JPH0754335A - Founation improvement method - Google Patents

Abstract

PURPOSE:To make it possible to create a clay soil and to accurately create an underground pile with a simple equipment. CONSTITUTION:Upon providing an agitation blade 30 on a monitor mechanism 7 of a high pressure material filling pipe 5, the agitation blade 30 of the high pressure material is changed over to an opened position Q after lowering it and a hardening underground pile is created in a slurry area 11 by agitating and mixing the surrounding soil with rotary jet, continuously injecting high pressure material, and rotary agitation of the agitation blade 30. At the slurry area 11, where soil is mixed by injecting high pressure material, an underground pile can be created with less energy because gems and stomes of heavier specific gravity go down to the bottom as they are caught by the agitation force of the agitation blade 30. Furthermore, excavation force is increased by the combination of agitation by the agitation blade 30 and injection of the high pressure material, thus making it possible to create clay soil as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a water blocking wall, an underground continuous wall,
Regarding the technology to improve the ground by forming the foundation structure in the stable construction of the foundation ground, etc., it is possible to improve the viscous ground, and to provide the one that allows the diameter of hardened underground piles to be checked and sludge treatment to be performed easily. To do.

[0002]

2. Description of the Related Art Generally, a mechanical agitation type ground improvement method in which a ground is perforated by a spiral drilling blade and filled with a hardening material has the following problems. (1) Since holes are drilled from top to bottom with a blade, it takes a lot of time to drill on hard ground such as cobblestone. In addition, unnecessary ground is drilled. (2) Due to (1) above, construction is not possible if there are obstacles such as buried pipes. (3) If the boring blade protruding from the rotating shaft contacts an existing structure, the structure may be damaged. (4) As the excavation energy increases as the excavation diameter increases,
A large machine is needed.

[0003]

2. Description of the Related Art On the other hand, as a means for solving the above problems (1) to (3), a jet grout type ground improvement method of kneading the ground with a swirling jet of high-pressure material has been conventionally known. . That is, as a jet grout type ground improvement method, for example, Japanese Patent Publication No. 4-4889 proposed by the present applicant is proposed.
There is one disclosed in Japanese Patent No. 4 publication. 11 (a)-(e)
FIG. 4 is an explanatory view showing the procedure of the jet grout type ground improvement method, where FIG. 3 (a) is an installation process, FIG. 2 (b) is a drilling process, FIG. 3 (c) is an injection test process, and FIG. ) Is a forming process, and FIG. 8E is a drawing and washing process. Hereinafter, this conventional technique will be described with reference to FIGS.

In the installation process << FIG. 11 (a) >>, an underground pile forming device M is installed on the ground. This underground pile construction device M is
The swivel lift drive device 1, the hardening material ultra-high pressure supply device 2, the ultra-high pressure water supply device 3 and the compressed air supply device 4 and the high-pressure material injection pipe 5 formed of a triple pipe supported by the swivel lift drive device 1 are provided. A swivel 6 is connected to the upper end of the high-pressure material injection pipe 5, and a monitor mechanism 7 is connected to the lower end of the high-pressure material injection pipe 5. The swivel 6 is provided with a jet inlet that also serves as the ultrahigh pressure water W and the ultrahigh pressure hardening material G, a high pressure air inlet and an ultrahigh pressure water inlet, and the jet inlet has a hardening material ultrahigh pressure supply device 2 The ultra high pressure water inlet is connected to the ultra high pressure water supply device 3, and the high pressure air inlet is connected to the compressed air supply device 4.

The monitor mechanism 7 is provided with a hardening material injection nozzle which is opened radially outward on its peripheral surface, and is opened at a position higher than the hardening material injection nozzle in a direction opposite to the opening direction of the hardening material injection nozzle. A water jet nozzle and an air nozzle for jetting air radially outward from the periphery of the water jet nozzle, and a water jet hole for jetting muddy water W at the time of excavating the vertical hole 10a at the lower part of the monitor mechanism 7. A metal crown for excavating the vertical hole 10a is attached.

