JP2015081408A - Soil improvement body construction method and soil improvement body construction tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a soil improvement body construction method which enables a large underground pile to be constructed at a low cost.SOLUTION: A soil improvement body construction tool 1 comprises: a leading pipe 2; a shaft body 4; a spiral blade 5 installed around the shaft body 4; a soil improvement material injection pipe provided inside the shaft body 4 along a length direction thereof; a lateral pipe perpendicular to the soil improvement material injection pipe; and a soil improvement material injection nozzle 7 installed at a tip of the lateral pipe. A section of the shaft body 4 where the spiral blade 5 is installed has a diameter which varies so as to be thick in a center thereof and get thin toward both edges thereof. Using the soil improvement body construction tool 1, a soil improvement body construction method constructs a soil improvement body in the ground in a manner that: lowers the soil improvement body construction tool 1 into the ground while rotating the shaft body 4 in a direction of downward rotation of the spiral blade 5 and discharging air through the leading pile 2; inversely rotates the shaft body 4 when the soil improvement body construction tool 1 reaches a predetermined depth; and injects the soil improvement material into the ground with an injection amount allowing waste sludge to be discharged above the ground while upwardly drawing the soil improvement body construction tool 1.

Description

TECHNICAL FIELD The present invention relates to a construction method for strengthening the ground by injecting a soil improvement material into the ground to create a ground pile and a tool used therefor.

As the improved construction method to create and strengthen underground piles in soft ground, the agitation method using ultra-high pressure injection, the auger mixing method and the bit mixing method using a large crawler pile driver were mainly used.

Further, in Patent Document 1 and Patent Document 2, the tip conduit, the shaft body, the spiral blade provided around the shaft body, and the soil provided in the shaft body along the length direction of the shaft body The direction in which the spiral blade descends using a soil conditioner building tool having a conditioner injection pipe, a horizontal pipe perpendicular to the soil conditioner injection pipe, and a soil conditioner discharge nozzle provided at the tip of the horizontal pipe The soil improvement body creation tool is lowered into the ground while discharging the air from the tip conduit, and when the soil improvement body formation tool reaches a predetermined depth, the shaft body is rotated in the reverse direction to A soil improvement body construction method is described in which a soil improvement material is discharged into the ground while pulling up the improvement body creation tool, and a soil improvement body is created in the ground. In the soil improvement body construction method of patent document 1 and patent document 2, the injection material with high cement concentration is used, and the ground improvement can be performed without discharging mud by setting the injection amount to a predetermined amount or less. . Therefore, the cost for the treatment of waste mud is eliminated.

JP 2003-90189 A JP 2007-205144 A

In the conventional auger agitation method using a large crawler pile driver, the construction machine is large, and the place where it can be constructed is limited. There is a problem that the cost is expensive.

The ultra-high pressure jet agitation method allows construction with a relatively compact machine, but there is a limit to the size of underground piles that can be created in a single operation. It has to be piled underground, and the construction time is long and expensive. In addition, a large amount of mud (discharge slime) is generated.

On the other hand, the soil improvement body construction method of patent document 1 and patent document 2 can be implemented with a small apparatus with a simple structure. Moreover, by setting the injection amount to a predetermined amount or less, the ground can be improved without discharging mud, and the cost for treating the mud is eliminated. And the built underground pile has sufficient strength. However, the soil improvement body construction method of patent document 1 and patent document 2 has a limit in the number of underground piles which can be created by one excavation, and is the same level as the underground pile by an ultrahigh pressure injection stirring method.

An object of this invention is to provide the soil improvement body construction method which can form a large underground pile and can be implemented at low cost.

