JPH09273148A - Weak ground improving equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a rise in ground due to injecting a filling agent by improving weak ground while discharging excess soil corresponding to the filled amount of filling agent while filling it from an outlet located above and rotating and raising agitating and filling shafts. SOLUTION: Agitating shafts 7, 7 are connected to an agitating shaft drive equipment. Agitating shafts 7, 7 are attached with screw vanes 9, 9 to the shaft bodies 8, 8 and auger screw shapes are formed. Also, the tips of the agitating shafts 7, 7 has agitating wings 13, 13 in a plurality of stages at the outer periphery of the shaft bodies 12, 12, and injecting shafts 11, 11 are provided with spiral wing-shaped excavating portions 14, 14 at the outer periphery of the lower portions of shaft bodies 12, 12. Agitating shafts 7, 7 and injecting shafts 11, 11 are rotated and raised while discharging the filling agent from filling agent discharging outlets 28, 28 located at a higher portion. Then, the ground is improved while discharging excess soil corresponding to the amount of injected agent. Thus, the expansion of volume in ground due to injected agent can be restricted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft ground improvement method and apparatus for improving a ground by injecting an injecting agent into ground soil and agitating and mixing the injecting agent, and particularly to a surrounding ground accompanying injection of the injecting agent. The present invention relates to a method and apparatus for improving soft ground that can mitigate the effects on the soil.

[0002]

2. Description of the Related Art In order to improve soft ground such as landfills,
There has been known a soft ground improvement method in which an injectant such as a cement-based hardening agent is injected into the ground, and these are stirred and mixed by a stirring blade, thereby hardening the ground to improve the ground.

This soft ground improvement method can be applied with certainty of improved strength (quality) and strength according to requirements. Compared to the drain method and compaction method, which can shorten the construction period because there is no embankment or leaving period. It has the advantages of being relatively inexpensive and adaptable to large depths (25 to 30 m or more) with little effect on the surrounding area, and in recent years its range of application and the machines used tend to be expanded.

[0004]

However, when the above-mentioned soft ground improvement method is applied to a soft ground in or around an urban area with the expansion of the application range and utilization opportunities as described above, the surrounding ground is adversely affected. The possibility has been pointed out. In other words, by injecting the injection agent into the ground, the volume of the ground expands, so that the ground rises or the ground acts on lateral pressure, which may affect adjacent structures. Sex. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a soft ground improvement method and apparatus capable of mitigating the influence on the surroundings of the ground to be improved as much as possible.

[0005]

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention employs the following means. That is, the invention according to the first aspect includes an agitation shaft having screw blades attached to the outer periphery and formed in an auger screw shape, and an injection shaft having a plurality of stages of agitation blades attached to the tip of the agitation shaft. Provided, and the soft ground improvement method to perform ground improvement by stirring and mixing the injection agent and the ground soil with the soft ground improvement device provided with the injection agent outlet above and below the injection axis, the following steps: It is characterized by having it.

(I) A step of rotating and lowering the agitation shaft and the pouring shaft to penetrate them into the ground to be ground improved. (II) At least a distance between the injection outlets before the ground improvement target depth. (3) The step of further rotating and lowering the stirring shaft and the injection shaft while discharging the injection agent from the injection agent discharge port located below the position (III) The injection located above after the tip of the injection shaft reaches the ground improvement target depth By rotating the stirring shaft and the injection shaft while discharging the injection liquid from the agent discharge port,
A step of discharging the surplus soil while stirring and mixing the ground soil and the injectant to improve the ground.

The invention according to the second aspect is such that a hollow stirring shaft formed into an auger screw shape with screw blades attached to the outer circumference and a vertical stirring shaft attached to the tip of the stirring shaft so as to be vertically movable. In a soft ground improvement device having an injection shaft having a plurality of stages of stirring blades, the injection shaft is formed into a double cylinder extending in the axial direction, and injection agent discharge ports are provided above and below it, respectively, and positioned above The injection agent discharge port to communicate with the inside of the outer cylinder of the double cylinder, and the injection agent discharge port located below communicates with the inside of the inner cylinder of the double cylinder. It is characterized in that a switching device is provided which connects the inside of the outer cylinder and the inside of the inner cylinder to the inside of the stirring shaft in accordance with the downward movement.

[0008]

According to the present invention, the agitating shaft and the injection shaft are rotated upward while discharging the injection material from the injection agent discharge port located above, thereby discharging surplus soil in an amount corresponding to the injection amount of the injection material. While the ground is being improved, the volume expansion of the ground due to the injection of the injection agent can be suppressed. Also,
Since the injectant is discharged from the injectant discharge port located at the lower position at least the distance between the injectant discharge ports than the ground improvement target depth, it is not improved when the injectant is discharged only at the time of rotation rise The ground can be improved by stirring and mixing the injected material also in the remaining ground.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 are views showing a soft ground improvement device according to an embodiment of the present invention. In these figures, reference numeral 1 is a soft ground to be improved (hereinafter,
It is a crawler-type base machine installed on G), and includes a crawler 2, a working unit 3, and a boom 4.
Is roughly configured from the support column 5 held vertically.

An agitation shaft drive device 6 is supported on the column 5 by an up-and-down drive device (not shown) so as to be vertically movable. The agitation shaft drive device 6 has a pair of hollow cylindrical agitation shafts 7 at its lower end. , 7 are connected side by side in the left-right direction (perpendicular to the plane of FIG. 1). As shown in FIG. 2, an injection shaft 11 is attached to the tip of the stirring shaft 7 so as to be vertically movable by a predetermined distance. Note that an injectant such as cement slurry is supplied to the inside of the stirring shaft 7 by an injectant supply means (not shown).

