JPS5926725B2 - Open cylindrical sand pile construction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a construction method for side drain foundation piles (hereinafter referred to as foundation piles) constructed on soft ground.

Improving soft soil by embedding sand or aggregate from the surface of the ground to the depths, forming a series of sand or aggregate piles in the ground that extend vertically, and using these as foundation piles. This method is already known.

However, foundation piles made by directly contacting sand or aggregate into the ground become deformed and distorted when the ground is subjected to horizontal forces, and sometimes end up being cut midway. The drawback was that the drainage effect was lost.

Therefore, the inventor proposed filling a fiber bag with sand or aggregate and burying the bag in the ground.

This proposal is described in Japanese Patent Publication No. 47-18462 and Japanese Patent Publication No. 47-29852.

In the above publication, it is necessary to use a fiber bag,
The bag is filled with sand or aggregate and then buried in the ground.

Therefore, the foundation pile formed in this way is covered with the bag even the lower end, and as a result, the entire surface is covered with fibers.

This is natural considering that the purpose of this was to prevent the foundation piles from deforming and distorting when the ground moved horizontally, and considering that in the early stages, thorough efforts were made to prevent deformation and distortion. Ta.

This inventor obtained various cheetahs by implementing the above method, and published the magazine "Construction" Vol. 8 No. 4 (
The method was technically explained on pages 67 to 75 (Published by Heavy Chemical Industry News Agency, April 1970).

It states that a strong bag should be used to fill the sand, and also shows a cross-section of the end of a pile when building a pile, stating that the end of the fiber cylindrical body must be closed. revealed.

In addition, a chart showing the results of pile loading tests has been published, but even from the shape of the chart, it is clear that the tip of the fiber cylinder must be closed.

Therefore, according to the description in this magazine, foundation piles must be covered with a bag even to the bottom end, and the entire surface must be covered with fibers.

Apart from the above-mentioned publication, Japanese Patent Publication No. 45-3006 also describes a method for constructing sand piles.

This construction method also involves covering the entire side of the sand pile with rigid pipes.

This is because this construction method first involves driving a hollow tube to a predetermined depth, then inserting a permeable tube into the hollow tube, filling the permeable tube with sand, and pulling out the hollow tube. This is because it emphasizes that the hollow tube is easy to pull out because the hollow tube and sand are not in direct contact during drawing.

Furthermore, although FIG. 3 of this publication shows that the lower part of the pile is constricted, in order to prevent this constriction, even the lower part must be covered with a water-permeable pipe.

This construction method also teaches that rigid pipes should be used as permeable pipes.

As described above, in the conventional sand pile, the entire side surface of the sand pile is covered with a bag or a water-permeable pipe.

The purpose of covering all the sides of the sand pile is that, as mentioned above, the purpose of the conventional method is to prevent the sand pile from being deformed and distorted due to the horizontal movement of soft ground. However, it was thought that if the sand piles were exposed, there would be more opportunities for the sand piles to become deformed and distorted, causing problems.

In addition, it is thought that conventional sand piles do not have sufficient strength as piles just by letting sand, etc. fall naturally, so it is thought that it is necessary to strongly compress the sand, etc. vertically, and do what is called compaction. I came here.

Naturally, where the man-made sand pile comes into contact with a layer of sand or gravel before compaction, there is no need to cover the sides of the sand pile with bags or permeable pipes.

The inventor discovered that even if the sand pile is not compacted, there is no need to cover the lower part of the sand pile with a pipe or bag.

This is because it has been found that even in soft ground, horizontal movement of the ground at depth is small.

Not only that, but if the sand is left exposed without attaching a pipe or bag to the bottom of the sand pile, the water absorption of the bottom of the sand pile will increase.
I found a good result.

This invention was made based on such knowledge.

In addition, the inventor also described the following as a cover for the upper part of the sand pile:
I learned that the rigid water-permeable pipe recommended in Japanese Patent Publication No. 45-3006 is rather inappropriate.

This is because a rigid tube becomes difficult to handle if it becomes long.

In addition, if a permeable pipe is inserted into a hollow pipe above ground and then the hollow pipe is driven underground, the permeable pipe does not need to be rigid, and it may be more convenient if it is flexible. Understood.

Therefore, the present invention uses a fiber mesh fabric, etc. previously proposed by the present inventor, to cover the upper part of the sand pile, and a flexible fiber cylindrical body with open upper and lower ends. I decided to use it.

