JP2663599B2 - Perforated pipe for liquefaction countermeasures and method of manufacturing the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a perforated pipe used in a method for preventing liquefaction of sandy ground that may cause liquefaction during an earthquake, and a method for producing the same.

[Conventional technology]

Conventionally, as a countermeasure against liquefaction, there is a method in which a large number of perforated pipes are discretely provided in the ground, and excessive pore water pressure generated during an earthquake is dissipated into the perforated pipe to prevent liquefaction (Japanese Unexamined Patent Publication No. 61-146910, JP-A-62-111416, etc.).

That is, as shown in FIG. 15, a perforated pipe 1 in which a large number of small holes 2 are drilled in the longitudinal direction and the circumferential direction, and a water-permeable filter 4 is provided in the hole portion, may cause liquefaction. By setting up at a predetermined depth in a certain sandy ground, excess pore water pressure generated in the sandy ground during an earthquake can be dissipated into the perforated pipe 1 through the holes 2. The water-permeable filter 4 is provided to prevent the sand from entering the inside of the perforated space 1 together with the pore water.

[Problems to be solved by the invention]

The above-described water-permeable filter 4 is usually made of a thin material such as nylon, and is easily damaged by contact with earth and sand, construction machinery and the like. And if it is damaged, it will not be able to play a sufficient role of preventing the intrusion of sand from the hole. Therefore, there is a problem that the perforated pipe 1 must be handled with care when it is transported or installed on the ground.

It is preferable that the filter 4 is usually mounted from the inside of the perforated pipe 1 in order to slightly reduce the possibility of damage due to contact with earth and sand, a construction machine, or the like. There is a risk that the space inside is narrow and the mounting operation becomes very complicated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and facilitates handling such as transportation of a perforated pipe and installation on the ground, and also facilitates the work of mounting a filter.

[Means for solving the problem]

The perforated pipe for liquefaction countermeasures of the present invention has a plurality of holes formed in a longitudinal direction and a circumferential direction, and a plug provided with a water-permeable filter is attached to the hole, whereby a perforated pipe is formed. This prevents the filter from being damaged when being transported or erected on the ground, and facilitates the work of mounting the filter. That is, the stopper is provided with a through hole in the axial direction, and a filter is provided in the through hole.

As a method for manufacturing a perforated pipe for liquefaction countermeasures, a perforated pipe with a filter can be easily manufactured by fitting and fixing the above-described stopper to each hole of the perforated pipe.
For example, if the shape of the plug has a truncated cone shape and the outer diameter gradually increases from the front end to the rear end, the plug can be fixed by pushing it into the hole. Also, an axial injection pipe is provided in the stopper, and a hardening material is injected from the injection pipe into a bag provided at the tip of the plug, and an enlarged portion is formed at the tip of the plug by hardening of the hardening material to form a perforated pipe. Can be fixed in the holes.

(Operation)

The liquefaction deterrent effect is basically the same as that of conventional perforated pipes.
It is allowed to escape through the hole of the perforated pipe into the hollow perforated pipe to prevent liquefaction. And, by using a method in which a plug with a filter mounted inside is attached to a hole of a perforated pipe, it is possible to prevent the filter from being damaged when the perforated pipe is transported or erected on the ground. Also, since the filter is already installed inside the stopper,
It is much easier to install the filter in a conventional perforated pipe.

〔Example〕

 Next, the illustrated embodiment will be described.

FIG. 1 shows an outline of a perforated pipe of the present invention. A plug 3 is attached to a perforated portion 13 of the perforated pipe 1 and a filter 4 is provided inside the plug 3. I have.

FIG. 2 shows an example of a method of attaching the stopper 3 to the perforated tube 1. FIG. 3 is a front view showing an outline of an example of the plug 3, FIG. 4 is a side view thereof, and FIG. 5 is a sectional view taken along line II in FIG.

In this embodiment, the plug 3 is composed of a shaft portion 5 and a head portion 6, has a bolt-like shape, and has a through hole 7 in its axial direction.
have. A water-permeable filter 4 is provided in the vicinity of the axial center of the through hole 7. The outer diameter of the shaft portion 5 is approximately the same as the diameter of the hole 2 of the perforated tube 1 at the distal end portion 8, and gradually increases from the distal end portion 8 toward the base 9. That is, FIG.
As shown in FIG. 5, a shaft portion 5 as a penetrating portion of the perforated pipe 1 into the hole 2 has an outer shape of a truncated cone.