As shown in FIG. 2, the stirring shaft 7 is formed as an auger screw as a whole by a hollow cylindrical shaft body 8 and a spiral screw blade 9 formed on the outer periphery of the shaft body 8. There is. In this embodiment, the stirring shaft 7
Are configured to be connectable in the longitudinal direction.

On the other hand, as shown in FIGS. 2 to 3, the injection shaft 11 has a shaft body 12 having a diameter substantially the same as that of the shaft body 8 of the stirring shaft 7, and a plurality of stages on the outer circumference of the shaft body 12. (In this embodiment, three stages) provided, and the spiral blade-shaped excavation portion 14 formed on the outer periphery of the lower end portion of the shaft body 12.
It is schematically composed of

As shown in FIGS. 2 to 4, a mounting cylinder 10 having the same diameter as the shaft body 8 is provided at the lower end of the stirring shaft 7, and the shaft body 8 and the mounting cylinder 10 are provided at the lower end and the upper end, respectively. The formed flanges 7a and 10a are connected to each other by bolting. The inner surface of the mounting cylinder 10 is formed in a hexagonal cross section, and the upper end 12a of the shaft end of the injection shaft 11 is formed to have a diameter reduced to a hexagonal cross section that fits into the inner surface of the mounting cylinder 10. .

On the inner surface of the mounting cylinder 10, bosses 15 and 15 having a length corresponding to one side of the hexagonal shape described above are engraved by extending in the horizontal direction, while the boss 15 of the shaft body upper end portion 12a is formed. A boss 16 having the same horizontal length as the boss 15 and a height higher than that of the boss 15 is engraved at a position facing
A pin 17 is fitted between the bosses 15 and 16.

Therefore, the injection shaft 11 rotates integrally with the stirring shaft 7 via the mounting cylinder 10 and the boss 16
Is attached to the stirring shaft 7 so as to be movable up and down by the height of. In addition, the shaft body upper end portion 12a and the shaft body
A step 12b is formed between the main body and the main body, and the lower end of the mounting cylinder 10 is configured to contact the step 12b when the shaft end 12 (that is, the injection shaft 11) reaches the uppermost end ( (See FIG. 4). That is, this step 12b is
Acts as a stopper for upward movement.

The shaft end 12 is formed in a hollow cylindrical shape, and a supply pipe 18 having a length over its entire length is arranged inside the shaft body 12 along the axis thereof. Thus, the shaft body 12 is formed in a double cylinder structure in which the shaft body 12 itself is an outer cylinder and the supply pipe 18 is an inner cylinder. The supply pipe 18 has an upper end extending to near the connection between the stirring shaft 7 and the mounting cylinder 10, an upper end opening thereof is closed, and through holes 19, 19,. Are drilled.

The supply pipe 18 is fixed to the inner surface of the shaft body 12 by ring-shaped fixing members 20 and 22 at the upper end of the shaft body 12 and slightly above the mounting position of the uppermost stirring blade 13. One fixing member 20 located at the upper end of the shaft body 12 is provided with through holes 21 in the thickness direction thereof. The other fixing member 22 is provided on the inner surface of the shaft 12 so as to close a gap between the inner surface of the shaft 12 and the outer surface of the supply pipe 18.

A ring-shaped switching member 2 is provided at the upper end of the supply pipe 18.
3 is externally fitted. The switching member 23 is fixedly held between the shaft body 8 of the stirring shaft 7 and the mounting cylinder 10, and has through holes 24 in the thickness direction thereof. The thickness of the switching member 23 is set in advance so that the through hole 19 of the supply pipe 18 is closed by the switching member 23 when the shaft body 12 of the injection shaft 11 reaches the lowermost end. (See FIG. 5). A bearing or the like is interposed between the switching member 23 and the outer surface of the supply pipe 18, so that the supply pipe 18 and the switching member 23 can slide relative to each other in a liquid-tight state.

Further, the switching member 23 at the upper end of the supply pipe 18
Similarly, a ring-shaped seal member 25 is externally fitted and fixed to the lower position. This sealing member 25 is
An elastic ring 26 such as a rubber ring is attached to the upper surface, and has a diameter slightly smaller than the inner diameter. Seal member 25
When the shaft 12 of the injection shaft 11 reaches the uppermost end, the sealing member 25 allows the through-holes 24, 2
4 The mounting position is set in advance so that the lower end opening can be closed (see FIG. 4).

From the above, the shaft body 1 of the injection shaft 11 is
When 2 reaches the uppermost end, the through-holes 24 and 24 at the lower end of the switching member 23 are closed by the seal member 25, and the upper-end through-holes 19 and 19 of the supply pipe 18 are located above the switching member 23. , The inside of the shaft 8 of the stirring shaft 7 communicates with the inside of the supply pipe 18 (see FIG. 4).

Similarly, when the shaft body 12 of the injection shaft 11 reaches the lowermost end, the switching member 23 closes the upper end through holes 19, 19 of the supply pipe 18 and the sealing member 25.
Is moved below the switching member 23, whereby the inside of the shaft 8 of the stirring shaft 7 is communicated with the space between the injection shaft 11, the inside of the shaft 12 and the supply pipe 18 (see FIG. 5). That is, the switching member 23 and the sealing member 25 switch the inside of the shaft 12 of the injection shaft 11 or the inside of the supply pipe 18 to the inside of the shaft 8 of the stirring shaft 7 to communicate with the inside of the shaft 8 of the stirring shaft 7 in accordance with the vertical movement of the shaft 12. Is composed.