In the drilling step << FIG. 11 (b) >>, the vertical hole excavating step and the injection tube inserting step are performed in parallel. That is, the high-pressure material injection pipe 5 is erected vertically at a predetermined construction position, the ultrahigh-pressure water supply device 3 is connected to the jet inlet of the swivel 6 connected to the upper part of the high-pressure material injection pipe 5, The water W is discharged downward from the water supply nozzle of the monitor mechanism 7 connected to the lower part of the pipe, the swivel / elevation drive device 1 is actuated, and the high pressure material injection pipe 5 is swung down to make a vertical hole 10a. , The high pressure material injection pipe 5 is inserted to a predetermined depth in the ground.

In the injection test process << FIG. 11 (c) >>, the hardening material ultra-high pressure supply device 2 is provided at the jet inlet of the swivel 6, the ultra-high pressure water supply device 3 is provided at the ultra-high pressure water inlet, and the compressed air supply device is provided at the air inlet. 4 are connected to each other, and the turning / lifting drive device 1 is actuated to drive the high-pressure material injection pipe 5 to turn at a trially set rotational speed and to raise it at a trially set rising stroke speed.

In the forming step << FIG. 11 (d) >>, the hardening material ultra-high pressure device 2 is operated to press-in the hardening material G such as cement milk from the hardening material inlet of the swivel 6, and the ultra-high pressure water supply device 3 is connected. The swivel 6 is operated to pressurize the ultrahigh pressure water W from the ultrahigh pressure water inlet of the swivel 6 and press the compressed air from the air inlet. As a result, the hardening material G is continuously ejected in the pipe radial direction from the lower injection nozzle of the monitor mechanism 7 assembled to the lower part of the high pressure material injection pipe 5, and the super high pressure water W is emitted from the upper injection nozzle in the pipe radial direction. To continuously jet.

Then, the swirl and pull-up drive device 1 is operated to drive the high-pressure material injection pipe 5 while swirling and driving, so that the hardened material G continuously ejected from the injection nozzle in the lower stage at an ultrahigh pressure is discharged. The ultra-high pressure water W continuously ejected from the jet nozzle of No. 2 is swirled and pulled up, and the ground around it is excavated and kneaded by the jet output, and the uncured underground pile P is formed in the sludge area 11. To create.

In the drawing and washing step << FIG. 11 (e) >>, the high-pressure material injection pipe 5 is drawn to the ground, and the inside of the pipe is washed with fresh water. Then, it moves to the next construction point and the uncured underground pile P is constructed in the soil by the same procedure. The foundation structure 13 is formed in the ground by hardening the uncured underground pile P.

[0011]

However, the above-mentioned prior art 2 has the following problems. (1) In dense ground such as clay ground, the excavation force of the jet jet of high-pressure material is insufficient, and the diameter of the underground pile cannot be confirmed (that is, the underground pile cannot be accurately constructed), Not suitable for construction at large depths. (2) When the diameter of the underground pile increases, a triple pipe is required as a high-pressure material injection pipe (specifically, a hardening material injection pipe), and the equipment becomes complicated and large. (3) Since the ground is excavated by a swirling jet of hardened material and muddy water that have been pumped at ultra-high pressure, a large amount of hardened material and muddy water are required, and the amount of sludge discharged increases, which incurs the cost of sludge treatment. Expensive. The present invention has been made in view of such circumstances, and an object thereof is to enable creation of clay ground and the like, and to create underground piles inexpensively and accurately with simple equipment. .

