JP2011256541A - Deep mixing method and deep mixing device for soil stabilization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deep mixing method for soil stabilization capable of expanding an improvement diameter without reducing advantages unique to a powder solidifying material.SOLUTION: An agitating shaft 10 excavates and penetrates into ground down to an improvement object portion of the ground by rotating the same around the center of the shaft. During this process, a fluidity improver is injected through a second injection port 16 provided at a tip of the agitating shaft 10 and in-situ soil and the fluidity improver are agitated and mixed with agitating blades 13 and 14 which rotate. Then, the agitating shaft 10 is pulled out from the improvement object portion of the ground by rotating the same around the center of the shaft. During this process, a powder solidifying agent is injected through a first injection port 15 provided on a back side of an upper agitating blade with respect to a rotation direction of the blade for constructing a columnar solidified body CB by agitating and mixing in-situ soil G and the power solidifying agent with the agitating blades 13 and 14 which rotate.

Description

  The present invention relates to a deep layer processing method and a deep layer processing apparatus suitable for the method.

In the deep mixing method, a stirring shaft equipped with a stirring blade is inserted into the ground, and the solidification material is supplied into the ground through the stirring shaft. This is a method that has been developed as a technology unique to Japan and has passed over 30 years since its popularization. The deep-mixing treatment method has a lot of achievements so far and is still widely used as a typical ground improvement method. Recently, it has been widely used overseas, and the deep-mixing treatment method is becoming an international method. is there.
The deep mixing treatment method is roughly divided into the slurry system direction in which cement-based solidification material is dissolved in water to form a slurry and supplied to the ground, and the powder-based method for supplying powdered solidification material directly into the ground. Can do. In general, the former is called the CDM method, and the latter is called the DJM method. The differences between the two methods are as follows.

(Difference in solidified material)
In the case of the slurry method, cement or cement-based solidified material is suitable, and fly ash and lime-based solidified material with high water absorption are not suitable, whereas in the case of the powder-based method, these materials are used as a base. Therefore, a low cost material can be selected.

(Excess soil)
In the slurry system construction method, since the solidified material is dissolved in water to make a slurry, the volume of the solidified material is increased correspondingly, and a slurry of about 20 to 30% of the improved ground is supplied. As a result, if the ground is saturated, that portion becomes surplus soil, which requires treatment and disposal. On the other hand, in the case of the powder system construction method, since the solidification material is adsorbed and solidified by the moisture in situ, there is no increase in volume of the solidification material as in the slurry system, and therefore, no excess soil is generated.

(Principle of stirring and mixing)
In the powder system construction method, the powder solidification material that is fed pneumatically is sprayed into the gap that can be momentarily behind the rotating stirring blade, and sprayed on the stirring surface (inner surface of the void) fluidized by the stirring blade. Adhere to the moisture inside. The air injected together with the powder solidifying material is discharged to the ground through the periphery of the shaft. The soft mud with the solidifying material attached is scraped off by a stirring blade at a helical depth pitch determined by the relationship between the rotation speed of the stirring blade and the axial movement speed of the stirring shaft, and mixed by being stirred on the surface. The By this scraping action by the stirring blade, a new solidified material adhering surface is created sequentially in the gap formed behind the stirring blade, and as a result of repeated adhesion, cutting and stirring of the solidified material, a highly mixed column is formed. Created. On the other hand, in the slurry system construction method, there is no adhesion phenomenon with the in situ soil of the solidifying material unlike the powder system construction method, so it is literally necessary to mix the solidifying material slurry and the in situ soil. For this reason, in order to improve the mixing performance, a device such as the shape of the stirring blade, the forward / reverse rotating blade, and the fixed blade is devised.
However, in the powder system construction method, it is said that the rotational resistance of the stirring blade during drilling penetration and solidification material stirring mixing is larger than that in the slurry system construction method and is proportional to the cube of the improved diameter. However, it was difficult to increase the size of the construction machine and it was inevitable that the construction machine would be increased in size.
In recent years when construction costs have been stagnation and overseas demand has been increasing, the cost has been reduced. By increasing the diameter, that is, by increasing the cross section, the construction volume per unit time is increased and the cost per m ³ is reduced. That is extremely important.

Japanese Patent No. 2790759 Japanese Patent No. 3509579

Therefore, the main problem of the present invention is to enable the diameter of the improved diameter to be increased without impairing the advantages unique to the powder system in the powder system construction method.
In addition, in the powder system construction method, a method of adjusting the water content ratio of the in-situ soil by supplying water to the original position during the mixing with stirring in the ground having a low water content ratio has been proposed (see Patent Documents 1 and 2). However, these technologies are intended to reduce the rotational resistance of the stirring blade as a result of the addition of water in the range where the water content ratio is adjusted in the ground with a low water content ratio. It is not intended to reduce the diameter.

The present invention that has solved the above problems is as follows.
<Invention of Claim 1>
While agitating shaft provided with a stirring blade projecting in the radial direction is rotated around the shaft center and drilled into the site to be improved in the ground, a fluidity improver is injected from the tip of the stirring shaft in the process, The in-situ soil and the fluidity improver are stirred and mixed by the rotating stirring blade,
Thereafter, while rotating the stirring shaft about the axis, the stirring shaft is pulled out from the state inserted into the improvement target portion, and in the process, the powder solidification material is injected behind the rotating direction of the stirring blade, and the stirring is rotated. The in-situ soil and the powder solidified material are stirred and mixed with a wing to form a columnar solidified body.
This is a deep mixing process.

(Function and effect)
The main feature of the present invention is that, prior to the supply of the powder solidifying material, a fluidity improver is supplied to the site to be improved to reduce the rotational resistance of the stirring blades during drilling and solidifying material stirring and mixing. . When the in-situ soil and the fluidity improver are mixed in this way, not only the rotational resistance of the stirring blade is reduced by the fluidity improvement and viscosity reduction of the in-situ soil, but also the agitation and mixing with the powder solidifying material later. Will also improve.

  It should be noted that the use of the fluidity improver in the present invention is not limited to the use of the friction reducing effect of the fluidity improver. In the powder system construction method, as described above, the powder solidified material is injected into the gap that can be momentarily behind the rotating stirring blade, and the soft mud soil to which the solidifying material adheres is the rotational speed of the stirring blade and the axial direction of the stirring shaft. It is scraped off by a stirring blade at a helical depth pitch determined by the moving speed and mixed by surface stirring, and high mixing is maintained by repeated adhesion, cutting and stirring of this solidified material. . In other words, in the case of the present invention, due to the skillful combination of the stirring and mixing principle of the powder solidifying material and the fluidity improver, the mixing property is hardly lowered even if the rotational resistance of the stirring blade during stirring and mixing is reduced. This is because, in the case of a general slurry mixing method in which the slurry-like solidified material and the in-situ soil are three-dimensionally stirred with a stirring blade, in order to obtain good mixing properties, In contrast to the fact that the rotational resistance must also be large.

