JPH07279157A - Ground improving body forming device and construction method - Google Patents

Abstract

PURPOSE:To smoothly discharge sludge, facilitate the mutual connection of hardener filling rods, and simplify the whole device. CONSTITUTION:A hardener filling rod 11 has an outer pipe 23 and a plurality of pipings 36, 37, 38, 39 provided therein, these pipings are held in such a manner as to be relatively rotatable around the longitudinal axis to the outer pipe, and connected to the outer pipe by mutually screwing them by screw parts 48 formed on the end part circumferential surfaces, and the hardener filling rod is rotated in a fixed direction for screwing the outer pipe by a driving device 14 at construction. This device has a sludge jet injection nozzle 65 for injecting a jet water containing air toward the sludge discharging direction of a sludge suction pipe 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground improvement apparatus and method for strengthening the ground by injecting a hardening agent into the ground to form a pile-like hardened ground improvement body in the ground.

[0002]

2. Description of the Prior Art While injecting a solution of a hardening agent such as cement milk from the hardening agent injection rod in the ground, and gradually pulling back the hardening agent injection rod in the longitudinal direction of the rod while rotating the hardening agent injection rod, A ground improvement method has been developed in which a pile-shaped hardened improved body is formed.
In this construction method, for example, in the case of a ground having poor water permeability, the ground surface rises due to an increase in the ground pressure at the injection point of the solution, which adversely affects adjacent structures, and the diameter of the improved body is limited to a small value. Therefore, it is necessary to discharge the sludge smoothly. On the other hand, it is necessary to appropriately change the length of the hardener injection rod according to the depth of the target ground,
Therefore, it is an important technical subject to make it possible to easily set the hardening agent injection rod to a required length.

[0003]

Conventionally, a hardener injection rod is provided with a suction port for sludge and the sludge is forcibly sucked from the suction port. A large lump of discharged mud was easily clogged at the mud suction port, and the lump of discharged mud sometimes hindered smooth discharge even in the discharge passage.

Further, in the past, since the curing agent injection rod was reciprocally rotated over a predetermined rotation angle in order to inject the curing agent to the surroundings, screw means can be used to connect the curing agent injection rods to each other. There wasn't. In other words, since the curing agent injection rod reciprocally rotates, it is preferable that the rotation direction is the direction in which the screw is tightened. However, when the rotation direction is in the direction in which the screw is loose, the screw of the connecting portion is loosened. However, it was not possible to adopt a simple screw connection on the outer circumference of the rod. Therefore, conventionally, a flange portion was provided at the joint portion of the hardener injection rods and bolts and nuts were used to fix the hardener injection rod at several locations in the circumferential direction. It was working.

On the other hand, a plurality of hoses such as a hardening agent and fresh water are connected to the hardening agent injection rod, but when the hardening agent injection rod is reciprocally rotated, a swivel is not necessarily used for these connecting portions. There is no. However, when the swivel is not used, the hoses become messy, and there is a drawback in that the hoses collide with each other during the reciprocating rotation and the hose is damaged.

Further, since the hardening agent injection rod is internally provided with a plurality of pipes, there is a problem that the apparatus becomes complicated.

[0007] The present invention has been made in view of the above, and improves the ground so that the sludge can be discharged smoothly, the hardener injection rods can be easily connected, and the entire apparatus can be simplified. The object is to provide a body building device and a construction method.

[0008]

A ground improvement body forming apparatus according to the present invention for achieving the above object comprises a hardening agent for forming a hole in the ground and improving the ground by a hardening agent injection rod. In the ground improvement body forming device for forming the ground improvement body on the target ground by moving the hardening agent injection rod in the rod longitudinal axis direction while injecting
The hardening agent injection rod has an outer pipe and a plurality of pipes installed in the outer pipe, holds the pipe so as to be rotatable relative to the outer pipe around a longitudinal axis, and also surrounds the outer pipe at its end portion. It is characterized in that the hardened material injecting rods are rotationally driven in a fixed direction in which a screw of the outer tube is tightened by a driving device at the time of construction, while being connected by being screwed to each other by screw portions formed on the surface.

The pipes installed inside the outer pipe are, for example, a sludge suction pipe, a hardening agent supply pipe, a jet water supply pipe, and an air supply pipe.

