JP2789803B2 - Liquefaction control piles and plugs for liquefaction control piles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is used when constructing a structure on a ground where liquefaction is likely to occur, while preventing liquefaction due to external vibrations such as earthquakes and waves. The present invention relates to a liquefaction-inhibiting pile for suppressing lateral flow and slip of the ground.

[Conventional technology]

Currently used liquefaction control methods include the ground compaction method and the crushed stone drain method that have been frequently used (Japanese Patent Application Laid-Open No.
No. 100919, Japanese Utility Model Publication No. 56-116434).
Applied to the ground where liquefaction is expected. Further, resin pipes provided with a filter on the pipe peripheral surface have been conventionally used for the purpose of collecting and draining pore water in the ground and as a measure against liquefaction. In addition, in recent years, in order to drain excess pore water in the ground during an earthquake or the like, a large number of holes have been drilled in a pile made of steel pipe, etc., and a water-permeable filter has been installed in the hole to prevent intrusion of earth and sand. A hollow holed pile which is expected to have the strength and rigidity of the pile in addition to the drainage effect (JP-A-61-146910)
Japanese Patent Application Laid-Open No. Sho 61-61), porous concrete pile
No. 83711) has been developed. In addition, a steel sheet pile is provided with a vertical pipe for drainage (Japanese Patent Application Laid-Open No. 62-146315).
Reference).

However, the soil compaction method has problems such as causing harmful vibrations during construction, and the crushed stone drain method has impaired drainage effect due to clogging or the like, and there is no guarantee of long-term function retention.

Further, a hollow holed pile disclosed in JP-A-61-146910,
In the porous concrete pile of No. 61-83711, the load carrying capacity of the pile body as a structure is reduced due to the holes for drainage.

Resin pipes with small holes in the pipe body have low strength and rigidity, so they can hardly be expected to resist unpredictable lateral flow or slippage due to earthquakes,
The construction method in the vertical direction of the pipe is limited to a construction method such as a method using the same casing pipe as that conventionally used in the crushed stone drain method in order to prevent the filter around the pipe from being damaged.

In addition, a steel sheet pile of JP-A-62-146315 with a vertical pipe for drainage only drains from the lower end to the upper end of the vertical pipe, and drains over the thickness of the ground where liquefaction may occur. It has no function, and there is doubt about the drainage effect as a liquefaction countermeasure.

In order to solve the above-mentioned problems, the applicant has communicated with a number of openings along the longitudinal direction of the pile at least in a predetermined section of the pile located in the ground where liquefaction may occur. A liquefaction-preventing pile provided with a drainage member provided with an aqueous filter has been proposed (see Japanese Patent Application No. 1-1112876).

If the above liquefaction prevention pile is used, excessive pore water pressure generated in the ground at the time of an earthquake or the like will cause pore water to penetrate the drainage member from the opening, and the gap in the drainage member or the gap between the pile body and the drainage member. It escapes by being drained through, and liquefaction around the pile is suppressed. At this time, intrusion of earth and sand is prevented by the filter at the opening.

Moreover, the seismic force can be restrained without lowering the strength and stiffness of the pile body, and can also resist the lateral flow and slip of the earthquake.

[Problems to be solved by the invention]

However, the above-described water-permeable filter is usually made of a synthetic fiber such as tetron or nylon, a synthetic resin, or a thin metal material, 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 sufficiently fulfill the role of preventing sand from entering through the opening. Therefore, there has been a problem that sufficient care must be taken during transportation and installation on the ground.

The present invention has been made to solve the above problems,
This facilitates the handling of liquefaction prevention piles, such as when transporting them to the ground and installing them on the ground, and also facilitates the work of installing filters.

[Means for solving the problem]

The present invention provides one or a plurality of drainage members forming a drainage channel along the longitudinal direction of the pile main body on the outer peripheral surface of the pile main body, and at least liquefaction of the drainage member is likely to occur in the ground. A liquefaction-preventing pile formed by drilling a large number of holes in a predetermined section facing the drainage member, wherein a plug provided with a filter is attached to each hole of the drainage member. The stopper has a through hole in the axial direction, and a filter is provided in the through hole.

For the drainage member, its cross-sectional shape (for example, circular,
The rectangle, triangle, U-shape, U-shape, etc.) and the material (steel, aluminum, synthetic resin, etc.) are not particularly limited, as long as the pile of the present invention is not damaged when installed in the ground. I just need.

The pile body is generally made of steel, but may be made of another metal, a synthetic resin, or another material as long as it has a necessary strength as a seismic reinforcing means of the pile or the ground.

In the through hole of the stopper, a filter protecting member having water permeability can be provided together with the filter to prevent the filter from being damaged by earth and sand. Also, in order to prevent the plug from coming off the drainage member when transporting the pile or installing on the ground, a detachment prevention portion having a diameter larger than the diameter of the drainage member hole may be provided at one or both ends of the plug. it can.

As a method for manufacturing the liquefaction-preventing pile, a liquefaction-preventing pile with a filter can be easily manufactured by fitting the above-described plug into each hole of the perforated drainage member. In this case, after attaching the drainage member to the pile main body in advance, the plug can be fitted into each hole drilled in the drainage member, but the manufacturing method is not particularly limited to this order.

In addition, the liquefaction-preventing pile of the present invention has a filter provided in a through hole of a plug and a filter protection member provided as necessary, so that a diesel hammer can be provided without using a casing pipe or the like to protect the filter. It can be installed directly on the ground with a hydraulic hammer, vibratory hammer, press-fitting machine or the like.

(Operation)

The principle of liquefaction prevention is that the pile of the present invention is installed on the ground, pore water in the ground is passed through a plug attached to the drainage member,
By making it possible to discharge between the hollow drainage member or the pile body and the drainage member, excessive pore water pressure generated in the liquefied ground during an earthquake is dissipated, and liquefaction is prevented.

Further, since the pile body does not need to be bored, the ground is restrained without lowering the strength and rigidity of the pile body, and the pile can be prevented from flowing laterally or sliding.

Figure 20 shows the results of a free-damping wave excitation experiment with a model of a liquefaction-preventing pile installed on liquefied ground. On the ground where the liquefaction-preventing piles were installed, the excess pore water pressure ratio was well within 0.5 or less, which had the effect of preventing liquefaction.
When only the ground is not installed, the excess pore water pressure ratio becomes 0.6 or more, and it is almost liquefied.