  Thus, according to the present invention, it is possible to increase the diameter of the improved diameter without losing the advantages inherent in the powder system (in other words, if the improved diameter is the same diameter, the drive device and the agitating blade can be reduced in size). This makes it possible to reduce the size of construction machines). Moreover, even if the in-situ soil has high adhesiveness, there is an effect that the lump of soil becomes difficult to adhere to the stirring blade and the stirring shaft. Furthermore, in the conventional powder system construction method, the fluidity of the agitated mixture of the in-situ soil and the solidified material is relatively poor, so that the air supplied to the in-situ area does not escape to the ground and remains as an air pool in the improved body. Although there is a risk of remaining, in the present invention, the use of the fluidity improver improves the fluidity and lowers the viscosity of the in situ soil, so the air supplied to the in situ rises along the outer peripheral surface of the stirring shaft and is exhausted. This also has the effect of facilitating the formation of air pockets.

<Invention of Claim 2>
The stirring shaft includes, as the stirring blade, a lower stirring blade provided at a tip portion and an upper stirring blade provided at a predetermined interval on the base end side with respect to the lower stirring blade,
In the drilling penetration process of the stirring shaft, if the lower stirring blade reaches a depth shallower than the distance between the upper stirring blade and the lower stirring blade than the fixing portion depth, then the tip of the stirring shaft reaches the fixing portion depth thereafter. The slurry solidifying material is jetted from the part, the in-situ soil and the slurry solidifying material are stirred and mixed by the rotating lower stirring blade, and the tip is processed.
After that, while rotating the stirring shaft around the axis, it is withdrawn from the inserted state after the tip portion treatment, and in the process, the powder solidification material is jetted behind the rotating direction of the upper stirring blade and rotates. The in-situ soil and the powder solidified material are stirred and mixed with the upper stirring blade to form a columnar solidified body.
The deep mixing method according to claim 1.

(Function and effect)
In this way, by combining the tip treatment with the slurry solidifying material, with a small rotational resistance over the entire insertion depth of the stirring shaft (that is, with the fluidity improver for the improved portion by the powder solidifying material, and for the tip portion) It becomes possible to build an improved body whose rotational resistance is reduced by the slurry solidifying material.

<Invention of Claim 3>
A stirring shaft provided with a stirring blade protruding in the radial direction, a first injection port provided on one side of the rotation direction of the stirring blade, and a second injection port provided at the tip;
A base machine that supports the stirring shaft and applies a rotational force, a lifting force, and a pushing force to the stirring shaft;
A first supply device for supplying the solidified powder material to the first injection port on the compressed air through the stirring shaft;
A second supply device provided separately from the powder solidifying material supply means, for supplying a fluidity improver to the second injection port through the stirring shaft;
A deep mixing apparatus characterized by comprising:

(Function and effect)
The same effects as those of the first aspect of the invention can be achieved.

<Invention of Claim 4>
The deep-mixing processing apparatus of Claim 3 which formed the streak process extended along the longitudinal direction of the stirring shaft from the vicinity of the said 1st injection nozzle in the outer peripheral surface of the said stirring shaft.

(Function and effect)
In the powder system construction method, the fluidity of the in-situ soil and the stirring mixture of this and the solidified material is relatively poor, so the air supplied to the in-situ region may not remain on the ground and remain as an air pool in the improved body. . On the other hand, when the stirrer shaft as described above is provided on the stirring shaft, the air gap formed behind the projection as the stirring shaft rotates becomes an air discharge passage, and the air supplied to the original position is the air discharge passage. As the air is raised and exhausted through the air, it is difficult for air pockets to occur.

<Invention of Claim 5>
On the surface on the first injection port side of the stirring blade, a ridge-like convex line extending from the blade base end to the blade tip portion along the radial direction is provided at a height position near the upper side of the first injection port. The deep layer processing apparatus according to claim 3 or 4, which is formed.

(Function and effect)
In the powder system construction method, the fluidity of the in-situ soil and the stirring mixture of this and the solidified material is relatively poor, so the air supplied to the in-situ region may not remain on the ground and remain as an air pool in the improved body. . In contrast, when the convex streaks as described above are provided, when the powder solidifying agent is ejected from the first ejection port, a gap is formed in two upper and lower stages behind the rotation direction of the stirring blade, and the lower side of the convex streaks is formed. The jetted air flows back to the main body pipe side through the gap above the convex muscle and is discharged to the ground through the main body pipe and the ground, so that it is difficult for the improved body to collect air.

  As described above, according to the present invention, in the powder system construction method, it is possible to increase the diameter of the improved diameter (or to reduce the size of the construction machine if the diameter is the same) without impairing the advantages specific to the powder system. Benefits are provided.

It is the schematic of a deep-layer mixing processing apparatus. It is a longitudinal cross-sectional view of a swivel joint part. It is an enlarged view which shows the stirring blade part of a stirring shaft. It is a cross-sectional view of a stirring shaft. It is an enlarged view which shows the stirring blade part of a stirring shaft. It is a cross-sectional view of a stirring shaft. It is a cross-sectional view which shows the upper stage stirring blade part of a stirring shaft. It is a cross-sectional view which shows the lower stage stirring blade part of the stirring shaft. It is the schematic which shows the state around the lower stage stirring blade at the time of excavation penetration. It is the schematic which shows the state around the upper stage stirring blade at the time of raising stirring. It is the schematic for demonstrating the compaction effect of a lower stage stirring blade. It is the schematic which shows the construction method example. It is the schematic which shows the construction method example.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows a deep mixing apparatus 1 according to the present invention, which includes a base machine 20 having a stirring shaft 10, a first supply device 30 for metering and feeding a powder solidified material, and a flow It is comprised with the 2nd supply apparatus 40 which manufactures a property improvement agent and a slurry solidification material, selectively switches these, and pumps.

  The base machine 20 is mounted on a leader 21 erected at the front end, an elevating part 22 provided so as to be movable up and down along the leader 21, an agitation shaft 10 supported by the elevating part 22, and the elevating part. And a rotation driving device 23 that rotates the stirring shaft 10 around the axis. The agitation shaft 10 is applied with a pushing force or a pulling force by raising and lowering the elevating unit 22, and a rotating force is given by the rotation driving device 23.

  As shown in FIGS. 3 to 8, the stirring shaft 10 includes a main body tube 12 having a swivel joint 11 attached to the head, and a lower stirrer blade provided at the tip of the main body tube 12 and protruding in both radial directions. 13 and an upper stirrer blade 14 that protrudes on both sides in the radial direction and is provided at a predetermined interval on the base end side with respect to the lower stirrer blade 13. For example, the main body tube 12 may be formed of a square tube as shown in FIGS. 3 and 4, or may be formed of a circular tube as shown in FIGS. 5 and 6.

