JPH1054027A - Large depth ground-improvement method and ground improvement machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate ground improvement in large depth by performing excavation while a delay hardening stabilizer is injected, discharging excavation soil and the delay hardening stabilizer upward of the partition part of a ground improvement machine, and pulling the ground improvement machine while the excavation soil and the hardening stabilizer are supplied downward of the partition part of the ground improvement machine. SOLUTION: Excavation of the ground is performed by a cutter drum 3 while a delay hardening stabilizer is injected through a slurry pipe 4. Excavation soil excavated by the cutter drums 3, 3 and the delay hardening stabilizer are discharged to the higher part than a partition part 6 by a soil lifting pump 5, and stirring and mixing thereof are promoted. After the cutter drum 3 reaches prescribed depth, the soil lifting pump 5 and the cutter drum 3 are reversely rotated, a ground improvement machine 2 is pulled while the excavation soil and the hardening stabilizer are supplied to an excavation hole. The lower excavation hole than the raising ground improvement machine 2 is tightly filled with the excavation soil and the hardening stabilizer. Thus, ground improvement of large depth whose stratum constitution is complicated can be performed easily.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an underground
It belongs to the technical field of a deep ground improvement method for excavating the ground to a deep depth of about 00 m to improve the ground to a ground strength, and a ground improvement machine used for implementing the method. However, the ground improvement machine is excellent in applicability to deep ground improvement, but it can be applied to ground improvement at medium to shallow depths as it is.

[0002]

2. Description of the Related Art Conventionally, a ground improvement material (hereinafter referred to as a ground stabilizing material or simply a soil stabilizing material, a hardening material, a solidifying material, etc.) is excavated in a soft ground and excavated into an excavated soil at an original position (in a drilling hole). As a ground improvement method and a ground improvement machine that injects, stirs, mixes, and stabilizes, so-called multi-shaft augers have been developed and implemented since around 1975. Has left many achievements. For example, reference is made to the inventions described in Japanese Utility Model Publication No. 58-10750, JP-A-63-300110, and the like.

[0003] Further, in recent years, as a measure for constructing a seawall of a port located on soft ground, a deep ground improvement method and a deep ground improvement machine capable of deep ground improvement have been developed. . For example, the invention described in Japanese Patent Application No. 7-107356 and drawings is referred to.

[0004]

The maximum depth that can be improved by a conventional general multi-axis auger type ground improvement machine is about 40.
m, and there is a problem that it cannot be dealt with when there is soft ground near 70 m to 100 m deep underground. Specifically, in the case of the improvement method using the conventional auger type soil improvement machine, the rotating shaft (kelly bar) becomes longer in proportion to the depth of the soil improvement, and the base machine of the soil improvement machine which supports this However, it is inevitably too large in scale, and the cost of machinery and equipment is enormous. Therefore, there is a limit to elongating the rotating shaft, which is not suitable for onshore construction.

An auger-type soil improvement machine is mainly intended for improvement of a sludge-like soft ground, and excavation and improvement of a ground where a gravel layer or soft rock having an N value of 50 or more exists underground is not possible. It is possible. Furthermore, in the improvement of the ground where gravel is mixed, gravel with a large specific gravity is deposited on the bottom of the drilling hole and causes an increase in the auger drilling torque.
At last, it is impossible to excavate, so it is impossible to improve the ground for large depths.

Accordingly, an object of the present invention is to solve the above-mentioned problem in Japanese Patent Application No.
A deep soil improvement method and a deep soil improvement machine according to the invention described in the specification and drawings of No. 107356 and the degree of perfection of the deep soil improvement machine are improved so that the soil improvement at a large depth of about 70 m to 100 m underground can be easily realized. It is an object of the present invention to provide an economical deep ground improvement method and a ground improvement machine which are easy to shorten the working time of improvement work, secure quality and accuracy, and easily control.