In order to solve the above-described problems, the soil improvement body construction method of the present invention includes a tip conduit, a shaft body, a spiral blade provided around the shaft body, and a shaft along the length direction of the shaft body. A soil improvement material injection pipe provided inside the body, a horizontal pipe perpendicular to the soil improvement material injection pipe, and a soil improvement material discharge nozzle provided at the tip of the horizontal pipe, the spiral body in the shaft The part where the blade is attached uses a soil improvement body creation tool configured so that the center part is thick and the both ends are thin along the axial direction,
Rotate the shaft body in the direction in which the spiral blade descends and lower the soil improvement body creation tool into the ground while discharging air from the tip conduit,
When the soil improvement material creation tool reaches a predetermined depth, the shaft is rotated in the reverse direction, and the soil improvement material is introduced into the soil improvement material injection pipe so that the soil improvement material is discharged to the ground while the soil improvement material creation tool is pulled up. The soil conditioner is supplied and discharged from the soil conditioner discharge nozzle into the ground to create a soil conditioner in the ground. It is preferable to use cement milk containing 700 kg or more and 800 kg or less of cement per 1 m ³ as the soil conditioner, and to inject 1000 liters or more of soil conditioner while pulling up the soil conditioner construction tool by 1 m. A plurality of vertical pipes provided at the lower end of the pipe, a horizontal pipe perpendicular to the vertical pipe, a curved pipe provided between the vertical pipe and the horizontal pipe, and a tapered portion provided at the upper end of the vertical pipe; It is particularly preferable to use a soil improvement material creation tool having a weight of 2000 to 2400 liters while the soil improvement material creation tool is pulled up by 1 m.

Further, the soil improvement body creation tool of the present invention is a shaft body, a spiral blade provided around the shaft body, and a soil improvement material provided in the shaft body along the length direction of the shaft body. Injection pipe, a plurality of vertical pipes provided at the lower end of the soil amendment material injection pipe, a horizontal pipe perpendicular to the vertical pipe, a curved pipe provided between the vertical pipe and the horizontal pipe, and an upper end of the vertical pipe A taper part provided in the part and a soil improvement material discharge nozzle provided at the tip of the horizontal pipe, the part to which the spiral blade is attached in the shaft body is thick at the center part along the axial direction, and both end parts Is configured to be thin.

According to the soil improvement body construction method and the soil improvement body construction tool of this invention, a large-diameter underground pile can be formed at a time. Therefore, the ground improvement work can be performed in a short period of time at a low cost.

It is a perspective view which shows a soil improvement body creation tool. It is the same section sectional front view. It is the bottom view. It is a partial cross section front view which shows another example of a soil improvement body creation tool. It is a top view which shows the example of the nail | claw of a soil improvement body creation tool. It is a partial cross section front view which shows the example of the lower end of a soil improvement material injection pipe. It is AA same sectional drawing. It is a front view which shows the construction machine provided with the soil improvement body creation tool. It is sectional drawing which shows an underground pile. It is a top view which shows the construction example by the conventional soil improvement body construction method. It is a top view which shows the construction example by the soil improvement body construction method of this invention.

EMBODIMENT OF THE INVENTION The form for implementing this invention is demonstrated based on drawing. FIG. 1 is a perspective view showing a soil improvement body creation tool, FIG. 2 is a front view of the same section, and FIG. 3 is a bottom view thereof. This soil improvement body creation tool is the same as that described in JP-A-2003-90189.