This invention involves first inserting a flexible cylindrical body made of fiber with open upper and lower ends into a hollow tube having an inlet for alligator sand or aggregate at one end, and then closing the bottom end of the hollow tube. , the hollow tube is inserted into the ground with the closed end facing down, and then sand or aggregate is poured from the inlet of the hollow tube, and the sand or aggregate is passed through the fiber tubular body and the sand or aggregate is lowered from the tubular body. The sand or aggregate piles are dropped into the tube and filled into the tube, forming a series of sand or aggregate piles that extend downwardly through the fiber tube, after which the two ends are opened and the hollow tube is pulled out. This provides a construction method for foundation piles, which is characterized by the removal of foundation piles.

Hereinafter, the present invention will be explained based on the accompanying drawings.

As shown in Figure 1, the foundation pile constructed by the method of this invention is one in which piles of sand or aggregate 4 are formed in soft ground A and extend vertically in series from the surface of the ground to the depths. It is.

This pile is constructed by depositing sand or aggregate by natural falling.

This pile consists of an upper pile part 1 and a lower pile part 2, the upper pile part 1 being surrounded by a flexible fiber cylinder 3 with open upper and lower ends, so that in the upper part there is no sand or aggregate (
Hereinafter, this will be referred to as sand, etc.) 4 is in contact with the ground A via the fiber cylindrical body 3.

Further, in the lower pile portion 2, sand etc. 4 is in direct contact with the ground A.

Next, the construction method for the above-mentioned foundation pile will be explained.

First, the flexible cylindrical body 3 made of fiber is inserted into the hollow tube 5 on the ground.

That is, as shown in FIG. 2, two lifting wires 6 are inserted into the hollow tube 5, and the lower end opening 1 of the hollow tube
A basket-shaped clamping device 8 is engaged with the lower end of the wire 6, and the open upper end opening of the flexible cylindrical body 3 is fitted into the lower end of the clamping device 8 and locked.

The lower end of the hollow tube 5 is provided with a tip shoe 9 that opens and closes naturally or hydraulically.

Further, at the upper end of the hollow tube 5, as shown in FIG. 4, there is a vibrator 10, an inlet 11 for sand, etc. and a winder 12 for the wire 6
, 12' are provided.

In this way, these as a whole constitute a sand pile making device.

As shown in FIG. 4A, the flexible fiber-made body 3 is made by placing the hollow tube 5 on the ground and driving the winders 12, 12' so that the lower end thereof is inside the hollow tube 5. inserted from.

When the flexible fiber cylindrical body 3 is inserted into the hollow tube 5, the tip shoe 9 is closed, as shown in FIG. 4B.

In this case, the fiber cylindrical body 3 may be suspended within the hollow tube 5 as shown in FIG. 4B, and the lower end of the cylindrical body 3 may be located in the middle of the hollow tube 5. As shown in FIG.
The lower end of the cylindrical body 3 may be held by the tip of the shoe 9.

Next, the vibrator 10 is started, and the sand pile construction device in the above state is press-fitted or driven into the ground A to a predetermined depth, as shown in FIG. 4C.

In this way, as shown in the fourth diagram, when the tip of the hollow tube reaches a predetermined depth, the press-fitting or driving is stopped.

When the lower end of the fiber cylindrical body 3 is located in the middle of the hollow tube 5, it may remain as it is, but when the lower end of the cylindrical body 3 is sandwiched between the tips of the shoes 9, the lower ends of the shoes 9 may be After loosening the tightening and opening the lower end of the cylindrical body 3, the lower end of the cylindrical body 3 is made free, and then the wire 6 is applied to move the cylindrical body 3, and the lower end of the cylindrical body 3 is made hollow. It is placed at a suitable location in the middle of the tube 5.

Thereafter, sand or the like is poured into the hollow tube 5 from the inlet 11 of the hollow tube 5.

At this time, the fiber cylindrical body 3 is maintained in a state in which the upper end is expanded by the clamping device 8 and is held concentrically with the hollow tube 5, so that sand, etc. falls through the cylindrical body 3. .

The lower end of the cylindrical body 3 is open, and the lower end is connected to the hollow tube 5.
Since the sand is located in the middle of the tube, the fallen sand passes through the cylindrical body 3 and accumulates downward, directly contacting the hollow tube 5 and forming a sand pile by natural fall.

Further, as the inflow of sand, etc. continues, the sand, etc. fills the inside of the fiber cylindrical body 3.

This forms a series of sand piles extending downwardly through the fiber tube.