[0007]

Means for Solving the Problems As means for solving the above problems, the invention according to claim 1 excavates the ground, injects ground stabilizing material into excavated soil at the original position, and stirs and mixes. In the soil improvement method to stabilize, the soil improvement machine supported by the extension type pillars has a cutter drum with at least one pair of horizontal shafts at the tip, and has a configuration in which a slurry discharge pipe is opened immediately above the cutter drum, Excavating the ground by the cutter drum to a large depth while injecting the slow-hardening stabilizer through the slurry discharge pipe, excavated soil excavated by the pair of cutter drums, and the slow-hardening stabilizer injected into this The mixture of the above shall be discharged above the partition of the ground improvement machine by the lifting pump,
The lifting process after the ground improvement machine reaches the predetermined depth,
While reversing the lifting pump and cutter drum,
The method is characterized in that a mixture of the excavated soil and the slow-hardening stabilizer is supplied to a portion below (in the excavation hole) below the partitioning portion of the ground improvement machine by a lifting pump. In other words, this is an improved penetration type discharge method in which a stabilizer is injected in parallel with excavation of the ground.

According to a second aspect of the present invention, there is provided a ground improvement method for excavating the ground, injecting a ground stabilizing material into excavated soil at an in-situ position, stirring and mixing the ground, and stabilizing the ground. The supported soil improvement machine is provided with at least a pair of horizontal shaft-based cutter drums at a tip end thereof, and has a configuration in which a slurry discharge pipe is opened immediately above the cutter drum. Excavation to a large depth, the excavated soil excavated by the pair of cutter drums is discharged above the partition of the soil improvement machine by a lifting pump, after the soil improvement machine reaches a predetermined depth In the lifting process, the lifting pump and the cutter drum are rotated in reverse, and the injection nozzle located above the partition of the ground improvement machine is rotated while rotating the injection nozzle. Mixture of the excavated soil and stability material with a Jozai injected into excavation soil of the same site and, respectively characterized in that while supplying downward from the partition portion of the soil improvement machine by Agetsuchi pump. In other words, it is an improved method of the drawing discharge type in which the stabilizer is injected when the excavator is pulled up.

According to a third aspect of the present invention, there is provided a ground improvement machine for excavating a ground vertically downward, injecting a ground stabilizing material into excavated soil at an original position, stirring and mixing the ground, and stabilizing the ground. At least one pair of horizontal shafts is provided with a cutter drum and driving means for the cutter drum at a tip end of a machine frame supported by a pillar suspended from the ground, and a slurry discharge pipe piped from the ground has an injection hole opened at a position immediately above the cutter drum. The excavator including the pair of cutter drums and the casing thereof, and a partition portion for partitioning the remaining upper portion substantially horizontally, directly above a portion where the pair of cutter drums scrapes up excavated soil. A lift pump for discharging the excavated soil to the upper portion through the partition portion and a driving means therefor are provided at positions. In other words, it is a ground improvement machine used in the penetrating discharge type improvement method according to claim 1.

The invention described in claim 4 is also a ground improvement machine for excavating the ground vertically downward, injecting ground stabilizing material into excavated soil at the original position, stirring and mixing the ground, and stabilizing the ground. At the end of the machine frame supported by a column suspended vertically, a cutter drum having at least a pair of horizontal shafts and a driving means for the cutter drum are provided, and a slurry discharge pipe piped from the ground relays a slurry switching valve to connect the cutter drum to the cutter drum. An injection hole is opened at a position directly above, and a partitioning part is provided which divides the lower part of the excavator including the pair of cutter drums and the casing thereof and the upper part of the excavator substantially horizontally, and the pair of cutter drums excavates. Immediately above the site where the soil is scraped up, a lifting pump and a driving means for discharging the excavated soil to the upper portion through the partition portion are provided. And a high-pressure slurry injection pipe is rotatably installed at a position where the stabilizer is injected into the excavated soil discharged to the upper part of the partition part, and the injection pipe is connected to the slurry switching valve and the high-pressure slurry injection valve is connected to the high-pressure slurry injection valve. It is characterized in that means for rotating and driving the slurry injection pipe are provided. In other words, it is a ground improvement machine used in the improvement method of the drawing discharge type according to the second aspect.

[0011] The partition part according to claim 3 or 4 is characterized in that it includes a movable partition plate for closing a gap between the outer periphery of the excavator and the wall of the excavation hole, and a driving means therefor.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION
Drilling the ground up to about 100m, injecting ground stabilizing material into excavated soil in situ, stir mixing to stabilize it, and deep soil improvement method that is preferably implemented as a ground improvement machine used in the method You. The deep ground improvement method according to the present invention is roughly classified into two embodiments, and the ground improvement machine is also roughly classified into two embodiments.

