JP2000054363A - Soil improvement equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide soil improvement equipment which does not depend on the expansion limit of sheet member or the maximum amplitude of the vibrating amplitude. SOLUTION: This soil improvement equipment is a hollow rod, and the rod 12 is spirally surrounded by vanes and this rod is a pipe member having a closed end portion inserted to the rod. In this case, a pipe member 13 with at least one opening 34 and a sheet member 14 restricting a closed space 36 connected to the opening in part of the pipe member are included.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a ground improvement device.

[0002]

2. Description of the Related Art At least one opening is provided in one of the ground improvement devices used for increasing the bearing capacity of a ground such as a sandy ground or a viscous ground and preventing liquefaction of the ground during an earthquake. There is an apparatus including a tube member and a sheet member attached to the tube member and defining a sealed space around part of the tube member and communicating with the opening (Japanese Patent Laid-Open No. 10-11493).
6).

According to this device, after the device is placed in the ground to be improved, high-pressure fluid is supplied to the closed space defined by the sheet member through the opening of the pipe member, and the sheet member is rapidly expanded. Thereby, an impact force can be exerted from the sheet member to the surrounding ground, whereby the surrounding ground is compacted. The rapid expansion of the sheet member can be repeated prior to the expansion by removing fluid in the enclosed space through the opening, thereby gradually increasing the degree of compaction of the surrounding ground.

A vibrating body is used as another ground improvement device. After the vibrating body is placed in the ground, the vibrating body vibrates to exert a repeated impact force on the surrounding ground, whereby the surrounding ground is gradually compacted.

The compaction of the surrounding ground occurs when the sheet member or the vibrating body surrounds the surrounding ground and expands the wall surface of the surrounding ground in contact therewith, and the progress of the compaction or the degree of the compaction is increased. Accordingly, the distance between the sheet member or the vibrating body and the wall surface of the surrounding ground increases.

In the conventional device, the maximum of this interval is substantially equal to the expansion limit of the sheet member or the maximum amplitude of the vibrator. Therefore, in order to increase the degree of compaction of the surrounding ground, that is, the degree of ground improvement, it is necessary to prepare a sheet member having a larger expansion limit or a vibrating body having a larger maximum amplitude. However, this has its own limitations, and there is also a limit to the degree of ground improvement.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a ground improvement apparatus which does not depend on the expansion limit of the sheet member. It is another object of the present invention to provide a ground improvement device which does not depend on the maximum amplitude of the vibrating body.

[0008]

According to the present invention, there is provided a ground improvement apparatus comprising: a rod having a hollow rod having blades spirally surrounding the rod; and a rod inserted into the rod.
A tube member having a closed end, wherein the tube member is provided with at least one opening; and a sheet member fixed to the tube member and defining a closed space surrounding a part of the tube member and communicating with the opening. including.

[0009] Another ground improvement apparatus according to the present invention is characterized in that the pipe member inserted into the hollow rod is used as a first pipe member and further fixed to the first pipe member. A second tubular member surrounding a portion of the member; and
A sheet member fixed to the first tube member and the second tube member and defining a sealed space surrounding another part of the first tube member and connected to an opening of the tube member;

In any of the ground improvement apparatuses, a notch provided at an end of the rod and a closed end of the pipe member (in other apparatuses, a first pipe member) are provided. With the nail accepted in the notch,
A plurality of drill bits each attached to the lower end of the rod and the claw, wherein the notch contacts the claw when the rod is rotated in one direction and reduces the rotational force of the rod. An edge for transmitting to the pipe member (first pipe member) and an edge for guiding the claw so that the claw comes out of the notch when the rod is rotated in the other direction. be able to.

[0011] Still another ground improvement device according to the present invention includes:
The hollow rod as a first rod includes a second rod disposed in the first rod, and a vibrator attached to the second rod.

[0012] The ground improvement device also includes a notch provided at an end of the first rod and a claw provided at an end of the second rod and received by the notch; A plurality of excavation bits respectively attached to the claw and the claw, wherein the notch contacts the claw when the first rod is rotated in one direction, and the first notch contacts the claw when the first rod is rotated in one direction. An edge for transmitting the rotational force of the rod to the second rod, and an edge for guiding the claw so that the claw comes out of the notch when the first rod is rotated in the other direction. And a part.