  As shown in FIGS. 3, 5, 7, and 8, the upper stirring blade 14 and the lower stirring blade 13 are attached with a predetermined inclination posture in which one side in the circumferential direction of the stirring shaft 10 is located below the other side. Thus, the rotation direction of the stirring shaft 10 at the time of penetration is the blade lower edge portion at the front side in the rotation direction, and the rotation direction at the time of pulling up is the opposite, and the blade upper edge portion is at the front side in the rotation direction. A cutter b1 protruding downward is attached to the lower edge portion of the lower stirring blade 13 at an appropriate interval in the radial direction. This cutter b1 is for cutting the ground at the time of excavation penetration. Further, a stirring blade b2 protruding downward is attached to the lower edge portion of the upper stirring blade 14 at an appropriate interval in the radial direction. Furthermore, the stirring blade b2 protruding upward is also attached to the upper edge portion of the lower stirring blade 13 at an appropriate interval in the radial direction. These stirring blades b2 exhibit a stirring action.

  On the outer surface of the main body pipe 12, a first injection port 15 is formed at a position behind the rotation direction when the upper stirring blade 14 is pulled up, and a second injection port 16 is formed at a position behind the rotation direction when the lower stirring blade 13 is inserted. An internal first line L1 and an internal second line L2 built in the main body pipe 12 are connected to the first injection port 15 and the second injection port 16, respectively. The internal first line L1 and the internal second line L2 can be formed by pipes or hoses.

  Further, in the illustrated example, on the rear side in the rotational direction when the upper stirring blade 14 is pulled up, a ridge extending from the blade base end to the vicinity of the tip portion along the radial direction at a height position near the upper side of the first injection port 15. A convex line 17 is formed. Further, in the illustrated example, a streak 18 extending along the longitudinal direction of the main body tube 12 is formed on the outer peripheral surface of the main body tube 12. As long as the streak 18 extends along the longitudinal direction, the streak 18 has a linear shape along the vertical direction as in the illustrated example, and a curved shape such as a spiral rising along the outer periphery of the main body tube 12. As long as it extends in the longitudinal direction, the convex streaks 1718 may have discontinuous portions as shown in FIG. When the main tube 12 is a square tube, it is preferable that the streak 18 is attached to the corner portion, and when the main tube 12 is a circular tube, the streak 18 is formed at a position corresponding to the upper stirring blade 14. .

  As shown in detail in FIG. 2, the head of the stirring shaft 10 is provided with a swivel joint 11 having a structure capable of simultaneously pumping powder and liquid through separate lines, and the first internal line L <b> 1 of the stirring shaft 10. The internal second line L2 is constantly and independently connected to the corresponding external first line L11 and external second line L12 via the swivel joint 11, and the external first line L11 is the first supply. The device 30 and the external second line L12 are connected to the second supply device 40, respectively.

  The first supply device 30 places a silo 31 for storing the powder solidified material, and puts the powder solidified material charged from the silo 31 on compressed air supplied from a compressor (not shown), and passes the external first line L11. And a sending machine 32 for sending out. In addition, the second supply device 40 has an external storage tank 41 for storing the fluidity improver liquid, an agitation tank 42 for storing the slurry solidifying material, and one of these storages selected by the switching valve 43. And a pump 44 for feeding through the two lines L12. As long as the fluidity improver is a chemical that improves the fluidity of the soil, it can be used regardless of powder or liquid, and is not particularly limited, but those containing a surfactant are suitable. is there. Examples of fluidity improvers include foaming agents (synthetic surfactants, resin soaps, proteins), fluidizers (surfactants are the main components, naphthalenesulfonic acid, which are known as admixtures for concrete, for example. Formaldehyde high condensate salts, melamine sulfonic acid formaldehyde high condensate salts, styrene sulfonic acid copolymer salts, etc.), AE agents, AE water reducing agents, water reducing agents, high performance AE water reducing agents and the like can be suitably used. The fluidity improver is preferably used by diluting with water or the like to obtain a liquid having an appropriate concentration.

  On the other hand, FIG. 12 shows an example of a construction method using the deep mixing processing apparatus 1. This example is an application example to a construction form in which a solidified columnar body CB is formed by jetting and agitating a powdered solidified material at the time of pulling up after excavating the stirring shaft 10. In this example, as shown in FIG. 12 (a), first, the agitation shaft 10 rotates around the axis and penetrates into the site to be improved in the ground. In order to prevent this, only compressed air is supplied, and the supply of the powder solidifying material is stopped, the switching valve 43 of the second supply device 40 is switched to the fluidity improver side, and the pump 44 is operated. The fluidity improver is delivered and injected from the second injection port 16 through the external second line L12 and the internal second line L2. As shown in FIG. 9, the fluidity improver injected from the second injection port 16 is dispersed in a gap S <b> 1 formed behind the lower stirring blade 13 in the rotation direction. Thereby, the in-situ soil G and the fluidity improver are agitated and mixed by the rotating stirring blades 13 and 14, and the in-situ soil G is improved in fluidity and reduced in viscosity. As a result, the rotational resistance of the stirring blades 13 and 14 at the time of drilling penetration is reduced, and even if the improved diameter is increased, the drilling penetration can be performed well, and the site to be improved is sprayed with the powder solidified material later. It becomes mud suitable for mixing. The improved diameter (stirring blade diameter) is not particularly limited, but according to the present invention, it can be about 1.5 to 3 m diameter compared to the conventional 1 m diameter.

  Next, as shown in FIG. 12 (b), the depth is shallower by the distance D1 between the upper stirring blade 14 and the lower stirring blade 13 than the depth of the fixing portion (the bottom of the improved portion) (should be shallower than the interval D1 minutes). In addition, if the lower stirring blade 13 has reached, the following tip processing can be performed as necessary. That is, when the lower stirring blade 13 reaches a predetermined depth, the switching valve of the second supply device 40 is switched to the slurry solidifying material side, and the slurry solidification is performed from the second supply device 40 as shown in FIG. The material is fed out and injected through the second injection port 16 through the external second line L12 and the internal second line L2, and further, while the stirring shaft 10 is rotated. Thereby, about the improvement object site | part of the front end side rather than the 1st injection port 15, a slurry solidification material can be supplied and a front-end | tip part improvement body can be created. Alternatively, after supplying the fluidity improver from the second supply device 40 and once excavating and penetrating to the fixing portion, the stirring shaft 10 may be pulled up by the interval D1 and the above-described tip portion processing may be performed from this state. In this case, the effect of reducing the rotational resistance of the stirring shaft 10 by the fluidity improver is exhibited up to the tip treatment section.