Further, the shaft body 12 above the fixing member 22 is provided with injection agent discharge ports 28, 28 having check valves communicating with the inside of the shaft body 12. Further, the shaft 12
Injection outlets 29 and 29 (see FIG. 2) having a check valve communicating with the supply pipe 18 are provided in the excavation portion 14 at the lower end. That is, the injection shaft 11 is provided with injection agent discharge ports (check valves) 28 and 29 at its upper and lower ends, respectively.

Next, a soft ground improving method which is an embodiment of the present invention will be described with reference to FIG. 6 using the soft ground improving apparatus having the above-mentioned structure. In this embodiment, the ground improvement is performed using two pairs (four) of the stirring shafts 7, 7.

(I) Start of penetration The pair of stirring shafts 7, 7 are connected to the stirring shaft driving device 6 (see FIG. 6).
(See (a)), the drive device 6 rotates the stirring shafts 7, 7 and the injection shafts 11, 11 to penetrate the ground G (see FIG. 6 (b)). With the stirring shafts 7, 7 fully penetrated, a pair of stirring shafts 7, 7 are further connected to the upper ends of the stirring shafts 7, 7 (see FIG. 6 (c)), and the above-described penetration process is continued. .

(II) Start of injection The injection agent discharge port (check valve) 29 located below the injection agent discharge port 28, 29 from the ground improvement target depth (broken line in FIG. 6).
At a stage before reaching the position by the interval between them (see FIG. 6 (d)), the injection agent is press-fitted and supplied into the shaft body 8 of the stirring shaft 7 by the injection agent supply means (not shown).

In this state, since the stirring shaft 7 and the pouring shaft 11 are rotating and descending, the force from the bottom to the top is exerted by the descending resistance, and the pouring shaft 11 is at the uppermost position. Therefore, inside the shaft body 8. Communicates with the inside of the supply pipe 18. Thereby, the injection supplied to the inside of the shaft body 8 reaches the injection discharge outlet 29 located below through the supply pipe 18 and is discharged from the discharge opening 29 into the ground G (see the arrow in FIG. 4). Then, by further rotating and lowering the stirring shaft 7 and the pouring shaft 11 to eject the infusate, the ground soil and the infusate are agitated and mixed to improve the ground in the distance between the ejection ports 28 and 29 (Fig. 6 (c)).

(III) Axial pull-up When the tip of the injection shaft 11 reaches the ground improvement target depth,
Next, the stirring shaft 7 and the injection shaft 11 are rotated to be rotated upward (see FIG. 6 (f)). Even in this state, the supply of the injecting agent from the above-mentioned injecting agent supplying means into the stirring shaft 7 is continued. In a state where the stirring shaft 7 is rotated and raised,
The injection shaft 11 is located at the lowermost position due to the upward-downward force caused by the rising resistance. Therefore, the inside of the shaft 8 is communicated with the space between the shaft 12 of the injection shaft 11 and the supply pipe 18. . As a result, the injection agent supplied to the inside of the shaft 8 is
Through the discharge port 28, and is discharged into the ground G from the discharge port 28 (see the arrow in FIG. 5). Then, the injection agent is discharged while the stirring shaft 7 and the injection shaft 11 are further rotated upward, whereby the ground soil is stirred and mixed with the injection agent to improve the ground.

When the injecting agent is injected into the ground G, the amount of ground soil corresponding to the injection amount of this injecting agent becomes excessive, which adversely affects the surrounding ground as described above. However, the surplus soil S is discharged to the ground by the screw blade 9 because the stirring shaft 7 is rotated up (see FIG. 6 (g)). The amount of soil S discharged may be appropriately determined in accordance with the amount of the injection agent injected, the soil properties, and the like, but this can be adjusted by the number of rotations of the stirring shaft 7.

Further, among the two stirring shafts 7, 7, the upper stirring shaft 7 appears on the ground, the stirring shaft 7 is disconnected, and the driving device 6 is connected to the stirring shafts 7, 7 again. (See FIG. 6 (h)). Then, while further rotating the stirring shaft 7 and the injection shaft 11, the injection agent is discharged into the ground G from the injection agent discharge port 28 located above, whereby the ground soil and the injection agent are stirred and mixed, and The ground improvement is performed while discharging the surplus soil S to the ground by the screw blade 9) (see FIGS. 6 (i) and 6 (j)).

The ground can be improved by the construction method described above. Here, in this embodiment, the ground is improved by a device in which the injection shaft 11 is provided at the tip of the agitating shaft 7 formed in an auger screw shape.
When the agitating shaft 7 and the pouring shaft 11 are rotated upward while being discharged, the screw blade 9 of the agitating shaft 7 discharges excess ground soil corresponding to the amount of the pouring agent to the ground. Can be. As a result, volume expansion due to the injection of the injection agent, which has been a concern in the past, can be suppressed, phenomena such as swelling of the ground and generation of unnecessary lateral pressure can be suppressed as much as possible, and the influence on the surrounding ground can be sufficiently reduced. . In addition, in this embodiment, since the injection agent discharge ports 28 and 29 are provided above and below the injection shaft 11, efficient ground improvement can be performed.