Fig. 21 shows the difference between the displacement of the pile during excitation and the constant displacement without excitation when the same load is applied to the pile on the ground where the liquefaction-preventing pile and the ordinary pile without liquefaction countermeasures are installed. This shows the pile. The displacement of the pile at the time of excitation is nearly three times larger than that of the normal pile in the case of the pile without measures, while it is about 1.5 times in the case of the pile for preventing liquefaction. From this, it is understood that considerable horizontal resistance can be expected in the ground where the liquefaction prevention pile is installed even during an earthquake.

Fig. 22 shows the horizontal load P when a horizontal load is applied to the ground on which liquefaction-preventing piles or non-measureable piles are installed, and on the ground where no piles are installed, by the loading plate, and the entire ground is vibrated on the way. And the load plate displacement δ. When a liquefaction-preventing pile is installed, horizontal resistance can be expected even during excitation, whereas when no countermeasure pile is installed, almost no horizontal resistance can be expected during excitation. In other words, in the ground where the liquefaction-preventing pile is installed, the pile periphery does not liquefy, and the pile exhibits horizontal resistance. Power is almost gone.

Fig. 23 shows the pull-out resistance of a pile at the time of excitation against the pull-out resistance at all times on a liquefied ground with liquefaction-preventing piles and ordinary piles without liquefaction measures installed. It is a thing. In the case of a pile without measures, the pull-out resistance of the pile at the time of vibration is reduced to about 10 to 20% or less of the normal, and almost no pull-out resistance can be expected. On the other hand, the liquefaction-preventing pile has almost the same pull-out resistance as always even when it is vibrated. This indicates that, in the liquefied ground, if the liquefaction-preventing pile of the present invention is used, even when an earthquake occurs, the peripheral frictional force of the pile can be obtained almost in the same manner as at all times, and a pile-type structure in which pulling force acts during an earthquake or an earthquake It is shown that there is a great effect of increasing the safety of general pile type structures in which a downward pushing force sometimes acts.

As described above, when the liquefaction-preventing pile is installed, the liquefaction of the ground during an earthquake can be prevented, and the horizontal resistance and the peripheral friction can be expected.

In addition, when the liquefaction-inhibiting pile of the present invention is used for a foundation pile of a structure or the like, liquefaction in the vicinity of the foundation pile where liquefaction is most likely to occur can be prevented, and the above-described effects can be expected. Can provide a high foundation pile.

Then, by using a method in which a plug having a filter mounted therein is attached to the hole of the drainage member, damage to the filter during transportation of the liquefaction prevention pile or standing on the ground can be prevented. In addition, by providing the filter protection member, especially when the pile of the present invention is installed on the ground, it is possible to prevent the filter from being damaged even if earth and sand enter in the axial direction of the plug. By providing the stopper at the end of the plug, the stopper can be reliably prevented from being detached even when the pile is installed on the ground.

As for the construction method, it is not necessary to adopt a method in which a casing pipe is press-fitted into the ground as in the past, or a casing auger is rotationally press-fitted and a mounting hole is provided in the ground, and a method of installing the pile is used. It can be directly pressed into the ground by a press-fitting machine, or can be directly driven into the ground by a device such as a vibro hammer or a diesel hammer. Therefore, the construction is much easier than before, and the construction method can have a wide range.

Further, in the method of manufacturing a pile according to the present invention, since a plug provided with a filter therein is merely fitted into a hole of a perforated drainage member, the liquefaction suppression described in Japanese Patent Application No. 1-112876 described above. It is much easier than installing a stake filter.

〔Example〕

Next, embodiments of the present invention will be described with reference to the accompanying drawings.

2 to 4 show an example in which a steel pipe is used as the pile body 1 and a channel steel 2a is welded to the pile body 1 as the drainage member 2. FIG. The drainage member 2 is provided with a large number of holes. Each hole has a through hole in the axial direction, and a plug 4 having a filter provided therein is mounted in the through hole. FIGS. 1 (a) and 1 (b) are enlarged views of the main part,
A drainage channel is formed between and the channel steel 2a.

In general, the length L of the drainage member 2 where the plug 4 is attached is equal to or longer than the length corresponding to the target liquefied layer thickness. However, this length L is used when the liquefaction-preventing pile of the present invention is used for the foundation pile of a structure, etc., and when the thick liquefied layer is at the top of the pile installation ground, the ground reaction force during an earthquake is limited only to the top of the pile. If the resistance as a pile foundation is sufficient, the length may be smaller than the length L of the liquefied layer.

In the embodiment shown in FIGS. 2A and 2B, the plug 4 is connected to the drainage member 2.
It is an example of the liquefaction suppression pile A provided up to the upper part.

The embodiment of FIGS. 3 (a) and 3 (b) is an example of the liquefaction-preventing pile A used when there is non-liquefied ground on the ground where liquefaction is likely to occur, and the upper part of the drainage member. Is not perforated.

4 (a) and 4 (b) are FIGS. 2 (a) and 2 (b).
In the embodiment of the present invention, the stopper 4 is used as the channel member 2a as the drainage member 2.
This is a case where only the web portion is provided, while both the web portion and the flange portion are provided.

In the drawing, reference numeral 13 denotes a tip protection plate provided at the tip of the drainage member 2 so that the resistance at the time of casting is reduced.

When it is necessary to punch a crushed stone layer or a boulder layer near the ground surface and drive a pile, as shown in FIG. May be attached. On the other hand, generally, a steel lid 17 may be attached to the upper end of the drainage member 2 as shown in FIG. In this case, the pore water at the time of the earthquake passes through the through hole of the plug on the upper part of the drainage member 2 as shown in FIG.
It is discharged to the outside of the drainage member 2. As another structure of the upper end of the drainage member, as shown in FIG.
It is also possible to attach 18 to make it possible to discharge pore water during an earthquake from this part. In this case, the filter 18 may have the same properties as those attached to the stopper, and it is desirable to attach a protection member such as a wire net or a resin net on the outer surface side to protect the filter 18.

FIG. 6 shows the pile A of FIG.
1, which shows an example in the case of being installed on the ground constituted by the support ground 22. Liquefaction ground 21 generated during earthquake
Underground water is drained due to the rise of excess pore water pressure
, And flows into a drainage channel 12 formed between the drainage member 2 and the pile body 1 to be drained. In FIG. 6, the flow path is indicated by arrows. By this action, the excess pore water pressure of the liquefied ground 21 near the pile A of the present invention is reduced, and the liquefaction of the ground is suppressed. Since the filter provided in the through hole of the plug 4 prevents sand from flowing into the drainage channel 5, the above-mentioned action works every time the earthquake is repeated, and gradually increases the strength of the ground that may be liquefied each time. You can also.