[0012]

The present invention employs a novel mechanical stirring method and jet grout method, respectively. That is, in the invention of claim 1, the swivel 6 is attached to the upper end of the high pressure material injection pipe 5, and the monitor mechanism 7 is attached to the lower end thereof, and the high pressure material injection nozzle 8 is attached to the upper part of the monitor mechanism 7.
, Each of which is provided with a stirring blade 30 at its lower portion, and the stirring blade 30 is configured to be capable of switching its posture between a folding posture R and an open posture Q, and the tip conduit 10 is inserted from the surface of the earth to a target depth in the ground, The material injection pipe 5 is lowered along the inside of the leading conduit 10 with the stirring blade 30 folded down and in the posture R, and the leading conduit 10 is moved up to switch the stirring blade 30 of the high pressure material feeding pipe 5 to the open posture Q to inject the high pressure material. While swirling and pulling up the pipe 5, the high-pressure material is continuously ejected from the high-pressure material injection nozzle 8 of the monitor mechanism 7 through the swivel 6 and the high-pressure material injection pipe 5 in the radial direction of the pipe. With the swirling jet of the high-pressure material and the swirling stirring of the stirring blades 30, the surrounding ground is excavated and kneaded and kneaded to form a sludge zone 11, and a hardened underground pile is formed in the sludge zone 11. Characteristic ground improvement method A.

The invention of claim 2 is characterized in that, in the invention of claim 1, the high-pressure material is a hardening material. According to the invention of claim 3, in the invention of claim 1, initially, the mud water W is used as the high-pressure material, and the ground is excavated by a swirling jet of the mud water W and swirling stirring of the stirring blades 30 while pulling up the high-pressure material injection pipe 5. Mix with stirring and mixing 1
1 is formed, and then when the high pressure material injection pipe 5 is lowered,
A core member 50 configured to be switchable between a folded position S and an open position T is provided with a core member 50 in a folded position S along the inside of the leading conduit 10.
, And a plurality of core materials 50 are embedded in the sludge area 11 in a horizontal direction in a radially open posture T in a multi-tiered manner, and then a hardening material G is used as a high-pressure material, and a high-pressure material injection pipe 5 is used. The sludge 11 in the sludge area 11 is replaced with the core material 50 and the hardened material G while pulling up. The turning of the high-pressure material injection pipe 5 includes both rotation in one direction and swing rotation. The high-pressure material is a high-pressure hardening material G, high-pressure muddy water W, or the like.

[0014]

[Action]

(1) The invention of claim 1 operates as follows. Swirl jet of high-pressure material consisting of hardened material or muddy water and stirring blade 3
Since the surrounding ground is excavated and kneaded with the turning of 0, the excavation force can be increased without increasing the jetting force of the high-pressure material as in Conventional Example 2. That is, since the high-pressure material is injected from the upper side of the stirring blade 30, when the high-pressure material injection pipe 5 is pulled up, the ground previously excavated by the jet of the high-pressure material is continuously excavated and stirred by the stirring blade 30. The load on the stirring blade 30 at that time is reduced. Further, in the sludge region 11 kneaded by the jet of high-pressure material, boulders or the like having a large specific gravity are captured and guided by the stirring force of the stirring blade 30, and the sludge region 1
Since it sinks to the bottom of No. 1, the efficiency of excavation and kneading and stirring work increases.

(2) In the invention of claim 2, since the hardening material such as cement milk is used as the high pressure material, the high pressure material injection pipe 5
Underground piles can be constructed in one step of descending and pulling up. (3) In the invention of claim 3, in the first step, muddy water is injected to form a cylindrical sludge area 11, and in the next step, a plurality of core materials 50 are vertically stacked in the soft sludge area 11. Since the hardening material is injected and injected while the high pressure material injection pipe 5 is continuously raised to replace the sludge in the sludge area 11 with the core material 50 and the high pressure material G, the strength of the underground pile is increased. To be enhanced.

