Water collection hole φ11o: outer diameter (main pipe part 11c)
φ11i: Inner diameter (main pipe part 11c)
φ21o: Outer diameter (first rear end locking part 21)
φ21i: Inner diameter (first rear end locking part 21)
φ12o: Outer diameter (main pipe part 12c)
φ22o: Outer diameter (second rear end locking part 22)
φ13o: Outer diameter (main pipe part 13c)
φ13i: Inner diameter (main pipe part 13c)
φ23o: Outer diameter (third rear end locking part 23)
φ23i: Inner diameter (third rear end locking part 23)
φ31i: Inner diameter (first tip locking part 31)
φ32i: Inner diameter (second tip locking part 32)
φ32o: Outer diameter (second tip locking part 32)
Z: Tube axis direction L21: Length of the first rear end locking portion 21 along the tube axis direction Z T21: Thickness L22 of the first rear end locking portion 21 along the direction perpendicular to the tube axis direction Z : Length T22 of the second rear end locking portion 22 along the tube axis direction Z: Thickness L23 of the second rear end locking portion 22 along the direction perpendicular to the tube axis direction Z: Third rear end locking portion Length T23 of the stop portion 23 along the tube axis direction Z: Thickness φ32i of the third rear end locking portion 23 along the direction orthogonal to the tube axis direction Z: Inner diameter (second tip locking portion 32)
D1: Depth (when driving the first tube body 11)
D2: Depth (when extruding the intermediate tube 13)
D3: Depth (when extruding the second tube 12)
Hlimit: Limit height L: Total length (drainage pipe)
G: Gap

Claims (5)

A drainage pipe comprising a plurality of pipe bodies and capable of being expanded and contracted by the plurality of pipe bodies,
a first pipe body having a main pipe portion having a tip portion, and a tip locking portion provided at the tip portion;
A main pipe part having a rear end part, and a main pipe part provided at the rear end part, which is substantially on the same plane as the rear end part of other pipe bodies when pressed or hit by the extrusion jig, so that it can be pressed or hit by the extrusion jig. a second tube body having a rear end locking portion capable of
Equipped with
The tip locking part is separate from the main pipe part of the first pipe body, and has an inner diameter smaller than the inner diameter of the main pipe part of the first pipe body,
The main tube portion of the second tube body is inserted into the tip locking portion with an outer diameter smaller than or equal to an inner diameter of the tip locking portion,
The rear end locking part is separate from the main pipe part of the second pipe body, and its outer diameter is less than or equal to the inner diameter of the main pipe part of the first pipe body, and greater than the inner diameter of the tip locking part. is enlarged so that it can be inserted into the main pipe part of the first pipe body and can be locked in the tip locking part, and the outer diameter thereof is larger than the outer diameter of the main pipe part of the second pipe body. Ku,
A drainage pipe characterized in that a depression or a protrusion is provided on a side surface of the rear end locking part . The length of the rear end locking portion along the tube axis direction of the second tube body is longer than the thickness of the rear end locking portion along the direction perpendicular to the tube axis direction. The drainage pipe according to claim 1. The recess is fitted with a protrusion that suppresses rotation of the rear end locking portion provided on a contact surface of the extrusion plate of the extrusion jig with the rear end locking portion, or
Alternatively, the protrusion fits into a recess that is provided on a contact surface of the extrusion plate with the rear end locking portion and suppresses rotation of the rear end locking portion. drainage pipe. The drainage pipe according to claim 1 , wherein the depression or the protrusion fits into a protrusion or a depression provided on the inner peripheral surface of the first pipe body. A liquefaction countermeasure construction method using the drainage pipe according to any one of claims 1 to 4 ,
The rear end locking part of each pipe body is pushed out into the ground by pressing or hitting with a pressing jig, and the second pipe body is made to reach below the groundwater level or soft ground, and the inside of the second pipe body is inserted into the ground. A liquefaction prevention method using drainage pipes that allows groundwater to flow into the drainage pipes to release excess pore water pressure.

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