  When the lower stirring blade 13 reaches the fixing portion depth, after the second supply device 40 is stopped, as shown in FIG. 13D, the stirring shaft 10 is pulled up while rotating in the direction opposite to the time of penetration. At the same time, the first supply device 30 is operated to inject the powder solidified material from the first injection port 15 through the external first line L11 and the internal first line L1. As shown in FIG. 10, the powder solidified material injected from the first injection port 15 is dispersed in a gap S <b> 2 formed behind the upper stirring blade 14 in the rotation direction. The soft mud to which the solidifying material adheres is scraped by a stirring blade at a spiral depth pitch determined by the relationship between the rotational speed of the upper stirring blade 14 and the axial movement speed of the stirring shaft 10 and is agitated in a plane. Mixed in. Further, in the illustrated example, as the stirring shaft 10 is pulled up, the excavation bit provided at the upper edge portion of the lower stirring blade 13 causes the surface stirring in the reverse direction following the upper stirring blade 14. Mixability is further improved. Then, as shown in FIGS. 13 (e) and 13 (f), the in-situ soil and the powder solidified material are well stirred and mixed by repeating the adhesion, cutting, and stirring of the solidified material, so that the columnar solidified body CB is obtained. Is created. Further, at this time, the lower stirring blade 13 exerts an action of pressing the mixed treated soil downward as shown by an arrow in FIG. 11, so that the improved body CB to be formed is well compacted.

  On the other hand, the air supplied together with the powder solidifying material is discharged to the ground along the outer surface of the stirring shaft 10 as shown in FIGS. 13 (d) and 13 (e). In particular, when the upper stirrer blades 14 have the convex streaks 17 on the back as in the illustrated example, as can be understood from the diagram shown in FIG. As shown by a two-dot chain line in FIG. 5, the air injected below the convex muscle 17 returns to the main body pipe 12 through the gap above the convex muscle 17 and is discharged to the ground between the main body pipe 12 and the ground. For this reason, it is difficult for the improved body to generate air pockets. Further, as shown in FIG. 5, when the stirrer protrusion 18 extending along the longitudinal direction of the stirrer shaft 10 is provided on the outer peripheral surface of the stirrer shaft 10, the rotation direction of the streak protrusion 18 is also shown in FIG. 5. Since a gap S3 leading to the ground along the outer surface of the main body pipe 12 is formed behind, this serves as an air discharge passage, and the air supplied to the original position rises (see the two-dot chain line arrow in FIG. 5) and exhausts. It becomes easy to be done.

  On the other hand, when it is necessary to improve to a depth (for example, 25 m or more) higher than the limit depth where the powder pressure is limited, drilling penetration is performed while supplying the fluidity improver from the second injection port 16 to the limit depth. Then, from the limit depth, as in the tip processing, the second injection port 16 is switched to the solidified material slurry injection, the penetration discharge is performed, the re-stirring is performed at the time of pulling up, and the slurry solidified material is formed in a portion deeper than the limit depth. A solidified column is formed, and when the first injection port 15 returns to the limit depth, the second supply device 40 is stopped and the first supply device 30 is operated to inject the powder solidified material from the first injection port 15. Thus, it is possible to form a solidified column with a powder solidified material shallower than the limit depth.

  In addition, the site to be improved may be a soft formation with a large water content, but in the case of a formation that has been tightened to some extent or a formation with a large adhesive strength, the amount of water added to the fluidity improver may be increased separately or in advance. It can be added to the site to be improved and adjusted to the in-situ soil G having an appropriate water content ratio with respect to the powder solidified material. For example, in a high water content formation, a small amount of active agent or a small amount of active agent close to the stock solution can be used. It should be noted that the injection amount and water addition amount of the active agent at each depth can be controlled by the initial setting when the stratum structure is known in advance. In the case of hydraulic drive, it can be detected and controlled from the hydraulic meter in the case of hydraulic drive. In the latter case, if a sensor that directly detects excavation thrust and rotational torque is attached, more accurate management becomes possible.

(Other)
(A) Unlike the above example, the first injection port 15 and the second injection port 16 can be provided at the same depth position in the stirring shaft 10. Further, the stirring blade may be a single stage. Furthermore, two stirring blades at the same stage are projected in the opposite direction in the illustrated example, but three or more stirring blades can be projected in the radial direction.
(B) If the position of the 2nd injection port 16 is a front-end | tip part of the stirring shaft 10, it may not be behind the rotation direction at the time of penetration of a stirring blade.
(C) In the above example, the slurry solidifying material is used in combination to perform the tip processing or the deep processing, but the slurry solidifying material may not be used in the present invention.
(D) The injection of the powder solidifying material can be performed not only when the stirring shaft 10 is pulled up but also in the process of re-penetrating after the stirring shaft 10 is pulled up once if the fluidity improver is stirred and mixed.
(E) In the present invention, a plurality of types of powder solidifying materials such as cement, cement-based solidified material, fly ash (coal ash), and lime-based solidified material can be simultaneously injected. In addition to providing the solidified material for each type and individually pumping / injecting, it is possible to press and inject using a common supply line in the case of materials that can be mixed in advance.
(F) In the present invention, the fluidity improver can be injected together with air at a high pressure, thereby improving the mixing property between the fluidity improver and the in-situ soil, and mixing the bubbles into the improved body. Weight reduction can be achieved. Similarly, when the slurry solidifying material is jetted, the slurry solidifying material can be jetted together with air at a high pressure.

  The present invention can be applied to a deep layer processing method and a deep layer processing apparatus.

  DESCRIPTION OF SYMBOLS 1 ... Deep layer processing apparatus, 10 ... Stirring shaft, 13 ... Lower stage stirring blade, 14 ... Upper stage stirring blade, 15 ... 1st injection port, 16 ... 2nd injection port.

  The present invention relates to a deep layer processing method and a deep layer processing apparatus suitable for the method.

In the deep mixing method, a stirring shaft equipped with a stirring blade is inserted into the ground, and the solidification material is supplied into the ground through the stirring shaft. This is a method that has been developed as a technology unique to Japan and has passed over 30 years since its popularization. Deep Mixing method is cited so far many achievements, current still widely used as a typical ground improvement method, in recent years, the spread begins overseas, deep mixing processing method is becoming an international construction methods is there.
The deep mixing treatment method is roughly divided into a slurry-based method in which cement-based solidification material is dissolved in water to form a slurry and supplied to the ground, and a powder-based method in which powdered solidification material is directly supplied to the ground. Can do. In general, the former is called the CDM method, and the latter is called the DJM method. The differences between the two methods are as follows.

(Difference in solidified material)
In the case of the slurry method, cement or cement-based solidified material is suitable, and fly ash and lime-based solidified material with high water absorption are not suitable, whereas in the case of the powder-based method, these materials are used as a base. Therefore, a low cost material can be selected.

