JP2001131950A - Method and device for improving ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for performing a satisfactory ground improvement. SOLUTION: This method for improving ground comprises arranging a tubular casing 12 and an impact force imparting device 16 in the ground, forced-feeding of a number of granular matters into between the impact force imparting device and the circumferential ground through the casing and the imparting of an impact force to the granular matters after or during the imparting of the impact force to the circumferential ground by the impact force imparting device, repeating the imparting of the impact force to the circumferential ground, the forced feeding of the granular matters and the imparting of the impact force to the granular matters in the part up to the ground surface, and forming an underground column consisting of the granular matters in the ground. The impact force imparting device 16 is supported by a rod 14 having one end part and the other end part, which is arranged rotatably within the casing 12, on the one end part 32 side thereof. The rod 14 is provided with a blade 18 spirally wound on at least a part of the rod 14 between the other end part thereof and the device. The device can be rotatably and removably mounted on the rod 14 through an attachment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for improving a ground.

[0002]

2. Description of the Related Art In order to improve ground support such as sandy ground and viscous ground, and to prevent ground liquefaction during an earthquake, the ground is expanded by supplying and discharging a high-pressure fluid or a pressurized fluid. And a hollow body capable of contraction is placed in the ground, and then the rapid expansion of the hollow body and the contraction of the hollow body are repeated (Japanese Patent Laid-Open No. 10-114936).
Alternatively, a vibrating body is arranged in the ground and the vibrating body is vibrated.

[0003] According to this, the surrounding ground is compacted or compacted by the impact force due to the rapid expansion of the hollow body in the ground. The surrounding ground is further compacted or consolidated by the repetition of rapid expansion and subsequent contraction of the hollow body. Similarly, the vibration of the vibrating body exerts repeated impacts on the surrounding ground, whereby the surrounding ground is gradually compacted or consolidated.

In any case, the ground is improved to be solid by compaction or compaction of the surrounding ground.

[0005] The compaction or compaction of the surrounding ground by the above-mentioned method is caused by applying an impact force to the surrounding ground to create a space between the surrounding ground and the hollow body or the vibrating body. Therefore, the degree of compaction or consolidation, that is, the degree of ground improvement depends on the size of the space, and the size of the space is determined by the expansion limit of the hollow body or the maximum amplitude of the vibrating body.

[0006] Where a higher degree of compaction or consolidation is desired in ground improvement, this can be achieved by providing a hollow body having a larger expansion limit or a vibrating body having a larger maximum amplitude. It is possible. However, this has its own limitations, which make it difficult to achieve better ground improvement.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and an apparatus for making a better ground improvement.

[0008]

According to the ground improvement method of the present invention, a tubular casing and an impact applying device are arranged in the ground, and an impact is applied to the surrounding ground by the impact applying device. After or during the application, a large number of granular materials are forcibly fed through the casing between the impact applying device and the surrounding ground, and the impact applying device applies an impact to the surrounding granular materials. And then
From the impact force application position to the ground surface, application of impact force to the surrounding ground during continuous or intermittent ascent of the casing and the impact force applying device, forcible feeding of the granular material and the granularity The application of the impact force to the object is repeated, thereby forming an underground pillar made of the granular material in the ground.

The ground improvement device of the present invention relates to a device for forming an underground pillar in the ground, and comprises a tubular casing disposed in the ground, and one end rotatably disposed in the casing. A rod having a portion and another end, an impact applying device supported on the rod at one end thereof, and an impact applying device for applying an impact to a surrounding ground in the ground, A blade provided on the rod and spirally surrounding at least a part of the rod between the other end of the rod and the impact applying device.

[0010] The ground improvement apparatus further includes a blade provided on the rod and spirally surrounding at least a part of the rod between one end of the rod and the impact applying device. It may be provided with a blade that spirally surrounds the casing. In addition, the ground improvement device may be configured such that the impact applying device is rotatable around the axis of the rod with respect to the rod.

In another aspect of the present invention, there is provided a ground improvement apparatus comprising: the casing, the rod, an impact applying device supported by the casing, and at least a part of the rod provided on the rod in a spiral shape. And surrounding blades.

The impact force applying device may be formed of a hollow body which can expand and contract by supplying and discharging a high-pressure fluid or a pressurized fluid.