FIG. 7 shows the pile A of FIG.
1, which shows an example in the case of being installed on the ground constituted by the support ground 22. Liquefaction ground 21 generated during earthquake
The groundwater flows into the drainage channel 12 due to the rise of the excess pore water pressure inside, and is drained out of the drainage channel 12 from the upper side of the drainage member 2. In FIG. 7, the path of this flow is indicated by arrows. By this action, the liquefied ground 21 near the pile A of the present invention
The liquefaction of the present invention is suppressed in the same manner as in the example of FIG. 6, and even if the earthquake is repeated, the plug 4 provided with the filter for preventing intrusion of earth and sand is attached to the hole of the drainage member 2. Pile A keeps the liquefaction deterrent effect.

FIG. 8 shows a drainage member 2 in which a large number of holes 3 are provided in an angle iron 2b instead of the above-described channel steel 2a, and a plug 4 having a filter installed in each hole 3 is attached. FIG. 9 shows a semicircular member 2c in which a number of holes 3 are provided and a plug 4 is provided in each hole 3.

The drainage member 2 may be made of a circular steel pipe or a square steel pipe.

FIGS. 10 (a) and 10 (b) show a case in which a large number of holes are drilled in a circular steel pipe 2d, and a member provided with a plug 4 having a filter installed in each hole is welded around a pile body 1 made of a steel pipe. Here is an example.

FIGS. 11 (a) to 11 (c) show a structure in which a large number of holes are formed in the ribbed panel 2e, and a member provided with a plug 4 having a filter in each hole is welded around the pile body 1 made of a steel pipe. This is an example of the case. In this case, when the pile main body 1 is made of a synthetic resin, the ribbed panel 2e can be made of a synthetic resin, and the ribbed panel 2e can be attached to the pile main body with an adhesive or resin welding. When employing a synthetic resin material for the ribbed panel 2e, it is preferable that the ribbed panel is integrally molded. Moreover, regardless of whether the ribbed panel 2e is made of steel or synthetic resin, the box-shaped structure as shown in FIG. 11 (c) can further increase the strength of the drainage member.

FIGS. 12 (a) and 12 (b) show an example in which a drainage member composed of a continuous box-shaped structural member 2f is attached to the entire surface around the pile body 1. FIG. Of course, a continuous panel with ribs as shown in FIG. 11 may be attached to the entire surface of the pile main body 1 and used as a drainage member. In the example of FIG. 12, the drainage member is a box-shaped structural member 2f having a partition, so that the strength can be greater than that of the ribbed panel 2e. If the drainage member shown in FIG. 12 is made of steel, the outer peripheral plate of the box-shaped structural member 2f is manufactured by welding one or more steel plates to give a predetermined curvature. In addition, if the bulkhead is welded and one or more inner peripheral plates are continuously or discontinuously welded to the bulkhead in the pile longitudinal direction,
The drainage member described above can be manufactured. Also, the twelfth
If the drainage member shown in the figure is made of synthetic resin, it can be assembled by resin welding as in the case of steel, and the outer peripheral plate, partition wall, and inner peripheral plate should be integrally formed continuously in the pile longitudinal direction. Can also. When the drainage member is made of steel, it is easy to manufacture the lid 17 at the upper and lower ends and the tip protection plate 13 from steel in terms of manufacturing. When the drainage member is made of synthetic resin, the lid 17 and the tip protection plate 13 may be made of steel or resin, but are integrated with the synthetic resin portion with an adhesive or the like. The drainage member is attached to the pile body by welding or an adhesive. At this time, an adhesive may be applied between the inner peripheral plate and the outer peripheral surface of the pile to increase the safety of the drainage member from being detached from the pile main body, or a drainage hole may be formed on the outer peripheral surface of the drainage member. A structure may be adopted in which a band is attached so as not to be blocked, and pressure is applied inside the pile in the radial direction. The above-described method of attaching to the pile main body can be similarly adopted when a ribbed panel without an inner peripheral plate is used as a drainage member.

In the embodiment shown in FIG. 12, if the outer peripheral plate is perforated and the plug with a filter of the present invention is fitted, the pile can be driven in, there is no clogging of earth and sand, and the effect of preventing liquefaction can be reliably obtained. A reliable liquefaction control pile with high reliability can be obtained.

The material of the drainage member described above is not limited to steel, but may be any of synthetic resins such as polyethylene, stainless steel, and aluminum. The attachment of the drainage member to the pile body can be performed by welding, bonding with an adhesive, brazing, or the like. The drainage member does not need to be joined to the pile main body over the entire length, and it is sufficient that the drainage member is joined so as not to be detached from the pile main body when the liquefaction suppressing pile of the present invention is driven into the ground. For example, when attaching a channel steel to a pile main body, it is not necessary to weld over the entire contact portion of the channel steel pile main body in terms of detachment of a drainage member at the time of driving.

When the method of fillet welding the upper and lower ends of the channel steel over a certain length is adopted, a gap is easily formed between the intermediate portion of the channel steel and the contact surface between the pile body due to irregularities between the two. If this gap is formed, there is a concern that earth and sand from the ground may flow into the drainage channel and block the drainage channel. Also, when the ground water is drained through the drainage channel in the drainage member during the liquefaction of the ground, part of the pore water flows out of the gap, and the discharged water flow is disturbed and the drainage resistance is increased. There are also concerns.

To prevent gaps in this case, apply a synthetic resin or styrene-butadiene rubber or asphalt-based water-stopping agent to the contact surface between the channel steel and the pile body to easily maintain sufficient watertightness as a drainage mechanism be able to.

Among the water stopping agents, a water absorbing and swelling water stopping agent provides higher watertightness. This type of water-stopping agent has a synthetic resin such as special urethane as a main component, and need only be applied to a predetermined portion by spraying or brushing. The coating film swells when immersed in fresh water or seawater, and has a property of increasing the thickness by about 8 to 10 times. Since there is always water in the ground where there is a possibility of liquefaction, this water absorption and swelling property is effective. In addition, as the water stopping agent, a viscoelastically solidified water absorbing and swelling flat water stopping agent made of the same material as above is used between the draining member and the contact surface of the pile body. Can be. In this case, the same water stopping effect as in the above case can be obtained.

Even if the water-stopping agent is mainly composed of styrene-butadiene rubber or asphalt, the watertightness of the contact surface between the drainage member and the pile can be obtained. This type of waterproofing agent may also be applied to a predetermined portion, and then the drainage member may be pressed against and attached to the pile body. Alternatively, a viscoelastically consolidated flat plate may be used between the contact surface of the drainage member and the pile body, and then the drainage member may be pressed into contact with the pile body. The material of the above-mentioned flat plate is desirably a material having viscoelasticity mainly composed of rubber, asphalt, or the like, but any water-stopping agent may be used as long as the material is watertight.