The perforated pipe 1 is transported with the plug 3 attached to the hole 2 and is erected in the ground, so that the plug 3 is sufficiently damaged so as not to be damaged in the process. It is necessary to have strong strength. Further, the outer diameter of the tip portion 8 of the shaft portion 5 is substantially the same as the diameter of the hole 2 of the perforated tube 1;
In addition, since the outer diameter of the base 9 is larger than the diameter of the hole 2, in order to insert it into the hole 2 of the perforated tube 1, the plug 3 needs to be made of a compressible material. Therefore, the material of the plug 3 is not particularly limited as long as the material satisfies the above-mentioned conditions. For example, hard vinyl chloride is conceivable.

The plug 3 is inserted into the hole 2 of the perforated tube 1 by pushing its shaft 5 with a required pushing force. At this time, the shaft portion 5 having the outer shape of the truncated cone receives a compressive force in its diameter direction, and the base portion 9 has a diameter substantially the same as that of the distal end portion 8. Therefore, the shaft peripheral surface 11 and the hole 2 of the perforated tube 1
A frictional force is generated between the plug 3 and the inner peripheral surface 12, and the plug 3 is fixed to the hole 1 by the frictional force. Therefore, when the perforated pipe 1 is erected in the ground, the plug 3 remains fixed to the hole 1 without falling off even if it receives resistance from the surrounding ground.

The plug 3 has a through hole 7 in the axial direction.
Since a water-permeable filter 4 is provided in the vicinity of the center in the axial direction, the perforated pipe 1 to which the plug 3 is attached is erected at a predetermined depth in a sandy ground where liquefaction may occur. The excess pore water pressure generated in the sandy ground during an earthquake can be dissipated into the perforated pipe 1 through the through hole 7 of the plug 3 and the sand enters the perforated pipe 1 together with the pore water. Can be prevented.

The material of the filter 4 is not particularly limited,
For example, a warp knitted fabric made of nylon or a nonwoven fabric made of polypropylene can be used. The position where the filter 4 is provided is not limited to the position shown in FIGS. 2 to 5, but may be provided inside the shaft 5 or the head 6 of the plug 3. However, in order to prevent the filter 4 from being damaged when transporting the perforated pipe 1 or standing on the ground, it is better not to install the filter 4 near the head 6.

In order to dissipate the excess pore water pressure, at least 3% of the total surface area of the perforated portion 13 of the perforated pipe 1 is required.
As described above, it is considered that an area that allows water to pass through is preferably 5% or more. Therefore, in the case of the present invention, the perforated pipe 1
The ratio of the total area of the through holes 7 of the plug 3 to the total surface area of the perforated portion 13 is at least 3% or more, preferably 5% or more.

6 to 9 show another embodiment. In this embodiment, the shaft 6 of the plug 3 is enlarged at its tip, and the shaft 6 does not necessarily have to be frustoconical as in the previous embodiment. That is, the portion other than the enlarged portion 10 may have a cylindrical shape having an outer diameter substantially equal to the diameter of the hole 2 of the perforated tube 1. FIG. 6 shows that the plug 3 is
FIG. 8 shows a state in which the stopper 3 is mounted in this state.
9 is a sectional view of the same. In this example, since it is difficult to insert the plug 3 in the state shown in FIG. 8 or FIG. 9 into the hole 2, it is attached to the hole 2 by the following method. That is, as shown in FIG. 7, before the plug 3 is attached to the hole 2, the tip of the shaft 6 is not enlarged. However, after the insertion into the hole 2, the injection pipe 14 is previously inserted into the shaft 5 so that the tip 8 can be enlarged by injecting the hardening material.
Is provided, and a bag 15 capable of storing a hardening material is provided at the tip. After inserting the stopper 3 into the hole 2, the hardening material is injected into the injection pipe 14.
The bag 15 is filled with a hardening material, and is enlarged at the shank tip 8 to form an enlarged portion 10 as shown in FIG. 6, FIG. 8 or FIG. You.
As a result, the stopper 3 is locked and fixed in the hole 2. The position where the filter 4 is provided is the same as that in the above-described embodiment.