The ground improvement apparatus to which the hollow body is applied may be, for example, as follows. The device comprises a tubular casing disposed vertically in the ground and a hollow rod rotatably disposed in the casing, at least allowing discharge of a pressurized fluid supplied therein. A rod having a lower end provided with one opening, a blade provided on the rod spirally surrounding at least a part of the rod, and rotatable around an axis of the lower end of the rod via an attachment; And a hollow body removably mounted and defining a closed space around the lower end of the rod communicating with the opening of the rod, the hollow body being capable of expansion and contraction by supply and discharge of the pressurized fluid. .

The attachment is fitted around the lower end of the rod so as to surround the rod, and the hollow body is attached to the rod so as to surround the attachment. Preferably, the opening of the rod is directed obliquely downward, and the hollow body is composed of two fabrics made of artificial fibers stitched together by a quilting process and a rubber sheet between the fabrics.

[0015]

According to the present invention, ground improvement can be performed as follows.

First, a tubular casing and an impact-applying device are placed underground. The casing can penetrate into the ground by applying a striking force or a pushing force to the casing, or by applying a rotating force to a casing having a spiral blade around the casing. The impact force applying device can be arranged underground together with the casing by arranging it inside.

After disposing the casing in the ground, the casing is slightly raised to expose the impact applying device inside to the outside. Depending on the state of the ground, the impact force applying device can be exposed by lowering the rod while leaving the casing as it is.

Next, the impact applying device is operated to apply an impact to the surrounding ground. Thereby, the wall surface of the surrounding ground surrounding the impact-applying device is pushed open, and a gap is created between the wall and the impact-applying device.

When the impact-applying device comprises a hollow body, the instantaneous expansion movement of the hollow body due to the supply of the high-pressure fluid to the hollow body gives an impact force to the surrounding ground.

In the gap between the wall surface of the surrounding ground expanded by receiving the impact force and the impact force applying device, the casing passes through the casing during the operation of the impact force applying device or during a temporary stop thereof. A large number of granular materials, such as sand and gravel, are forcibly sent from the ground and filled.

At this time, the rod supporting the impact applying device is rotated, whereby the spiral blade surrounding at least a part of the rod is rotated. The granular material thrown into the casing is smoothly fed into the gap by the rotation of the spiral blades without being blocked in the casing. At this time, if the impact force applying device is rotatable around the axis with respect to the rod, the impact force applying device can be maintained in a non-rotating state with respect to the rotating rod.

The large number of granular materials fed into the gap are subjected to an impact force by the impact force applying device, and are thereby made dense. In addition, the wall surface of the surrounding ground is further expanded through the granular material, and the gap is enlarged.

Therefore, by repeating the supply of the granular material to the gap and the application of the impact force to the granular material, a large number of granular materials having a larger diameter are formed around the impact applying device. A part (bottom) of the underground pillar is formed. As a result, in the surrounding ground made of sandy ground, it is compacted, and in the case of cohesive ground, it is compacted and the ground is improved. .

Thereafter, the casing is raised, and the operation of the impact force applying device and the supply of the large number of granular materials at the raised position are repeated, so that the soil having a uniform diameter extending vertically in the ground. Middle pillars are created, and ground improvement along the soil pillars is performed.

When a spiral blade is provided between the impact applying device and one end (lower end) of the rod, when the casing is pulled up, the rod is rotated to rotate the blade. The granular material can be forcibly fed into the trace of the rod.

Further, in the other construction device, an impact force applying device supported by a casing is operated in the ground, thereby creating a gap between the impact force applying device and the surrounding ground. Then, by rotating the rod in the casing and the spiral blades provided in the casing while raising the casing, the granular material can be forcibly pushed through the casing to the trace of the casing. , Thereby forming a large-diameter soil pillar,
Ground improvement can be performed.

Further, since it is possible to form a large-diameter underground pillar, the interval between the underground pillars when a plurality of underground pillars are formed can be made relatively large. As a result, it is possible to improve the ground by forming soil pillars with a small installation quantity. Further, according to the present invention, the present invention can be similarly applied to a case where a sandy ground and a viscous ground alternately appear. Further, according to the present invention, since the operation of the impact force applying device is performed in the ground, it is possible to minimize the influence of noise, vibration, and the like accompanying the ground improvement.

