JPH06235215A - Liquefaction preventing pile and method of construction using this pile - Google Patents

Abstract

PURPOSE:To obtain a stabilized liquefaction preventing function, and to improve the supporting function by forming a drain layer integrally with the peripheral surface of an existing pile, of bags filled with draining material such as ballast, and inserting the pile into an excavated pile hole. CONSTITUTION:A liquefaction preventing pile 10 formed with a drain layer 40, which is formed of bags 30 filled with the draining material, is inserted into a pile hole H. At this stage, existing piles 20 are joined together at need and located underground, and the upper end is hit lightly to insert the existing piles 20 and the draining material into a fixed ground G for fixation. Pore water of the underground starts to permeate the draining material through the bags 30 immediately after the execution, and the pore water is drained over the ground through water passages formed among the draining material. The pore water of the underground is thereby drained over the ground to prevent the liquefaction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention relates to a foundation pile for civil engineering construction,
In particular, the present invention relates to a structure having both a function of supporting a building and a function of preventing liquefaction of the ground.

[0002]

2. Description of the Related Art Conventionally, the following three construction methods are known as measures for preventing liquefaction of the ground. A so-called gravel drain construction method in which gravel is installed in a columnar shape (for example, JP-A-63-315721, JP-B-62-48008, etc.) Japanese Patent Laid-Open No. 2-225710, etc.) A so-called sealing method for driving the node piles while filling gravel between the nodes of the node piles.

[0003]

However, the above-mentioned conventional method has the following problems. Problems of Conventional So-called Gravel Drain Construction Method Although the above-mentioned conventional so-called gravel drain construction method is effective as a countermeasure against liquefaction, it does not have a building supporting function by itself.

For this reason, construction of the construction method and construction of piles must be performed separately on the same site, which requires double construction time, making it difficult to shorten the construction period and reducing construction costs. However, there was a problem in that Problems of the conventional method of installing a perforated pipe The above-mentioned method of installing a conventional perforated pipe, like the above-mentioned conventional gravel drain method, is effective as a countermeasure against liquefaction, but easily causes clogging. Therefore, there is a problem that a sufficient drain effect cannot be expected.

Further, if a large number of water drainage holes are formed in the side wall of the pipe, the strength of the pipe itself is lowered, so that it is used only as a drain pipe or as an antibody by making the pipe itself excessively thick. I needed to be able to. Problems of conventional so-called sealing method The above-mentioned conventional so-called sealing method has both a function of supporting a building and a function of preventing liquefaction of the ground.

However, due to noise and vibration pollution associated with pile driving,
There was a problem that the construction method could not be used in most areas such as densely built areas. In addition to this, it is necessary to fill a necessary and sufficient amount of gravel between the nodes when driving the node piles, but the gravel was ubiquitous. Therefore, the liquefaction prevention piles and the construction method using the liquefaction prevention piles according to claims 1 and 2 are made in view of the problems of the above-described conventional construction method, and the purpose thereof is a bag. It is possible to prevent the drain material such as gravel from being lost by the body and to fill the necessary and sufficient drain material, and as a result, to easily obtain a stable liquefaction preventing function and a supporting function.

[0007]

The present invention is to achieve the above-mentioned object, and the contents thereof will be described below with reference to the embodiments shown in the drawings. The liquefaction prevention pile (10) according to claim 1, wherein the drain layer (40) is integrally formed on the peripheral surface of the ready-made pile (20) with a bag body (30) filled with a drain material such as gravel. Is characterized by.

According to the construction method of claim 2, after the drain layer (40) is integrally formed on the peripheral surface of the prefabricated pile (20) with the bag body (30) filled with the drain material such as gravel, A feature is that a ready-made pile (20) having a drain layer is inserted and embedded in a pile hole (H) that has been excavated in advance.

[0009]

According to the liquefaction prevention pile (10) of claim 1, the pile (10) is inserted and embedded in the pile hole (H) previously excavated, so that the structure has a supporting function and a liquid state. Anti-aging function can be obtained. That is, ready-made piles (20) buried in the ground (G)
Has a function of supporting a building.

Further, the drain layer (40) made of the drain material on the peripheral surface of the ready-made pile (20) can drain the pore water in the ground to the ground. According to the pile (10) constructed by the construction method according to the second aspect, it is possible to obtain the support function and the liquefaction prevention function of the building, like the liquefaction prevention pile according to the first aspect.