(Excess soil)
In the slurry system construction method, since the solidified material is dissolved in water to make a slurry, the volume of the solidified material is increased correspondingly, and a slurry of about 20 to 30% of the improved ground is supplied. As a result, if the ground is saturated, that portion becomes surplus soil, which requires treatment and disposal. On the other hand, in the case of the powder system construction method, since the solidification material is adsorbed and solidified by the moisture in situ, there is no increase in volume of the solidification material as in the slurry system, and therefore, no excess soil is generated.

(Principle of stirring and mixing)
In the powder system construction method, the powder solidification material that is fed pneumatically is sprayed into the gap that can be momentarily behind the rotating stirring blade, and sprayed on the stirring surface (inner surface of the void) fluidized by the stirring blade. Adhere to the moisture inside. The air injected together with the powder solidifying material is discharged to the ground through the periphery of the shaft. The soft mud with the solidifying material attached is scraped off by a stirring blade at a helical depth pitch determined by the relationship between the rotation speed of the stirring blade and the axial movement speed of the stirring shaft, and mixed by being stirred on the surface. The By this scraping action by the stirring blade, a new solidified material adhering surface is created sequentially in the gap formed behind the stirring blade, and as a result of repeated adhesion, cutting and stirring of the solidified material, a highly mixed column is formed. Created. On the other hand, in the slurry system construction method, there is no adhesion phenomenon with the in situ soil of the solidifying material as in the powder system construction method. Therefore, it is necessary to literally mix and agitate the solidifying material slurry and the in situ soil. For this reason, in order to improve the mixing performance, a device such as the shape of the stirring blade, the forward / reverse rotating blade, and the fixed blade is devised.
However, in the powder system construction method, it is said that the rotational resistance of the stirring blade during drilling penetration and solidification material stirring mixing is larger than that in the slurry system construction method and is proportional to the cube of the improved diameter. However, it was difficult to increase the size of the construction machine and it was inevitable that the construction machine would be increased in size.
In recent years when construction demand has been stagnation and overseas demand has been increasing, cost reductions are inevitable. It is extremely important to increase the construction volume per unit time and reduce costs by increasing the diameter, that is, by increasing the cross section. It is.

Japanese Patent No. 2790759 Japanese Patent No. 3509579

Therefore, the main problem of the present invention is to enable the diameter of the improved diameter to be increased without impairing the advantages unique to the powder system in the powder system construction method.
In addition, in the powder system construction method, a method of adjusting the water content ratio of the in-situ soil by supplying water to the original position during the mixing with stirring in the ground having a low water content ratio has been proposed (see Patent Documents 1 and 2). However, these technologies are intended to reduce the rotational resistance of the stirring blade as a result of the addition of water in the range where the water content ratio is adjusted in the ground with a low water content ratio. It is not intended to reduce the diameter.

The present invention that has solved the above problems is as follows.
<Invention of Claim 1>
A lower stirring blade projecting in the radial direction provided at the distal end, an upper stirring blade projecting in the radial direction provided at a predetermined interval on the proximal end side with respect to the lower stirring blade, and the upper stirring blade A first injection port provided at a position behind the rotational direction when pulling up, and a second injection port provided at a position behind the rotational direction when penetrating the lower stirring blade,
A first supply device for supplying a powder solidified material to the first injection port through compressed air through the first internal line in the stirring shaft;
A second supply configured to supply a fluidity improver liquid containing a surfactant to the second injection port through an internal second line in the stirring shaft, which is constituted by a supply line different from the first supply device. Using the device,
The agitation shaft rotates around the axis and penetrates into the site to be improved in the ground, and in the process, the fluidity improver liquid is injected from the second injection port at the tip of the agitation shaft and rotates. The in situ soil and the fluidity improver liquid are stirred and mixed by the stirring blade,
Thereafter, the stirring shaft is rotated around the axis and pulled out from the state where it has been inserted into the improvement target portion, and in the process, the powder solidification material is injected from the first injection port behind the stirring blade in the rotation direction. Then, the in-situ soil and the powder solidified material are stirred and mixed by the rotating stirring blade to form a columnar solidified body.
This is a deep mixing process.

(Function and effect)
The main feature of the present invention is to supply the fluidity improver liquid to the site to be improved prior to the supply of the powder solidifying material, thereby reducing the rotational resistance of the stirring blades during drilling and solidifying material stirring and mixing. is there. When the in-situ soil and the fluidity improver liquid are mixed in this way, not only the rotational resistance of the stirring blade is reduced by the fluidity improvement and viscosity reduction of the in-situ soil, but also the subsequent stirring with the powder solidifying material. Mixability is also improved.

It should be noted that the use of the fluidity improver solution in the present invention is not limited to the use of the friction reducing effect of the fluidity improver solution . In the powder system construction method, as described above, the powder solidified material is injected into the gap that can be momentarily behind the rotating stirring blade, and the soft mud soil to which the solidifying material adheres is the rotational speed of the stirring blade and the axial direction of the stirring shaft. It is scraped off by a stirring blade at a helical depth pitch determined by the moving speed and mixed by surface stirring, and high mixing is maintained by repeated adhesion, cutting and stirring of this solidified material. . In other words, in the case of the present invention, due to the skillful combination of the stirring and mixing principle of the powder solidifying material and the fluidity improver liquid , the mixing property is hardly lowered even if the rotational resistance of the stirring blade during stirring and mixing is reduced. . This is because, in the case of a general slurry mixing method in which the slurry-like solidified material and the in-situ soil are three-dimensionally stirred with a stirring blade, in order to obtain good mixing properties, In contrast to the fact that the rotational resistance must also be large.

Thus, according to the present invention, it is possible to increase the diameter of the improved diameter without losing the advantages inherent in the powder system (in other words, if the improved diameter is the same diameter, the drive device and the agitating blade can be reduced in size). This makes it possible to reduce the size of construction machines). Moreover, even if the in-situ soil has high adhesiveness, there is an effect that the lump of soil becomes difficult to adhere to the stirring blade and the stirring shaft. Furthermore, in the conventional powder system construction method, the fluidity of the agitated mixture of the in-situ soil and the solidified material is relatively poor, so that the air supplied to the in-situ area does not escape to the ground and remains as an air pool in the improved body. However, in the present invention, the fluidity of the in-situ soil is improved and the viscosity is lowered by using the fluidity improver solution , so that the air supplied to the in-situ region rises along the outer peripheral surface of the stirring shaft and is exhausted. There is also an effect that it becomes easy to be carried out and it becomes difficult to generate air pockets.