The hardening material is a material having a property of hardening over time, and for example, a cement mortar, a polymer mortar, a synthetic resin, or the like can be used.

10 to 14 show still another embodiment. In this embodiment, the stopper 3 has the through-hole 7 in the axial direction and has the water-permeable filter 4 in the same manner as in the above-described embodiment, except that the stopper 3 comprises only the shaft portion and does not have the head. It has a structure. Therefore, as shown in FIG. 10, when the plug 3 is inserted into the hole 2, the head or the like in the above-described embodiment does not protrude on the outer peripheral surface of the perforated tube 1,
When the perforated pipe 1 is erected in the ground, the possibility that the plug 3 is damaged is reduced.

FIG. 11 is a side view of the plug 3 in this embodiment, and FIG. 12 is a sectional view. FIG. 13 is a side view when the filter 4 is provided at the tip of the plug 3 in the plug 3 having no head, and FIG. 14 is a sectional view of the same.

[Effect of the Invention] A thin filter that is easily damaged during transportation or construction in the ground is installed in the axial center of the plug,
Since direct contact with surrounding sand and the like is avoided, transportation and construction are facilitated.

Since the perforated pipe is installed in the ground without damaging the thin filter, intrusion of earth and sand into the perforated pipe main body is completely prevented, and the liquefaction inhibiting effect can be maintained for a long time.

The thin filter is provided inside the stopper in advance. Therefore, a perforated tube with a filter can be manufactured by inserting a plug into the hole of the perforated tube, thereby facilitating the manufacturing operation.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an outline of a perforated pipe for liquefaction countermeasures according to the present invention, FIG. 2 is a vertical sectional view showing an attached state of a plug in one embodiment, FIG. 3, FIG. 4 and FIG. FIG. 6 is a front view, a side view, and a cross-sectional view of the plug in the embodiment of FIG. 2, FIG. 6 is a vertical cross-sectional view showing a mounting state of the plug in another embodiment, and FIG. FIG. 8 and FIG. 9 are side views and cross-sectional views, respectively, showing the state of the plug after injection of the hardening material in the embodiment of FIG. 6, and FIG. FIG. 11 is a vertical sectional view showing another embodiment, and FIGS. 11 and 12 are side and sectional views of the stopper in the embodiment of FIG. 10, respectively.
FIG. 14 and FIG. 14 are a side view and a sectional view, respectively, showing a modification of the plug in the embodiment of FIG. 10, and FIG. 15 is a perspective view showing an example of a conventional perforated tube. DESCRIPTION OF SYMBOLS 1 ... Perforated pipe, 2 ... Hole, 3 ... Plug, 4 ... Filter, 5 ... Shaft, 6 ... Head, 7 ... Through hole, 8 ... Tip, 9 ... Base , 10 ... enlarged part, 11 ... shaft part peripheral surface, 12
…… the inner peripheral surface of the hole, 13 …… the perforated part, 14 …… the injection tube, 15 ……
bag

Claims (4)

(57) [Claims] A plug is attached to each of the holes of a perforated pipe having a plurality of holes formed in a longitudinal direction and a circumferential direction, and the plug is provided with a through hole in an axial direction thereof. A perforated pipe for liquefaction countermeasures, characterized in that a filter is provided in the through-hole. 2. The plug according to claim 1, wherein at least a portion penetrating into the hole of the perforated tube has a truncated conical outer shape, and an outer diameter gradually increases from a front end to a rear end. Perforated pipe for liquefaction prevention. 3. A plug having a through-hole in an axial direction, and a plug provided with a filter in the through-hole is fitted and fixed to each hole of the perforated tube. Or the method for producing a perforated pipe for liquefaction prevention according to 2 above. 4. A plug is provided with an injection pipe in the axial direction, and a hardening material is injected from the injection pipe into a bag provided at a tip of the plug, and the hardening material hardens to form a tip of the plug. The method for producing a perforated pipe for liquefaction prevention according to claim 1, wherein an enlarged portion is formed in the perforated pipe to fix the stopper in a hole of the perforated pipe.