[0013]

Operation and Effect of the Invention Using the device according to the present invention,
Ground improvement can be performed as follows.

First, the rod is screwed into the ground through the helical blades of the rod by rotating the rod in one direction about its axis. Thereby, the pipe member and the sheet member in the rod (in other devices,
The first and second pipe members and the sheet member) are guided underground.
Next, the rod is rotated in the other direction to raise the rod. Thereby, a part of the pipe member (the same as the first pipe member) in the rod and a sheet member around the part are exposed to the outside of the rod. Thereafter, a high-pressure fluid is supplied from above the ground into the pipe member (first pipe member). The high-pressure fluid flows into the closed space defined by the sheet member via the opening of the tube member (first tube member). Accordingly, the sheet member is rapidly expanded, and an impact force is exerted on the ground around the sheet member, whereby the surrounding ground can be compacted.

Next, the inside of the pipe member (the same as the first and second pipes)
A negative pressure is applied between the two pipe members to discharge the fluid in the closed space through the inside of the pipe member (between the first and second pipe members), thereby contracting the sheet member. .

After or during the application of the negative pressure, the depth position of the rod in the ground is maintained and the rod is rotated in the other direction. Thereby, when screwing the rod, the spiral blade pushes the earth and sand cut from the ground between the sheet member after contraction or contraction and the surrounding ground under the feeding action of the blade. it can.

Instead of applying the negative pressure, the inside of the pipe member (between the first and second pipe members) is opened to the atmosphere, and during this time, the earth and sand is released between the sheet member and the surrounding ground. You can push it in between. Due to the pushing of the earth and sand, the sheet member receives a pressing force, and the fluid in the closed space is discharged through the pipe member (between the first and second pipe members), and the sheet member is contracted. .

As a result, all or a part of the space between the sheet member and the wall surface of the surrounding ground is filled with earth and sand. Thereafter, expansion and contraction of the sheet member and pushing of the earth and sand are repeated. In order to replenish the earth and sand sent by the spiral blades, earth and sand or a suitable number of granular materials are introduced from above the ground into the feeding action area of the blades.

According to this, the wall surface of the surrounding ground which receives the impact force due to the re-expansion of the sheet member after the earth and sand or a large number of particulate matter is pushed is substantially defined by the earth and sand or the large number of granular matter. Therefore, the distance between the contracted sheet and the wall surface of the surrounding ground can be kept within the expansion limit of the sheet member. Therefore, the degree of compaction of the surrounding ground, that is, the degree of ground improvement can be increased regardless of the expansion limit of the sheet member.

In addition, when notches and claws are provided at the end of the rod and at the end of the pipe member, respectively, when a plurality of excavation bits are provided at the end of the rod and the claw, respectively, When rotating in one direction and screwing it into the ground, the rotational force of the rod is transmitted to the tube member (the same as the first tube member) via the claw to rotate it together with the rod, The ground can be excavated with these excavation bits, thereby facilitating screwing of the rod into the ground. Further, when the rod is rotated in the other direction, the rod rises, and at the same time, the claw moves along the guide edge of the notch, and the tube member (the first tube member) moves downward. It is forcibly moved, whereby a part of the pipe member and the sheet member are placed underground.

In the soil improvement device having the vibrating body, as in the soil improvement device having the sheet member, the first rod is rotated in one direction and screwed into the ground to thereby form the second rod. The vibrating body attached to the ground can be placed in the ground, and the ground around the vibrating body can be compacted by the vibration of the vibrating body in the ground. The space created between the vibrating body and the wall surface of the surrounding ground due to compaction is earth and sand or a large number of granular materials utilizing the feeding action of the spiral blade accompanying rotation of the first rod. Can be satisfied in whole or in part. As a result, the vibration of the vibrating body can be transmitted to the surrounding ground via the earth and sand or the granular material, whereby the surrounding ground can be compacted within the range of the maximum amplitude of the vibrating body. .