In the apparatus in which the impact applying device is formed of the hollow body and the hollow body is attached to the rod via an attachment, the expansion and contraction operation during the ground improvement or the ground When the hollow body is damaged by the upward movement, by pulling up the rod and replacing the attachment, the hollow body can be replaced easily and in a short time. In addition, the work efficiency of ground improvement can be improved.

When the direction of the opening of the rod is obliquely downward, the flow resistance of the pressurized fluid passing therethrough can be reduced, and the rod fed into the hollow body through the opening can be reduced. Since the pressurized fluid is directed obliquely downward, the granular material around the hollow body which is subjected to the impact force is compacted obliquely downward.

Further, when the hollow body has a sandwich structure of a rubber sheet sewn by quilting and a pair of fabrics sandwiching the rubber sheet,
A contraction effect due to the elastic return of the rubber sheet in the hollow body after expansion can be expected, and if a crack occurs in the woven fabric that defines the surface of the hollow body, the crack is stopped in a region surrounded by sewing thread. , The chain expansion can be avoided.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, an example of an apparatus for forming an underground pillar in the ground and improving the ground by densifying the ground around the underground pillar is generally described. This is indicated by reference numeral 10.

The ground improvement apparatus 10 includes a tubular casing 12 disposed in the ground, a rod 14 rotatably disposed in the casing 12 around its axis, and a rod 14.
And a blade 18 (FIG. 2) provided on the rod 14.

The casing 12 is provided with blades 19 provided on the outer peripheral surface and extending spirally around the periphery except for the upper part. The casing 12 is made of, for example, a steel pipe having an outer diameter of 400 mm.

The casing 12 is vertically supported by a self-propelled base machine 20 installed on the ground in order to arrange the casing 12 in the ground for forming the underground pillar in the ground.

The base machine 20 includes a vertically extending post 22, a grip 24 supported by the post 22 and capable of moving up and down along the post, a guide 26, and a motor (not shown). The post 22 is rotatable about a horizontal axis and can be tilted by rotating it.

The casing 12 has, at its upper end,
The grip 24 is rotatably gripped by the grip 24.
And extends downward through a guide 26 located below.

The grip 24 also has a mechanism (not shown) for transmitting the rotational power of the motor to the casing 12 and rotating the casing 12 about its axis.

By operating the base machine 20, the lower end of the casing 12 gripped by the grip 24 is pressed against the ground and the casing 12 is rotated in one direction (for example, clockwise) around its axis, and Action of the blades 19 causes the casing 12
8 and placed underground. Conversely, if the casing 12 is rotated in another direction (for example, counterclockwise),
Under the action of the blade 19, the underground casing 12 can be raised.

The casing 12 may not have the blade 19. In this case, the casing 12 can be penetrated and arranged in the ground by applying a striking force or a pushing force to the casing 12 using an appropriate mechanical force.

The rod 14 in the casing 12 is hollow and extends movably in the axial direction with respect to the casing 12. The rod 14 has a closed one end (lower end) 32 and a hose 3 through a swivel 29.
0 is connected to the other end (upper end). Lower end 3
2 is tapered downward (see FIG. 2).

The rod 14 is provided with at least one (in the illustrated example, a plurality of) openings 34 (FIG. 2) that open to the peripheral surface at a position above the lower end 32. These openings 34 form passage holes for a later-described high-pressure fluid or pressurized fluid used to expand and contract a hollow body or sheet member 40 described below as an example of the impact force applying device 16.

The swivel 29 can be seated on the upper end of the casing 12. When the swivel 29 is in the seated position, the lower end 32 of the rod 14 and the impact applying device 16 are moved from the lower end of the casing 12 to the outside. Exposure to

The rod 14 can be rotated about its axis together with the blade 18 via another motor (not shown) mounted coaxially with the swivel 29 at the upper end of the casing 12. .

By the rotation of the blades 18, a large number of granular materials 36 described later (FIG. 2) which are charged into the casing 12 and fill the same.
Receives feed force from the upper end of the casing toward the lower end thereof, and is prevented from staying in the casing 12.

The hose 30 is provided with a pump for supplying a high-pressure fluid or high-pressure fluid such as high-pressure water or high-pressure air into the rod 14 via a valve (not shown), or a fluid supply source such as an air compressor. (Not shown) and rod 1
4 is connected to a negative pressure source (not shown) such as a water pump or a vacuum pump for applying a negative pressure to the inside. Instead of connecting to the negative pressure source, the hose 30 may open to the atmosphere via the valve. The fluid supply source and the negative pressure source are installed on the ground.

