JP2003147756A - Compacted sand pile creating construction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an efficient compacted sand pile creating construction method and a device capable of smoothly discharging a sand pile material from a hollow pipe, and capable of obtaining optimal compacted sand pile strength. SOLUTION: This construction method creates a compacted sand pile in the weak ground by successively repeating an extracting process of discharging the sand pile material 2 in the hollow pipe 1 to a extraction trace by extracting the hollow pipe 1 by the proper length after intruding the hollow pipe 1 up to the prescribed depth and a process of re-intruding the hollow pipe 1 up to reaching the ground surface. Water is added so that a discharge quantity in the ground of the sand pile material 2 existing in the hollow pipe 1 before the extracting process becomes within ±5% of the optimal moisture content ratio of the sand pile material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compaction sand pile construction method and device having excellent compaction effect.

[0002]

2. Description of the Related Art A compacted sand pile construction method is known as a method for improving the ground by placing sand piles in soft ground such as sand ground. This compacted sand pile construction method is
After the hollow pipe filled with the sand pile material is penetrated to a predetermined depth, the hollow pipe is pulled out to an appropriate length, and the pulling step of discharging the sand pile material in the hollow pipe to the pulling trace, and the hollow pipe. Repeat the process of re-penetration until it reaches the surface,
This is a method of constructing compacted sand piles in soft ground. In the compaction sand pile construction method, it is also known that the maximum compaction effect is exhibited if the sand pile material cast in soft ground is compacted in the vicinity of the optimum water content ratio of the sand pile material. .

Conventionally, as a method of adjusting the sand pile material cast in soft ground to near the optimum water content ratio of the sand pile material,
Before the sand pile material was put into the hollow pipe, it was adjusted at a predetermined adjustment facility or plant at the construction site. That is, in advance, the water content of the sand pile material to be used is subtracted from the original water content of the sand pile material to replenish and adjust the water content, and then the adjusted sand pile material is applied to the hollow pipe. I was throwing in.

[0004]

However, the method of adjusting the sand pile material to the vicinity of the optimum water content ratio before the sand pile material is charged into the hollow tube is the drop force generated when the sand pile material is charged into the hollow tube from the hopper. Since the hollow pipe is compacted by the pressure and vibration in the pipe, there is a problem that the sand pile material is difficult to be discharged from the hollow pipe in the drawing process. In order to forcibly discharge such a sand pile material from the hollow pipe, the supply air for extraction can be made to flow at a high pressure or in a large amount. But,
In this method, there is a problem that the jetted supply air after the sand pile material is discharged damages the existing adjacent sand piles. Further, there are many troublesome problems such as installation costs of plants and adjustment facilities and management of adjustment methods.

Therefore, an object of the present invention is to efficiently discharge compacted sand pile material from a hollow pipe and to obtain an optimum compacted sand pile strength, and an efficient compacted sand pile construction method and method. To provide a device.

[0006]

Under such circumstances, as a result of intensive investigations by the present inventors, in a construction method for constructing a compacted sand pile in soft ground, the sand pile existing in the hollow pipe before the drawing step If water is added to the amount of material discharged into the ground or to the sand pile material in the process of being discharged in the extraction process so as to be within ± 5% of the optimum water content ratio of the sand pile material, sand It is possible to discharge the pile material from the hollow pipe without difficulty, and it is possible to obtain the optimum compaction sand pile strength, and as a result, it is possible to reduce the number of sand piles and to perform efficient construction. The present invention has been completed.

That is, according to the present invention (1), after the hollow pipe is penetrated to a predetermined depth, the hollow pipe is pulled out to an appropriate length, and the sand pile material in the hollow pipe is discharged to the withdrawal trace,
The process of re-penetrating the hollow pipe is repeated sequentially until reaching the surface of the earth, and in the method of constructing a compacted sand pile in soft ground, in the ground of sand pile material in the hollow pipe before the drawing step The amount of discharge is ± of the optimum water content of the sand pile material.
The present invention provides a method for constructing compacted sand piles in which water is added so that the content is within 5%. According to the present invention, with respect to the sand pile material that has been put into the hollow tube and before the drawing step, the sand pile material is watered so as to have an optimum water content ratio, so that the sand pile material is not yet compacted. Not in. Therefore, the sand pile material can be easily discharged from the hollow pipe as compared with the conventional case where the sand pile material is put into the hollow pipe after being adjusted to the vicinity of the optimum water content ratio. In addition, since the sand columns placed in the extraction trace in the extraction process are in the vicinity of the optimum water content ratio, it is possible to obtain sand piles with optimum compaction strength during subsequent re-penetration. Since one sand pile has the optimum compaction strength, the number of sand piles in the entire construction area can be reduced as compared with the conventional one, and construction efficiency is improved.