When notches and claws are provided at ends of the first and second rods, respectively, and when a plurality of excavation bits are provided at the ends of the first rod and the claws, respectively, As in the device having the member, when the first rod is rotated in one direction and screwed into the ground, the rotational force is transmitted to the second rod via the claw to rotate the second rod. Accordingly, the ground can be excavated in cooperation with the excavation bits of both rods. Further, when the first rod is rotated in the other direction and raised, the claw moves along the guide edge of the notch, and the second rod is forcibly moved downward. Occurs. Thereby, the vibrating body can be exposed to the outside of the first rod.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, an example of a ground improvement apparatus according to the present invention is indicated by reference numeral 10 as a whole.

The ground improvement device 10 includes a hollow rod 12
And a pipe member 13 inserted into the rod 12, and the pipe member 1
3 attached to the sheet member 14.

The rod 12 includes a tubular main body 16 and the main body 1.
6 which are fixed to the outer peripheral surface of the blade 6 and extend helically around the periphery except for the upper end thereof. Body 1 of rod 12
6 has an outer diameter of, for example, 14 cm, and the blades 18 have a pitch of 30 to 35 cm.

The rod 12 is supported vertically by a self-propelled base machine 20 installed on the ground.

The base machine 20 includes a vertically extending post 22, a grip 24 supported on the post 22 and capable of moving up and down along the post, a guide 26, and a motor (not shown).

The rod 12 is rotatably gripped by a grip 24 at the upper end of the body 16 and extends through a guide 26 located below the grip 24.
The grip 24 also has a mechanism (not shown) for transmitting the rotational power of the motor to the body 16 of the rod 12 and rotating the rod 12 about its axis.

By operating the base machine 20, the lower end of the rod 12 gripped by the grip 24 is pressed against the ground, and the rod 12 is rotated in one direction (for example, clockwise) around its axis. The rod 12 is screwed into the ground 28 by the action of the blade 18 of the rod. Conversely, when the rod 12 is rotated in the other direction (for example, counterclockwise), the rod 12 rises underground under the action of the blade 18.

The tube member 13 extends so as to be relatively movable in the axial direction with respect to the rod 12. The pipe member 13 has one end (upper end) to which a hose 30 is connected via a swivel 29 and a closed other end (lower end) 32.
The lower end 32 is tapered downward.

The swivel 29 can be seated on the upper end of the rod 12, and when the swivel 29 is in the seated position, the lower end 32 of the tube member 12 and the seat member 14 are moved from the lower end of the rod 12 to the outside. Exposure to

The hose 30 is connected to a high-pressure fluid supply source (not shown) such as a pump for supplying high-pressure fluid such as high-pressure water and high-pressure air into the pipe member 13 via a valve (not shown), and a high-pressure fluid supply including an air compressor. (Not shown) and a negative pressure source (not shown) including a water pump, a vacuum pump, and the like for applying a negative pressure to the inside of the pipe member 13. Instead of connecting to the negative pressure source, it may be opened to the atmosphere via the valve.

As shown in FIG. 2, the tube member 13 is provided with at least one opening 34 (a plurality of openings 34 opening on the lower end peripheral surface in the illustrated example).

The sheet member 14 has a cylindrical shape as a whole, and surrounds a part of the tube member 13 above the lower end 32 of the tube member 13. The upper and lower ends of the sheet member 14 are air-tightly or liquid-tightly fixed to the peripheral surface of the tube member 13 at positions above and below the opening 34 of the tube member 13, respectively. Thereby, a space (sealed space) 36 is formed around a part of the pipe member 13, and the space 36 is
Is in communication with

The sheet member 14 has a property of impervious to a liquid such as water or a gas such as air, and has a strength that does not cause cracks due to contact with gravel or soil in the ground 28. Is done. Suitable materials include, for example, a sheet material made of a rubber sheet material, a fabric made of aramid fiber, a fabric made of high-strength polyethylene fiber (for example, Dyneema (trademark) manufactured by Toyobo Co., Ltd.), and the like. As the fabric made of Dyneema, for example, a fabric having a thickness of 0.63 mm can be selected. The woven fabric is provided with a resin coating for improving liquid tightness and air tightness as necessary.