That is, as described above, in this embodiment, unnecessary soil accompanying the injection of the injecting agent is discharged by the stirring shaft 7, so that the injection of the injecting agent into the ground is raised by the stirring shaft 7, that is, the stirring shaft 7. It is preferable that the rotation is performed at the time of rotation increase. In this case, in order to improve the stirring and mixing efficiency of the ground soil and the injection, an injection outlet is provided above the stirring blade 13, and a configuration in which the stirring blade 13 follows the rise of the injection outlet is preferable. Needless to say. However, if the injection agent discharge port is provided only above the stirring blade 13, when the injection agent discharge is started from the time when the stirring shaft 7 or the like is pulled up, the injection agent is placed on the ground where the stirring blade 13 is located at this time. Are left unmodified without being injected.

However, in this embodiment, the stirring blades 13, 1
Dispensing agent discharge ports 28 and 29 are provided above and below the injection shaft 11 provided with 3,..., Respectively, and the discharge port 29 positioned below the distance from the ground improvement target depth by a distance between the discharge ports 28 and 29 in front thereof. The ground is improved by rotating and lowering the stirring shaft 7 etc. while discharging the injection material from the above. Therefore, when the discharge port is provided only at the upper side as described above, the ground is injected into the part of the ground which is left as unimproved. The agent can be injected to improve the ground.

Moreover, since the injection agent is discharged from the lower discharge port 29, the stirring blades 13, ... Follow the discharge port 29, which is highly preferable because the mixing efficiency of the soil and the injection agent is high. Further, in this embodiment, the stirring shaft 7
When the rotation is ascended, the ground is improved by discharging the injectant from the injectant outlet 28 located above, so that the stirring blades 13,... Follow the outlet 28 in this case as well, as described above. The stirring and mixing efficiency of the soil and the injection agent is very high, which is very preferable.

From the above description, according to this embodiment, the excess soil S is discharged to the ground by the stirring shaft 7 when the stirring shaft 7 and the like are pulled up, thereby mitigating the influence on the surrounding ground as much as possible, and stirring the soil. Wings 13, ... and injectant discharge ports 28, 29
Thus, ground improvement can be performed by stirring and mixing the ground soil as much as possible, and the efficiency can be made very good.

Further, in this embodiment, the injection shaft 11 is attached to the stirring shaft 7 so as to be vertically movable for a predetermined distance, and the vertical movement of the injection shaft 11 causes the switching device 27 to move the injection shaft 11 up and down. Since the communication with the injectant discharge ports 28, 29 located is switched, the injectant is automatically discharged from the upper discharge port 28 or the lower discharge port 29 according to the rising or lowering of the rotation of the injection shaft 11. The construction method described above can be realized with a simple configuration without providing a special control mechanism.

The soft ground improvement method and apparatus of the present invention are not limited to the details of the embodiment, and various modifications are possible. As an example, the switching of the injection agent discharge ports 28 and 29 is not limited to the vertical movement of the injection shaft 11, but various means such as a flow path switching means at the time of injecting the soil improvement agent by a conventional double pipe are adopted. it can. Further, the injectant discharge ports 28 and 29 are provided with the stirring blades 13 and 1, respectively.
It is not necessary to provide it separately from 3, ..., and the inside of the blades 13 ... may be hollow and a discharge port may be provided at its tip. Further, in the above embodiment, the stirring shaft 7 is vertically
Although the ground has been connected to improve the ground, it goes without saying that the number of connected stirring shafts 7 or the presence or absence of connection may be appropriately selected according to the depth of the ground to be improved. Further, in the above-described embodiment, the discharge port 2 is changed from the ground improvement target depth.
Although the ejection of the infusate was started before the distance between 8 and 29, it goes without saying that the ejection of the infusate may be started before this.

[0037]

As described above in detail, according to the present invention, the stirring shaft and the injection shaft are rotated and raised while discharging the injecting agent from the injecting agent discharge port located above, whereby the screw of the stirring shaft is rotated. The ground is improved by stirring and mixing the ground soil and the pouring agent with the stirring blades provided on the pouring shaft, while discharging the surplus soil corresponding to the pouring amount of the pouring agent to the ground with the blades. It is possible to suppress the volume expansion of the ground due to the injection of the injection agent, which has been a concern in the past. As a result, it is possible to suppress phenomena such as swelling of the ground and generation of unnecessary lateral pressure as much as possible, and to sufficiently mitigate the influence on the surrounding ground.

Further, since the injectant is discharged from the injectant discharge port located below the ground improvement target depth by at least the distance between the injectant discharge ports, the injectant is discharged only when the rotation is increased. At this time, the ground can be improved by stirring and mixing the injecting agent with respect to the ground that remains unimproved. Moreover, when the stirring shaft or the like is rotated and lowered, the injectant is discharged from the lower discharge port, and when the stirring shaft or the like is rotated and raised, the injectant is discharged from the upper discharge port. Since the stirring blade follows the discharge port, the stirring and mixing efficiency of the soil and the infusate is high, which is very preferable.

Therefore, according to the present invention, the excess soil is discharged to the ground by the screw blades of the stirring shaft when the stirring shaft and the like are pulled up, and the influence on the surrounding ground is mitigated as much as possible, and the stirring blade and the injection agent are discharged. Through the outlet, the ground soil can be thoroughly mixed with stirring to improve the ground, and its efficiency can be made very good.