[0016]

【The invention's effect】

(1) The invention of claim 1 has the following effects. Even in the ground, hard parts such as cobblestones sink to the bottom of the sludge area and can be easily removed, so compared to Conventional Example 1,
Underground piles can be created with less energy (ie simple equipment). Since the excavation force is enhanced by combining the stirring of the stirring blades and the injection of the high-pressure material, by applying the present invention to dense ground such as clay ground, it is possible to contribute to the efficiency of the ground improvement method. Since the stirring diameter of the sludge area can be roughly determined by the stirring blade, the diameter of the underground pile can be confirmed at the same time as construction, and the underground pile can be accurately constructed. Due to the above, since a large excavating force can be obtained without increasing the jetting force of the hardened material unlike the conventional example 2, the consumption of the hardened material is reduced, and accordingly, the amount of sludge discharged is reduced. Mud disposal costs will also be low.

(2) According to the second aspect of the invention, the underground pile can be constructed quickly and simply in one step. (3) In the invention of claim 3, the sludge zone 11 is previously formed with mud water, the core material 50 is embedded in the sludge zone 11, and the sludge in the sludge zone 11 is used as the core material 50 and the high pressure material G. Because it replaces
High strength underground piles can be quickly constructed with little energy.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 are explanatory views showing the procedure of the ground improvement method of the present embodiment, FIG. 4 is an overall explanatory view of an underground pile building device, FIG. 5 is an explanatory view of a swivel and a slime (sludge) collector, and FIG. 7 is an explanatory view of a high-pressure material injection pipe and a monitoring mechanism, FIGS. 7 and 8 are explanatory views of a stirring blade, FIG. 9 is a perspective view of a main part showing a blade configuration of the stirring blade, and FIG. 10 is an explanatory view of a core material.

The underground pile forming device M, as shown in FIG. 4, is a turning / elevating drive device 1 projecting forward of the main body of the device.
And a leading conduit 10 supported by the turning / lifting drive device 1,
The high-pressure material injection pipe 5 inserted into the front conduit 10, the swivel 6 attached to the upper end of the high-pressure material injection pipe 5, and the front conduit 10
And a slime discharge pump (not shown) communicating with the discharge port 21a of the slime collector 20. As shown in FIGS. 4 and 6, a monitor mechanism 7 is connected to the lower end of the high-pressure material injection pipe 5, and the monitor mechanism 7 has a pair of stirring blades 30.
・ 30 is attached so that it can be opened and closed.

As shown in FIGS. 6 (A) and 6 (B), the high-pressure material injection pipe 5 is composed of a double pipe, and in the state in which the swivel 6 and the monitor mechanism 7 are connected to the high-pressure material injection pipe 5, Each of the jet inlet 6c and the air inlet 6a of the swivel 6 has a jet passage 8g and an air passage 8e of the monitor mechanism 7, respectively.
Through the high pressure material injection nozzle 8a and the air nozzle 8d. High-pressure material injection nozzle 8a of the monitor mechanism 7
Is opened radially outward on its peripheral surface, and the air nozzle 8
d is formed so as to eject the high-pressure air A radially outward from the periphery of the high-pressure material injection nozzle 8a.

As shown in FIG. 5 (A), the swivel 6 has an air passage 6e formed in the center thereof and a jet passage 6g formed in the periphery thereof. A rod 40 for measuring the opening angle of the stirring blade 30 is vertically inserted into the air passage 6e so that the rod 40 can move up and down.
a projects from the upper end surface of the swivel 6. Swivel 6
A detection device 41 including an optical sensor or the like for detecting the protruding height of the rod upper end portion 40a faces the upper end portion of the pair of stirring blades 30, 30 of the monitor mechanism 7.
Of the degree of opening (ie, excavation diameter) of the measured value display device 42
Is configured to display. It should be noted that the jet passage 6g communicates with a hardening material ultra-high pressure supply device or a water ultra-high pressure supply device, and the air passage 6e communicates with a compressed air supply device.