According to this, when the high-pressure fluid is supplied from the high-pressure fluid source into the pipe member 13, the high-pressure fluid flows through the opening 34 of the pipe member into the space 36 defined by the sheet member 14. . Thereby, the sheet member 14
Rapidly changes from a contracted state to an expanded state.

In the ground improvement, the base machine 20
By operating the rod 12, the rod 12 is rotated in one direction, screwed into the ground 28, and lowered underground to a predetermined depth (depth requiring ground improvement). During this time, the lower end 32 of the inner pipe member 13 hits the ground 28 and the rod 1
2 not exposed from the lower end. Further, the pipe member 13 and the rod 1
2 is filled with the sheet member 14 in a contracted state, so that almost no earth or sand flows into this gap.
Further, the tapered lower end of the pipe member 13 contributes to the reduction of the penetration resistance of the rod 12 into the ground 28.

Thereafter, the rod 12 is reversed to slightly raise the rod. As the rod 12 rises, the pipe member 13 and the sheet member 14 inside the rod 12 move down the trace of penetration of the rod 12. The rod 12 is raised until the swivel 29 at the upper end of the pipe member 13 is seated on the upper end of the rod 12. As a result of raising the rod 12, the lower end of the tube member 13 and the sheet member 14 are exposed from the rod 12 to the outside. Thereby, the sheet member 14 is disposed underground.

Next, the pipe member 1 is supplied from the high-pressure fluid supply source.
The high-pressure fluid is supplied into the space 36 defined by the sheet member 14 through the inside 3 and the opening 34 thereof, and the sheet member 14 is rapidly expanded. Due to this rapid expansion, the sheet member 14 hits the surrounding ground 38 and the surrounding ground 3
8 to the impact force. As a result, the surrounding ground 38 is compacted. In order to cause rapid expansion of the seat member 14, a rotary valve, a solenoid valve, or the like is attached to the opening 34 or the head of the pipe member 13, and the opening time of the opening 34 can be controlled by operating these valves. it can. The impact force of the sheet member 14 on the surrounding ground 38 is, for example,
It can be set to 30 kg / cm ² .

Next, the valve was switched to change the hose 3
0 to the negative pressure source, the sheet member 14
Sucks the fluid in the space 36 defined by
To shrink. A space created by compaction of the surrounding ground 38 appears between the contracted or contracted sheet member, that is, the contracted sheet member 14 and the wall surface of the surrounding ground 38.

Next, while maintaining the height position of the grip 24 of the base machine that grips the rod 12, the rod 12 is rotated in the other direction while maintaining the depth of the rod 12 in the ground.

By rotating the rod 12 in the other direction, when the rod 12 is screwed into the ground from the ground, its blade 18
Is helically sent along the blades 18 and pushed downward from the lower end of the rod 12, and furthermore, the sheet member 14 in the contracted state and the surrounding ground 3
8 and is forcibly fed into the space between the walls.

Sheet member 1 prior to the feeding of the earth and sand
The rapid expansion and contraction of 4 are performed once or multiple times, respectively, depending on the hardness, properties, etc. of the surrounding ground 38.
For example, when the surrounding ground 38 is relatively hard, the expansion and contraction of the sheet member 14 are performed a plurality of times. This makes it possible to obtain a space having a size similar to the size of the space obtained by one expansion and one contraction of the sheet member 14 when the surrounding ground 38 is relatively soft.

Rod 1 for feeding earth and sand
The rotation of the second member 2 in the other direction can be started either after or before completion of the predetermined number of expansions and contractions of the sheet member 14.

By feeding the earth and sand, all or a part of the space between the sheet member 14 after contraction or contraction and the surrounding ground 38 can be filled with the earth and sand.

When the interior of the hose 30 is opened to the atmosphere by switching the valve, the seat member 14
And the earth and sand are similarly fed between the ground and the compacted surrounding ground 38 around the ground. Due to the feeding of the earth and sand, the sheet member 14 receives a pressing force, and the fluid inside the sheet member 14 is released into the atmosphere through the pipe member 13, the hose 30, and the like.
The sheet member 14 is contracted, and the space between the contracting sheet member 14 and the surrounding ground 38 is filled with the earth and sand.