Further, a sludge discharge hole communicating with the sludge suction pipe is formed in the peripheral surface of the hardening agent injecting rod, and is communicated with the jet water supply pipe to inject in the sludge discharging direction. A nozzle is provided in the drainage hole. Preferably, the sludge jet injection nozzle has a double structure consisting of a central core nozzle and a peripheral nozzle surrounding the core core nozzle, and the core nozzle is connected to the jet water supply pipe and the peripheral nozzle is connected to the air supply pipe. Communicate with. No opening / closing lid is provided in the mud hole.

A hardener injection nozzle communicating with the hardener supply pipe is provided on the peripheral surface of the hardener injection rod. In some cases, the hardener injection nozzle is composed of a central core nozzle and a peripheral nozzle surrounding the core nozzle. It has a double structure, and the core nozzle is in communication with the curing agent supply pipe and the peripheral nozzles are in communication with the air supply pipe.

Further, in the ground improvement body construction method according to the present invention, a hole is formed in the ground and a hardening agent injection rod is used to inject the hardening agent for improving the ground at a high pressure by the hardening agent injection rod. In the ground improvement body construction method of forming a ground improvement body on the target ground by moving in the longitudinal direction of the rod, the curing agent injection rod has an outer pipe and a plurality of pipes installed in the outer pipe, and the pipe is The outer tube is held so as to be rotatable relative to the outer tube about its longitudinal axis, and the outer tube is connected by being screwed with each other by a threaded portion formed on the peripheral surface of the end of the outer tube. It is characterized in that the construction is carried out by rotationally driving in a fixed direction in which the screw is tightened.

Further, at the time of construction, the sludge is sucked from a sludge drain hole provided on the peripheral surface of the hardening agent injecting rod, and jet water is jetted in the sludge draining direction. Preferably, the jet water is jetted in a state of being surrounded by high pressure air.

[0014]

The inner pipe is held rotatably with respect to the outer pipe about the longitudinal axis, and the outer pipes are screwed together by the threaded portions formed on the peripheral surface of the end to connect the plurality of outer pipes. This facilitates the work of connecting the outer tubes. Further, by performing the construction while rotating and driving the hardening agent injection rod in a fixed direction in which the screw of the outer pipe is tightened, it is possible to prevent the screw of the outer pipe from loosening during the construction.

The sludge jet jet nozzle, which jets the sludge in the direction of the sludge, crushes the sludge and urges the sludge in the discharging direction to promote smooth discharge of the sludge. By injecting high-pressure air at the same time so as to surround the jet water, the pushing force of the jet water is increased and the air lift effect is also boosted.
Sludge is discharged more smoothly.

[0016]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of a ground improvement body constructing apparatus according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of a base end swivel portion of the hardener injection rod, and FIG. 3 is an intermediate portion of the hardener injection rod. 4 is a sectional view of the tip monitor portion of the curing agent injection rod, and FIG.
V sectional view, FIG. 6 is a VI-VI sectional view of FIG. 4, and FIG. 7 is an exploded sectional view of an intermediate portion of the hardener injection rod.

In FIG. 1, reference numeral 11 denotes a hardening agent injection rod, and the hardening agent injection rod 11 has its base end (upper end in FIG. 1).
The suspension unit 12 is supported by a suspension device (not shown) via a wire 13 and the rod intermediate portion is held by a drive device (boring machine) 14.
The hardener injection rod 11 is rotationally driven in a predetermined direction around the longitudinal axis by 4 and is moved forward and backward along the longitudinal axis. Further, 15 is a sludge recovery device, 16 is a high-pressure curing agent supply device, 17 is a high-pressure water supply device, and 18 is a high-pressure air supply device. Each is provided with a swivel portion 19 of the curing agent injection rod 11 via a hose group 20. It is connected.

The hardener injection rod 11 has a generally cylindrical shape, and has a swivel portion 19 at the proximal end and a monitor portion 21 at the distal end.
And an intermediate portion 22 located between them.
As shown in FIG. 5, the hardening agent injecting rod 11 has a sludge suction passage 24, which extends along the longitudinal axis inside the outer pipe 23.
A total of four passages are provided: a curing agent supply passage 25, a jet water supply passage 26, and an air supply passage 27.