The soil improvement body creation tool 1 which concerns on this invention is a loop type bit which has a helical blade | wing around a shaft body. A tip conduit 2 is provided at the tip, and a cutting tip 3 is provided. While cutting the ground with the cutting tip 3, the leading conduit 2 enters the ground. A shaft body 4 is provided following the leading conduit 2, and a spiral blade 5 is provided around the shaft body 4. Although the shaft body 4 is hollow, as shown in FIG. 2, the portion where the spiral blade 5 is provided is configured such that the central portion is thick and the both end portions are narrow along the axial direction. Here, as shown in FIG. 2, the shape is such that a cone is connected to both sides of the cylinder, and the diameter increases from both ends toward the center. And even if it sees with the whole shape containing the helical blade | wing 5, the diameter becomes large as a whole toward both ends from the center part. The maximum diameter of the spiral blade 5 is preferably 400 mm or more, and preferably 2000 mm or less so as not to increase the scale of the facility. In this example, the maximum diameter of the spiral blade 5 is 1100 mm. Further, the central portion of the shaft body 4 has a constant thickness, and the shaft diameter changes at a constant rate above and below the central portion, and the taper angle is about 22 °. As will be described later, the taper angle of the shaft body 4 has a useful function for smoothly sending earth and sand to the rear when the spiral blade 5 travels in the ground. It is preferable to make the degree. The spiral blade 5 has a pitch that makes one round every time it travels 160 mm in the axial direction, and circulates along the length of the shaft body 4. In the range where the shaft body 4 is tapered, the outer diameter of the spiral blade 5 increases at a constant rate toward the center. On the other hand, in the range where the thickness of the shaft body 4 is constant, the outer diameter of the spiral blade 5 is also constant. In this example, the spiral blade 5 makes a full circle with the maximum outer diameter, and when viewed from the bottom view, the outer shape forms a perfect circle, so the shaft will shake when digging. Without going straight.

Although the shaft body 4 is hollow, an inner pipe is provided inside, and the inner pipe is a soil conditioner injection pipe connected to a soil conditioner discharge nozzle 7 (injectant discharge port). The soil improvement material discharge nozzle 7 is provided outward at a position where the diameter of the shaft body 4 is the largest. In this example, a plurality of soil conditioner discharge nozzles 7 are provided. A gap between the shaft body and the inner tube serves as a passage for compressed air, and compressed air can be ejected from the tip of the front conduit 2.

A plurality of plate-like claws 6 are respectively attached to the upper and lower surfaces of the spiral blade 5. The claw 6 is provided in a direction in contact with the circumference centered on the shaft body 4, that is, so that the thickness direction of the claw 6 is a radial direction. When digging, the nail | claw 6a provided in the lower surface of the spiral blade | wing 5 sharply stirs soil, and agitates soil effectively.

FIG. 4 is a partial cross-sectional front view showing another example of the soil improvement body creation tool. It is the same as the soil improvement body creation tool described in Patent Document 2. In this example, the claws 6 are provided on the outer peripheral portion of the spiral blade 5 in addition to the upper and lower surfaces of the spiral blade 5. By this nail | claw of an outer peripheral part, earth and sand can be cut still more effectively.

FIG. 5 is a plan view showing an example of a nail of the soil improvement body creation tool. It is made of a plate-like metal, and the central portion has a constant width. And the pointed tip part is provided in the both sides, and it has the shape of a hexagonal column as a whole. With this sharp tip, the claw 6 can effectively cut earth and sand when the spiral blade 5 rotates in either direction.

FIG. 6 is a plan view showing an example of the lower end of the soil amendment material injection pipe, and FIG. 7 is a sectional view of the same. The lower end portion of the soil conditioner injection pipe is characteristic of the soil conditioner building tool of the present invention. In Patent Document 1 and Patent Document 2, two horizontal tubes 10 are connected at right angles to the soil conditioner injection tube 8 at the lower end of the soil conditioner injection tube 8 to form a T-shape. And the soil improvement material discharge nozzle 7 is connected to the horizontal pipe 10. On the other hand, in the example of FIGS. 6 and 7, a plurality of vertical pipes 12 and a horizontal pipe 10 perpendicular to the vertical pipe 12 are provided at the lower end of the soil improving material injection pipe 8, and the vertical pipe 12 and the horizontal pipe 10 are further provided. A curved tube 11 is provided between the two. Here, the three vertical pipes 12 are bundled and connected to the soil improvement material injection pipe 8, and the soil improvement material injection pipe 8 has a tapered diameter at the connection portion. In addition, a tapered portion having an inner diameter that narrows downward is also provided at the upper end portion of the vertical tube.