<Invention of Claim 2>
In the excavation and penetration process of the agitation shaft, the fluidity improver liquid is injected from the second injection port, and the in situ soil and the fluidity improver liquid are agitated and mixed by the rotating agitating blades, from the fixing unit depth. If the lower stirring blade reaches a depth shallower than the interval between the upper stirring blade and the lower stirring blade, the slurry solidifying material is sprayed from the second injection port at the tip of the stirring shaft to the fixing portion depth thereafter. Then, the in situ soil and the slurry solidified material are agitated and mixed by the rotating lower agitating blade, and the tip portion is processed.
Thereafter, while rotating the agitation shaft around the axis, it is pulled out from the inserted state after the tip portion treatment, and in the process, the powder solidification material is fed from the first injection port behind the rotation direction of the upper agitation blade. A columnar solidified body is formed by stirring and mixing the in-situ soil and the powder solidified material with the upper stirring blades that are jetted and rotated.
The deep mixing method according to claim 1.

(Function and effect)
In this way, by combining the tip treatment with the slurry solidifying material, with a small rotational resistance over the entire insertion depth of the stirring shaft (that is, with the fluidity improver liquid for the improved portion by the powder solidifying material and for the tip portion) (The rotation resistance is reduced by the slurry solidifying material, respectively).

<Invention of Claim 3>
A lower stirring blade projecting in the radial direction provided at the distal end , an upper stirring blade projecting in the radial direction provided at a predetermined interval on the proximal end side with respect to the lower stirring blade, and the upper stirring blade a first injection port provided in the position in the rotational direction behind the stirring shaft and a second injection port provided at a position of penetration during the rotation direction behind the lower stirring blade,
A base machine that supports the stirring shaft and applies a rotational force, a lifting force, and a pushing force to the stirring shaft;
A first supply device for supplying a powder solidified material to the first injection port through compressed air through the first internal line in the stirring shaft;
A second fluidity improver liquid containing a surfactant is pumped and supplied to the second injection port through an internal second line in the stirring shaft, which is constituted by a supply line different from the first supply device . A supply device ,
The agitation shaft rotates around the axis and penetrates into the site to be improved in the ground, and in the process, the fluidity improver liquid is injected from the second injection port at the tip of the agitation shaft and rotates. The in situ soil and the fluidity improver liquid are stirred and mixed by the stirring blade,
Thereafter, the stirring shaft is rotated around the axis and pulled out from the state where it has been inserted into the improvement target portion, and in the process, the powder solidification material is injected from the first injection port behind the stirring blade in the rotation direction. A deep-mixing processing apparatus, wherein the in-situ soil and the powder solidified material are stirred and mixed by the rotating stirring blade to form a columnar solidified body .

(Function and effect)
The same effects as those of the first aspect of the invention can be achieved.

<Invention of Claim 4>
The deep-mixing processing apparatus of Claim 3 which formed the streak process extended along the longitudinal direction of the stirring shaft from the vicinity of the said 1st injection nozzle in the outer peripheral surface of the said stirring shaft.

(Function and effect)
In the powder system construction method, the fluidity of the in-situ soil and the stirring mixture of this and the solidified material is relatively poor, so the air supplied to the in-situ region may not remain on the ground and remain as an air pool in the improved body. . On the other hand, when the stirrer shaft as described above is provided on the stirring shaft, the air gap formed behind the projection as the stirring shaft rotates becomes an air discharge passage, and the air supplied to the original position is the air discharge passage. As the air is raised and exhausted through the air, it is difficult for air pockets to occur.

<Invention of Claim 5>
A stirring blade protruding downward is attached to a lower edge portion of the upper stirring blade with a radial interval, and a stirring blade protruding upward is also radially attached to the upper edge portion of the lower stirring blade. 5. The deep mixing apparatus according to claim 3 or 4, wherein the deep mixing apparatus is attached at an interval .

  As described above, according to the present invention, in the powder system construction method, it is possible to increase the diameter of the improved diameter (or to reduce the size of the construction machine if the diameter is the same) without impairing the advantages specific to the powder system. Benefits are provided.

It is the schematic of a deep-layer mixing processing apparatus. It is a longitudinal cross-sectional view of a swivel joint part. It is an enlarged view which shows the stirring blade part of a stirring shaft. It is a cross-sectional view of a stirring shaft. It is an enlarged view which shows the stirring blade part of a stirring shaft. It is a cross-sectional view of a stirring shaft. It is a cross-sectional view which shows the upper stage stirring blade part of a stirring shaft. It is a cross-sectional view which shows the lower stage stirring blade part of the stirring shaft. It is the schematic which shows the state around the lower stage stirring blade at the time of excavation penetration. It is the schematic which shows the state around the upper stage stirring blade at the time of raising stirring. It is the schematic for demonstrating the compaction effect of a lower stage stirring blade. It is the schematic which shows the construction method example. It is the schematic which shows the construction method example.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows a deep mixing apparatus 1 according to the present invention, which includes a base machine 20 having a stirring shaft 10, a first supply device 30 for metering and feeding a powder solidified material, and a flow It is comprised with the 2nd supply apparatus 40 which manufactures a property improvement agent liquid and a slurry solidification material, selectively switches these, and pumps.

  The base machine 20 is mounted on a leader 21 erected at the front end, an elevating part 22 provided so as to be movable up and down along the leader 21, an agitation shaft 10 supported by the elevating part 22, and the elevating part. And a rotation driving device 23 that rotates the stirring shaft 10 around the axis. The agitation shaft 10 is applied with a pushing force or a pulling force by raising and lowering the elevating unit 22, and a rotating force is given by the rotation driving device 23.

  As shown in FIGS. 3 to 8, the stirring shaft 10 includes a main body tube 12 having a swivel joint 11 attached to the head, and a lower stirrer blade provided at the tip of the main body tube 12 and protruding in both radial directions. 13 and an upper stirrer blade 14 that protrudes on both sides in the radial direction and is provided at a predetermined interval on the base end side with respect to the lower stirrer blade 13. For example, the main body tube 12 may be formed of a square tube as shown in FIGS. 3 and 4, or may be formed of a circular tube as shown in FIGS. 5 and 6.

  As shown in FIGS. 3, 5, 7, and 8, the upper stirring blade 14 and the lower stirring blade 13 are attached with a predetermined inclination posture in which one side in the circumferential direction of the stirring shaft 10 is located below the other side. Thus, the rotation direction of the stirring shaft 10 at the time of penetration is the blade lower edge portion at the front side in the rotation direction, and the rotation direction at the time of pulling up is the opposite, and the blade upper edge portion is at the front side in the rotation direction. A cutter b1 protruding downward is attached to the lower edge portion of the lower stirring blade 13 at an appropriate interval in the radial direction. This cutter b1 is for cutting the ground at the time of excavation penetration. Further, a stirring blade b2 protruding downward is attached to the lower edge portion of the upper stirring blade 14 at an appropriate interval in the radial direction. Furthermore, the stirring blade b2 protruding upward is also attached to the upper edge portion of the lower stirring blade 13 at an appropriate interval in the radial direction. These stirring blades b2 exhibit a stirring action.