The present invention (2) further comprises a drawing step in which, after the hollow tube is penetrated to a predetermined depth, the hollow tube is drawn out to an appropriate length, and the sand pile material in the hollow tube is discharged to the drawing mark. In the method of constructing compacted sand piles in soft ground by repeating the step of re-penetrating the hollow pipe in order, until the surface of the ground, water is added to the sand pile material in the process of being discharged in the extraction step, and then pulled out. The sand column formed in the trace provides a compaction sand pile construction method in which the optimum water content of the sand pile material is within ± 5%. According to the present invention, in addition to exhibiting the same effect as the above-mentioned invention, the sand pile material in the middle of discharging in the drawing step is hydrolyzed so as to have the optimum water content ratio, so that the sand pile material can be easily removed from the hollow pipe. Can be discharged.

Further, in the present invention (3), the water addition is performed by an inner jet ejector having an injection port on the inner wall of the hollow tube which is in contact with the discharged amount of the sand pile material charged in the hollow tube. (1) The compaction sand pile construction method described in (1) is provided. According to the present invention, the effect achieved by the invention described in (1) can be obtained by a simple method of injecting water from the inner jet ejector.

Further, the present invention (4) provides the compacted sand pile construction method according to (2), wherein the water addition is performed by an inner jet or an inner jet ejector having an injection port on the inner wall near the tip of the hollow tube. It is provided. According to the present invention, the effect of the invention described in (2) can be obtained by a simple method of injecting water from the inner jet or the inner jet ejector attached to the tip of the hollow pipe.

Further, the present invention (5) comprises a drawing step in which after the hollow tube is penetrated to a predetermined depth, the hollow tube is drawn to an appropriate length, and the sand pile material in the hollow tube is discharged to the drawing trace. The step of re-penetrating the hollow pipe is sequentially repeated until reaching the surface of the earth, which is a construction device for forming a compacted sand pile in soft ground, and the tip of the sand pile material put into the hollow pipe. One or more inner jet ejectors having an injection port are provided on the inner wall of the hollow pipe which is in contact with one discharge amount on the side, or an inner jet or an inner jet having an injection port on the inner wall near the tip of the hollow pipe is provided. The present invention provides a compacted sand pile forming device which is provided with a jet ejector. According to the present invention, the invention described in (1) or (2) above can be reliably carried out by using the forming apparatus having a simple structure.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a compaction sand pile construction method and an apparatus used in the construction method according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective view of a distal end portion of a hollow tube used in the compaction sand pile construction method of the present example, and FIG. 2 is a diagram illustrating the compaction sand pile construction method of the present example. . The hollow pipe 1 used in the compaction sand pile construction method according to the first embodiment is one amount of the sand pile material put into the hollow pipe 1 which is placed in the extraction trace, that is, Inner jet ejectors 3a, 3b for water supply having jet ports 32a, 32b at two positions, a lower position 7a and an upper position 7b, of an inner wall 7 of the hollow pipe 1 which is in contact with the sand pile material 2 corresponding to the sand removal height h. It is equipped with.

The inner jet ejectors 3a and 3b are not particularly limited, and known ones can be used. In this example, the inner jet ejectors 3a and 3b are a water jet generator with a built-in ejector (not shown), one end of which is connected to the water jet generator, and the other end of which is arranged in the longitudinal direction of the circumferential surface of the hollow tube 1. A jet port 32 extending along the tip
The water jet pipes 31a and 31b are attached so that a and 32b are directed toward the inside of the hollow pipe 1. That is, compressed air accompanied by water is ejected from the ejection ports 32a and 32b. The ejector is a mechanism in which water is drawn into the compressed air flow and is entrained to supply a mixed flow of compressed air and water.
In addition to the above, the installation location may be such that it is installed near the ejection ports 32a and 32b. Moreover, if the ejection port of the inner jet ejector is installed on the inner wall 7 corresponding to the sand removal height h of the hollow tube 1, the number of installations, the installation location, and the direction of the opening are not particularly limited. It is preferable to provide 2 to 8 inner jet outlets at appropriate intervals in the up-down direction and the circumferential direction from the viewpoint that water can be evenly supplied to the sand pile material corresponding to the sand removal height. In the hollow tube 1 of FIG. 1, the sand pile material discharged several times in the subsequent drawing process is put in the upper portion 9 of the sand removal height h.
Further, reference numeral 8 indicates a situation where the sand pile material is discharged. Examples of sand pile materials include sand and crushed stone. Further, the water jet pipes 31a and 31b may be attached along the inner wall of the hollow pipe.