In the soil improvement body formation tool of patent document 1 and patent document 2, since the soil improvement material injection pipe 8 and the horizontal pipe 10 are connected at right angle, the soil improvement material which flows in this right angle bending receives big resistance. Therefore, it becomes difficult to obtain a high flow rate. On the other hand, in the example of FIGS. 6 and 7, the lower end of the soil conditioner injection pipe 8 and the inlet of the vertical pipe 12 are tapered, and the vertical pipe 12 and the horizontal pipe 10 are connected by the curved pipe 11. The soil improvement material flows smoothly from the soil improvement material injection tube 8 to the horizontal tube 10 without receiving a large resistance. Therefore, a high flow rate can be obtained.

FIG. 8 is a front view showing a construction machine provided with a soil improvement body creation tool. The work carriage 23 is self-propelled with an endless track 24 and can easily move the entire apparatus at a construction site. A leader 26 is attached to the work carriage 23 via an arm 25 that can move up and down. The leader 26 is a sliding attachment device that attaches the chuck 27 so as to be movable up and down. A swivel and an intermediate rod are attached to the work carriage 23, and the soil improvement body creation tool 1 is attached to the tip thereof.

The intermediate rod is a hollow tube similar to the shaft body of the soil improvement body creation tool, and has a triple tube structure including an inner tube and an outer tube. There are several lengths such as 6m, 4m and 2m, and they can be connected and disconnected from each other. Similarly, the swivel has a triple-pipe structure, and the soil improvement material and compressed air can be introduced by connecting the injectant hose 28 and the air hose 29.

Next, the soil improvement body construction method using a soil improvement body creation tool is demonstrated. When the work carriage 23 is moved to the construction site, the angle of the arm 25 is adjusted and the leader 26 is set up vertically. The uppermost intermediate rod is passed through the chuck 27, and the intermediate rod is grasped by the chuck 27. A swivel 9 is connected to the uppermost intermediate rod, and the soil improvement body creation tool 1 is connected to the lowermost intermediate rod. The chuck 27 can rotate the intermediate rod 22 in both forward and reverse directions by hydraulic drive. That is, the intermediate rod 22 functions as a drive shaft that transmits the rotation of the chuck 27 to the soil improvement body forming tool 1 at the tip. An injectant hose 28 and an air hose 29 are connected to the swivel 9, and each hose is connected to a grout pump and a compressor (not shown) of the plant. The swivel 9, the intermediate rod 22 and the soil improvement body creation tool 1 each have a triple pipe structure, but when connected, the passages of air and infusate are connected.

When digging with the soil improvement body formation tool 1, air is sent with a compressor and ejected from the tip of the soil improvement body formation tool 1, and the spiral blades of the soil improvement body formation tool 1 are rotated so as to advance downward. After digging to some extent, the intermediate rod 22 is added to dig deeper. In order to smoothly feed the cut earth and sand, the spiral blade loop has a shape in which the diameter increases from the tip toward the center, and the diameter decreases toward the top. Here, the larger the spiral blade, the stronger the force of holding down the sand and sand, which is advantageous. However, resistance is applied to the spiral blade in the ground, and the resistance is particularly large in the central portion where the diameter of the loop is large. When the shaft body has a constant thickness, the blades are shaped so as to protrude greatly at the center, and a large force is applied and the blades are easily damaged. In addition, the force applied to the shaft body increases and is easily damaged. In the soil improvement body creation tool 1 of the present invention, the portion of the shaft body 4 to which the spiral blade 5 is attached has a thick central portion and narrow both end portions along the axial direction. Therefore, the spiral blade and the shaft body are strong even in the central part, and since the earth and sand are smoothly sent backward while digging, the soil improvement body creation tool 1 is less likely to be damaged in the ground during construction. Construction can be done on hard ground or clayey places.