At the upper end of the casing 12, a hopper 38 communicating with the inside of the casing is arranged and fixed. The hopper 38 is provided with a space 46 to be described later formed in the ground.
2 (FIG. 2). The granules 36 in the hopper 38 fall into the casing 12, that is, the annular space between the casing 12 and the rod 14, and the annular space is filled with the plurality of granules. The particulate matter is guided to the gap 46 through the casing 12. As the granular material, for example, sand, gravel, shell crushed pieces, slag, coal ash, dredged earth and sand, construction remaining soil, concrete crushed pieces, locally generated soil granulated using a solidifying material such as cement, or the like is used. be able to.

The illustrated impact applying device 16 comprises a hollow body or a sheet member 40. The sheet member 40 has a cylindrical shape as a whole, and surrounds a part of the rod 14 at a position above a lower end portion (one end portion) 32 of the rod.

The upper and lower ends of the sheet member 40 are preferably air-tightly or liquid-tightly fixed to the peripheral surface of the rod 14 at positions above and below the opening 34 of the rod 14, respectively. As a result, a closed space 42 (FIG. 2) is formed around a part of the rod 14.
The space 42 communicates with the opening 34.

The sheet member 40 has a property of impervious or difficult to pass 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 earth and sand in the ground 28. Are selected.

Examples of suitable materials include a sheet material made of rubber, a woven fabric made of aramid fiber, a woven fabric made of high-strength polyethylene fiber (for example, Dyneema (trademark) manufactured by Toyobo Co., Ltd.), and a PBO (polypara There is a sheet material made of a phenylene benzobisoxazole) fiber (for example, ZYLON (trademark) manufactured by Toyobo Co., Ltd.), a natural hemp material, or the like. As the Dyneema fabric,
For example, one having a thickness dimension 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.

When a pressurized fluid is supplied from the fluid source into the rod 14 through the hose 30, the pressurized fluid flows through the opening 34 of the tube member into the space 42 defined by the sheet member 40. Thereby, the sheet member 40
Rapidly changes from a contracted state to an expanded state. A rotary valve, a solenoid valve, or the like can be attached to the opening 34 or the head of the rod 14 in order to control the opening time of the opening 34 to cause rapid expansion of the seat member 40.

When the earth pillar is formed for ground improvement, the casing 1 is operated by operating the base machine 20.
2 is rotated in one direction and screwed into the ground 28 to lower the ground to a predetermined depth.
2 is placed underground.

During this time, the lower end 32 of the internal rod 14 hits the ground 28 and is not exposed from the lower end of the casing 12. In addition, since the gap between the rod 14 and the casing 12 is filled with the contracted sheet member 40 at the lower ends thereof, there is almost no inflow of earth and sand into this gap. Further, the tapered lower end of the rod 14 contributes to reducing the penetration resistance of the casing 12 with respect to the ground 28.

Next, the casing 12 is reversed to slightly raise the casing. As the casing 12 rises, the rod 14 and the sheet member 40 inside the casing 12 relatively descend along the trace of penetration of the casing 12. The casing 12 is raised until the swivel 29 at the upper end of the rod 14 is seated on the upper end of the casing 12.

When the casing 12 is raised, the rod 1
4 and the sheet member 40 are
From the outside. Thereby, the sheet member 40
Is placed underground. Alternatively, the rod 14 may be lowered with respect to the casing 12 and pushed into the ground to expose the lower end of the rod and the sheet member.

Next, a hose 30,
Through the rod 14 and its opening 34, the sheet member 4
The pressurized fluid is supplied into the space 42 defined by 0, and the sheet member 40 is rapidly expanded. Due to this rapid expansion, the sheet member 40 hits the surrounding ground 44 and exerts an impact force on the surrounding ground 44. As a result, the sheet member 4
The wall surface of the surrounding ground 44 surrounding 0 is expanded by the sheet member 40. Thereby, the surrounding ground 44 is compacted (in the case of sandy ground) or compacted (in the case of viscous ground). Sheet member 4 for surrounding ground 44
The impact force from 0 can be set to, for example, 3 MPa.

Next, by actuating the negative pressure source (not shown), the fluid is sucked from the space 42 defined by the sheet member 40 through the opening 34, the rod 14, and the hose 30. Shrink 40.