In the swivel portion 19 at the base end, as shown in FIG. 2, a central rotating shaft 29 and an outer pipe connecting shaft 30 have a plurality of bearings 31 on a support frame 28 on which the above-mentioned hanging portion 12 is formed. It is rotatably supported about the longitudinal axis. Each of the central rotating shafts 29 has the above-mentioned sludge suction passage 2
4, hardening agent supply passage 25, jet water supply passage 26, and four holes 32, 33, 3 forming part of the air supply passage 27.
4, 35 are formed, and the sludge suction pipe 36, the hardening agent supply pipe 37, the jet water supply pipe 38, and the air supply pipe 39 are provided at the tips (lower ends in FIG. 2) of the holes 32, 33, 34, 35, respectively.
Is formed so as to be detachably fitted and locked. Note that the jet water supply pipe 38 and the air supply pipe 39 are not shown in FIG. 2 (see FIG. 5).

On the other hand, the base end of the hole 32 into which the sludge suction pipe 36 is fitted is opened at the base end surface (upper end surface) of the central rotating shaft 29 and communicates with the sludge discharge port 40 of the support frame 28. The base ends of the other holes 33, 34, 35 are open to the peripheral surface of the rotation center shaft 29, and annular grooves 41, 42 are provided in the sliding contact surface of the support frame 28 with the center rotation shaft 29, respectively. Through 43, the hardener supply port 44 of the central rotation shaft 29, the jet water supply port 45,
It communicates with the air supply port 46. These mud holes 40 and the respective supply ports 44, 45, 46 have the above-mentioned hose group 20.
(Not shown in FIG. 2) are connected to each of the sludge recovery devices 1
5, the high-pressure curing agent supply device 16, the high-pressure water supply device 17, and the high-pressure air supply device 18 communicate with each other.

Here, depending on the construction process, the curing agent supply path 2
5 may be supplied with high-pressure water for drilling instead of the curing agent, and therefore, in this embodiment, the curing agent supply port 4 is used.
4 is provided with a switching valve (not shown) for communicating the high-pressure water supply device 17 in place of the high-pressure curing agent supply device 16. Alternatively, another high-pressure water supply device may be provided and switched to the high-pressure curing agent supply device 16.

Further, reference numeral 47 in FIG. 2 denotes a lubricant supply portion for lubricating each sliding contact portion. A threaded portion 48 is engraved on the peripheral surface of the tip end of the outer pipe connecting shaft 30.
3 is detachably screwed. Outer tube 23
Is composed of a plurality of members each having a length that is easy to handle, and these members are appropriately connected according to the depth of the construction target portion to obtain a required length. Similarly, the sludge suction passage 24, the curing agent supply passage 25, the jet water supply passage 26, and the air supply passage 27 have a plurality of sludge suction pipes 36 each having a length corresponding to the length of the outer pipe 23, and curing. Agent supply pipe 3
7, a jet water supply pipe 38, an air supply pipe 39, and a connecting sleeve 49.

That is, as shown in FIGS. 3 and 5, the outer tube 23 is screwed to each other by the threaded portions 48 formed on the circumferential surfaces of both ends thereof to have a required length, and one end of the outer tube 23 is made of the outer material. While being screwed to the pipe connecting shaft 30, a connecting sleeve 49 is disposed inside the outer pipe 23 in correspondence with the position of the screw connecting portion. The connection sleeves 49 each have a sludge suction pipe 3
6, hardening agent supply pipe 37, jet water supply pipe 38, and air supply pipe 39 corresponding to four holes 5 penetrating in the longitudinal direction
0, 51, 52, 53 (in FIG. 3, only the holes 50, 51 corresponding to the sludge suction pipe 36 and the hardening agent supply pipe 37 are shown) are formed, and both ends of each hole 50, 51, 52, 53 are formed. A sludge suction pipe 36, a hardening agent supply pipe 37, a jet water supply pipe 38, and an air supply pipe 39 are formed in each of which an enlarged diameter portion is detachably fitted and locked. The connecting sleeve 49 is attached to the outer tube 23 so as to be relatively rotatable about its longitudinal axis.