A first embodiment of the deep ground improvement method is as follows.
This is a penetrating discharge type improvement method in which the ground is improved while pouring a slow-hardening stabilizer in parallel with the excavation of the ground. It is described in claim 1 and, as described in FIGS. 1 to 3, the ground improvement machine 2 supported by the extension type column 1 is provided with at least one pair of cutter drums 3, 3 by a horizontal shaft at a tip end thereof. And the injection hole 4 of the slurry discharge pipe 4
a is opened, and a slow-hardening stabilizer (typically a slow-hardening cement slurry or the like) is passed through the slurry discharge pipe 4.
Excavation of the ground with the cutter drum 3 is performed to a target large depth. Therefore, since the stabilizing material and the excavated soil are stirred and mixed at the same time as excavation of the ground, the slow-hardening stabilizing material is adjusted so that the hardening is delayed until the pulling process after excavating to the predetermined depth is completed. The extension work of the strut 1 accompanying the progress of the excavation (or the division work at the time of the pulling process) is performed by setting and fixing the strut 1 of the excavator 2 which has already entered the excavation hole 8 at the ground level and fixed. It is temporarily supported and fixed by the device 7.

A mixture of the excavated soil excavated by the pair of cutter drums 3 and 3 and the slow-hardening stabilizer injected into the excavated soil is sequentially and promptly moved by the earth-lifting pump 5 of the ground improvement machine. It is discharged above the partition 6 of the improved machine 2. Therefore, even in the discharging process by the earth pump 5, the agitation and mixing of the excavated soil and the stabilizer are promoted. Also,
Even in the improvement of the ground in which the gravel having a large specific gravity is mixed, the gravel is not deposited at the time of excavation. Therefore, the excavation torque of the cutter drum 3 does not increase, and the excavation at a large depth can be easily performed.

After the ground improvement machine 2 reaches a predetermined depth, the lifting process is performed by the above-described earth pump 5 and cutter drum 3.
And the mixture of the excavated soil and the slow-hardening stabilizer is supplied by the earth-lifting pump 5 to a portion (in the excavation hole) below the partition 6 of the ground improvement machine 2. Therefore, the operation of the earth pump 5 reduces not only the loading pressure of the mixture that resists the lifting of the ground improvement machine 2 at the nearest position, but also generates a floating force (reaction of the downward pumping action). Then, the lifting operation of the ground improvement machine 2 is easy. The mixture of the excavated soil and the stabilizer is densely filled in the excavation hole below the ascending ground improvement machine 2 to form a high quality improved ground.

According to the first large depth ground improvement method,
The excavated soil and the slow-hardening stabilizer are agitated and mixed at the stage of soil excavation by the cutter drum 3, and a mixture of the excavated soil and the slow-hardening stabilizer is grounded by the earth-lifting machine 2 by the earth-lifting pump 5.
The stirring and mixing are also performed in the moving process of discharging the liquid from above the partition portion 6. Further, in the lifting process after the ground improvement machine 2 reaches a predetermined depth, the mixture of the excavated soil and the slow-hardening stabilizer is lifted by the earth lift pump 5 into the partitioning portion 6 of the soil improvement machine 2.
Since the stirring and mixing are performed even in the moving process of supplying the material to the lower side, a sufficiently high quality improved ground can be created. The slow-acting stabilizer is adjusted so that the curing phenomenon is delayed until the pulling process is completed.

Next, a second embodiment of the deep ground improvement method is to excavate to a predetermined depth while injecting muddy water (usually bentonite muddy water) from an injection hole of a slurry discharge pipe. This method is a drawing-out discharge type improvement method in which a ground is improved by injecting a normal stabilizer (usually a normal cement slurry or the like) when the machine is pulled up. As described in claim 2 and as described in the drawings, the ground improvement machine 2 also supported by the extension type column 1 has at least one pair of cutter drums 3 with a horizontal shaft at the tip end, and directly above it. An injection hole 4a of the slurry discharge pipe 4 is opened at a position, and the ground is excavated by the cutter drum 3 to a large depth while supplying muddy water through the slurry discharge pipe 4. That is, the stabilizer is not yet injected at this intrusion stage.