When sand or the like is allowed to flow into the hollow tube 5, the shoe 9 of the naturally open type will open naturally.

If the shoe 9 is operated by hydraulic pressure, the shoe 9 is opened by hydraulic pressure.

Thereafter, the sand pile making device is pulled up and the hollow pipe 5 is pulled out from the ground A.

Then, as shown in Fig. 4E, a cylindrical body? The sand and the like 4 remain in the soft ground A, where the exposed lower pile portion 2 of the sand pile first appears, and then the upper pile portion 1 surrounded by the fiber cylindrical body 3 appears.

In this way, the hollow tube 5 is pulled up to the state shown in FIG. 4F, and the clamping device is positioned outside the hollow tube 5.

After that, when the fiber cylindrical body 3 and the clamping device 8 are uncoupled,
The cylindrical body 3 leaves the sand pile making device.

Therefore, when the sand pile construction device is removed, the foundation pile according to the present invention will be constructed here.

In the above-mentioned construction process, in order to ensure that sand etc. enters the fiber cylindrical body 3, a separate inner pipe is attached to the lower part of the inlet 11, and the fiber cylindrical body 3, which is the inner pipe, is It is preferable to insert it into the upper end opening so that sand etc. from the inflow port flows into the cylindrical body 3 through the inner tube.

The foundation pile constructed by the method of the present invention is a sand pile formed by simply depositing sand or aggregate by natural fall.

This foundation pile is suitable for improving ultra-soft ground with a high moisture content and high sensitivity ratio.

Since the fiber cylindrical body surrounds the top of the sand pile, it will not deform or distort even if it moves horizontally on soft ground.

The lower part of the sand pile is not surrounded by the fiber cylinder, but because the horizontal movement is small in the lower part of the soft ground,
Not affected by deformation and distortion.

Moreover, since the sand piles are in direct contact with the ground at the bottom,
It has a large water absorption capacity and therefore a strong drain effect.

Since the length corresponding to the lower part of the fiber cylindrical body can be saved in the soil, the cost for installing foundation piles can be reduced.

This foundation pile has the advantages mentioned above.

Furthermore, since the method of this invention uses a flexible cylindrical body made of fibers, it can be bent and folded freely, making it easy to handle the cylindrical body. Can be used.

Furthermore, since the fiber cylindrical body is first inserted into the hollow tube and then the hollow tube is inserted into the ground, the cylindrical body is flexible and The cylindrical body can be easily inserted into a hollow tube, and the cylindrical body can be reliably positioned at a desired position within the hollow tube.

In addition, when inserting the cylindrical body into the ground by holding it with the shoe at the end of the hollow tube, pull up the cylindrical body within the hollow tube after driving it into the ground. It can be brought to the position reliably.

After the hollow tube is inserted into the ground in this way, sand or the like is allowed to flow in, so that the foundation pile can be reliably installed at a predetermined position.

In addition, sand piles are constructed by simply allowing sand or aggregate to fall and accumulate, making them most suitable for improving ultra-soft ground with a high water content and a high sensitivity ratio, and it is easy to construct sand piles. .

In short, the method of the present invention has the advantage that a foundation pile whose only upper part is covered with a cylindrical body made of fiber can be easily and reliably attached.

[Brief Description of the Drawings] Fig. 1 is a partially cutaway front view of a foundation pile constructed by the method of the present invention, and Fig. 2 is a cross section showing one mode of inserting a fiber cylindrical body into a hollow pipe. FIG. 3 is a partially cutaway sectional view of a hollow tube showing a mode in which a cylindrical body made of fiber is fixed to the tip of the hollow tube. FIG. 4 is a model diagram showing the construction process. In the figure, 1 is an upper pile part, 2 is a lower pile part, 3 is a cylindrical body made of fiber, 4 is sand, etc., and 5 is a hollow tube.

Claims (1)

[Claims] 1. Insert a flexible cylindrical catfish made of fibers with open upper and lower ends into a hollow tube with an inlet for alligator sand or aggregate at one end, then close the other end of the hollow tube to close the closed end. Insert the hollow tube into the ground with the top facing down, then pour sand or aggregate from the inlet of the hollow tube, pass through the fiber cylindrical body, and let the sand or aggregate fall below the cylindrical body. Characteristics of filling the tube and forming a series of sand or aggregate piles extending downwardly through the fiber tube, then opening the two ends and withdrawing the hollow tube. A construction method for sand drain foundation piles.