Further, according to the present invention, the injection shaft is attached to the stirring shaft so as to be vertically movable for a predetermined distance, and the injecting agent discharge port positioned above and below the injection shaft is moved by the switching device as the injection shaft moves up and down. Since a device that can switch the communication with the injection port is used, the injection agent is automatically discharged from the upper discharge port or the lower discharge port in response to the rotation rise or fall of the injection shaft, and any special control mechanism must be provided. Without this, the above-mentioned construction method can be realized with a simple configuration.

[Brief description of drawings]

FIG. 1 is a front view showing an overall configuration of a soft ground improvement device for showing an embodiment of the invention of claim 2.

FIG. 2 is an enlarged front view showing the inside of a circle II in FIG. 1;

FIG. 3 is a front view showing only an injection shaft.

FIG. 4 is a vertical cross-sectional view showing a state where the injection shaft reaches the uppermost end.

FIG. 5 is a vertical cross-sectional view showing a state where the injection shaft reaches the lowermost end.

FIG. 6 is a process drawing for explaining one embodiment of the invention regarding the soft ground improvement method of claim 1.

[Explanation of symbols]

 G Ground S Ground soil 6 Stirring shaft drive device 7 Stirring shaft 9 Screw blade 11 Injection shaft 13 Stirring blade 18 Supply pipe 27 Switching device 28, 29 Injectant discharge port

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[Procedure amendment]

[Submission date] December 11, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

Title: Soft ground improvement device

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft ground improvement apparatus for improving the ground by injecting an injecting agent into the ground soil and stirring and mixing them, and particularly, to reliably inject the soil into the soil within a predetermined radius. The present invention relates to a soft ground improvement device with which the effect of stirring and mixing with an agent is enhanced.

[0002]

2. Description of the Related Art As a device for improving soft ground such as landfills, an injection agent such as a cement-based hardening agent is injected into the ground, and these are agitated and mixed by a stirring blade to harden the ground. Conventionally, a soft ground improvement device for improving ground is known.

[0003] In this conventionally known soft ground improvement device, an unimproved area where the injection agent is not injected remains due to the position of the inlet. Since the injectate is agitated at the same time as it is discharged, the injectate may not reach a position away from the injection port and may not be reliably injected into a predetermined radius range, and improved strength (quality) cannot be reliably obtained. . Stirring of the injection agent causes unevenness, and a ground improvement area with uniform strength cannot be obtained. At present, it has drawbacks such as the above, and its application range is limited.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to reliably inject into a predetermined radius range, to reliably obtain improved strength (quality), and to improve the agitation of the injection agent. It is an object of the present invention to provide a soft ground improvement apparatus that can obtain a ground improvement area having uniform strength.

[0005]

In order to solve the above-mentioned problems, the present invention adopts the following constitutions. That is, the invention according to claim 1 comprises a stirring shaft formed into an auger screw shape with screw blades attached to the outer periphery, and an injection shaft having a plurality of stages of stirring blades attached to the tip of the stirring shaft, And a soft ground improvement device having an injectant discharge port provided above and below the injection shaft, further comprising a following composition, by stirring and mixing the injectant and the ground soil, the ground It is a soft ground improvement device for improvement.

(I) The injection shaft is formed in a double cylinder extending in the axial direction. (Ii) The upper injection agent discharge port is located higher than the uppermost one of a plurality of stages of stirring blades provided on the injection shaft. Further, a lower injection agent discharge port is provided below the lowermost one of the stirring blades. (Iii) The upper injection agent discharge port is communicated with the inside of the outer cylinder of the double cylinder. The lower injection agent outlet is connected to the inside of the double cylinder

[0007]

In the present invention, when the stirring shaft and the injection shaft are penetrated into the target ground, and the position of the lower injection agent discharge port is at a position at least a distance between the injection agent discharge ports above and below the ground improvement target depth, While injecting the injectant only from the lower injectant ejecting port, the injectant ejected from the injecting agent is allowed to penetrate to the target depth while stirring. After that, when the stirring shaft and the injection shaft are raised from the target depth, the injection agent is discharged only from the upper injection agent discharge port, and the injection agent is raised while being stirred. Accordingly, to so that infusate over the improvement section throughout the depth direction of interest is continuously injected, Kai
Since the injecting agent is first injected into the soil in the good section and is then agitated by the agitating blade, the injecting agent is injected over the entire predetermined radius range and uniform mixing is possible.

[0008]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 are views showing a soft ground improvement device which is one embodiment of the present invention. In these drawings, reference numeral 1 is a crawler type base machine installed on a soft ground (hereinafter, simply referred to as ground) G to be improved, and is vertically held by a crawler 2, a working unit 3 and a boom 4. The pillar 5 is roughly configured.

A stirring shaft driving device 6 is supported on the support column 5 by a vertical movement driving device (not shown) so as to be vertically movable. The stirring shaft driving device 6 has a pair of hollow cylindrical stirring shafts at its lower end. 7 and 7 are connected side by side (perpendicular to the plane of FIG. 1). At the tip of the stirring shaft 7, as shown in FIG.
The injection shaft 11 is attached so as to be vertically movable for a predetermined distance. Note that an injectant such as cement slurry is supplied to the inside of the stirring shaft 7 by an injectant supply means (not shown).

As shown in FIG. 2, the stirring shaft 7 is formed into an auger screw shape as a whole by a hollow cylindrical shaft 8 and a spiral screw blade 9 formed on the outer periphery of the shaft 8. I have. In this embodiment, the stirring shaft 7
Are configured to be connectable in the longitudinal direction.