As a result, a gap 46 appears between the contracted or contracted sheet member, that is, the contracted sheet member 40, and the wall surface of the surrounding ground 44 facing the sheet member.

The space 46 contains the casing 12 and the rod 1.
A number of granules 36 filling the annular space between them are fed and supplied. At this time, the rod 14 is driven to rotate, and the blade 18 that rotates together with the rod
A downward feeding force is exerted on the granular material 36 in the inner portion 2. As a result, the granular material 36 is forcibly fed into the gap 46 and supplied.

The blade 18 is provided so as to surround a part of the rod 14 above the sheet member 40. Instead of the illustrated example, the blade 18 is provided at an arbitrary height position of the rod 14, or 14 can be provided so as to extend over the entire length. Further, the pitch or size of the blades 18 may be gradually reduced from the upper end side to the lower end side of the rod 14 (see FIG. 3).

The sheet member 40 prior to the supply of the granular material 36
Rapid expansion and contraction of the surrounding ground 4
4 is performed once or a plurality of times depending on hardness, properties, and the like. For example, when the surrounding ground 44 is relatively hard, the expansion and contraction of the sheet member 40 are performed a plurality of times. This makes it possible to obtain a gap having the same size as the gap 46 obtained by one expansion and one contraction of the sheet member 40 when the surrounding ground 44 is relatively soft.

Further, according to the ground condition, the construction speed or the compaction energy per unit area applied to the ground can be adjusted.

By switching the valve, the hose 30
Is released to the atmosphere, after the hose 30 is released to the atmosphere, the granular material is similarly supplied to the gap 46 between the sheet member 40 and the compacted or compacted surrounding ground 44 therearound. I do.

The supply of the granular material 36 causes the sheet member 40
Receives a pressing force from the periphery thereof, the fluid in the space 42 defined by the sheet member 40 is released into the atmosphere through the rod 14, the hose 30, and the like, the sheet member 40 is contracted, and the contracted sheet member 40 and its surroundings A void 46 formed between the ground 44 and the ground 44 is filled with the granular material 36.

Thereafter, the steps of rapid expansion and contraction of the sheet member 40 and supply of the granular material 36 are repeated. The number of times of expansion and contraction of the sheet member 40 is, for example, 50-100 times / minute, respectively.

The repeated rapid expansion of the sheet member 40 causes the large number of granular materials 36 supplied to the gap 46 between the sheet member 40 and the surrounding ground 44 to expand and contract during the expansion and contraction of the sheet member. It will be fruited. In addition, the wall surface of the surrounding ground 44 is further expanded through the granular material 36, whereby the surrounding ground 44 is further compacted or compacted, and the area occupied by the granular material 36 is expanded in the horizontal direction. This region forms the bottom of the earth pillar 48 to be created.

After the bottom of the earth pillar 48 is formed, the casing 12 is rotated in the other direction and slightly raised. At this time, together with the casing 12, the rod 14 and the seat member 40 seated on the upper end of the casing 12 via the swivel 29 also rise.

In the raised position, the above steps, ie,
Rapid expansion and contraction of the sheet member 40 and the granular material 3
6 is repeated. By alternately performing the ascending of the casing 12 and the sheet member 40 and the repetition of the above-described process at the ascending position, an underground pillar 48 having a uniform diameter and extending vertically is formed in the ground.

Alternatively, from the initial depth position to the ground, the casing 12, the rod 14, and the seat member 4
Also, the above-mentioned soil column can be similarly formed by increasing the value of "0" at an appropriate speed and repeating the above-mentioned process during this time.

By the way, when raising the rod 14,
The lower end 32 of the rod is placed in a part of the soil column 48 immediately after the construction.
Drawbacks occur. As a means for filling the trace with the granular material 36, preferably, another blade 50 (FIG. 2) spirally surrounding at least a part of the rod 14 between the lower end 32 of the rod and the sheet member 40. Provide.

According to this, when the rod 14 is raised together with the casing 12, the rod 14 is rotated to forcibly feed the granular material 36 existing above the rod 14 into the above-mentioned trace, and the granular trace 36 Can be satisfied. At this time, the blades 18 located above the sheet member 40 also rotate in the same direction, and serve to send out the granular material 36 in the casing 12 toward the other blades 50.

Instead of providing other blades 50, the lower end 32 of the rod can be set as short as possible. According to this, the volume of the trace can be minimized, whereby the decrease in the density of the soil column can be minimized.