[0011]

1 to 4 show a first embodiment of the present invention, FIG. 1 is an explanatory view showing a state in which a liquefaction prevention pile is inserted into a pile hole, and FIG. 2 is a liquefaction prevention pile. FIG. 3 is a side view showing the appearance of the liquefaction prevention pile, and FIG. 4 is an explanatory view showing a state in which the liquefaction prevention pile is buried in the ground.

In FIG. 1, reference numeral 10 denotes a liquefaction prevention pile, which is roughly classified into a ready-made pile 20 and a bag body 30 that is slightly larger than the ready-made pile 20 and encloses the ready-made pile 20. This bag 30
And a drain material such as gravel filled in a gap between the bag 30 and the ready-made pile 20. For the ready-made pile 20, for example, a node pile having a high friction supporting force is used. For example, the maximum diameter is 4
Knot piles with a length of 4 cm and a total length of 12 m are used.

The ready-made pile 20 is not limited to the node pile, and although the friction supporting force is inferior to that of the node pile, a straight round pile, a straight square pile, a tapered pile or the like can also be used. The bag body 30
As shown in FIG. 1, it has a cylindrical shape and its inner diameter is set to be larger than the maximum diameter of the ready-made piles 20, for example, 55 cm. Then, the bag body 30 has an upper surface opened and a lower surface closed by a bottom portion, and the ready-made pile 20 is inserted into the bag body 30 by utilizing, for example, an open upper surface of the bag body 30. Also,
The total length of the bag body 30 is set to be substantially equal to the total length of the ready-made piles 20.

The bag body 30 is not limited to a cylindrical shape and may be formed in a rectangular tube shape. In terms of strength of the bag body 30, the pile
It suffices if the drain material can be held and held until the 10 is inserted and installed in the pile hole H. In terms of the material of the bag body 30, it is preferable that it has sufficient water permeability, and, for example, a sewn woven fabric or a non-woven fabric, a seamlessly knitted fiber, or a wire net can be used. Further, it is preferable that the weave or the stitch of the bag body 30 or the mesh of the wire mesh is within a range in which the drain material does not drop.

Further, it is possible to use a water-impermeable material, but after the pile 10 is inserted into the pile hole H, it is easily damaged by friction with the surrounding ground G by light hitting, and water permeability can be secured. ,
Alternatively, a substance that corrodes in a short period of time or a substance that can be dissolved by absorbing water can be used. The drain material is preferably natural gravel or crushed stone. In addition, waste construction materials, slag, etc. can be used as the drain material.

In particular, a concrete type of construction waste material, particularly lightweight foam concrete, is preferable from the viewpoint of effective use of the waste material and weight reduction of the drain material. Pile with the above configuration
The manufacturing method of 10 will be described below. First, the ready-made pile
As shown in FIG. 2, 20 is inserted inside the bag body 30 from the upper surface of the opening. Then, the drain material is filled into the gap between the inner peripheral surface of the bag body 30 and the outer peripheral surface of the ready-made pile 20 from the upper surface of the opening of the bag body 30.

Then, the drain material is preferably filled in the outer peripheral surface of the prefabricated pile 20 with a substantially uniform thickness. In addition, you may make it exist unilaterally on one side or both sides of the ready-made pile 20 as needed. Further, only the ready-made pile 20 is put inside the bag body 30, and in this state, the bag body 30 and the ready-made pile 20 are hung and inserted into the pile hole H, and then the drain material is inserted from the upper surface of the opening of the bag body 30. May be filled.

By filling the drain material as described above, the drain layer 40 can be integrally formed on the peripheral surface of the ready-made pile 20 by the bag body 30 filled with the drain material such as gravel. In addition, to prevent the drain material filled in the bag body 30 from spilling,
As shown in FIG. 3, the open end of the bag body 30 may be bound and held by a wire, a string, or the like. Further, the bag body 30 is deformed by the weight of the drain material, and the drain layer 40 on the peripheral surface of the ready-made pile 20 is
In order to prevent the bag 30 from becoming rough or dense depending on the place, it is advisable to hold several parts in the height direction of the bag body 30 in a bundle with a wire, a string or the like.

Next, a method of constructing the liquefaction prevention pile 10 having the drain layer 40 described above will be described. Liquefaction prevention pile 10
Is buried in the adaptive ground G by the so-called pre-boring method, as shown in FIG. As shown in FIG. 4, first, the liquefaction prevention pile 10 is applied to the adaptive ground G with an earth auger or the like.
The pile hole H that can be sufficiently inserted is excavated. The inner diameter of the pile hole H at this time is set equal to or slightly larger than the outer diameter of the bag body 30 of the liquefaction prevention pile 10.