On the other hand, as shown in FIGS. 2 and 3, the injection shaft 11 has a shaft 12 having substantially the same diameter as the shaft 8 of the stirring shaft 7, and a plurality of steps around the shaft 12. (Three stages in this embodiment) provided, and a spiral blade-shaped excavation portion 14 formed on the outer periphery of the lower end portion of the shaft 12.
It is schematically composed of

At the lower end of the stirring shaft 7, as shown in FIGS. 2 to 4, a mounting cylinder 10 having the same diameter as the shaft body 8 is provided. The formed flanges 7a and 10a are connected to each other by being bolted. The inner surface of the mounting cylinder 10 is formed in a hexagonal cross section, and the upper end 12a of the shaft end of the injection shaft 11 is formed to have a diameter reduced to a hexagonal cross section that fits into the inner surface of the mounting cylinder 10. .

On the inner surface of the mounting cylinder 10, bosses 15, 15 having a length corresponding to one side of the above-mentioned hexagon are engraved so as to extend in the horizontal direction, while the bosses 15 of the shaft upper end 12a are provided. A boss 16 having the same horizontal length as the boss 15 and a height higher than the boss 15 is engraved at a position facing
A pin 17 is fitted between the bosses 15 and 16.

Accordingly, the injection shaft 11 rotates integrally with the stirring shaft 7 via the mounting cylinder 10 and the boss 16
Is attached to the stirring shaft 7 so as to be movable up and down by the height of. In addition, the shaft body upper end portion 12a and the shaft body
A step 12b is formed between the main body and the main body, and the lower end of the mounting cylinder 10 is configured to contact the step 12b when the shaft end 12 (that is, the injection shaft 11) reaches the uppermost end ( (See FIG. 4). That is, this step 12b is
Acts as a stopper for upward movement.

The shaft end 12 is formed in a hollow cylindrical shape, and a supply pipe 18 having a length extending over the entire length thereof is arranged inside the shaft body 12 along the axis thereof. Thus, the shaft body 12 is formed in a double cylinder structure in which the shaft body 12 itself is an outer cylinder and the supply pipe 18 is an inner cylinder. The supply pipe 18 has an upper end extending to near the connection between the stirring shaft 7 and the mounting cylinder 10, an upper end opening thereof is closed, and through holes 19, 19,. Are drilled.

The supply pipe 18 is fixed to the inner surface of the shaft 12 by ring-shaped fixing members 20 and 22, respectively, at the upper end of the shaft 12 and slightly above the mounting position of the uppermost stirring blade 13. One fixing member 20 located at the upper end of the shaft body 12 is provided with through holes 21 in the thickness direction thereof. The other fixing member 22 is provided on the inner surface of the shaft 12 so as to close a gap between the inner surface of the shaft 12 and the outer surface of the supply pipe 18.

A ring-shaped switching member 2 is provided at the upper end of the supply pipe 18.
3 is externally fitted. The switching member 23 is fixedly held between the shaft body 8 of the stirring shaft 7 and the mounting cylinder 10, and has through holes 24 in the thickness direction thereof. The thickness of the switching member 23 is set in advance so that the through hole 19 of the supply pipe 18 is closed by the switching member 23 when the shaft body 12 of the injection shaft 11 reaches the lowermost end. (See FIG. 5). A bearing or the like is interposed between the switching member 23 and the outer surface of the supply pipe 18, so that the supply pipe 18 and the switching member 23 can slide relative to each other in a liquid-tight state.

The switching member 23 at the upper end of the supply pipe 18
Similarly, a ring-shaped seal member 25 is externally fitted and fixed to the lower position. This sealing member 25 is
An elastic ring 26 such as a rubber ring is attached to the upper surface, and has a diameter slightly smaller than the inner diameter. Seal member 25
When the shaft 12 of the injection shaft 11 reaches the uppermost end, the sealing member 25 allows the through-holes 24, 2
4 The mounting position is set in advance so that the lower end opening can be closed (see FIG. 4).

As described above, the shaft 1 of the injection shaft 11
When 2 reaches the uppermost end, the through-holes 24 and 24 at the lower end of the switching member 23 are closed by the seal member 25, and the upper-end through-holes 19 and 19 of the supply pipe 18 are located above the switching member 23. , The inside of the shaft 8 of the stirring shaft 7 communicates with the inside of the supply pipe 18 (see FIG. 4).

Similarly, when the shaft body 12 of the injection shaft 11 reaches the lowermost end, the switching member 23 closes the upper end through holes 19 of the supply pipe 18 and the sealing member 25.
Is moved below the switching member 23, whereby the inside of the shaft 8 of the stirring shaft 7 is communicated with the space between the injection shaft 11, the inside of the shaft 12 and the supply pipe 18 (see FIG. 5). That is, the switching member 23 and the sealing member 25 switch the inside of the shaft body 12 of the injection shaft 11 or the inside of the supply pipe 18 to the inside of the shaft body 8 of the agitation shaft 7 in accordance with the vertical movement of the shaft body 12 to communicate with each other. Are configured.

The shaft 12 above the fixing member 22 is provided with injecting agent discharge ports 28 having a check valve communicating with the inside of the shaft 12. Further, the shaft 12
Injection outlets 29 and 29 (see FIG. 2) having a check valve communicating with the supply pipe 18 are provided in the excavation portion 14 at the lower end. That is, the injection shaft 11 is provided with injection agent discharge ports 28 and 29 at the upper and lower ends thereof,
A check valve is provided at the discharge port.