In short, when there is no need to worry about a gap between the pile body and the drainage member contact area, generally, the drainage member is welded to the pile body so that it does not separate from the pile body during construction. If it is only necessary that the water-stopping agent is partially attached, and there is a concern that the water-stopping property is at the contact surface between the drainage member and the pile main body, a water-stopping agent may be used at a necessary portion.

The number of drainage members attached to the outer peripheral surface of the pile body is shown in Fig. 2 ~
In the example of FIG. 4, FIG. 8 to FIG.
Appropriately determined according to the target liquefied ground, the nature of the earthquake, the cross-sectional area of the drainage channel of the drainage member, the outer shape of the pile, the arrangement of the pile, and the like. In general, the drainage members are generally arranged almost uniformly on the outer peripheral surface of the pile body.

When placing piles continuously on the ground and preventing liquefaction of only the ground on one side of the piles, install one or more drainage members on the outer peripheral surface of the pile located on the ground side targeted for liquefaction prevention. May be installed.

In addition, as an application example of the liquefaction prevention pile of the present invention, in the examples of FIGS. 2 to 4 and FIGS. 8 to 11, a so-called LT type (a pair of angle steel A liquefaction-inhibited steel pipe sheet pile can be obtained by providing a joint that is found in existing steel pipe sheet piles, such as a combination of steel and T-section steel, and a PP type (pipe structure having a slit). In this case, a drainage member is attached to the outer peripheral surface of the steel pipe sheet pile facing the ground to be subjected to liquefaction suppression, and the liquefaction suppression steel pipe sheet pile is manufactured. By appropriately adopting the method, the liquefaction-preventing pile can be rationally manufactured, the manufacturing cost can be reduced, and the liquefaction-preventing pile having high drainage reliability can be provided.

FIG. 13 shows an example of a cross section of the plug 4 and an example of a method of attaching the plug 4 to the drainage member 2. FIG. 14 (a) is a side view of the stopper 4 of FIG. 13, and FIG. 14 (b) and FIG.
FIG. 14C is a front view and a rear view.

In this embodiment, the stopper 4 is composed of a shaft 5 and a stopper preventing stopper.
9, 10 and a filter protection member 8, and has a through hole 6 in the axial direction. And the through hole 6
A filter 7 having water permeability is provided on the inner side of the drainage member 2 of the filter protection member 8 therein. The outer diameter of the plug shaft 5 is substantially the same as the diameter of the hole 3 of the drainage member 2. The diameter of the plug removal prevention parts 9 and 10 is larger than the diameter of the hole 3 of the drainage member 2. The filter protection member 8 is desirably provided integrally with the plug shaft 5, and the protection member 8 is provided with many small holes in order to ensure water permeability.

The liquefaction-preventing pile of the present invention is usually transported in a state where a plug is attached to the hole of the drainage member, and is further erected in the ground to be used for preventing liquefaction of the ground. Must be strong enough not to be damaged during the process. Further, in order to insert the plug into the hole of the drainage member, at least the plug removal prevention portion needs to be made of a material having some flexibility. In addition, the filter protection member protects relatively thin and weak filters such as nylon filters from damage when transporting, standing, and operating the liquefaction prevention pile. Need to secure. Also from this point of view, it is desirable to manufacture the filter protection member integrally with the stopper, but it is of course possible to attach the filter protection member separately later. The material of the plug is not particularly limited as long as it satisfies the above conditions.From the results of the experiment of fitting into the hole of the plug and the experiment of placing the liquefaction inhibiting pile of the present invention into the ground, etc. For example, synthetic resins such as vinyl chloride, polyethylene, nylon, and polypropylene, and rubber are considered suitable.

The filter protection member is provided with a small hole for water permeability, but the shape of the small hole is not particularly limited, such as a circle or a square. It is desirable that the diameter and mesh of each small hole of the filter protection member be substantially the same.
If the filter does not have a protective member, the filter may be damaged by friction with sand (rough sand) having a relatively large particle diameter when the liquefaction prevention pile is erected. The size should be smaller than the size of the target rough sand. The material of the filter protection member may be, for example, the above-mentioned synthetic resin such as vinyl chloride, polyethylene, nylon, or polypropylene, rubber, or the like, and the required strength may be ensured by adjusting the hole diameter or mesh and pitch of the protection member.

In the embodiment shown in FIGS. 13 and 14, the filter protection member 8 also serves as a primary filter for preventing the rough sand from flowing into the drainage member 2, and the filter inside the protection member 8 is used. 7 serves to prevent relatively fine soil particles that have passed through the filter protection member 8 from flowing into the drainage member.

Although the filter protection member 8 is single in the embodiment of the stopper shown in FIG. 13, a plurality of filter protection members 8 may be provided as shown in FIG. 15 in order to further enhance the protection function of the filter.

As the filter, a stainless steel filter, a synthetic fiber filter, or a synthetic resin filter may be used. When there is concern about rusting, the latter filter is preferable.For example, use a synthetic fiber warp knitted fabric such as nylon, polyethylene monofilament, or polyester, or a nonwoven fabric such as polypropylene or polyester fiber. Can be. Further, a filter may be formed by combining synthetic fibers or synthetic resins, or combining or overlapping synthetic fibers and a synthetic resin.

For example, in the plug shown in FIGS. 13 and 15 having a filter protection member, a thin synthetic fiber filter may be provided in a single layer, or this filter may be provided in a double layer. In addition, as another installation example of the filter, on one or both sides of a synthetic fiber filter made of a thin warp knitted cloth or a non-woven fabric, a synthetic resin filter thicker than this synthetic fiber filter and having a larger mesh, or a synthetic fiber filter is used. It is also possible to use a filter reinforced by laminating synthetic resin nets which are thicker than the filter and have many small holes larger than the mesh. In this case, a filter or a net made of a synthetic resin having a large mesh plays the role of the above-described filter protection member. In this case, it is not necessary to use a separate filter protection member.

The mesh or gap of a warp knitted fabric or nonwoven fabric as a filter, or a stainless steel filter, etc., should be used in consideration of the particle size distribution of the soil (generally sandy ground) to prevent liquefaction, etc. It is good to set so as not to cause clogging. This mesh or gap can be set as large as about 1 to 3 mm on the ground where liquefaction is possible, and on the ground where the particle size of the soil is particularly large and relatively evenly distributed. The ground is small, and it is 1 to 1
It is better to set smaller than about 3mm. It is desirable that the filter be thin to prevent clogging. If the filter mesh or gap can be set as large as about 1 to 3 mm, filter protection with the same material and strength as the above-mentioned filter protection member, and with a hole diameter or mesh set to about 1 to 3 mm It is also possible to make only the member function as a filter.