As shown in FIG. 7, these connections are made by a sludge suction pipe 36, a hardening agent supply pipe 37, and a jet water supply pipe 3.
8. The air supply pipe 39 (the supply pipes 38 and 39 are not shown in FIG. 7) is connected to the corresponding connection sleeve 49.
The holes 50, 51, 52, 53 of the outer tube 23,
It is formed by screwing and screwing the mutual screw parts 48 of each other. Here, the screw portion 48 of the outer tube 23 has a screw direction so that the screw is tightened when the hardening agent injection rod 11 is rotationally driven in relation to the driving rotation direction of the driving device 14 described above. Is selected. Therefore,
This tightening can be performed easily and quickly by using the driving force of the drive unit 14 with the hardener injection rod 11 attached to the drive unit 14, and likewise easily removed. When tightening is completed, each tube 3
The ends of 6, 37, 38, 39 have respective holes 50, 51, 52,
It fits exactly into the expanded diameter portion of 53 without any gap to form a leak-free passage. An O-ring 54 is provided on the contact surfaces of the tubes 36, 37, 38, 39 and the holes 50, 51, 52, 53. On the other hand, in the process of tightening the screws, the inner connecting sleeve 49 does not rotate even when the outer tube 23 rotates, so that even if the plurality of tubes 36, 37, 38, 39 are present, they may be twisted. There is no. In this way
By connecting multiple tubes of appropriate length as necessary,
A desired rod length can be easily obtained.

At the tip of the hardening agent injection rod 11, the monitor section 21 for injecting water and hardening agent is provided. As shown in FIG. 4 and FIG. 6, the monitor section 21 includes four sludge suction passages 24, a hardening agent supply passage 25, a jet water supply passage 26, and a portion of the air supply passage 27. Holes 55, 56, 57, 58 are formed and each hole 5
A sludge suction pipe 36, a hardening agent supply pipe 37, a jet water supply pipe 38, and an air supply pipe 39 are detachably fitted and locked at the base ends (upper end in FIG. 4) of 5, 56, 57, and 58, respectively. The enlarged diameter portion is formed.

A drilling water jet nozzle 59 for jetting forward is provided on the tip end surface of the monitor portion 21, and a hole 56 forming a part of the hardener supply passage 25 communicates with this jet nozzle 59. . A check valve 60 is provided at the tip of the drilling water jet nozzle 59 to allow forward jetting but prevent backflow into the hole 56 from the outside. Incidentally, in FIG.
Is a steel ball that closes the tip of the hole 56, and is introduced from above the hole 56 when necessary in the construction process as described later.

A hardener injection nozzle 62 for injecting in a direction perpendicular to the rod longitudinal axis is provided on the peripheral wall surface of the monitor portion 21 of the hardener injection rod 11, and the hole 5 is provided in this.
A branch hole 63 communicating with 6 is communicated.

A mud discharge hole 64 is formed in the peripheral surface of the monitor portion 21 at the base end side (upper side) of the curing agent injection nozzle 62.
A hole 55 forming a part of the sludge suction passage 24 communicates with the upper portion of the sludge discharge hole 64. A sludge discharge jet nozzle 65 for injecting in the sludge discharge direction in the hole 55 is provided at a position facing the hole 55 in the lower portion of the sludge discharge hole 64. The sludge jet injection nozzle 65 has a double structure consisting of a central core nozzle and surrounding nozzles surrounding it, and as shown in FIG. 6, the core nozzle constitutes a part of the jet water supply passage 26. Holes 57 communicating with each other, and the air supply path 2 is provided to the surrounding nozzles.
Holes 58 forming a part of 7 communicate with each other. The mud discharge hole 64 is not provided with an opening / closing cover for the sake of simplifying the structure.

The ground improvement body is constructed by using the present apparatus as described above. FIG. 8 is an explanatory view showing this construction process. First, in the hole-drilling step of FIG. 8A, high-pressure water as hole-drilling water is supplied from the high-pressure water supply device 17 to the hardening agent supply passage 25, and is injected from the hole-penetrating water injection nozzle 59.
At the same time, the sludge recovery device 15 is operated to activate the sludge suction passage 24.
From the sludge jet injection nozzle 65 while sucking sludge from the sludge and supplying high-pressure water and high-pressure air from the high-pressure water supply device 17 and the high-pressure air supply device 18 to the jet water supply passage 26 and the air supply passage 27, respectively. . Then, while driving the hardener injection rod 11 in the tightening direction of the screw by the drive device 14, the hardener injection rod 11 is moved down into the ground to drill a hole.
The rotation direction of the driving device 14 is the direction in which the screw portion 48 is tightened, so that the screw is not loosened during the construction.