Next, one mode of the soft ground improvement method using the soft ground improving apparatus of the present invention having the above-mentioned structure will be described with reference to FIG. In addition, in this construction example,
An example of performing ground improvement using two pairs (four) of stirring shafts 7 and 7 will be shown.

(I) Start of Penetration A pair of stirring shafts 7, 7 are connected to a stirring shaft driving device 6 (FIG. 6).
(See (a)), the drive device 6 rotates the stirring shafts 7, 7 and the injection shafts 11, 11 to penetrate the ground G (see FIG. 6 (b)). With the stirring shafts 7, 7 fully penetrated, a pair of stirring shafts 7, 7 are further connected to the upper ends of the stirring shafts 7, 7 (see FIG. 6 (c)), and the above-described penetration process is continued. .

(Ii) Start of injection When the lower injection agent discharge port 29 reaches a position just before the ground improvement target depth (broken line in FIG. 6) by a distance between the injection agent discharge ports 28 and 29 (FIG. 6). (See (d)), the injection agent is press-fitted and supplied into the shaft body 8 of the stirring shaft 7 by an injection agent supply means (not shown).

In this state, since the stirring shaft 7 and the injection shaft 11 are rotating and descending, a downward-to-upward force is exerted by the downward resistance, and the injection shaft 11 is at the uppermost position. Is connected to the inside of the supply pipe 18. As a result, the infusate supplied to the inside of the shaft body 8 reaches the lower infusate discharge port 29 through the supply pipe 18, and is discharged into the ground G from this discharge port 29 (see the arrow in FIG. 4). Then, by further rotating and lowering the stirring shaft 7 and the pouring shaft 11 to eject the infusate, the ground soil and the infusate are agitated and mixed to improve the ground in the distance between the ejection ports 28 and 29 (Fig. 6
(c)).

(Iii) Pulling up the shaft When the tip of the injection shaft 11 reaches the ground improvement target depth,
Next, the stirring shaft 7 and the injection shaft 11 are rotated to be rotated upward (see FIG. 6 (f)). Even in this state, the supply of the injecting agent from the above-mentioned injecting agent supplying means into the stirring shaft 7 is continued. In a state where the stirring shaft 7 is rotated and raised,
The injection shaft 11 is located at the lowermost position due to the upward-downward force caused by the rising resistance. Therefore, the inside of the shaft 8 is communicated with the space between the shaft 12 of the injection shaft 11 and the supply pipe 18. . As a result, the injection agent supplied to the inside of the shaft 8 is
Through to the upper injection agent discharge port 28, and the discharge port 28
Is discharged into the ground G (see the arrow in FIG. 5). And
Further, the injecting agent is discharged while the stirring shaft 7 and the injecting shaft 11 are rotated and raised, and the ground soil is stirred and mixed with the injecting agent to improve the ground.

When the injection is injected into the ground G, the amount of ground soil corresponding to the injection amount of the injection becomes excessive and adversely affects the surrounding ground as described above. However, the surplus soil S is discharged to the ground by the screw blade 9 because the stirring shaft 7 is rotated up (see FIG. 6 (g)). The amount of soil S discharged may be appropriately determined in accordance with the amount of the injection agent injected, the soil properties, and the like, but this can be adjusted by the number of rotations of the stirring shaft 7.

Further, with the upper stirring shaft 7 of the two connected stirring shafts 7 and 7 appearing on the ground, the stirring shaft 7 is disconnected, and the driving device 6 is connected to the stirring shafts 7 and 7 again. (See FIG. 6 (h)). Then, while further rotating the stirring shaft 7 and the injection shaft 11, the injection agent is discharged into the ground G from the injection agent discharge port 28 located above, whereby the ground soil and the injection agent are stirred and mixed, and The ground improvement is performed while discharging the surplus soil S to the ground by the screw blade 9) (see FIGS. 6 (i) and 6 (j)).

The ground can be improved by the construction method as described above. However, the soft ground improvement apparatus according to the present invention used in such a construction example has a stirring shaft 7 formed in an auger screw shape. Since the device is provided with the injection shaft 11 at the tip, when the injecting agent is discharged into the ground G and the stirring shaft 7 and the injection shaft 11 are rotated and raised to pull them up, the screw blade 9 of the stirring shaft 7 is used. It is possible to discharge the surplus ground soil corresponding to the injection amount of the injection agent to the ground. As a result, volume expansion due to the injection of the injection agent, which has been a concern in the past, can be suppressed, phenomena such as swelling of the ground and generation of unnecessary lateral pressure can be suppressed as much as possible, and the influence on the surrounding ground can be sufficiently reduced. .

Furthermore, in the embodiment of the present invention, the stirring blades 13 and 13, the stirring blade is set in the injection shaft 11 ... it is provided
Since the injecting agent discharge ports 28 and 29 are provided above and below the height position where the ink is removed, the injecting agent discharge ports 28 and 29 are positioned below the injecting agent discharge holes 28 and 29 from the ground improvement target depth. While discharging the injection agent from the outlet 29, the stirring shaft 7
Since the ground can be improved by rotating and lowering etc., injecting agent can be injected also into the ground left unmodified as compared with the device in which the discharge port is provided only above as described above. .

Moreover, since the lower injection agent discharge port 29 is located further below the lowest stirring blade, the stirring blades 13, ...
Follows the lower discharge agent discharge port 29, and the upper injection agent discharge port 28 is further above the uppermost stirring blade, so that the stirring blades 13, ... Follow the upper discharge agent discharge port 28. In any case, since the discharged injecting agent is injected to a predetermined radius and then the stirring action is performed, the stirring and mixing efficiency of the soil and the injecting agent is high, and a uniform and improved area of a predetermined radius is obtained. can get.