The permeability of the filter in liquefaction countermeasures depends on the ground where the liquefaction-preventing pile is installed, but is generally 10 ^-2 cm / sec to 10 ^-1.
It is preferably about cm / sec or more. In addition, since the pore size or mesh of the filter protection member is generally larger than the filter mesh or gap, if the filter has the prescribed permeability, the permeability when the filter protection member and the filter are superimposed also has the prescribed specifications. can do.

13 and 15, the plug with filter 4 in the embodiment of FIG.
The fitting of the drainage member 2 into the hole 3 can be easily carried out by applying the plug / removal prevention part 10 to the hole 3 and hitting the plug / removal prevention part 9 with a hammer or the like. . Since the diameter of the plug removal prevention part 10 is larger than the diameter of the hole formed in the drainage member 2, the diameter is reduced to the hole diameter at the time of mounting, and when the plug removal prevention part 10 passes through this hole, the diameter is expanded and the mounting is completed. Therefore, the material of the stopper needs to have elasticity or flexibility. To facilitate the installation of the stopper 4,
As shown in FIG. 14, a slit 11 may be provided from the shaft portion 5 of the plug 4 to the plug removal preventing portion 10. In the example of FIG. 14, four slits 11 are provided. However, the width, length and number of the slits 11 are adjusted so that the plug 4 can be easily fitted and the plug 4 does not come off after fitting. What is necessary is just to change suitably according to the material of 4 and the length of the shaft part 5.

If the stopper 4 is attached as described above, the stopper removal prevention part 9,
By virtue of 10, the plug 4 is mechanically fixed to the hole 3 of the drainage member 2, so that the liquefaction-preventing pile of the present invention does not come off during transportation or construction.

FIGS. 16, 17, 18 and 19 show another embodiment of the plug 4 with a filter. In these examples, the stopper shaft 5 has a truncated cone shape. The material of the stopper 4 and the characteristics of the filter 7 are the same as those in the above-described example. If there is a possibility that the filter 7 may be damaged, it is desirable to provide a filter protection member 8.

The embodiments shown in FIGS. 16 and 17 correspond to FIGS. 13, 14 and 15 respectively.
The shape of the shaft portion 5 is different from that of the embodiment shown in the figure, and the structure is such that the stopper preventing portion 10 at the tip is omitted. FIG. 18,
The embodiment shown in FIG. 19 is an example in which the detachment preventing section 9 is further removed from the embodiment shown in FIGS.

The plug 4 in these embodiments is inserted and inserted into the hole 3 of the drainage member 2 by pushing the shaft 5 with a required pushing force. At this time, the shaft portion 5 having the outer shape of a truncated cone receives a compressive force in its diameter direction, and the base portion also has a diameter substantially the same as that of the distal end portion. Therefore, a frictional force is generated between the peripheral surface of the shaft portion 5 and the inner peripheral surface of the hole 3, and the plug 4 is fixed to the hole 3 by the frictional force. Therefore, when the liquefaction-inhibiting pile of the present invention is erected in the ground, the plug 4 does not fall off and remains fixed to the hole 3 even if it receives resistance from the surrounding ground.

In order to more securely fix the plug 4 to the hole 3, the plug 4 may be fitted into the hole 3 after applying an adhesive to the peripheral surface of the shaft 5 of the plug 4.

In the case of the plug 4 shown in FIGS. 16 and 17, the plug 4 has a plug detachment prevention portion 9 on the surface side of the drainage member 2, and when the liquefaction prevention pile is constructed, the soil and the drainage member of the pile 1 are used. Even when the outer surfaces come into contact with each other, earth and sand are prevented from entering the through-hole 6, so that the filter 7 can be prevented from being damaged.

Since the examples shown in FIGS. 18 and 19 do not have plug removal prevention parts 9 and 10, when the penetration pressure of earth and sand is applied in the pile radial direction during the construction of the liquefaction suppression pile, or when the liquefaction suppression pile is put into service, In the case where the pile vibrates in the horizontal direction and the pressure of the earth and sand is applied in the pile radial direction, etc., the friction force between the outer peripheral surface of the shaft portion 5 of the plug 4 and the inner peripheral surface of the hole 3 of the drainage member 2 reduces the penetration pressure. You should consider whether you can resist. According to an experiment, it was found that a necessary resistance was obtained by appropriately adjusting the outer diameter of the plug shaft with respect to the hole of the drainage member. Further, in order to securely fix the plug in the hole of the drainage member, an adhesive may be used as described above. The example shown in FIGS. 18 and 19 has an advantage that the plug 4 does not have the plug removal preventing parts 9 and 10, so that the plug material can be reduced.

The above three types of plugs may be selected according to the conditions of transportation, construction, and service of the liquefaction prevention pile. Generally, it is easy to fit the drainage member into the hole, and the locking and fixing to the hole is reliable, and the stopper removal portions 9 and 10 shown in FIG. 13, FIG. 14 or FIG. If the stopper is used, it is possible to obtain a liquefaction-inhibiting pile that sufficiently satisfies predetermined performance and conditions.

In order to use the liquefaction suppression pile of the present invention for liquefaction prevention,
The situation of installation on the liquefied ground 21 is shown in FIGS. 24 and 25.

Liquefaction prevention piles A are installed at intervals necessary to prevent liquefaction of the ground. When a pile having a relatively small diameter is used, the pile diameter may be generally about 40 to 200 mm or more, and the interval between the piles may be generally about 200 to 3000 mm or more.
Liquefaction using high rigidity and strength materials such as steel pipes, steel / concrete composite pipes (for example, so-called SC piles or cast-in-place concrete-filled steel pipes filled with concrete), concrete piles, etc. Deterrent pile A
Liquefaction prevention pile A not only prevents the liquefaction ground 21 from liquefaction but also restrains the liquefaction ground 21 and stabilizes it. . In particular, when the ground surface or the liquefied layer lower surface is inclined, it has been confirmed that the ground may slip due to liquefaction, which may result in a catastrophic disaster. The effect will be exhibited.

In order to ensure the soil confinement effect of the liquefaction prevention pipe A, the liquefaction prevention pile A should be built up to the non-liquefied ground 22 with the liquefaction prevention pile A tightened, and the head of the liquefaction prevention pile A should be made of steel bar. ,
It may be tied with a binding material such as a shaped steel.