The excavated soil excavated by the pair of cutter drums 3 and 3 is discharged to a portion above the partition 6 of the ground improvement machine by the earth pump 5 of the ground improvement machine 2. Due to the rapid and rapid movement of the excavated soil, excavation of the ground where the gravel with a large specific gravity exists does not cause sedimentation of the gravel, so that excavation at a large depth can be easily performed. In the lifting step after the ground improvement machine 2 reaches a predetermined depth, the excavated soil discharged to a position above the partitioning portion 6 of the ground improvement machine 2 by reversing the earth lifting pump 5 and the cutter drum 3 is used. While rotating the injection nozzle 9 positioned at the site, the ordinary stabilizer is pressed in, and then the mixture of the excavated soil and the stabilizer is removed by the earthlifting pump 5 into the partitioning portion 6 of the ground improvement machine 2.
This is done by feeding into the borehole below. As a result, the stirring and mixing are sufficiently performed repeatedly even in the moving process by the pump. In addition, the movement of the mixture reduces the mounting pressure of the mixture of excavated soil and stabilizer that resists the lifting of the ground improvement machine 2, and generates a force to float as a reaction to the downward pump action. The lifting operation 2 is easily performed. In addition, a mixture of excavated soil and a stabilizing material is densely filled in the excavation hole below the trace where the ascending soil improvement machine 2 has risen, so that a high-quality improved ground is created.

Next, the ground improvement machines applied to each of the deep ground improvement methods roughly classified into the two embodiments as described above also have the two embodiments (the invention according to claims 3 and 4). Are roughly divided into Both inventions are basically ground improvement machines that excavate the ground vertically downward, inject ground stabilizing material into excavated soil in situ, stir and mix, and stabilize,
The configuration of the third aspect of the invention is common. On the other hand, the difference between the two inventions is that, in the case of the invention described in claim 4, in the ground improvement machine 2, the lower part of the excavator including the pair of cutter drums 3, 3 and its casing and the upper part of the other part are substantially horizontal at the middle part. A high-pressure slurry injection pipe 9 is rotatably installed at a position suitable for injecting a stabilizer into the excavated soil discharged by the earth-lifting pump 5 above the partitioning portion 6 which is divided into:
The injection pipe is connected to the slurry switching valve 10,
A means 11 for rotating and driving the high-pressure slurry injection pipe 9 is provided.

The partitioning portion 6 of the ground improvement machine 2 according to the third or fourth aspect has a structure including a movable partitioning plate 14 for closing a gap between the outer periphery of the excavator and the wall of the excavation hole, and a driving means 15 therefor. (See FIG. 2). Next, a ground improvement machine according to the fourth aspect of the invention, which is configured to be applicable to both ground improvement methods, will be described based on the embodiment shown in FIGS.

A strut unit 1 is constructed as a replenishment type in which strut units of unit length are successively extended to penetrate or are divided and lifted, and suspended vertically from the ground.
Are supported by a column gripping / pulling-out device 7 installed on the ground level (FIG. 1). This support gripping and extracting device 7
A vertical push-in or pull-out drive means 7b is provided on a base 7a, and a clamp mechanism 7c supported on the other end side of the drive means 7b grips and fixes the column 1. The next column unit is added to the column 1 gripped and fixed by the clamp mechanism 7c, or the joint is disassembled to perform a division (separation) operation. By driving the driving means 7b up and down while holding the column 1 by the clamp mechanism 7c, the column 1 and thus the ground improvement machine 2 are forcibly penetrated or pulled up. It is preferable that a clamp mechanism is also provided on the base 7a as a means for securely and safely performing the operation of penetrating or pulling up the column 1 like a caterpillar operation.

At the end of the machine frame 12 supported by the column 1 having the above-described structure, the cutter drums 3, 3 rotating around a pair (or a plurality of pairs) of horizontal shafts 17 are installed downward, and the cutter drums 3, 3 are positioned directly above the cutter drums. A flat casing 13 is provided substantially horizontally. As shown in FIG. 3, the horizontal shaft 17 of the cutter drum 3 is supported by a bearing plate 21 provided downward at the center of the casing 13. A hydraulic (or electric) motor 16 for rotating the cutter drum 3 is installed on the upper surface of the casing 13, and both are described in, for example, the above-mentioned Japanese Patent Application No. 7-107356 and the drawings. In addition to the worm-type transmission mechanism that employs a long worm shaft and a worm as described above, a configuration in which communication is performed by a transmission mechanism such as a chain drive type gear drive type or the like according to use conditions is adopted and implemented. The cutter drum 3 can sharply excavate not only the gravel ground having an N value of 50 or more but also soft rock or other hard ground.
Therefore, the ground can be excavated irrespective of the formation of the stratum, so that it is possible to cope with a deep ground improvement. For example, since the connection surface with the already improved solid ground can be cut, continuity and integrity of the improved ground can be easily secured.