The sludge (sludge) generated by the drilling is sucked from the sludge hole 64 into the sludge suction passage 24. In this case, the high-pressure jet water jetted from the sludge jet injection nozzle 65 removes the sludge. It is crushed and urged in the discharging direction to be discharged smoothly. Further, in the sludge jet injection nozzle 65, high-pressure air is also jetted at the same time so as to surround the high-pressure jet water, so that the push-up force of the jet is increased and the air lift effect is also boosted, so that the sludge can be smoothly discharged. it can.

When the drilling is completed, next, as shown in FIG. 8B, a steel ball 61 is put into the hardening agent supply passage 25 to form the hole 5
The tip of 6 is closed and the drilling water injection nozzle 59 is closed. As described above, the hardening agent supply path 25 is used for both drilling water and the hardening agent, and the switching is performed by inserting the steel ball 61, whereby the structure and the switching operation can be extremely simplified. is there.

Subsequently, in the curing agent injection step shown in FIG. 8C, the high pressure curing agent supply device 16 is provided in the curing agent supply path 25.
The high-pressure curing agent is supplied from the above and is injected from the curing agent injection nozzle 62 through the branch hole 63. At the same time, sludge recovery device 1
5 is operated to suck the sludge from the sludge suction passage 24, and high-pressure water and high-pressure air are supplied to the jet water supply passage 26 and the air supply passage 27 from the high-pressure water supply device 17 and the high-pressure air supply device 18, respectively. And ejected from the sludge jet injection nozzle 65. Then, the drive device 14 rotates the hardening agent injection rod 11 in the tightening direction of the screw and gradually raises it in the rod longitudinal axis direction.

Similar to the above-described drilling step, the sludge replaced with the hardening agent is sucked into the sludge suction passage 24 through the sludge hole 64. In this case, the high pressure jetted from the sludge jet injection nozzle 65 is used. By adjusting the jet and high-pressure air appropriately, it is possible to control the amount of sludge and maintain the ground pressure properly.

In each of the above steps, the hardener injection rod 1
Since there is a swivel part 19 even when 1 is rotated, the hose group 2
0 does not oscillate, it is possible to prevent the hose group 20 from colliding and being damaged, and it is possible to prevent the hose group 20 from becoming disordered.

In the above description of the construction process, an example in which the hardening agent injection rod 11 is made vertical is described, but it is also possible to make the hardening agent injection rod 11 inclined or horizontal. In addition, when constructing horizontally, it is desirable not to inject air in order to prevent the accumulation of air in the hole.

Further, in the above-described embodiment, only the curing agent is injected from the curing agent injection nozzle 62, but like the sludge jet injection nozzle 65, this is the central core nozzle and the surrounding area surrounding it. With a double structure consisting of nozzles,
The curing agent may be injected from the core nozzle and the air may be injected from the peripheral nozzles, and the curing agent may be incorporated with the air. By wrapping with air, the reaching distance of the curing agent can be further extended.

[0037]

As described above in detail with reference to the embodiments, according to the present invention, the outer tube of the hardening agent injection rod can be connected very easily, and the working time can be shortened. Also, by providing a sludge jet injection nozzle, it is possible to smoothly discharge the sludge, which allows injection of a large amount of hardening agent, shortening the construction time and increasing the diameter of the improved product. Can be planned. Further, the device of the present invention has an advantage that it can be simply configured as a whole.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a ground improvement body building device according to an embodiment of the present invention.

2 is a cross-sectional view of a proximal end swivel portion of the hardener injection rod of the embodiment of FIG.

3 is a cross-sectional view of an intermediate portion of the hardener injection rod of the embodiment of FIG.

4 is a cross-sectional view of a tip monitor portion of the hardener injection rod of the embodiment of FIG.

5 is a sectional view taken along line VV of FIG.

6 is a sectional view taken along line VI-VI in FIG.

FIG. 7 is an exploded cross-sectional view of an intermediate portion of the hardener injection rod of the embodiment of FIG.

FIG. 8 is an explanatory diagram showing a construction process by the ground improvement body creating device.