When digging to the final depth, the soil excavation tool 1 is pulled up while rotating the spiral blades so that the rotation direction of the chucks 27 is reversed. At this time, the injection agent is introduced from the injection agent hose 28, and the injection agent is injected into the ground from the injection agent discharge port of the soil improvement body creation tool 1. When pulling up, the nail on the upper surface of the spiral blade stirs the earth and sand. Since the claw on the lower surface of the spiral blade is cut off in the direction of travel during reverse rotation, the soil and sand are also smoothly fed backward. And, in the soil improvement body construction method according to the present invention, the mechanical stirring of the earth and sand and the stirring of the earth and sand by the injection of the injection agent are performed simultaneously, the cut earth and sand and the injection agent are efficiently mixed, the injection material is The amount of sand and infusate that has been successfully taken into the ground and cut into the ground as mud is extremely small. When pulling up, the work proceeds while removing the intermediate rods sequentially, contrary to when digging. If it raises to predetermined | prescribed height, injection | pouring of an injection will be stopped and the soil improvement body formation tool 1 will be pulled up. When the construction of one hole is completed in this way, the work carriage 23 is moved to the next position and the same construction is repeated.

Here, the injection used as a soil improvement material in this soil improvement body construction method is demonstrated. Cement milk containing 700 kg or more and 800 kg or less of cement per 1 m ^{3 is} used as a soil conditioner. In the soil improvement body construction method of Patent Document 1 and Patent Document 2, 1000 kg of cement is used per 1 m ^3. Compared with this, the amount of cement used is significantly reduced in the soil improvement material of this example. The cement concentration is similar to or lower than that of cement milk containing 760 kg of cement per 1 m ³ used in the ultra-high pressure jet stirring method called the JSG method or the CJG method.
In particular, the following examples are suitable.
Blast furnace cement 700kg, water 667kg, admixture (trade name Sunflow SW-2000S: Nippon Paper Industries Co., Ltd.) 5kg
By this blending, cement milk containing 700 kg of cement per 1 m ³ is obtained. This is because the amount of cement used is smaller than in the case of the ultra-high pressure jet stirring method, and the material cost can be greatly reduced. In particular, the material cost can be reduced by 30% compared to the construction methods of Patent Document 1 and Patent Document 2.

Here, the injection amount of the soil improvement material will be described. In invention of patent document 1 and patent document 2, the construction method by which waste mud is not discharged | emitted on the ground was implement | achieved by making the injection amount of a soil improvement material or less into a predetermined value or less. When a spiral blade with a loop diameter of about 1100 mm is used, if the injection is up to 800 liters while pulling up the soil improvement material of 1 m, the exhausted mud is completely removed due to the powerful stirring of the spiral blade and the soil uptake action. Underground piles can be created without discharging. Therefore, in the inventions of Patent Document 1 and Patent Document 2, the injection amount is kept below that. The construction method of the present invention is characterized by injecting an injecting agent that exceeds this predetermined value and discharging the mud to the ground. When up to 800 liters of infusate can be taken into the soil without being discharged to the ground for raising 1 m of soil conditioner, for example, 1000 liters or more of infusate is injected. In order to obtain a large underground pile, it is preferable to inject a soil improvement material of 2000 liters or more and 2400 liters or less while pulling up the soil improvement body creation tool by 1 m. Disappear.

FIG. 9 is a cross-sectional view showing the underground pile. The right figure shows the underground pile by the method of patent document 1 and patent document 2, and the left figure shows the underground pile by the method of this invention. Both use spiral blades with an outer diameter of 1100 mm and inject at a pressure of 180 kg / m ² . The soil improvement body creation tool 1 is pulled up at a speed of 7 minutes per 1 m (Patent Document 1 and Patent Document 2) or 11.5 minutes (the present invention). The soil is sandy soil with N ≦ 10.