Further, in order to eliminate the corotation of the sheet member 40 when the blade 18 is rotated to supply the granular material 36 to the gap 46 generated by the application of the impact force, the sheet member 40 is attached to the rod 14. On the other hand, it can be rotatable around the axis of the rod (FIGS. 3 and 5). Thereby, the sheet member 4 with respect to the surrounding ground 44 is
Thus, the frictional resistance of the rod 14 can be reduced, the abrasion of the sheet member 40 can be reduced, and the rotational resistance of the rod 14 can be reduced.

In the example shown in FIG. 3, the sheet member 40 is attached to the rod 14 via an attachment 52 coaxially attached to the lower end 32 of the rod 14 having a tubular body open at both ends.

The attachment 52 has an open upper end portion 54 and a closed lower end portion 56, and is formed of a cylindrical body that tapers from the open upper end portion 54 to the closed lower end portion 56, and the open upper end portion 54 is a lower end of the rod. Surrounding the part 32.

The open upper end portion 54 of the attachment has an annular convex portion 58 provided on its inner peripheral surface. Convex part 58
Is received in an annular concave portion 60 provided at the lower end portion 32 of the rod and opened to the outer peripheral surface thereof so as to be movable in the circumferential direction along the concave portion 60. Thereby, the attachment 52 and the sheet member 40 attached to the attachment 52 are rotatable relative to the rod 14 around the axis thereof. A bearing 62 for reducing frictional resistance between the concave portion and the convex portion 58 is disposed in the concave portion 60 of the rod.

The sheet member 40 is disposed so as to surround the periphery of the attachment 52, and is attached at its upper end and lower end to the upper end 54 and the lower end 56 of the attachment in a liquid-tight or air-tight manner, respectively.

Further, the attachment 52 is provided with a plurality of openings 61 penetrating the wall surface between the upper and lower ends 54 and 56 thereof. The pressurized fluid can enter and exit the space 42 defined by the sheet member 40 through the openings 61. In the drawing, arrows 64 and 66 indicate the movement of the pressurized fluid supplied to the space 42 from inside the rod 14 passing through the opening 61 and the movement of the pressurized fluid discharged into the rod 14 from the space 42, respectively. The lower end 32 of the rod
Any leakage of the pressurized fluid from between the upper end of the attachment and the upper end 54 of the attachment has little effect on the expansion and contraction of the sheet member 40. Further, the attachment 52 and the sheet member 40 attached thereto are attached.
Can be easily replaced with the rod 14 as needed. The example shown in FIG. 5 will be described later.

As shown in FIG. 4, instead of attaching the sheet member 40 to the rod 14, the sheet member 40 can be attached to the casing 12, particularly to the lower end 68 so as to surround the same. In this case, the lower end 6 of the rod
A space 42 is formed between 8 and the sheet member 40. The rod 14 and the blade 18 are housed in the casing 12 and are not exposed outside the casing 12, as in the example shown in FIGS.

The supply of the pressurized fluid to the space 42 and the discharge of the pressurized fluid from the space 42 are performed, for example, by attaching a pipe 70 to the casing 12 and extending the outside of the casing 12 vertically along the casing. Can be done via

In the ground improvement device 10 shown in FIG.
In the ground, after the expansion and contraction operations of the sheet member 40 are repeated to form the above-described space around the sheet member 40, or during the contraction operation is repeated, the casing 12
And rotate the rod 14 and the blade 18 in the casing 12. As a result, the granular material 36 in the casing 12 is forcibly sent out from the lower end portion 68 of the casing 12 to below. As a result, the voids are filled with a large number of granular materials 36, and an underground pillar made of these granular materials 36 is formed.

Next, reference is made to FIG. 5 and FIG.

In the example shown in FIG. 5, an attachment 72 having a cylindrical shape as a whole is used.

The attachment 72 is provided at the lower end 3 of the rod.
2 is fitted so as to surround it. The sheet member 40 is attached to the attachment 72 so as to surround the attachment 72.

The attachment 72 is located at the lower end 32 of the rod.
And an upper end portion and a lower end portion fitted with each other, and side portions connected to these. Each end of the attachment 72 includes a sleeve 74 and a cylindrical slide bush 76 embedded in the sleeve 74 and defining a part of the inner peripheral surface of the sleeve.