Slurry discharge pipes 4 are arranged at the left and right sides of the casing 13 shown in FIG. 2, and an injection hole 4a is opened immediately above the cutter drum 3.
Slurry hose 18 laid from the slurry preparation and supply device or muddy water preparation and supply device prepared on the ground
Is connected to the slurry discharge pipe 4 via a slurry switching valve 10 fixed to an upper part of a machine frame 12. Therefore, when the stabilizer is injected from the injection hole 4a of the slurry discharge pipe 4 during excavation of the ground by the cutter drum 3, stirring and mixing are performed sufficiently and sufficiently in combination with the excavation operation.

A partitioning portion 6 is provided which divides the lower part of the excavator including the pair of cutter drums 3, 3 and its casing 13 and the upper part of the excavator substantially horizontally at an intermediate portion. At the position immediately above the site where the pair of cutter drums 3 and 3 lift up the excavated soil, an earth-lifting pump 5 that discharges the excavated soil to the upper portion through the partition portion 6 and the casing 13 is provided. . A motor 19 as a means for driving the earth pump 5 is installed on a support base 22 fixed to a machine frame, and a rotating shaft 19 a is connected to the pump 5. A screw type or screw type structure is suitable for the earth pump 5, but the structure type is not particularly limited.

As shown in FIG. 3, the partition portion 16 also includes a movable partition plate 14 whose tip comes close to or abuts on the wall of the excavation hole and exerts a partitioning effect for the upper and lower spaces. Driving means 15 for tilting the movable partition plate 14
Is provided. Therefore, the excavated soil discharged to the upper part of the partition part 16 by the earth pump 5 keeps its position as it is, and does not fall naturally to the cutter drum part again. Therefore, the phenomenon that the excavated soil is entangled with the cutter drum does not occur, and there is no fear that gravel or the like having a large specific gravity is deposited, and the excavation torque does not increase due to this.

The high-pressure slurry injection pipe 9 is rotatably supported by the support base 22 at a position where the stabilizer can be evenly and uniformly injected into the excavated soil discharged to the upper part of the excavator by the above-mentioned earth pump 5. is set up. The injection pipe 9 is connected to the slurry switching valve 10 by a hose 23. Further, a means 11 for rotating and driving the high-pressure slurry injection pipe 9 is provided.

Therefore, in particular, when the ground improvement method of the drawing discharge type is carried out, when the high-pressure slurry injection pipe 9 is driven to rotate and high-pressure injection of the stabilizer is performed, stirring and mixing with the excavated soil are performed well. And the mixture is discharged one after another
Thus, even in the moving process of supplying the material to the lower side of the cutter drum 3, more sufficient stirring and mixing is performed, which contributes to the formation of a high quality improved ground. Reference numeral 20 in the figure denotes a stabilizer for controlling and maintaining the attitude (vertical accuracy) of the ground improvement machine 2.

[0028]

According to the deep soil improvement method and the soil improvement machine of the present invention, the cutter drum 3 has an N value of 5
Since zero or more hard ground, soft rock, and the like are sharply and efficiently cut (excavated), it is possible to easily perform ground improvement at a large depth where the stratum configuration is complicated. In addition, since the cutter drum can surely cut the connection surface with the improved ground, continuity (integration) of the improved ground can be easily ensured.

According to the present invention, the excavated soil excavated by the cutter drum 3 is immediately discharged to a portion above the partition portion by a lifting pump, and at least the excavated soil and gravel are entangled around the cutter drum to reduce the rotational torque. Since the inconvenience to increase does not occur, ground improvement at a large depth can be easily performed, and ground improvement of uniform and high quality can be performed.

[Brief description of the drawings]

FIG. 1 is an elevation view showing a construction drawing of a ground improvement method according to the present invention.

FIG. 2 is a vertical sectional view in the front direction of the ground improvement machine.