The liquefaction-inhibiting pile of the present invention can be directly driven into the ground by a vibro hammer, a diesel hammer, a hydraulic hammer, a press-fitting machine, or the like, and the construction is extremely simple. When installing a resin pipe with many small holes and a thin filter wound around the pipe that is easily broken around the ground, a steel pipe casing pipe is rotationally press-fitted with an auger and built up to a predetermined depth. After that, the resin pipe is erected to a predetermined depth through a casing pipe, then the casing pipe tip is opened, the casing pipe is pulled out from the ground, and the resin pipe is left in the liquefied layer. (This method is similar to the method in which the crushed stone is left in the liquefied layer of crushed stone and the crushed stone pile is provided in the ground in the conventional crushed stone drain method). However, in the conventional method, the outer diameter of the casing pipe (usually about 100 to 125 mm)
In the construction, there is a difference between the outer diameter of the resin pipe and the outer diameter of the resin pipe (usually about 50 to 100 mm), and the ground near the periphery of the resin pipe after being installed on the ground is inevitably loosened.

Loosening the liquefied layer before the installation of drainage pipes (perforated resin pipes, etc.) is to loosen the ground further because the main body is in a loose state and the danger of liquefaction is lost. The excess pore water pressure tends to increase in a short time. That is, the danger of liquefaction is further increased.

Therefore, the drainage pipes to be installed have a higher opening ratio, and unless the arrangement intervals are made closer, it becomes impossible to dissipate the excess pore water pressure of the ground in a short time.

On the other hand, if the opening ratio of the drainage pipe is increased, the rigidity and strength of the pipe are reduced, and the number of holes is increased, so that the cost becomes higher. Also, if the spacing between drain pipes is made closer,
The cost of liquefaction countermeasures increases, and the rate of ground loosening due to the installation of drainage pipes increases.

As described above, the conventional construction method of loosening and softening the liquefied ground during the installation of the drainage pipe has a significant drawback, and the liquefaction countermeasure effect can be said to be low. In addition, a shaking table test was conducted with a low-rigidity drain pipe installed on loose ground.
It was found that even if the drain pipes were arranged quite densely, the effect of preventing liquefaction of the ground was small.

Conventional drain pipes have a thin filter installed around the pipe to prevent sediment from entering the pipe, and this easily breakable filter breaks due to friction with the ground, so the drain pipe could not be driven directly into the ground .

However, the liquefaction-preventing pile provided with the plug according to the present invention has a structure in which the filter is not broken even if it is directly driven into the ground, and has a great feature.

Indeed, the particle size distribution range 0.05 to 2.0 mm, the average particle diameter D ₅₀ = 0.48
mm, a liquefaction-preventing pile with a large number of plugs of the present invention attached to the ground where the N value of the standard penetration test is 35 or less is hammered out, and then the liquefaction-preventing pile is pulled out, and the filter of the plug part is damaged. An experiment was performed to confirm that the filter was not damaged at all. The ground to be subjected to liquefaction countermeasures is usually a relatively loose ground having an N value of 15 or less, and the liquefaction inhibiting pile according to the present invention can withstand direct driving and has sufficient practicality.

Therefore, the liquefaction prevention pile of the present invention can be directly erected on a liquefied ground by a vibro hammer, a diesel hammer, a hydraulic hammer, a press-fitting machine, etc., without using a casing pipe as in the related art, and the ground is loosened. There is no.

FIGS. 27 and 28 show construction examples of the liquefaction inhibiting pile of the present invention.

FIG. 27 shows a pile driving machine 14 equipped with a hammer 15 such as a diesel hammer or a vibro hammer, and a liquefaction-inhibiting pile according to the present invention or a perforated pile or perforated pipe proposed by the inventors shown in FIG. 26. It shows the situation of standing on the ground.

FIG. 28 shows another construction method, in which a liquefaction-preventing pile or the above-mentioned perforated pile or perforated pipe is connected to a hydraulic excavator 14.
This shows a situation where the vibratory hammer 15a attached to a stands upright on the liquefied ground 21.

FIG. 29 shows an example in which the caisson structure 23 used as a seawall, a quay, etc. is reinforced by earthquake resistance. Regarding the ground 21a that may be liquefied under the rubble mound 24, the liquefaction-preventing pile A of the present invention is used to cope with a circular slip, but there is a possibility that liquefaction may occur on the back side of the caisson structure 23. As for the ground 21, as shown in FIG. 26 proposed by the present inventors as a liquefaction countermeasure pipe B, a hollow perforated pile or perforated pipe whose main body is made of steel, synthetic resin or the like may be used. Good. The arrangement of the liquefaction prevention pile A and the liquefaction prevention pipe B is only an example, and the caisson structure is used as another arrangement.
Liquefaction control piles can be provided around 23 appropriately.

FIG. 30 shows an example in which the liquefaction-preventing pile A of the present invention is used as a foundation pile of a building 25. In this case, the length of the pile portion provided with a plug in the drainage member to take measures against drainage generally needs to be not less than the thickness of the liquefied ground 21. However, if the liquefied ground 21 on which the foundation pile is installed is so thick that it is not necessary to prevent liquefaction over the entire liquefaction layer in terms of foundation pile design, Need not be longer than the liquefied layer thickness. Since the liquefaction-preventing pile A is used as the foundation pile of the building 25, a steel pipe or the like having a large holding strength is desirable as the pile, and a steel pipe for a building foundation pile generally has a pile diameter of about 400 to 800 mm.

In this case, as shown in FIG. 13, the liquefaction prevention pile A is used not only as the foundation pile of the building 25 but also as a liquefaction prevention pipe B.
May be provided on the ground around the building 25 to reinforce the building 25. Needless to say, the liquefaction prevention pipe B on the ground around the building and the liquefaction prevention pile A as the foundation pile of the building may have different specifications such as a pile diameter and a pile length. Further, as the liquefaction prevention pipe B provided around the building for earthquake-resistant reinforcement of the ground, a liquefaction prevention pipe having a structure different from that of the liquefaction prevention pile A of the present invention may be used. That is, as a liquefaction countermeasure pipe having a different structure, a hollow hole proposed by the inventor, having a number of small holes in the pipe body and providing a filter for preventing sediment inflow inside or outside the pipe. Stake or perforated pipe, liquefaction suppression pipe with a drain member integrated with the pipe around the pipe without drilling a hole in the pipe body, liquefaction with a drain member integrated with the surrounding of steel rod, etc. There are restraining members and the like.

Examples of the hollow holed pile or the holed tube proposed by the inventors include those having a structure as shown in FIGS. 26 (a) to 26 (d). Liquefaction countermeasure B in Fig. 26 (d)
Shows a state in which a cap 45 is provided at the upper end, but this cap 45 is made of synthetic resin or rubber, etc.
After the countermeasure pipe is directly cast on the ground, it has a structure to cover the top of the pipe in order to keep the inside of the pipe hollow.