A plurality of (four in the illustrated example) side portions of the attachment 68 are arranged at intervals in the circumferential direction of the two sleeves 74 and are fixed to the two sleeves 74 to interconnect the two sleeves 74. It consists of a rib 78 (FIG. 6)
reference).

As shown in FIG. 3, the sheet member 40 is disposed so as to surround the attachment 72. At the upper end and the lower end of the sheet member 40, both ends of the attachment 72 are respectively fastened by appropriate fastening members (not shown). It is attached to the peripheral surface of the sleeve 74 in a liquid-tight or air-tight manner.

The lower end 32 of the rod shown in FIG.
4 is composed of a small-diameter free end portion located below and an upper portion having a larger diameter than this, and a step portion 80 exists between these portions. On the other hand, both sleeves 74 have an inner diameter corresponding to the diameter of the free end portion and the upper portion of the rod 14, respectively.

Accordingly, the attachment 72 is formed by fitting the free end portion and the upper portion of the rod 14 into the sleeves 74 thereof and bringing the lower sleeve 74 into contact with the step portion 80 of the rod. It can be attached to the part 32. At this time, rod 1
4 and the inner peripheral surfaces of both slide bushes 76 are slidably in contact with each other, and the space 42 defined by the sheet member 40 communicates with the opening 34 of the rod.

The attachment 72 can be removed from the lower end 32 of the rod by pulling it.

Therefore, when it becomes necessary to replace the sheet member 40, the rod 14 is pulled up to the ground, the attachment 72 is removed from the lower end 32, and the rod 14 is replaced with another attachment. Can be easily and quickly exchanged.

The number of the rod openings 34 connected to the space 42 defined by the sheet member 40 is
It can be 3. In addition, each opening 34 is connected to the rod 1
4 may be opened in a direction perpendicular to the axis, but the resistance to the fluid is reduced, and the pressure of the fluid flowing into the sheet member 40 through the opening 34 against the sheet member 40 is changed. For control, it is desirable to be directed obliquely downward. According to this, a pressing force obliquely downward is applied to the granular material 36 around the sheet member 40 through the sheet member 40, and the granular material 36 can be guided to the trace of the rod 14.

Next, as shown in FIGS. 7 and 8, the sheet member 40 preferably has a three-layer structure or a sandwich structure.

That is, the aramid fiber woven fabric, the non-aramid-based high-strength polyethylene fiber woven fabric, P
A pair of sheets 82 made of a man-made fiber woven fabric made of a BO fiber woven fabric or the like, a natural hemp material woven fabric, and a rubber as described above which is arranged between these two sheets 82 and sewn by quilting. And a sheet 84 made of the same.

Instead of this example, only a pair of sheets 82 can be sewn together by quilting or both sheets 82 can be bonded together with an adhesive.

According to this, the contraction function based on the elastic return action of the rubber sheet 84 can be provided to the sheet member 40. Further, the sewing thread 86 used for sewing by the quilting process defines a large number of, for example, rectangular regions 88 on the surface of the sheet member 40. For this reason, for example, when a crack occurs in a certain rectangular area 88, the crack is stopped in the one rectangular area 88, and it is possible to prevent the crack from developing over a wide area beyond the rectangular area. Thereby, the degree of damage to the sheet member 40 can be kept small.

In any of the above examples, the underground pillar 48 having a uniform diameter can be formed. From this, groundwater can be guided to the ground from the ground improved by the formation of the underground pillars through the underground pillars 48, whereby the ground can be further improved.

Further, in any of the above-mentioned examples, the casing 12 can penetrate the ground with the slanted state. According to this, an underground pillar extending diagonally in the ground near the existing structure or in the ground immediately below the existing structure can be formed, and the ground can be improved.

[Brief description of the drawings]

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

FIG. 2 is a schematic cross-sectional view showing an enlarged lower end portion of the ground improvement device.

FIG. 3 is a schematic sectional view showing another example of the lower end portion of the ground improvement device in an enlarged manner.

FIG. 4 is a schematic partial cross-sectional view showing an enlarged lower end portion of another example of the ground improvement device.

FIG. 5 is an enlarged longitudinal sectional view showing still another example of the lower end of the ground improvement device.

FIG. 6 is a schematic end view taken along line 5-5 of FIG. 5;

FIG. 7 is a schematic longitudinal sectional view of a hollow body or a sheet member.