As shown in FIG. 5 (B), the slime collector 20 has an injection pipe communicating portion 5A which is connected to the upper end of the high-pressure material injection pipe 5 through a screw portion 5c, and the injection pipe communicating portion 5A. Fixed to the upper end of the portion 5A, the communication portion 6 of the swivel 6
A boss communication part 15 for rotatably connecting d, and a leading conduit communication part 1 fixed to the boss communication part 15 via a collar part 16.
0A, a case body 21 that is relatively rotatably assembled to the upper half of the leading conduit communication portion 10A via an angular bearing 17, and a slime discharge port 21a that projects from the side of the case body 21. ing.

That is, when the front conduit 10 is constrained by the chuck mechanism of the turning / lifting drive device 1 and a rotational force is applied to the front conduit 10, the rotational force is transmitted from the front conduit 10 via the screw portion 10c. Communication part 10A, collar part 16, boss communication part 1
5, the injection pipe communicating portion 5A, and the high pressure material injection pipe 5 are sequentially transmitted to the monitor mechanism 7. Further, as shown in FIG. 2, the slime discharge port 21a communicates with the insertion gap 20a between the leading conduit 10 and the high-pressure material injection pipe 5, and by operating the slime discharge pump, the insertion gap 20a is opened. It is configured to discharge slime as a mud passage.

The pair of stirring blades 30 are shown in FIGS.
As shown in (A) and FIG. 8, the fulcrum shaft 3 is attached to the monitor mechanism 7.
The guide rod 33 supported downwardly through the monitor mechanism 7 and the link mechanism 34 interposed between the guide rod 33 and each of the stirring blades 30 and the guide rod 33 is externally fitted along the guide rod 33. In combination with the elastic spring 32, the elastic spring 3
At 2, the link mechanism 34 is biased upward. Therefore, when there is a restraint such as the front conduit 10 in the outer space, it is in the folded posture R (see FIG. 7 (A)), and when it is released from the restraint, it is opened by the biasing force of the elastic spring 32. The posture is switched to Q (see FIG. 7 (B) and FIG. 8). Also, FIG.
As shown in FIG.
0b is engaged with the stirring blade 30, and the rod 40 is configured to be able to descend and cooperate with the opening operation of the stirring blade 30.

The ground improvement method according to the above embodiment will be described below. a. Installation / Drilling Step << FIG. 1 (A) >> The pile forming device M is installed on the ground, and the leading conduit 10 is inserted in advance to a target depth in the ground without using the high-pressure material injection pipe 5. That is, a dedicated swivel 6A is provided at the upper end of the leading conduit 10.
And a monitor 2 for a leading conduit having a dedicated metal crown is connected to the lower end. The tip conduit 10 is vertically set at a predetermined construction position, and the swirl 6A has a muddy water inlet 6
A bentonite muddy water supply device (not shown) is connected to c, the bentonite muddy water W is discharged downward from the monitor 2, the swivel / elevation drive device 1 is operated, and the leading conduit 10 is swung down to make a vertical hole. While piercing 10a, the leading conduit 10 is inserted to a predetermined depth in the ground.

B. Assembling process of high pressure material injection pipe with stirring blade << Fig. 1 (B) >> As shown in Fig. 1 (B) and Fig. 7 (A), the high pressure material injection pipe 5 is inserted into the tip conduit 10. I will lower it. At this time, the stirring blade 30 provided in the monitor mechanism 7 at the lower end of the high-pressure material injection pipe 5 maintains the folded posture R by the inner wall of the leading conduit 10.

C. Slime recovery device mounting process << Fig. 1 (C) >> A slime recovery device 20 is attached to the upper end of the high pressure material injection pipe 5, and the high pressure material injection pipe 5 and the swivel 6 are connected and connected via this slime recovery device 20. To do. Further, the monitoring mechanism 7 of the high-pressure material injection pipe 5 is projected downward from the lower end edge of the front conduit 10, so that the front conduit 10, the high-pressure material injection pipe 5, and the stirring blade 30 are provided.
It is configured so that the and can be driven to rotate and pull up integrally. At this time, as shown in FIG. 1 (C), FIG. 4 and FIG.
Since the restraint on the inner wall of the front conduit 10 is released, the folding posture R is switched to the open posture Q by the urging force of the elastic spring 32. Reference numeral 25 in FIG. 1 is a hanging hook for suspending the swivel 6, the high-pressure material injection pipe 5 and the like. It is used from a safety point of view when the front conduit 10 is replaced by the chuck mechanism of the drive device 1.