Thereafter, the steps of rapid expansion and contraction of the sheet member 14 and supply of the earth and sand are repeated.
The number of times of expansion and contraction of the sheet member 14 is, for example, 50-100 times / minute, respectively.

When the above steps are repeated, the amount of the earth and sand gradually decreases, so that the supply amount from the ground is supplemented. In the illustrated example, earth and sand 40 are piled up around the rod 12 on the ground, and the earth and sand 40 are similarly carried underground by the blade 18 of the rod rotated in the other direction and supplied to the space. You.

Instead of the earth and sand 40, a large number of granular materials including sand, crushed stone, slag, crushed pieces of shells, regenerated aggregate of concrete, and the like can be supplied to the space from the ground.

Since at least a part of the space between the sheet member 14 and the surrounding ground 38 is filled with the earth and sand or a large number of particles, the sheet member 14 is repeatedly formed.
The impact force is applied to the surrounding ground 38 due to the rapid expansion of the soil through the earth and sand or the granular material. Therefore, the surrounding ground 38 can be compacted by the expansion of the sheet member 14 within the expansion limit.

After the ground improvement is completed by repeating the above steps, the gripper 24 of the base machine 20 is raised along the post 22 so that the rod 12
The tube member 13 seated on the upper end of the rod 12 via the swivel 29 and the sheet member 14 are pulled up to the ground.

Further, not only the ground improvement of the soil layer at one depth position but also the ground improvement at a plurality of depth positions can be performed. This is performed by raising the rod 12, the pipe member 13, and the sheet member 14 to another depth position after the ground improvement at one depth position is completed, and repeating the process at the other depth position. Can be.

Further, the rod 12, the pipe member 13 and the sheet member 14 are raised at an appropriate speed from the initial depth position to the ground, and during this time, the above-described steps are repeated. Up to this point, the ground can be improved.

As shown in FIG. 3, a vibrating body 42 can be used in place of the sheet member 14 as a means for applying an impact force to the surrounding ground 38.

The illustrated vibrating body 42 is made of a vibroflot attached to the lower end of another rod (second rod) 44 extending in the axial direction inside the rod 12 (first rod). The vibroflot is connected to a second rod 44 via a shock absorber 46. Thereby, the vibroflot (vibrating body 4)
The vibration of 2) is secured, and the transmission of the vibration to the second rod is interrupted.

The second rod 44 is connected to the pipe member 1 shown in FIG.
Similarly to 3, the first rod 12 can be vertically moved relative to the first rod 12. Also, at the upper end of the second rod 44,
A suitable seating member (not shown) that can be seated is attached to the upper end of the first rod 12. When the seat member is seated on the upper end of the first rod 12, the vibrating body 42 is exposed from the lower end of the first rod 12 to the outside.

The vibrating body 42 is a sheet member 14 shown in FIG.
In the same manner as in the above, a rotating force is applied to the first rod 12 in a state where the first rod 12 is accommodated in the first rod 12 to lower the ground to a predetermined depth, and then the first rod 12 is rotated in the opposite direction. Let this rise slightly. During this time, the second rod 44 keeps it in its depth position. As a result, the upper end of the first rod 12 abuts on the seating member of the second rod 44, and the vibrating body 42
2 protrudes outside from the lower end. Thereby, the vibrating body 42 is disposed underground.

After placing the vibrating body 42 in the ground, the vibrating body 42 is vibrated at the depth position. By this vibration, the surrounding ground 38 is compacted by receiving an impact force. The compaction creates a space between the vibrating body 42 and the wall surface of the ground 38 around the vibrating body 42.

During the vibration of the vibrating body 42, the first rod 12
Are rotated in the opposite direction, and the blades 18 of the first rod 12 are rotated.
The earth and sand filling the space is sent to and supplied to the space between the vibrating body 42 and the wall surface of the surrounding ground 38. Further, as described above, the earth and sand or the granular material prepared on the ground can be supplied to the space by the reverse rotation of the first rod 12.

As a result, at least a part of the space is filled, and the impact force due to the vibration of the vibrating body 42 is applied to the surrounding ground 38 via the earth and sand or the granular material. Therefore, the compaction of the surrounding ground 38 by the vibrator 42 can be continued within the range of the maximum amplitude of the vibrator 42.