  On the outer surface of the main body pipe 12, a first injection port 15 is formed at a position behind the rotation direction when the upper stirring blade 14 is pulled up, and a second injection port 16 is formed at a position behind the rotation direction when the lower stirring blade 13 is inserted. An internal first line L1 and an internal second line L2 built in the main body pipe 12 are connected to the first injection port 15 and the second injection port 16, respectively. The internal first line L1 and the internal second line L2 can be formed by pipes or hoses.

  Further, in the illustrated example, on the rear side in the rotational direction when the upper stirring blade 14 is pulled up, a ridge extending from the blade base end to the vicinity of the tip portion along the radial direction at a height position near the upper side of the first injection port 15. A convex line 17 is formed. Further, in the illustrated example, a streak 18 extending along the longitudinal direction of the main body tube 12 is formed on the outer peripheral surface of the main body tube 12. As long as the streak 18 extends along the longitudinal direction, the streak 18 has a linear shape along the vertical direction as in the illustrated example, and a curved shape such as a spiral rising along the outer periphery of the main body tube 12. As long as it extends in the longitudinal direction, the convex streaks 1718 may have discontinuous portions as shown in FIG. When the main tube 12 is a square tube, it is preferable that the streak 18 is attached to the corner portion, and when the main tube 12 is a circular tube, the streak 18 is formed at a position corresponding to the upper stirring blade 14. .

  As shown in detail in FIG. 2, the head of the stirring shaft 10 is provided with a swivel joint 11 having a structure capable of simultaneously pumping powder and liquid through separate lines, and the first internal line L <b> 1 of the stirring shaft 10. The internal second line L2 is constantly and independently connected to the corresponding external first line L11 and external second line L12 via the swivel joint 11, and the external first line L11 is the first supply. The device 30 and the external second line L12 are connected to the second supply device 40, respectively.

The first supply device 30 places a silo 31 for storing the powder solidified material, and puts the powder solidified material charged from the silo 31 on compressed air supplied from a compressor (not shown), and passes the external first line L11. And a sending machine 32 for sending out. In addition, the second supply device 40 has an external storage tank 41 for storing the fluidity improver liquid, an agitation tank 42 for storing the slurry solidifying material, and one of these storages selected by the switching valve 43. And a pump 44 for feeding through the two lines L12. Flow improver liquid, Ri chemicals der to improve the fluidity of the soil are those containing a surfactant. Examples of fluidity improvers include foaming agents (synthetic surfactants, resin soaps, proteins), fluidizers (surfactants are the main components, naphthalenesulfonic acid, which are known as admixtures for concrete, for example. Formaldehyde high condensate salt, melamine sulfonic acid formaldehyde high condensate salt, styrene sulfonic acid copolymer salt, etc.), AE agent, AE water reducing agent, water reducing agent, high performance AE water reducing agent and the like can be suitably used. The fluidity improver is preferably used by diluting with water or the like to obtain a liquid having an appropriate concentration.

On the other hand, FIG. 12 shows an example of a construction method using the deep mixing processing apparatus 1. This example is an application example to a construction form in which a solidified columnar body CB is formed by jetting and agitating a powdered solidified material at the time of pulling up after excavating the stirring shaft 10. In this example, as shown in FIG. 12 (a), first, the agitation shaft 10 rotates around the axis and penetrates into the site to be improved in the ground. In order to prevent this, only the compressed air is supplied, and the supply of the powder solidifying material is stopped, the switching valve 43 of the second supply device 40 is switched to the fluidity improver liquid side, and the pump 44 is operated. The fluidity improver liquid is sent out from the second injection port 16 through the external second line L12 and the internal second line L2. As shown in FIG. 9, the fluidity improver liquid injected from the second injection port 16 is dispersed in the gap S <b> 1 formed behind the lower stirring blade 13 in the rotation direction. As a result, the in-situ soil G and the fluidity improver liquid are stirred and mixed by the rotating stirring blades 13 and 14, and the in-situ soil G is improved in fluidity and reduced in viscosity. As a result, the rotational resistance of the stirring blades 13 and 14 at the time of drilling penetration is reduced, and even if the improved diameter is increased, the drilling penetration can be performed well, and the site to be improved is sprayed with the powder solidified material later. It becomes mud suitable for mixing. The improved diameter (stirring blade diameter) is not particularly limited, but according to the present invention, it can be about 1.5 to 3 m diameter compared to the conventional 1 m diameter.

Next, as shown in FIG. 12 (b), the depth is shallower by the distance D1 between the upper stirring blade 14 and the lower stirring blade 13 than the depth of the fixing portion (the bottom of the improved portion) (should be shallower than the interval D1 minutes). In addition, if the lower stirring blade 13 has reached, the following tip processing can be performed as necessary. That is, when the lower stirring blade 13 reaches a predetermined depth, the switching valve of the second supply device 40 is switched to the slurry solidifying material side, and the slurry solidification is performed from the second supply device 40 as shown in FIG. The material is fed out and injected through the second injection port 16 through the external second line L12 and the internal second line L2, and further, while the stirring shaft 10 is rotated. Thereby, about the improvement object site | part of the front end side rather than the 1st injection port 15, a slurry solidification material can be supplied and a front-end | tip part improvement body can be created. Alternatively, after supplying the fluidity improver solution from the second supply device 40 and once excavating the fixing portion, the stirring shaft 10 may be pulled up by the interval D1 and the tip portion processing may be performed from this state. . In this case, the effect of reducing the rotational resistance of the agitation shaft 10 by the fluidity improver liquid is exhibited up to the tip treatment section.

  When the lower stirring blade 13 reaches the fixing portion depth, after the second supply device 40 is stopped, as shown in FIG. 13D, the stirring shaft 10 is pulled up while rotating in the direction opposite to the time of penetration. At the same time, the first supply device 30 is operated to inject the powder solidified material from the first injection port 15 through the external first line L11 and the internal first line L1. As shown in FIG. 10, the powder solidified material injected from the first injection port 15 is dispersed in a gap S <b> 2 formed behind the upper stirring blade 14 in the rotation direction. The soft mud to which the solidifying material adheres is scraped by a stirring blade at a spiral depth pitch determined by the relationship between the rotational speed of the upper stirring blade 14 and the axial movement speed of the stirring shaft 10 and is agitated in a plane. Mixed in. Further, in the illustrated example, as the stirring shaft 10 is pulled up, the excavation bit provided at the upper edge portion of the lower stirring blade 13 causes the surface stirring in the reverse direction following the upper stirring blade 14. Mixability is further improved. Then, as shown in FIGS. 13 (e) and 13 (f), the in-situ soil and the powder solidified material are well stirred and mixed by repeating the adhesion, cutting, and stirring of the solidified material, so that the columnar solidified body CB is obtained. Is created. Further, at this time, the lower stirring blade 13 exerts an action of pressing the mixed treated soil downward as shown by an arrow in FIG. 11, so that the improved body CB to be formed is well compacted.