The liquefaction countermeasure pipe B on the back side of the caisson structure in the embodiment shown in FIG. 29 may have the above-described structure.

For the seismic reinforcement of the ground around the building, the conventional liquefaction countermeasure method such as the sand compaction pile method or the vibration compaction method for compacting the ground may be used, or the crushed stone drain method, cement or lime may be used. Alternatively, a deep mixing method or a cutoff method using an underground continuous wall or steel sheet pile may be used.

FIG. 32 shows an example in which the liquefaction inhibiting pile of the present invention is applied as a foundation pile of a pier. In the event of an earthquake, pore water in the ground flows into the drainage member 2 through the plug 4 of the drainage member 2 and is discharged from the upper portion of the drainage member 2 to the upper side of the ground through the crushed stone portion 31 to prevent liquefaction of the ground. I do. Therefore, the horizontal ground reaction force of the pile can be reliably obtained in the ground, and a safe foundation can be provided. The material of the main body of the liquefaction prevention pile A is desirably a steel pipe or the like, and the liquefaction countermeasure part may be only a part of the foundation pile corresponding to the liquefaction ground 21. Also in this example, as the seismic reinforcement of the ground around the footing 26, the liquefaction-preventing pile A of the present invention may be used to enhance the seismic reinforcement of the foundation of the bridge.

Further, as shown in FIG. 33, as a reinforcement of the ground around the footing, a liquefaction countermeasure pipe B having a structure different from that of the liquefaction prevention pile A of the present invention is used in the same manner as in the case of the above-described seismic reinforcement of a building.
(The above-mentioned hollow holed pile or perforated tube proposed by the inventors (see FIG. 26), liquefaction suppression tube, liquefaction suppression member, etc.) may be used together, or conventional liquefaction countermeasures You may use a construction method together.

The pipe diameter of the liquefaction prevention pile A is determined from the examination of the foundation pile,
When the pile body material is a steel pipe, about 400 to 1400 mm is usually used in many cases. The liquefaction countermeasure pipe B may have the same structure as the liquefaction prevention pile A, but generally has a pipe diameter of, for example, 40 to 200 m.
The pipe may be made relatively small, such as about m. In this case, the pipe body material is preferably a steel pipe, but a synthetic resin pipe may be used as long as the pipe has predetermined rigidity and strength.

The method for discharging pore water from the ground during an earthquake through the liquefaction deterrent pile A to the outside of the ground may be the same as in the case of FIG. 32, but as shown in FIG. A drain pipe 32 having a hollow cross-sectional area necessary for the smooth discharge of interstitial water from the ground is installed, and this drain pipe 32 is piped into the footing 26 of the pier to discharge the interstitial water from the liquefied ground out of the ground. You may.

The liquefaction prevention pile A and the liquefaction countermeasure pipe B of the present invention can also be applied as seismic reinforcement of an abutment, which is a lower structure of a bridge, similarly to the application example to the pier described above.

As another application example, FIG. 34 shows an example in which a common groove is seismically reinforced using a liquefaction prevention pile A. When the surrounding ground 21 is liquefied during an earthquake, the common groove 33 provided in the liquefied layer receives an upward pressure and tends to float. As shown in Fig. 23, the use of liquefaction-preventing piles, which can be expected to have the same pull-out resistance even at the time of an earthquake, can significantly reduce the lifting effect compared to conventional countermeasures using ordinary piles. growing.

Slope walls such as those found in embankments generally have low seismic safety, but when embankments are installed on liquefied ground, the risk of embankment collapse is high, and liquefaction countermeasures are required.
In addition, in the case of embankments installed on the ground where the lower surface of the liquefaction layer is inclined, the embankment in the past collapsed and many catastrophic disasters occurred, so it is essential to take measures against liquefaction regardless of the new or existing embankment It is.

In the above case, as shown in Fig. 35, liquefaction-preventing piles and liquefaction countermeasures pipes can be cast on liquefied ground or embankment to ensure a liquefaction countermeasure.

FIG. 35 (a) shows an example in which a liquefaction inhibiting pile is cast on the liquefied ground 21 when the embankment 34 is constructed on the liquefied ground 21.
For example, if a liquefaction prevention pile made of steel pipe is used,
In addition to preventing liquefaction, the embankment 34 and the liquefied ground 21 can be prevented from sliding and destruction, and safety is enhanced.

FIG. 35 (b) shows an example in which a liquefaction-inhibiting pile is pierced through the embankment 34 to enhance the seismic reinforcement of the embankment 34. Also in this case, it is desirable that the anti-main body has strength and toughness like a steel pipe.

When the embankment is constructed, the risk of liquefaction is high in the liquefied ground near the embankment with a small loading load near the embankment. Therefore, as shown in FIGS. 35 (a) and (b), It is effective to erupt the liquefaction prevention pile on the liquefied ground 21 in this part. However, when it is difficult to place liquefaction-preventing piles below the embankment as in the case of existing embankments, Fig. 35 (c)
As shown in the figure, even if a liquefaction-preventing pile is placed on the side of the bank of the embankment 34, liquefaction of the side ground can be prevented, and the circular slip resistance can be increased.

FIG. 35 (d) shows that in addition to the seismic strengthening method shown in FIG. 35 (a), drainage of rainwater is performed using a liquefaction countermeasure pipe having the filter plug of the present invention attached to the slope wall of the embankment 34. In this example, the slope wall is prevented from collapsing due to intrusion of rainwater or the like, and the slope wall is reinforced with a tube material having strength greater than that of the material forming the embankment 34. As the liquefaction countermeasure pipe, a pipe made of a small-diameter steel pipe, which is proposed by the inventors and shown in FIG. 26, is preferable. Regardless of the embankment, as a method for reinforcing a slope wall that is likely to collapse due to rainwater or the like, the above-described small-diameter liquefaction prevention pipe can be used as a drain pipe and a reinforcing material for the slope wall. In this case, the liquefaction countermeasure pipe equipped with the plug of the present invention can be directly driven into the slope wall, and there is no clogging of the filter due to earth and sand, so that the effect can be expected permanently.

[Effects of the Invention] The liquefaction-preventing pile of the present invention can extremely easily fit and fix a plug provided with a filter in a hole of a drainage member having a hole without using an expensive machine. It is easy to manufacture.

In addition, since the filter is provided in the through hole of the stopper, the filter is hardly damaged.

Also, once fixed, it will not come off from the hole of the pipe due to impact, friction, etc. during transportation, construction, operation,
Quality is also guaranteed.