The ground improvement using the vibrating body 42 can be performed at a plurality of depth positions or during the ascent of the vibrating body 42 as in the case of using the sheet member 14. That is, at each depth position or the vibrating body 4
During the rise of the ground 2, the ground improvement can be performed by supplying the earth and sand or the large number of granular materials to the space generated between the vibrating body 42 and the surrounding ground.

By the way, the device 10 shown in FIGS.
In the embodiment, both the supply path and the discharge path for the high-pressure fluid are defined by the pipe member 13. However, as shown in FIGS.
And the ground improvement device 10 having the following.

The device 10 shown in FIGS. 4 to 7 differs from the device 10 shown in FIGS. 1 and 2 in the following points. That is, in addition to the tube member 13, there is another tube member (second tube member) 52, and the upper and lower ends of the sheet member 14 are connected to the first tube member 13 and the second tube member 52. Are respectively fixed, and the space 36 defined by the sheet member 14 is
That is, it communicates with the opening 34 of the first pipe member 13 and the discharge path 50.

The second tube member 52 has a shorter length than the first tube member 13, and has an outer diameter larger than the first tube member 13 and smaller than the inner diameter of the rod 12. Second
The tube member 52 is fixed to the first tube member 13 and coaxially surrounds a part of an upper side of the first tube member.

Thus, a discharge path 50 which is an annular space is formed between the first pipe member 13 and the second pipe member 52. On the other hand, the supply path 48 is defined in the first pipe member 13. The supply path 48 and the discharge path 50 are connected to the high-pressure fluid supply source and the negative pressure source, respectively. The discharge path 50 can be opened to the atmosphere via a valve as in the above-described example. The sheet member 14 surrounds a part of the lower part of the first tube member 13.

The ground improvement apparatus 10 shown in FIGS. 4 to 7 can perform the ground improvement in the same manner as the apparatus shown in FIGS. 1 and 2. However, at the time of ground improvement, the high-pressure fluid flows into the space 36 defined by the sheet member 34 through the supply path 48 and the opening 34, but the fluid in the space 36 is guided to the outside through the discharge path 50.

The ground improvement apparatus 10 shown in FIGS. 4 to 7 further includes a plurality (four in the illustrated example) of notches 54 provided at the lower end of the rod 12, more specifically, at the lower end of the main body 16. And a plurality of pawls 56 provided at the closed lower end 32 of the first tube member and received in the respective notches 54, and a plurality of intervening portions provided at the lower ends of the main body 16. And at least one excavating bit 60 provided on each claw 56.

In the illustrated example, four notches 54 are arranged at equal intervals in the circumferential direction of the main body 16, and the four claws 56 are arranged so that they form a cross when viewed from below.

Each notch 54 has two edges 62, 64
(See FIG. 4), and both edges 62 and 64
Extending toward the lower end of the opening. More specifically, one edge 62 extends in the axial direction of rod 12 and the other edge 64 extends at an angle with one edge 62.

One edge 62 of each notch is
When 2 is rotated in one direction for screwing into the ground, it hits each other pawl 56 and transmits the rotational force of the rod 12 to the first pipe member 13 via the pawls. As a result, the first pipe member 13 rotates together with the rod 12, and the excavation bits 58 and 60 provided therein cooperate to excavate the ground.

Accordingly, even when there is a relatively hard layer (for example, an N value is 20 to 30) above the formation to be improved, or when there is an obstacle such as gravel, etc., these bits 58 , 60, the device 10 can be easily and reliably penetrated into the ground.

Since the other edge 64 extends obliquely, when the rod 12 is rotated in the other direction, the claws 56 abutting each edge 64 are moved toward the open lower end of the rod 12. I will guide you to. As a result, the first pipe member 13 is forced to be exposed from the rod 12, and the ground improvement is started by the rise of the rod accompanying rotation of the rod 12 in the other direction.
3 and the sheet member 14 surrounding it can be left underground.

The arrangement of the notch 54, the claw 56, and the excavating bits 58, 60 can be similarly applied to both the ground improvement device shown in FIGS. 1 and 2 and the ground improvement device shown in FIG.