[Explanation of symbols]

 11 Hardening Agent Injection Rod 14 Drive Device 15 Sludge Recovery Device 16 High Pressure Hardening Agent Supply Device 17 High Pressure Water Supply Device 18 High Pressure Air Supply Device 19 Swivel Part 20 Hose Group 21 Monitor Part 22 Middle Part 23 Outer Tube 24 Exhaust Sludge Suction Path 25 Hardener supply passage 26 Jet water supply passage 27 Air supply passage 28 Support frame 29 Center rotation shaft 30 Outer pipe connecting shaft 32, 33, 34, 35 hole 36 Sludge suction pipe 37 Hardener supply pipe 38 Jet water supply pipe 39 Air supply pipe 40 Mud discharge ports 41, 42, 43 Annular groove 44 Curing agent supply port 45 Jet water supply port 46 Air supply port 47 Lubricant supply part 48 Screw part 49 Connecting sleeve 50, 51, 52, 53 hole 54 O-ring 55, 56, 57, 58 Hole 59 Drilling Water Injection Nozzle 60 Check Valve 61 Steel Ball 62 Hardener Injection Nozzle 63 Branch 64 Haidoroana 65 hydro-jet injection nozzle

Claims (11)

[Claims] 1. A ground improvement by forming a hole in the ground and moving the hardening agent injection rod in the rod longitudinal axis direction while injecting a hardening agent for improving the ground with a high pressure by the hardening agent injection rod. In a ground improvement body forming device for forming a body on a target ground, a hardening agent injection rod has an outer pipe and a plurality of pipes installed in the outer pipe, and the pipe is arranged relative to the outer pipe about a longitudinal axis. While being rotatably held, the outer tube is connected by being screwed together with a threaded portion formed on the peripheral surface of the end portion thereof. A ground improvement body constructing device characterized in that it is driven to rotate in a fixed direction. 2. The ground improvement body construction apparatus according to claim 1, wherein the pipes installed inside the outer pipe are a sludge suction pipe, a hardening agent supply pipe, a jet water supply pipe, and an air supply pipe. . 3. A sludge discharge hole communicating with the sludge suction pipe is formed in the peripheral surface of the hardening agent injection rod, and is discharged with the jet water supply pipe in the direction of the sludge discharge. The ground improvement body forming apparatus according to claim 2, wherein a jet injection nozzle is provided in the mud discharge hole. 4. The sludge jet injection nozzle has a double structure consisting of a central core nozzle and a peripheral nozzle surrounding the core nozzle. The core nozzle communicates with the jet water supply pipe and the peripheral nozzle The ground improvement body building apparatus according to claim 3, wherein the ground improvement body is communicated with the air supply pipe. 5. The soil improvement body constructing apparatus according to claim 3, wherein the mud discharge hole is not provided with an opening / closing lid. 6. The ground improvement body constructing apparatus according to claim 2, wherein a hardening agent injection nozzle communicating with the hardening agent supply pipe is provided on a peripheral surface of the hardening agent injection rod. . 7. The hardening agent injection nozzle has a double structure composed of a central core nozzle and a peripheral nozzle surrounding the core nozzle. The core nozzle communicates with the hardening agent supply pipe, and the peripheral nozzle is connected to the peripheral nozzle. The ground improvement body constructing device according to claim 6, wherein the device is in communication with an air supply pipe. 8. The ground improvement body constructing apparatus according to claim 1, wherein the hardening agent injection rod has a swivel portion that guides the pipe to the outside. 9. Ground improvement by forming a hole in the ground and moving the hardening agent injection rod in the rod longitudinal axis direction while injecting a hardening agent for improving the ground at a high pressure by the hardening agent injection rod. In the ground improvement body construction method for forming a body on a target ground, a hardening agent injection rod has an outer pipe and a plurality of pipes installed in the outer pipe, and the pipe is relatively opposed to the outer pipe about a longitudinal axis. The outer tube is rotatably held and is connected to each other by screwing the outer tube with a threaded portion formed on an end peripheral surface thereof, and the hardening agent injection rod is rotationally driven in a certain direction in which the outer tube is screwed. A method for constructing a ground improvement body, which is characterized by carrying out construction. 10. The ground improvement body according to claim 9, wherein the sludge is sucked from a sludge drain hole provided on the peripheral surface of the hardening agent injecting rod, and jet water is jetted in the drainage direction. Construction method. 11. The ground improvement body construction method according to claim 10, wherein the jet water is jetted in a state of being surrounded by high-pressure air.