D. Stirring test process << Fig. 1 (D) >> As shown in Fig. 1 (D) and Figs. 4 and 5 (A), a compressed air supply device is provided at the air inlet 6a of the swivel 6, and a muddy water super high pressure is provided at the jet inlet 6c. The supply devices are connected to each other, the bentonite muddy water W is continuously jetted from the high-pressure material jet nozzle 8a of the monitor mechanism 7 in the pipe radial direction, and the high-pressure air A is jetted from the air jet nozzle 8d around the jet nozzle 8a. The pipe swivel / elevation drive device 1 is operated to swivel the leading conduit 10 at a trially set rotational speed.
As a result, the stirring blade 30 swirls together with the high pressure material injection pipe 5. If the injection test is successful, move to the creation process.

E. Construction process by excavation / agitation << Fig. 2 (E) >> The swirl / elevation drive device 1 is actuated to drive the leading pipe 10 and the high-pressure material injection pipe 5 while swirling and driving them, thereby making the muddy water W at ultrahigh pressure. Is continuously ejected, the ground is excavated by the jet jet flow and the stirring blades 30 are stirred, and the mud water W and the ground are stirred and kneaded to strongly mudize the ground within the required diameter. Further, the stirring blade 30 is 3 to 50 rp
Rotated under the condition of m, the muddy water W is 30 to 400 kg / cm
² , under the condition that the discharge rate is 70 to 300 l / min, the compressed air A is 6 to 15 kg / cm ² , 1.5 to 5.0 m ³ / min.
Are injected under the conditions of. As shown in FIG. 9 (A), the stirring blade 30 may be formed so as to incline toward the rotation direction as it approaches the tip 30a, and may be rotated in one direction, or as shown in FIG. 9 (B). In addition, the upper portion may be formed in a substantially mountain shape 30b and swung in the forward / reverse direction.

In this case, as shown in FIG. 4, since the surrounding ground is excavated by the swirling jet flow of the muddy water W and the air A, and the ground is strongly excavated by the swirling stirring of the stirring blade 30,
Even if the jet pressure of the jet flow is weaker than that of Conventional Example 2, the excavating force is increased. Moreover, since the muddy water W and the air A are jetted on the upper side of the stirring blade 30, when excavating while pulling up the high-pressure material injection pipe 5, the ground excavated to some extent by these jets is further excavated by the stirring blade 30, The load that the stirring blade 30 bears is smaller than that in Conventional Example 1. Moreover, in the sludge area 11 kneaded by the jet jet, the cobbles having a large specific gravity are caught and guided by the stirring force of the stirring blades 30 and are sunk and removed downward. The efficiency of excavation, kneading and stirring work is increased without significantly lowering the efficiency.

The open angle measuring rod 40 rises corresponding to the open attitude Q of the stirring blade 30, and the elevating position of the rod upper end 40a is measured by the detecting device 41.
The opening of the stirring blade 30, and hence the excavation diameter, can be confirmed by the measurement value display device 42. That is, when an obstacle such as a buried pipe is encountered, the opening of the stirring blade 30 is reduced due to its resistance. The opening of the stirring blade 30 can be determined by visually observing the vertical position of the rod upper end 40a, or Measured value display device 4
Since it can be easily confirmed by 2, the presence of obstacles can be easily known. Further, there is no fear of damaging the buried pipe.