Further, in any of the above-described types of ground improvement apparatuses, the rod 12 can penetrate the ground in a state where the rod 12 is not inclined but inclined. According to this, it is possible to improve the ground near the existing structure or immediately below the existing structure in the same manner as described above.

Further, the spiral blade 18 has, for example, a lower portion from the start end to a position just before reaching the end, instead of the illustrated example having the same diameter and the same pitch from the start end (lower end) to the end end (upper end). The portion may have a large diameter and a large pitch, and the upper portion extending from the portion to the end may have a small diameter and a small pitch. According to this, the rod 12 can be rotated with a small rotating power, and the lower portion secures a large pushing force of the earth and sand or the granular material into the space, and the upper portion is prepared on the ground. The smooth feeding action of the soil or the granular material 40 can be ensured.

Further, the blade surrounding the lower end portion of the rod body 16 and having a short distance from the start end to the end can be formed. According to this, it is possible to induce the collapse of the earth and sand from the surrounding ground around the upper portion of the rod body 16 where the blade is not provided, and to supply the collapsed earth and sand to the space under the guide action of the blade. it can.

[Brief description of the drawings]

FIG. 1 is a schematic view of a ground improvement device according to the present invention.

FIG. 2 is a schematic sectional view showing a part of a tube member and a sheet member in an enlarged manner.

FIG. 3 is an enlarged schematic cross-sectional view showing a part of a second rod and a vibrating body in another example of the ground improvement device.

FIG. 4 is a schematic partial cross-sectional view showing a part of first and second pipe members and a sheet member in still another example of the ground improvement device in an enlarged manner.

FIG. 5 is an enlarged schematic view showing a part of first and second pipe members housed in a rod and a sheet member.

FIG. 6 is a schematic view showing a part of a rod.

FIG. 7 is a schematic partial cross-sectional view showing a part of the first and second pipe members and a sheet member in an enlarged manner.

FIG. 8 is a bottom view of a rod main body provided with a notch and a drill bit, and a first pipe member provided with a claw and a drill bit.

FIG. 9 is a bottom view of a first pipe member provided with a claw and a drill bit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Ground improvement apparatus 12 Hollow rod 13 Pipe member 14 Sheet member 38 Peripheral ground 42 Vibrating body 44 Second rod 52 Second pipe member 54 Notch 56 Claw 58, 60 Drilling bit 62, 64 Edge of notch

Claims (5)

[Claims] 1. A hollow rod having a blade spirally surrounding the hollow rod, and a tubular member having a closed end inserted into the rod, wherein at least one opening is provided. A pipe member, fixed to the pipe member,
A ground improvement device, comprising: a sheet member that defines a closed space connected to the opening around a part of the pipe member. 2. A rod having a hollow end and having a blade spirally surrounding the hollow rod, and a tubular member having a closed end inserted into the rod, wherein at least one opening is provided. A first tube member, a second tube member fixed to the first tube member and surrounding a part of the tube member, and fixed to the first tube member and the second tube member; A ground improvement device, comprising: a sheet member defining a closed space connected to the opening around another part of the first pipe member. 3. A notch provided at an end of said rod and a claw provided at a closed end of said first tube member and received by said notch, and an end of said rod and said claw. A plurality of digging bits respectively attached to the first pipe member, wherein the notch contacts the claw when the rod is rotated in one direction and transmits a rotational force of the rod to the first pipe member. The device according to claim 1 or 2, comprising an edge and an edge guiding the claw so that the claw comes out of the notch when the rod is rotated in the other direction. 4. A first rod having a hollow first rod having wings spirally surrounding the first rod, and
And a vibrating body attached to the second rod. 5. A notch provided at an end of said first rod and a claw provided at an end of said second rod and received by said notch, and a notch of said first rod. An end portion and a plurality of drill bits each attached to the pawl, wherein the notch contacts the pawl when the first rod is rotated in one direction and rotates the first rod. An edge for transmitting force to the second rod and an edge for guiding the pawl so that the pawl comes out of the notch when the first rod is rotated in the other direction. Item 5. The apparatus according to Item 4.