FIG. 8 is a front view of the sheet member shown in FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Ground improvement device 12 Casing 14 Rod 16 Impact-applying device 18 Spiral blade 32 Lower end part of rod 40 Sheet member (hollow body) 72 Attachment 82, 84 Textile layer and rubber plate layer of sheet member

Continued on the front page (72) Inventor Norio Watanabe 2-1 Tsukudo-cho, Shinjuku-ku, Tokyo Headquarters of Kumagaya Gumi Tokyo Co., Ltd. (72) Inventor Hirokazu Tanaka 2-1 Tsukudo-cho, Shinjuku-ku, Tokyo Tokyo, Kumagaya Gumi Headquarters (72) Inventor Satoshi Kobayashi 2-1 Tsukudo-cho, Shinjuku-ku, Tokyo Tokyo Headquarters, Kumagaya Gumi Co., Ltd. (72) Inventor Masahiro Hattori 119 Itocho, Chuo-ku, Kobe, Hyogo Japan 72) Inventor Keiji Inaba 119 Ito-cho, Chuo-ku, Kobe City, Hyogo Prefecture, Japan Nippon Kaiiko Co., Ltd. (72) Inventor Kiyoharu Kuji 119, Ito-cho, Chuo-ku, Kobe City, Hyogo Prefecture Nippon Kaiko Co., Ltd. Ryoji Toyosawa 119, Ito-cho, Chuo-ku, Kobe-shi, Hyogo Japan F-term (reference) 2D043 CA06 DB02 DB05 DB08 DB22 EA01 EA02 EA06 EA10

Claims (12)

[Claims] A tubular casing and an impact-applying device are arranged in the ground, and the impact-applying device is applied through the casing after or during the application of an impact force to the surrounding ground by the impact-applying device. A large number of granular materials are forcibly fed between the device and the surrounding ground, and the impact force imparting device applies an impact force to the surrounding granular materials. At
Applying an impact force to the surrounding ground during continuous or intermittent ascent of the casing and the impact applying device;
A method for improving ground, in which forcible feeding of the granular material and application of an impact force to the granular material are repeated, thereby forming an underground pillar made of the granular material in the ground. 2. A tubular casing disposed in the ground,
A rod having one end and the other end rotatably disposed in the casing, and an impact force applying device supported on the one end side of the rod, wherein the impact force is applied to the surrounding ground in the ground. And a blade provided on the rod, the blade surrounding at least a part of the rod spirally between the other end of the rod and the impact force applying device. Improved equipment. 3. The apparatus according to claim 2, further comprising a vane provided on the rod and spirally surrounding at least a part of the rod between one end of the rod and the impact applying device. . 4. The apparatus according to claim 2, further comprising a vane spirally surrounding the casing. 5. The device according to claim 2, wherein the impact-applying device is rotatable relative to the rod about an axis of the rod. 6. A tubular casing disposed in the ground,
A rod rotatably disposed in the casing, an impact force applying device supported by the casing, and an impact force applying device for applying an impact force to a surrounding ground in the ground, and provided on the rod. And a blade spirally surrounding at least a part of the rod. 7. The device according to claim 2, wherein the impact-applying device is a hollow body that can expand and contract by supplying and discharging a pressurized fluid. 8. A tubular casing disposed vertically in the ground, and a hollow rod rotatably disposed in the casing to permit discharge of a pressurized fluid supplied therein. A rod having a lower end provided with at least one opening, a blade provided on the rod and helically surrounding at least a part of the rod, and rotating about the axis of the lower end of the rod via an attachment; A hollow body removably and removably mounted and defining an enclosed space around the lower end of the rod communicating with the opening of the rod, the hollow body being capable of expansion and contraction by supply and discharge of the pressurized fluid. Equipped with a ground improvement device. 9. The apparatus of claim 8, wherein the attachment is fitted around the lower end of the rod and the hollow body is attached to and surrounds the attachment. . 10. The apparatus according to claim 8, wherein the opening of the rod is directed obliquely downward. 11. The hollow body is composed of two woven fabrics made of artificial fibers sewn to each other by a quilting process or two woven fabrics made of artificial fibers sewn to each other by a quilting process and a rubber between the two fabrics. 9. The device according to claim 7, wherein the device comprises a sheet. 12. The apparatus according to claim 8, further comprising vanes spirally surrounding the casing.