The inner circle in FIG. 9 indicates the outer diameter of the spiral blade 5 of 1100 mm, and the spiral blade 5 passes through this portion. And the external shape of the underground pile in which the outer circle | round | yen is formed is shown. In the methods of the inventions of Patent Document 1 and Patent Document 2, high-concentration cement milk containing 1000 kg of cement per 1 m ³ is used as a soil conditioner, and 800 liters of soil condition is improved while the soil conditioner building tool is pulled up by 1 m. Inject the material. Thereby, the soil improving material penetrates from the tip of the spiral blade 5 to a distance of 400 mm. Moreover, this soil improvement material is taken in also to the center part by rotation of the helical blade | wing 5, and is stirred uniformly with earth and sand. Thus, an underground pile having a diameter of 1900 mm is created. This underground pile has a strength of 30 kg / m ² or more.

On the other hand, in the example of the left figure, which is the construction method of the present invention, cement milk containing 700 kg of cement per 1 m ³ is used as a soil improvement material, and 2300 liters of soil improvement material is added while the soil improvement body creation tool is pulled up by 1 m. inject. At this time, the soil improvement material penetrates from the tip of the spiral blade 5 to a distance of 1000 mm, and a large underground pile having a diameter of 3100 mm is formed. This underground pile also has sufficient strength of 30 kg / m ² or more.

By injecting 2300 liters of soil conditioner, mud is discharged on the ground. However, even in this construction method, 800 liters are absorbed into the ground by the action of taking up the sand and sand by the rotation of the spiral blades 5, so only 1500 liters exceeding it are discharged as a mixture of earth and sand and cement milk. The This is a much smaller amount than the mud discharged by the ultra-high pressure jet stirring method described later.

As mentioned above, in the soil improvement body construction method of this invention, while using the soil improvement body creation tool provided with the spiral blade 5, by injecting the soil improvement material which dares to discharge | emit waste mud, inexpensive cement Milk is used, and the size of underground piles is dramatically improved. Therefore, in addition to reducing material costs, the number of underground piles is also reduced, and construction costs are greatly reduced. In the construction method of the present invention, waste mud is generated, so that it costs money to treat it as waste, but there is a cost reduction exceeding that amount. In addition, since the number of creations is reduced, the time required for construction is also shortened. The pulling time required for the creation of underground piles per piece is 1.6 times longer in the present invention, but due to the reduction in the number of underground piles created, the overall construction time is one-third. Shortened to the extent. For example, in order to create an improved body with a volume of 648 m, the method of the inventions of Patent Document 1 and Patent Document 2 takes 72 days, whereas in the present invention, it is shortened to about 23 days.

Furthermore, the construction example by the soil improvement body construction method of this invention is demonstrated compared with the conventional construction method. FIG. 10 is a plan view showing a construction example by the conventional soil improvement body construction method, and FIG. 11 is a plan view showing a construction example by the soil improvement body construction method of the present invention. A sheet pearl is driven along the outer periphery of a rectangle having a length of 10000 mm and a width of 18000 mm, and an improved body is formed therein.

First, the example of the conventional soil improvement body construction method is demonstrated. It is an example of an ultra-high pressure jet stirring method called a JSG method or a CJG method. Cement milk containing 760 kg of cement per m ^{3 is} used as a soil conditioner. In sandy soil with N ≦ 10, the CJG method injects 3600 liters of soil conditioner while pulling up the device by 1 m. As a result, 1777 m ³ of waste mud is generated as industrial waste. In the JSG method, 2280 liters of soil conditioner is injected while the device is lifted by 1 m, and 1085 m ³ of waste mud is generated.

In the conventional soil improvement body construction method, the diameter of the underground pile formed at one time is 2000 mm. It is necessary to form 74 underground piles in the range of 10000 mm long and 18000 mm wide. Even so, there are places where the improved body has not been made in the peripheral area, and if it is going to strengthen the ground so far, it will be necessary to further inject chemicals. In addition, in the method of invention of the above-mentioned patent document 1 and patent document 2, since the diameter of an underground pile is still smaller, 80 underground piles are needed in the same range.