Next, the compaction sand pile construction method of this example will be described. In the compaction sand pile construction method in the first embodiment, after the hollow tube 1 is penetrated to a predetermined depth, the hollow tube 1 is pulled out to an appropriate length, In the method of constructing compacted sand piles in soft ground by sequentially repeating the drawing step of discharging the sand pile material 2 and the step of re-penetrating the hollow pipe 1, the hollow before the drawing step. The amount of the sand pile material in the pipe 1 discharged into the ground, that is, the sand pile material 2 indicated by the sand removal height h
Is a method of adding water so as to be within ± 5% of the optimum water content ratio of the sand pile material. That is, the time of addition of water in this example is before the drawing step, and specifically, either in the final stage during the penetration or during the re-penetration.

In the compacted sand pile construction method according to the first embodiment, first, the hollow tube 1 is penetrated to a predetermined depth (FIG. 2 (a)). Then, before the drawing step, the sand pile material existing in the hollow pipe 1 is added to the amount discharged into the ground. The emission amount is a design matter and is known in advance. The optimum water content of the sand pile material used and the amount of water originally contained in the sand pile material are also known. Therefore, the amount of water added is obtained from these known amounts. Optimum water content refers to the water content that gives the maximum dry density when compacted while increasing the water content of soil by a certain compaction method,
It depends on the nature of the soil. The water addition is performed so that the sand pile material 2 is within ± 5%, preferably within ± 3% of the optimum water content ratio of the sand pile material. When the optimum water content ratio is within the above range, the compacted sand pile has the optimum strength in the subsequent re-penetration step.

The withdrawal performed after the addition of water is performed by discharging the sand pile material 2 into the ground with compressed air supplied from above the hollow tube 1. As a result, loose sand pillars 2a are formed in the extraction traces (FIG. 2 (b)). Next, the hollow tube 1 is re-penetrated, the loose sand column is compacted, and the compacted sand pile 2b having the height H is formed. This process is repeated until the ground surface is reached, and compacted sand piles are created in soft ground. According to the compaction sand pile construction method in the first embodiment, the hollow tube 1
Since it is added to the sand pile material 2 that has been put into the pre-drawing step before the drawing process to have an optimum water content ratio, when it is put into the hollow pipe after being adjusted to near the conventional optimum water content ratio. In comparison, the sand pile material can be easily discharged from the hollow pipe. Further, since the sand pillar 2a placed in the extraction trace in the extraction step is in the vicinity of the optimum water content ratio, the sand pile 2b having the optimum compaction strength can be obtained during the subsequent re-penetration. As a result, since one sand pile has an optimum compaction strength, the number of sand piles in the entire construction area can be reduced as compared with the conventional one, and construction efficiency is improved.

Next, a compaction sand pile construction method in the second embodiment of the present invention and a hollow pipe used in the construction method are shown in FIG.
And FIG. 4 will be described. FIG. 3 is a perspective view of a distal end portion of a partially cut hollow tube used in the compaction sand pile construction method of this example, and FIG. 4 is a diagram illustrating the compaction sand pile construction method of this example, respectively. . In the second embodiment, the first
The same components as those of the embodiment are given the same reference numerals and the description thereof will be omitted, and different points will be mainly described.
That is, in the hollow tube 1A, a pair of inner jets 3c and 3d for water supply are attached to the inner wall near the tip of the hollow tube 1A so that the injection ports 32c and 32d face each other from both sides. Further, in the compaction sand pile construction method of this example, water is added to the sand pile material during discharging in the drawing process. Inner jet 3 in this example
c and 3d are water jet generators not shown in the figure, one end is connected to the water jet generator, and the other end is the hollow tube 1
The water jet pipes 31c, 31 extending in the longitudinal direction of the peripheral surface of the water jet pipes 32c, 32d at the tips thereof are attached to the inner wall 17 of the tip portion of the hollow tube 1A toward the inside.
It consists of d and. That is, a water jet is supplied from the jet ports 32c and 32d. Inner wall 1 near the tip of the hollow tube 1A
The number of installed jets, the direction of the jets, and the like are appropriately selected as the jets of the inner jets installed in 7
It is preferable that 2 to 4 pieces are installed on the peripheral surface of the tip of the sand pile at equal intervals because the sand pile material to be discharged can be evenly added. The inner jet is not particularly limited and may be only a water jet, but the use of an inner jet ejector in which water is entrained in compressed air allows the discharged sand pile material to be instantly and uniformly added. Is preferred.