The soft ground improvement device of the present invention is not limited to the details of the embodiment, and various modifications are possible. As an example, the switching of the upper and lower injection agent outlets 28, 29 is not limited to the vertical movement of the injection shaft 11, but also the flow path switching at the time of injection of the soil improvement agent by the conventional double pipe hollow stirring shaft. Various means such as means can be adopted.

Further, in the above-mentioned construction example, the stirring shaft 7 is vertically
Although the ground has been connected to improve the ground, it goes without saying that the number of connected stirring shafts 7 or the presence or absence of connection may be appropriately selected according to the depth of the ground to be improved. Further, in the above-mentioned construction example, the injection of the infusate was started before the ground improvement target depth by the distance between the upper and lower infusate injection ports 28 and 29, but the injection of the infusate is started before this. It goes without saying that it is okay.

[0034]

According to the present invention, since the stirring shaft has the screw blade and the injection shaft has the stirring blade, the stirring shaft and the injection shaft are rotated and raised while discharging the injection agent from the upper injection agent discharge port. When doing so, while discharging the excess soil corresponding to the injection amount of the injecting agent to the ground by the screw blade of the stirring shaft, by stirring and mixing the ground soil and the injecting agent with the stirring blade provided on the injection shaft. The ground can be improved, and the volume expansion of the ground due to the injection of the injection agent, which has been a concern in the past, can be suppressed. As a result, it is possible to suppress phenomena such as swelling of the ground and generation of unnecessary lateral pressure as much as possible, and to sufficiently mitigate the influence on the surrounding ground.

Moreover, when the stirring shaft or the like is rotated and lowered, the injection agent is discharged from the lower injection agent discharge port, and when the stirring shaft or the like is rotated and raised, the injection agent can be discharged from the upper discharge port. Since the injection agent discharge port is provided further above and below the height position of the stirring blade, it is possible to prevent the unimproved area from remaining.

In addition to these effects, in the present invention, since the stirring blade provided on the injection shaft follows the discharge port during the injection and stirring, the injection agent is surely injected within a predetermined radius range, which is an improvement. The strength (quality) is surely obtained, and the ground strength according to the demand is obtained. Since there is no unevenness in the stirring of the injection material, a ground improvement column having uniform strength can be obtained within a predetermined radius. An excellent effect is obtained.

[Brief description of drawings]

FIG. 1 is a front view showing the overall configuration for showing an embodiment of a soft ground improvement device according to the present invention.

FIG. 2 is a front view showing an enlarged view of a circle II in FIG.

FIG. 3 is a front view showing only an injection shaft.

FIG. 4 is a longitudinal sectional view showing a state where an injection shaft reaches an uppermost end.

FIG. 5 is a longitudinal sectional view showing a state where an injection shaft reaches a lowermost end.

FIG. 6 is a process diagram for explaining a soft ground improvement method as a construction example using the soft ground improving device according to the present invention.

[Explanation of Codes] G Ground S Ground soil 6 Stirring shaft drive device 7 Stirring shaft 9 Screw blade 11 Injection shaft 13 Stirring blade 18 Supply pipe 27 Switching means 28, 29 Injectant discharge port

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomio Hayashi 2-16-1, Kyobashi, Chuo-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Takuro Odawara 2-1-1-1, Kyobashi, Chuo-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Masayuki Kurosawa 5-8-23 Funabori, Edogawa-ku, Tokyo Kurosawa Iron Works Co., Ltd. (72) Inventor Tsutomu Ikeda 5-8-23 Funabori, Edogawa-ku, Tokyo Kurosawa Iron Works Co., Ltd.

Claims (2)

[Claims] 1. An injection shaft comprising an agitating shaft formed in an auger screw shape with screw blades attached to an outer periphery thereof, and an injection shaft having a plurality of stages of stirring blades attached to a tip of the agitation shaft. When the soil is improved by agitating and mixing the infusate and the ground soil with the soft soil improvement device having the injectant discharge port above and below, the agitating shaft and the injecting shaft are rotated and lowered to make them ground. Step of injecting into the ground to be improved, and further stirring shaft and injection while injecting the injectant from the injectant discharge port located below at a position at least a distance between the injectant discharge ports from the ground improvement target depth Rotating and lowering the shaft, and after the tip of the pouring shaft reaches the ground improvement target depth, while rotating the stirring shaft and pouring shaft while ejecting the pouring agent from the pouring agent discharge port located above. By doing so, the soil soil and the injecting agent are stirred and mixed while discharging the excess soil to perform the soil improvement to the ground surface. 2. A hollow stirring shaft formed into an auger screw shape with screw blades attached to the outer periphery, and an injection shaft having a plurality of stages of stirring blades attached to the tip of this stirring shaft so as to be vertically movable for a predetermined distance. The injection shaft is formed in a double cylinder extending in the axial direction, and injection agent discharge ports are provided above and below the injection cylinder, and the injection agent discharge port located above is outside the double cylinder. While being communicated with the inside of the cylinder, the injectant discharge port located below is communicated with the inside of the inner cylinder of the double cylinder, and the injection shaft is externally attached to the injection shaft according to the upward and downward movements of itself. A soft ground improvement device comprising a switching device for communicating the inside of the cylinder and the inside of the cylinder to the inside of the stirring shaft.