FIG. 3 is a side view of the ground improvement machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Prop 2 Ground improvement machine 17 Horizontal axis 3 Cutter drum 4 Slurry discharge pipe 4a Injection hole 5 Lifting pump 9 High pressure slurry injection pipe 6 Partition part

Continuing from the front page (72) Inventor Satoshi Saito 1-5-1, Otsuka, Inzai City, Chiba Prefecture Inside the Technical Research Institute, Takenaka Corporation (72) Inventor Toshiaki Tsuchiya 8-21-1, Ginza, Chuo-ku, Tokyo Stock Company (72) Inventor Minoru Suzuki 8-21-1, Ginza, Chuo-ku, Tokyo Co., Ltd.Hiroshi Kojima (72) Inventor Heizo Kojima 8-2-1, Ginza, Chuo-ku, Tokyo Takenaka Civil Engineering Co., Ltd.

Claims (5)

[Claims] 1. A ground improvement method for excavating the ground, injecting ground stabilizing material into excavated soil at an in-situ position, and stirring and mixing the ground to stabilize the ground. A cutter drum is provided with at least one pair of horizontal shafts, and a slurry discharge pipe is opened immediately above the cutter drum,
Excavating the ground by a cutter drum to a large depth while injecting the slow-hardening stabilizer through the slurry discharge pipe, excavated soil excavated by the pair of cutter drums,
The mixture with the slow-hardening stabilizer injected into this is discharged above the partitioning part of the soil improvement machine by the earth-lifting pump, and the lifting step after the soil improvement machine reaches the predetermined depth,
Reversing the lifting pump and the cutter drum, while performing a mixture of the excavated soil and the slow-hardening stabilizer below the partitioning part of the ground improvement machine by the lifting pump, and performing each of the large depths. Ground improvement method. 2. A ground improvement method for excavating the ground, injecting ground stabilizing material into excavated soil at an in-situ position, and stirring and mixing the ground to stabilize the ground. A cutter drum is provided with at least one pair of horizontal shafts, and a slurry discharge pipe is opened immediately above the cutter drum,
Excavation of the ground by a cutter drum to a large depth while supplying muddy water through the slurry discharge pipe, and excavated soil excavated by the pair of cutter drums is discharged upward from a partitioning part of a ground improvement machine by a lifting pump. That, the lifting process after the ground improvement machine reaches the predetermined depth,
Invert the earth pump and cutter drum, inject the ordinary stabilizer into the excavated soil of the same part while rotating the injection nozzle located above the partition part of the ground improvement machine, and the excavated soil and the stable material The mixture of the above shall be supplied while being supplied below the partition of the ground improvement machine by the earth pump.
Deep soil improvement method characterized by each. 3. A ground improvement machine for excavating the ground vertically downward, injecting ground stabilizing material into excavated soil at an in-situ position, and mixing and stabilizing the ground, which is supported by a column suspended vertically from the ground. A cutter drum having at least a pair of horizontal shafts and driving means for the cutter drum at a tip end of the machine frame, and a slurry discharge pipe piped from the ground has an injection hole opened at a position immediately above the cutter drum; A lower part of the excavator including the cutter drum and its casing, and a partition part that divides the remaining upper part substantially horizontally, and the partition part is located immediately above a part where the pair of cutter drums lift up the excavated soil. A soil improvement machine characterized by being provided with a lifting pump for penetrating and discharging excavated soil to the upper part and a driving means therefor. 4. A ground improvement machine for excavating the ground vertically downward, injecting ground stabilizing material into excavated soil in situ, and mixing and stabilizing the ground, and supported by a column suspended vertically from the ground. At the end of the machine frame is provided at least a pair of horizontal shafts with a cutter drum and a driving means therefor, and a slurry discharge pipe piped from the ground has an injection hole opened at a position immediately above the cutter drum via a slurry switching valve. A lower portion of the excavator including the pair of cutter drums and the casing thereof, and a partition portion for partitioning the remaining upper portion substantially horizontally, and a position immediately above a portion where the pair of cutter drums scrapes up excavated soil. A lifting pump and a driving means for discharging the excavated soil to the upper portion through the partition portion, and a driving means therefor; A high-pressure slurry injection pipe is rotatably installed at a position where the stabilizer is injected into the excavated soil, and the injection pipe is connected to the slurry switching valve and means for rotating and driving the high-pressure slurry injection pipe. Are provided, respectively, a ground improvement machine characterized by the following. 5. The ground improvement machine according to claim 3, wherein the partition portion includes a movable partition plate for closing a gap between the outer periphery of the excavator and the wall of the excavation hole, and driving means therefor.