In the compacted sand pile construction method according to the second embodiment, first, the hollow tube 1A is penetrated to a predetermined depth (FIG. 4 (a)). Then, the sand pillar 2a formed in the extraction trace by being added to the sand pile material in the process of being discharged in the drawing step has a moisture content within ± 5% of the optimum water content of the sand pile material.
It is preferably within ± 3% (FIGS. 4B and 4C).
The amount of water added is determined by the same method as in the first embodiment. Next, the hollow tube 1A is re-penetrated, the loose sand column is compacted, and the compacted sand pile 2b having the height H is formed. Do this one by one
Repeat until the surface of the ground, to create compacted sand piles in soft ground. According to the compaction sand pile construction method of the second embodiment, the same effect as that of the first embodiment is obtained, and in addition to the optimum moisture content ratio with respect to the sand pile material being discharged in the drawing process, The sand pile material 2 can be easily discharged from the hollow tube 1A because it is watered so that

As the compaction sand pile forming device used in the present invention, a known device can be used except for the feature of the end portion of the hollow tube. That is, a spiral blade may be provided on the outer peripheral surface of the hollow tube, and a drill bit may be provided at the tip of the hollow tube. Also, the hollow pipe lifting device is not particularly limited, for example, by a rack and pinion, by a chain and sprocket, by pulling a wire rope, etc. that can obtain a reaction force from the leader at the time of penetration and extraction. Alternatively, a vibro hammer may be used.

[0020]

According to the present invention, the sand pile material can be easily discharged from the hollow pipe, and the optimum compaction sand pile strength can be obtained. As a result, the number of sand piles can be reduced, and the construction period can be shortened to achieve efficient construction.

[Brief description of drawings]

FIG. 1 is a perspective view of a distal end portion of a partially cut hollow tube used in a compaction sand pile construction method according to a first embodiment.

FIG. 2 is a diagram illustrating a compaction sand pile construction method according to the first embodiment.

FIG. 3 is a perspective view of a distal end portion of a partially cut hollow tube used in a compaction sand pile construction method according to a second embodiment.

FIG. 4 is a diagram illustrating a compaction sand pile construction method according to a second embodiment.

[Explanation of symbols]

1, 1A hollow tube 2 Sand pile material 2a Loose sand column adjusted to the optimum water content 2b Compacted sand pile Jet ejector inside 3a and 3b 3c, 3d Inner jet 7 inner wall 17 Inner wall of hollow tube tip 31a, 31b, 31c, 31d Water jet piping 32a, 32b Jet outlet for mixed flow of water and compressed air 32c, 32d Water jet outlet

Claims (5)

[Claims] 1. A drawing step for drawing a hollow tube to a predetermined depth, drawing the hollow tube to an appropriate length, and discharging sand pile material in the hollow tube to the drawn-out trace, and re-penetrating the hollow tube. In the method of constructing compacted sand piles in the soft ground by repeating the steps of and sequentially until reaching the ground surface, the amount of the sand pile material in the hollow pipe before the drawing step is discharged into the ground, A compacted sand pile construction method characterized by adding water so that it is within ± 5% of the optimum water content of the sand pile material. 2. A hollow tube is penetrated to a predetermined depth, then the hollow tube is drawn out to an appropriate length, and a sand pile material in the hollow tube is discharged to the drawing-out trace, and the hollow tube is re-penetrated. In the method of constructing compacted sand piles in soft ground by sequentially repeating the steps of and Is ± 5 of the optimum water content of the sand pile material
% Of the compacted sand pile construction method. 3. The water addition is performed by an inner jet ejector having an injection port on the inner wall of the hollow pipe which is in contact with the discharged amount of the sand pile material charged in the hollow pipe. Compaction sand pile construction method described. 4. The compacted sand pile construction method according to claim 2, wherein the water addition is performed by an inner jet or an inner jet ejector having an injection port on the inner wall near the tip of the hollow tube. 5. A hollow tube is penetrated to a predetermined depth, then the hollow tube is drawn out to an appropriate length, and a sand pile material in the hollow tube is discharged to the drawn-out mark, and the hollow tube is re-penetrated. It is a construction device that sequentially repeats the process of performing up to the surface of the earth to create a compacted sand pile in soft ground, and the sand pile material put into the hollow pipe is used once One or more inner jet ejectors having an injection port are provided on the inner wall of the hollow pipe which is in contact with the discharge amount, or an inner jet or an inner jet ejector having an injection port is provided on the inner wall near the tip of the hollow pipe. A compaction sand pile forming device characterized by being one of the above.