The stopper fixed to the hole of the drainage member of the liquefaction prevention pile has a filter in the through hole that is not clogged with soil and soil, and has high water permeability and high strength for preventing filter damage. By providing a protective member integrally with the main body of the plug, the filter can be prevented from being damaged during transportation, construction, and operation, and pore water in the ground can be smoothly discharged into the pipe during an earthquake.

In addition, by providing a slit in the plug body, the manufacturing error of the hole can be absorbed by utilizing the flexibility or elasticity of the plug body, and the hole can be easily fitted into the hole of the drainage member.
Further, by providing a stopper for preventing the stopper from detaching from the drainage member at the end of the stopper, it is possible to prevent the stopper from mechanically detaching from the hole of the drainage member.

The liquefaction-preventing pile of the present invention can be directly driven into the ground using a normal construction machine such as a vibro hammer, a hydraulic hammer, a diesel hammer, or a press-fitting machine without using a casing pipe or the like for protecting the filter. Construction work is extremely easy because pore water in the ground can be drained from the outer periphery of the pile body of the liquefaction prevention pile. Also, the ground is not loosened during construction.

[Brief description of the drawings]

1 (a) and 1 (b) are perspective views showing a main part of a liquefaction inhibiting pile according to the present invention, and FIGS. 2 (a) and (b) are perspective views and a horizontal cross section showing an embodiment of the present invention. Figures, FIGS. 3 (a) and 3 (b)
Is a perspective view and a horizontal sectional view showing a modification thereof, FIGS. 4 (a) and 4 (b) are perspective and horizontal sectional views showing still another modification, and FIG. 5 is a plug protection at a lower end portion of a drainage member. FIGS. 6 and 7 are vertical cross-sectional views showing an example of an installation state, FIG. 8 is a horizontal cross-sectional view when angle iron is used as a drainage member, FIG. Fig. 10 is a horizontal sectional view when a semicircular member is used as a drainage member, Figs. 10 (a) and 10 (b) are a horizontal sectional view and a perspective view showing another embodiment of the liquefaction inhibiting pile of the present invention, 11 (a) to 11 (c) are horizontal cross-sectional views and perspective views showing still another embodiment, and horizontal cross-sectional views of essential parts showing modifications thereof, and FIGS.
(B) is a horizontal sectional view and a perspective view showing still another embodiment, FIG. 13 is a vertical sectional view showing an example of a state where a plug is attached to a drainage member, and FIGS. 14 (a) to (c) are 13 is a side view, a front view and a rear view of the stopper shown in FIG. 13, and FIG. 15 is a vertical sectional view showing an example in which a filter protection member is provided on the stopper twice.
The figure is a vertical sectional view showing a mounted state in another embodiment of the stopper, FIGS. 17 (a) to (c) are a front view, a side view and a sectional view of the stopper of FIG. 16, respectively, and FIG. FIG. 19 (a) is a vertical sectional view showing a mounted state in still another embodiment.
(B) is a side view and a sectional view of the stopper in FIG. 18, respectively.
Fig. 20 is a graph showing the change over time of the excess pore water pressure ratio by the free damping wave excitation experiment, Fig. 21 is a graph showing the acceleration and displacement ratio of pipes (five arrangements) in the experiment on the liquefaction prevention pile, and Fig. 22
The graph shows the relationship between the horizontal resistance and the displacement of the loading plate in the experiment on the liquefaction control pile, FIG. 23 is the graph showing the pull-out resistance of the pile installed on the liquefied ground, and FIGS. FIG. 26 (a) is a plan view and a vertical cross-sectional view showing an example of disposing the liquefaction-inhibiting pile of the present invention on the ground where liquefaction may occur.
(D) is a perspective view showing an example of a hollow perforated pile or a perforated pipe which can be used together with the liquefaction suppressing pile of the present invention, FIG. 27 and FIG.
The figure is a vertical sectional view showing the state of driving the liquefaction-preventing pile into the ground, and FIGS. 29 to 34 and 35 (a) to (d) show the liquefaction-preventing pile according to the present invention. It is a vertical sectional view showing various examples in the case of also using as a pile etc. A: Liquefaction control pile, B: Liquefaction prevention pipe, 1 ... Pile body, 2 ... Drainage member, 2a ... Channel steel, 2b ...
… Angle steel, 2c… Semicircular member, 2d… Circular steel tube, 2e… Rib panel, 2f… Box box structural member, 3… Hole, 4…
Plug, 5 ... Shaft, 6 ... Through-hole, 7 ... Filter, 8
…… Filter protection member, 9,10 …… Plug release prevention part, 11…
... Slit, 12 ... Drainage channel, 13 ... Tip protection plate,
14 …… Excavator, 15… Vibro hammer, 16 ……
Protective metal fittings, 17 lid, 21, 21a liquefied ground, 22 non-liquefied ground, 23 caisson structure, 24 rubble mound, 25 building, 26 footing, 31 ... Crushed stone part, 32
…… Drain pipe, 33 …… Community ditch, 34 …… Embankment

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Michinobu Nishitani 1-3-1 Otemachi, Chiyoda-ku, Tokyo Sumitomo Metal Industries, Ltd. (56) References JP-A-2-132219 (JP, A) Kaihei 2-70028 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) E02D 3/10 101

Claims (5)

(57) [Claims] 1. A pile member having one or more drainage members forming a drainage channel along the longitudinal direction of the pile main body is provided on the outer peripheral surface of the pile main body, and at least liquefaction of the drainage member may occur. In a liquefaction suppressing pile formed by drilling a number of holes in a predetermined section facing a certain ground, a plug having an axial through-hole and a filter provided in the through-hole is provided to the drainage member. A liquefaction-preventing pile, which is attached to each of the drilled holes. 2. The liquefaction-preventing pile according to claim 1, wherein a water-permeable filter protecting member for preventing damage to the filter is provided in the through hole of the plug together with the filter. 3. A plug for a liquefaction-inhibiting pile according to claim 1, comprising a shaft portion having a through hole in an axial direction, and a filter provided in said through hole. 4. A plug for a liquefaction-inhibiting pile according to claim 3, wherein a through-hole of said shaft portion is provided with a filter protecting member having water permeability for preventing damage to the filter together with said filter. . 5. A detachment preventing portion having a diameter larger than a diameter of a hole formed in the drainage member is formed at both ends of the shaft portion, and at least one of the detachment preventing portions exerts a force. The plug of the liquefaction-inhibiting pile according to claim 3 or 4, wherein the plug is elastically deformed by this, and can be mounted in the hole of the pipe.