As shown in FIG. 4, the predetermined area 11 is smoothly converted into sludge, and the sludge in this sludge area 11 is pushed up by the jet jet flow and sucked up by the slime discharge pump, and the front conduit 10 and the high pressure material It is discharged from the slime discharge port 21a of the slime collector 20 through the sludge passage 20a between the injection pipe 5 and the pipe. This facilitates injection of the curing agent described below.

F. Step of Withdrawing High-Pressure Material Injection Pipe with Stirring Blade << FIG. 2 (F) >> The high-pressure material injection tube 5 having the stirring blade 30 attached thereto is pulled out from the inside of the leading conduit 10 by the hanging hook 25.

G. Step of Assembling Curing Material Injection Pipe and Core Material << Fig. 2 (G) >> While descending another curing material injection pipe 5a along the inside of the leading conduit 10, The core material 50 is lowered along the gap. A swivel 6 is connected to the hardening material injection pipe 5 a via a slime collector 20. As shown in FIGS. 10 (A) and 10 (B), the core member 50 includes a plurality of core rods 52 that are rotatably supported by a ring 51 in a radially openable and closable manner, and a support shaft 53 that connects the ring 51. Support shaft 53
And a link mechanism 54 mounted on the core rod 52, and an elastic spring 55 for externally fitting the support shaft 53 to urge the link mechanism 54 upward.
Composed of and. As shown in FIG. 2 (G), the core material 50 holds the folded posture S in the leading conduit tube 10 and is lowered to the sludge region 11 along the hardening material injection pipe 5a, as in the stirring blade 30. When the restraint of the front conduit 10 is released, the open posture T is switched by the urging force of the elastic spring 55.

H. Curing material injection step << Fig. 2 (H) >> 0 to 50 kg of curing material G from the lower end of the curing material injection pipe 5a
When the hardening material injection pipe 5a is driven to rise while being jetted under the conditions of cm ² and 70 to 300 l / min, the ultra-high pressure hardening material G pushes up the sludge in the sludge area 11, and the sludge is injected into the tip conduit 10 and the high pressure material injection pipe 5. It is discharged from the slime discharge port 21a of the slime recovery unit 20 through the sludge discharge passage 20a between them. As a result, the slurry in the slurry area 11 is replaced with the core material 50 and the hardening material G.

I. Drawing and Washing Process << FIG. 3 (I) >> The hardening material injection pipe 5a is drawn out from the tip conduit 10, and the inside of the pipe is washed with fresh water. A cylindrical underground pile P having a core material 50 is formed in the predetermined ground area 11. That is, a plurality of core materials 50 are embedded in the underground pile P in a vertically multi-tiered manner, and the strength of the underground pile P is increased.

The function of the ground improvement method of the above embodiment will be described. First, even in the ground, hard parts such as cobblestones sink to the bottom of the sludge area 11 and can be easily removed, so that less energy is required (ie, Underground piles can be created (with simple equipment). Further, since the excavation force is increased by combining the stirring of the stirring blade 30 and the injection of the high-pressure material, this embodiment can be easily applied to the improvement of dense ground such as clay ground. Further, since the stirring blade 30 can substantially determine the stirring diameter of the sludge region 11 and the opening angle measuring rod 40 can precisely measure the opening angle, it is possible to know the existence of obstacles and damage the buried pipe or the like. It is possible to accurately construct the underground pile P without doing so. Moreover, since a large excavating force can be obtained without increasing the jetting pressure of the hardened material G as in the case of the conventional example 2, the hardened material G is consumed less, and accordingly, the amount of sludge discharged is also reduced. The cost of mud treatment can be reduced.

On the other hand, in the present invention, in the stirring process by the stirring blade 30 shown in the above embodiment, instead of injecting the muddy water W, the hardening material G is directly injected and the high pressure material injection pipe 5 is lowered and pulled up. You may construct underground pile P in one process. In this case, the step of injecting the hardening material in the latter half of the above-mentioned embodiment can be omitted, and the underground pile P can be constructed one step more quickly and easily. It is not always necessary to build the core material 50, but when building the core material 50, the core material 50 is built immediately when the injected hardened material G is uncured.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a first-stage procedure of a ground improvement method of this embodiment.