  On the other hand, the air supplied together with the powder solidifying material is discharged to the ground along the outer surface of the stirring shaft 10 as shown in FIGS. 13 (d) and 13 (e). In particular, when the upper stirrer blades 14 have the convex streaks 17 on the back as in the illustrated example, as can be understood from the diagram shown in FIG. As shown by a two-dot chain line in FIG. 5, the air injected below the convex muscle 17 returns to the main body pipe 12 through the gap above the convex muscle 17 and is discharged to the ground between the main body pipe 12 and the ground. For this reason, it is difficult for the improved body to generate air pockets. Further, as shown in FIG. 5, when the stirrer protrusion 18 extending along the longitudinal direction of the stirrer shaft 10 is provided on the outer peripheral surface of the stirrer shaft 10, the rotation direction of the streak protrusion 18 is also shown in FIG. 5. Since a gap S3 leading to the ground along the outer surface of the main body pipe 12 is formed behind, this serves as an air discharge passage, and the air supplied to the original position rises (see the two-dot chain line arrow in FIG. 5) and exhausts. It becomes easy to be done.

On the other hand, when it is necessary to improve to a depth (for example, 25 m or more) higher than the limit depth where the powder pressure is limited, excavation is performed while supplying the fluidity improver liquid from the second injection port 16 to the limit depth. From the limit depth, as with the tip treatment, switch to the solidified material slurry injection from the second injection port 16, perform intrusion discharge, re-stir at the time of pulling up, and slurry solidified material deeper than the limit depth When the first injection port 15 returns to the limit depth, the second supply device 40 is stopped and the first supply device 30 is operated to inject the powder solidified material from the first injection port 15. It is also possible to create a solidified column with a powder solidifying material shallower than the limit depth.

In addition, the improvement target site may be a soft formation with a large water content, but in the case of a formation that is tightened to some extent or a formation with a large adhesive force, by separately adding or increasing the amount of water added to the fluidity improver liquid , It is possible to adjust to the in-situ soil G having an appropriate water content ratio with respect to the powder solidified material by adding water to the site to be improved in advance. For example, in a high water content formation, a small amount of fluidity improver solution or a small amount of fluidity improver solution close to the stock solution can be used. In addition, the injection amount and water addition amount of the fluidity improver liquid at each depth can be controlled by the initial setting when the stratum structure is known in advance, and in other cases or when it is automated, the ground condition is changed. It can also be detected and controlled from an ammeter in the case of electric motor drive and from an oil pressure meter in the case of hydraulic drive. In the latter case, if a sensor that directly detects excavation thrust and rotational torque is attached, more accurate management becomes possible.

(Other)
(A) Two stirring blades at the same stage protrude in the opposing direction in the illustrated example, but three or more stirring blades may protrude in the radial direction.
( B ) In the above example, the slurry solidifying material is used in combination to perform the tip processing or the deep processing, but in the present invention, the slurry solidifying material may not be used.
( C ) The injection of the powder solidifying material can be performed not only when the stirring shaft 10 is pulled up but also in the process of re-penetrating after lifting the stirring shaft 10 once it is after stirring and mixing of the fluidity improver liquid. .
( D ) In the present invention, a plurality of types of powder solidifying materials such as cement, cement-based solidified material, fly ash (coal ash), and lime-based solidified material can be simultaneously injected. In addition to providing the solidified material for each type and individually pumping / injecting, it is possible to press and inject using a common supply line in the case of materials that can be mixed in advance.
(E) In the present invention, the fluidity improver liquid can be jetted together with air at a high pressure, thereby improving the mixing property between the fluidity improver liquid and the in-situ soil and improving by mixing bubbles in the improved body. The weight of the body can be reduced. Similarly, when the slurry solidifying material is jetted, the slurry solidifying material can be jetted together with air at a high pressure.

  The present invention can be applied to a deep layer processing method and a deep layer processing apparatus.

  DESCRIPTION OF SYMBOLS 1 ... Deep layer processing apparatus, 10 ... Stirring shaft, 13 ... Lower stage stirring blade, 14 ... Upper stage stirring blade, 15 ... 1st injection port, 16 ... 2nd injection port.

Claims (5)

While agitating shaft provided with a stirring blade projecting in the radial direction is rotated around the shaft center and drilled into the site to be improved in the ground, a fluidity improver is injected from the tip of the stirring shaft in the process, The in-situ soil and the fluidity improver are stirred and mixed by the rotating stirring blade,
Thereafter, while rotating the stirring shaft about the axis, the stirring shaft is pulled out from the state inserted into the improvement target portion, and in the process, the powder solidification material is injected behind the rotating direction of the stirring blade, and the stirring is rotated. The in-situ soil and the powder solidified material are stirred and mixed with a wing to form a columnar solidified body.
This is a deep mixing process. The stirring shaft includes, as the stirring blade, a lower stirring blade provided at a tip portion and an upper stirring blade provided at a predetermined interval on the base end side with respect to the lower stirring blade,
In the drilling penetration process of the stirring shaft, if the lower stirring blade reaches a depth shallower than the distance between the upper stirring blade and the lower stirring blade than the fixing portion depth, then the tip of the stirring shaft reaches the fixing portion depth thereafter. The slurry solidifying material is jetted from the part, the in-situ soil and the slurry solidifying material are stirred and mixed by the rotating lower stirring blade, and the tip is processed.
After that, while rotating the stirring shaft around the axis, it is withdrawn from the inserted state after the tip portion treatment, and in the process, the powder solidification material is jetted behind the rotating direction of the upper stirring blade and rotates. The in-situ soil and the powder solidified material are stirred and mixed with the upper stirring blade to form a columnar solidified body.
The deep mixing method according to claim 1. A stirring shaft provided with a stirring blade protruding in the radial direction, a first injection port provided on one side of the rotation direction of the stirring blade, and a second injection port provided at the tip;
A base machine that supports the stirring shaft and applies a rotational force, a lifting force, and a pushing force to the stirring shaft;
A first supply device for supplying the solidified powder material to the first injection port on the compressed air through the stirring shaft;
A second supply device provided separately from the powder solidifying material supply means, for supplying a fluidity improver to the second injection port through the stirring shaft;
A deep mixing apparatus characterized by comprising:   The deep-mixing processing apparatus of Claim 3 which formed the streak process extended along the longitudinal direction of the stirring shaft from the vicinity of the said 1st injection nozzle in the outer peripheral surface of the said stirring shaft.   On the surface on the first injection port side of the stirring blade, a ridge-like convex line extending from the blade base end to the blade tip portion along the radial direction is provided at a height position near the upper side of the first injection port. The deep layer processing apparatus according to claim 3 or 4, which is formed.

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