In this construction, the CJG method requires a total work period of 63 days for drilling and 26 days for improvement material injection, and a total of 99 days, and the JSG process requires 72 days. The total construction cost is 66,800,000 yen for the CJG method and 54,280,000 yen for the JSG method.

Below, the construction example of this invention is demonstrated. The composition of the soil improvement body construction tool and the soil improvement material to be used, and the injection amount are as described above. In this example, 37 underground piles are sufficient to create the same range. There are almost no places in the periphery where the improved body does not spread. The construction period required for this is 23.13 days.

As mentioned above, according to the construction method of this invention, construction cost can be reduced significantly. Compared to the most inexpensive JSG method and the methods described in Patent Document 1 and Patent Document 2 described above, 18 million yen has been reduced.

The construction period is also shortened to one-third or less. Shortening the construction period not only leads to a reduction in costs, but also has immeasurable advantages such as the merit of being able to provide construction results to the contractor early.

1. Soil excavation tool2. Tip conduit3. Cutting tip 4. 4. Shaft body 5. Spiral blade Nails 7. Soil improver discharge nozzle (injectant outlet)
8). Air outlet 9 Soil improver injection pipe (inner pipe)
10. Horizontal tube 11. 11. Curved tube Vertical tube 21. Construction machine 22. Intermediate rod 23. Work carriage 24. Endless track 25. Arm 26. Leader 27. Chuck 28. Injectant hose 29. Air hose

Claims (4)

A leading conduit, a shaft body, a spiral blade provided around the shaft body, a soil conditioner injection pipe provided inside the shaft body along the length direction of the shaft body, and a soil conditioner injection A horizontal pipe perpendicular to the pipe, and a soil improvement material discharge nozzle provided at the tip of the horizontal pipe, the portion of the shaft body to which the spiral blade is attached has a thick central part along the axial direction and both end parts Using a soil improvement body creation tool configured to become thin,
Rotate the shaft body in the direction in which the spiral blade descends and lower the soil improvement body creation tool into the ground while discharging air from the tip conduit,
When the soil improvement material creation tool reaches a predetermined depth, the shaft is rotated in the reverse direction, and the soil improvement material is introduced into the soil improvement material injection pipe so that the soil improvement material is discharged to the ground while the soil improvement material creation tool is pulled up. A soil improvement body construction method that supplies and discharges soil improvement material into the ground from the soil improvement material discharge nozzle to create a soil improvement body in the ground. The soil improvement according to claim 1, wherein cement soil containing 700 kg or more and 800 kg or less of cement per 1 m ³ is used as the soil improvement material, and 1000 liters or more of soil improvement material is injected while the soil improvement body creation tool is pulled up by 1 m. Body construction method. A plurality of vertical pipes provided at the lower end of the soil amendment material injection pipe, a horizontal pipe perpendicular to the vertical pipe, a curved pipe provided between the vertical pipes and the upper end of the vertical pipe The soil improvement body creation method of Claim 2 which inject | pours a soil improvement material of 2000 liters or more and 2400 liters or less using the soil improvement body creation tool which has the taper part, and pulling up the soil improvement body construction tool 1m. A shaft body, a spiral blade provided around the shaft body, a soil improvement material injection pipe provided inside the shaft body along the length direction of the shaft body, and a lower end of the soil improvement material injection pipe A plurality of vertical tubes provided, a horizontal tube perpendicular to the vertical tube, a curved tube provided between the vertical tube and the horizontal tube, a tapered portion provided at the upper end of the vertical tube, and a horizontal tube A soil improvement material discharge nozzle provided at the tip, and the portion to which the spiral blade is attached in the shaft body is constructed so that the central portion is thick and the both end portions are thin along the axial direction tool.

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