FIG. 2 is an explanatory diagram showing a procedure in the middle stage of the ground improvement method of the present embodiment.

FIG. 3 is an explanatory diagram showing a procedure of a latter stage of the ground improvement method of the present embodiment.

FIG. 4 is an overall explanatory view of an underground pile building device.

5A is a vertical sectional view of a swivel, and FIG. 5B is a vertical sectional view of a slime collector.

6A is a vertical cross-sectional view of a high-pressure material injection pipe and a monitor mechanism, and FIG. 6B is a cross-sectional plan view of the monitor mechanism.

FIG. 7 (A) is a side view showing the stirring blade in a folded posture, and FIG. 7 (B) is a front view showing the stirring blade in an opened posture.

FIG. 8 is a side view of an essential part showing an open attitude of a stirring blade.

9 (A) and 9 (B) are half-part perspective views showing different blade shapes of the stirring blades.

10 (A) is a left half side view of the core member, FIG.
(B) is a plan view of the core material.

FIG. 11 is an explanatory diagram showing a procedure of a jet grout type ground improvement method of the related art 2.

[Explanation of symbols]

5 ... High-pressure material (curing material) injection pipe, 6 ... Swivel, 7 ...
Monitor mechanism, 8 ... High-pressure material injection nozzle,
10 ... Front conduit, 11 ... Sludge area, 20
... slime collector, 30 ... stirring blade, 40 ... open angle measuring rod, 50 ... core material, P ... stirring blade folding posture, Q ... stirring blade opening posture, S ... core material folding posture, T ... core Material open position, A ... High pressure air, G ... High pressure material (hardened material), W ...
High-pressure material (muddy water), P ... Unhardened underground pile.

Claims (2)

[Claims] 1. A swivel at the upper end of the high pressure material injection pipe (5).
The monitor mechanism (7) is attached to the lower end of the monitor mechanism (6), the high-pressure material injection nozzle (8) is installed in the upper part of the monitor mechanism (7), and the stirring blade (30) is installed in the lower part thereof. 30) is configured so that the posture can be switched between the folded posture (R) and the open posture (Q), the front conduit (10) is inserted from the surface to the target depth in the ground, and the high pressure material injection pipe (5) is connected first. Stirrer along the conduit (10)
(30) is lowered in the folded position (R) and the leading conduit (10) is raised to agitate the high pressure material injection pipe (5).
(30) is switched to the open position (Q), the high pressure material injection pipe (5) is swung and pulled up, and the monitor mechanism is operated via the swivel (6) and the high pressure material injection pipe (5).
By continuously injecting the high-pressure material in the pipe radial direction from the high-pressure material injection nozzle (8) of (7), the swirling jet of the high-pressure material and the stirring blade are continuously injected.
The surrounding ground is excavated by swirling and stirring in (30), and the mixture is stirred and kneaded to form a sludge zone (11).
A ground improvement method characterized in that a hardened underground pile (P) is created in 1). 2. Initially, muddy water (W) is used as the high pressure material,
While pulling up the high pressure material injection pipe (5), the ground is excavated by the swirling jet of muddy water (W) and the swirling stirring of the stirring blade (30), and the mixture is stirred and kneaded to form the sludge area (11). At the time of lowering the pipe (5), a core member (50) configured to be capable of switching between a folded position (S) and an open position (T) is folded along the inside of the tip conduit (10) (S).
, And a plurality of core materials (50) are buried in the sludge area (11) in a horizontal radial open posture (T) in a multi-step manner up and down, and then a hardening material (G) is applied as a high pressure material. The ground improvement method according to claim 1, wherein the sludge (11) in the sludge zone (11) is replaced with a hardening material (G) while the high-pressure material injection pipe (5) is being pulled up.