Then, as shown in FIG. 1, the liquefaction prevention pile 10 is suspended and inserted into the hole H of the pile. If the ready-made piles 20 need to be joined together, the ready-made piles 20 may be installed in the ground while being joined together. Finally, although not shown, the upper end of the prefabricated pile 20 is tapped with a monken or the like, and the impact completes the adaptation of the prefabricated pile 20 and the drain material to the surrounding ground G.

Of course, the so-called MT method of injecting cement milk into the bottom of the pile hole to solidify it, or any other known method may be used. Thus, the drain layer 40 formed of the drain material with which the bag body 30 is filled is formed between the prefabricated pile 20 and the surrounding ground G. Therefore, the drain layer 40 can drain the interstitial water in the ground to the ground and prevent liquefaction.

That is, immediately after the construction,
It permeates the drain material through the bag body 30 and is drained to the ground through a water channel (not shown) formed between the drain materials.
Therefore, even if an earthquake or the like occurs immediately after construction, liquefaction can be effectively prevented. It should be noted that when the ready-made pile 20 is tapped, the bag body 30 may be damaged by friction with the surrounding ground G. In this way, if the bag body 30 is damaged,
It is possible to prevent deterioration of water permeability due to clogging of the bag body 30.

If the bag body 30 is corrosive or water-soluble, if it stands for a while after the construction, the bag body 30 will be corroded or dissolved and disappear, so that the pore water in the ground will become drainage material. It permeates directly and is discharged to the ground. In addition, the pile 10 was installed on the sand ground that is likely to be liquefied by the above-mentioned construction method, and after carrying out a load test, it was left as it was.

[0024] After that, after the occurrence of the earthquake, it was observed that the main pile 10
Liquefaction had not occurred in the vicinity. Further, after that, when the loading test was performed again, the bearing capacity was 1.15 times the initial value. It is considered that this is due to the drainage of water from the surrounding ground G and the change over time in the frictional force.

5 and 6 show another embodiment of the present invention. FIG. 5 is a partial cross-sectional perspective view of the bag body, and FIG. 6 shows a state in which the bag body is wound around a prefabricated pile. Partial side views are respectively shown. The feature of this embodiment is that the bag body 30 is divided into a plurality of parts. That is, as shown in FIG. 5, the bag body 30 has a bale shape with one end opened, and after filling the drain material from the open end, the open end is sealed. Then, the bag bodies 30 are connected in a string to form a band.

As shown in FIG. 6, the bag body 30 connected in the form of a band is fixed by spirally winding it around the outer circumference of the ready-made pile 20.
According to the present embodiment, since the bag body 30 can be divided, not only the strength of the bag body 30 can be reduced, but also the manufacturing thereof and the fixing to the ready-made pile 20 can be easily performed.

[0027]

Since the present invention is constituted as described above, it has the following effects. Claim 1
According to the liquefaction prevention pile and the construction method using the liquefaction prevention pile according to claim 2, the bag body prevents the drain material such as gravel from falling off, and thus a necessary and sufficient drain layer is formed in advance on the peripheral surface of the ready-made pile. it can. As a result, a stable liquefaction preventing function and a supporting function can be easily obtained.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a state in which a liquefaction prevention pile according to a first embodiment is inserted into a pile hole.

FIG. 2 is a sectional view of an essential part of the liquefaction prevention pile according to the first embodiment.

FIG. 3 is a side view showing the appearance of the liquefaction prevention pile according to the first embodiment.

FIG. 4 is an explanatory diagram showing a state in which the liquefaction prevention pile according to the first embodiment is buried in the ground.

FIG. 5 is a partial cross-sectional perspective view of a bag body according to a second embodiment.

FIG. 6 is a partial side view showing a state in which the bag body according to the second embodiment is wound around a prefabricated pile.

[Explanation of symbols]

 10 Liquefaction prevention pile 20 Ready-made pile 30 Bag body 40 Drain layer G Ground H Pile hole

Claims (2)

[Claims] 1. A liquefaction prevention pile, characterized in that a drain layer is integrally formed on a peripheral surface of a ready-made pile with a bag body filled with a drain material such as gravel. 2. After the drain layer is integrally formed on the peripheral surface of the ready-made pile with a bag body filled with a drain material such as gravel,
A method for constructing a liquefaction prevention pile, characterized in that a ready-made pile having this drain layer is inserted and buried in a pile hole dug in advance.