JP2010053668A - Construction method of columnar soil improving body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a construction method of a columnar soil improving body, contributing to the improvement of the original ground making effective use of soil generated from construction, as well as, reducing the disposal amount of waste outside the field for the whole soil generated in the field in association with the construction of mainly a foundation structure. <P>SOLUTION: The columnar soil improving body is constructed, by carrying out excavation while rotating a casing 1, constituted of a tapered part mounted with an excavating head at the chip and compacting and consolidating the peripheral ground to the side, and a cylindrical part continuous with the tapered part; and after excavating to a predetermined depth, in a state of a casing head projecting from the ground surface, soil 6 generated from construction of a structure from the casing head is thrown into the casing, until its top face is located above the ground surface, mixing and agitating soil in the casing 1 including the soil 6 generated from construction, by an agitation blade 7 while injecting a soil improving material into the soil inside the casing 1, and pulling up the agitation blade 7 and the casing 1 to the ground. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention creates a space by consolidating the original ground using a special casing, throws the site-generated soil generated by the construction and dismantling of the structure into the space, and into the soil containing the site-generated soil It is related with the construction method of the columnar ground improvement body which solidifies the soil containing this field generation | occurrence | production soil, and constructs a columnar ground improvement body by mixing and stirring a ground improvement material.

The present invention belongs to the field of deep layer improvement of ground improvement methods.
This deep ground improvement method is a ground improvement intended for the ground up to a relatively deep formation, and a ground improvement body is constructed by stirring and mixing the ground and the ground improvement material in situ.
The image of the conventional deep ground improvement method is shown in FIGS.
In this deep ground improvement method, the ground is mechanically stirred using a stirring rod with stirring blades (Figs. 9 and 10), and the hardened material is discharged from the tip of a small hollow rod at high pressure to rotate the rod. It is divided into the construction method (FIG. 11) which carries out the injection stirring of the ground.
Both are mixed and stirred in the in-situ ground.

On the other hand, one approach to environmental problems in construction is to reduce industrial waste generated by construction and demolition of structures.
Here, industrial waste generated during construction and dismantling of structures includes (1) excavated surplus soil discharged with pile construction, (2) excavated surplus soil associated with construction of foundation slabs and foundation beams, (3) Residual soil generated during construction work, (4) Demolished concrete or reinforced concrete.
In this specification, these remaining soils are collectively referred to as construction generated soils.

  Although the above-mentioned industrial waste, that is, the target areas where construction generated soil should be reduced, is wide-ranging, in recent years also in the basic structure field, sand, crushed stone and other intermediary materials are discharged into the ground and left in the ground. Technical developments such as the soft ground improvement method that forms a solid body and the liquefaction countermeasure method using locally generated soil are also being carried out, but they are not so popular.

For example, as a soft ground improvement method, the casing pipe 1 is penetrated into the ground to a predetermined depth along the leader of a heavy machine, and sand, crushed stone or other intermediate material is introduced and filled from the hopper into the hollow casing pipe body. When penetrating into the ground, the cone-shaped shu is closed through the nail piece through the penetration resistance so that the soil of the ground does not enter the inside of the casing pipe body, and after reaching a predetermined depth, The casing pipe is raised and the screw is pushed and lowered to forcibly open each nail piece, so that the shoe is opened and the interstitial material in the casing pipe body is discharged and left in the ground to form a pile-like body. Such a construction method has been proposed.
Japanese Patent No. 2747924

As a liquefaction countermeasure method, a hollow pipe is inserted into a soft sandy ground, and the pile is pulled out and filled with industrial waste containing construction waste soil to create a pile. The pile is filled with traces after the hollow tube is pulled out by compressing the surrounding ground by compressing it while shearing and deforming the surrounding ground with the side pushing force acting on the surrounding ground when the hollow tube penetrates. When the pile material is likely to be liquefied when it is improved so that the ground is not liquefied by holding it with a material, a predetermined amount of solidified material such as lime or cement is added to the construction material soil of the pile material. Therefore, a soft sandy ground improvement method that prevents liquefaction of pile materials has been proposed.
Japanese Patent No. 2887578

However, the invention described in Patent Document 1 uses the selected intermediate material and does not use construction generated soil, and is not intended for disposal or effective use of construction generated soil.
Moreover, although the pile of the invention described in Patent Document 2 itself is prevented from being liquefied, it is possible to support the structure or reduce its settlement by giving strength. It is not a columnar ground improvement body.
Furthermore, each construction requires a special construction machine, so it has not yet spread to general construction sites.

  The present invention was created in order to solve these problems, and the amount of waste disposal outside the site is mainly targeted for the above-mentioned construction-generated soil generated mainly on the site in connection with the construction of the foundation structure. It aims at providing the construction method of the columnar ground improvement body which contributes to the improvement of the original ground which not only reduces but effectively utilizes construction generated soil.

The invention according to claim 1 is the construction method of the columnar ground improvement body, wherein the excavation head is mounted at the tip, and the peripheral ground is laterally compacted and compacted, and the tapered portion and the cylindrical portion continuous therewith. After excavation while rotating the configured casing and excavating to a predetermined depth, the construction generated soil generated by the construction of the structure from the casing head is put into the casing, and the construction generated soil is contained. A columnar ground improvement body was constructed by mixing and stirring with a stirring means while injecting a ground improvement material into the soil in the casing, lifting the stirring means to the ground, and then lifting the casing to the ground.
The invention according to claim 2 is also a method for constructing a columnar ground improvement body, wherein a plurality of tapered tap-out pieces are closed, and the peripheral ground is compacted laterally and contiguous with the tapered tip. After the press-fitting is advanced while rotating the casing composed of the cylindrical portion and press-fitted to a predetermined depth, the construction generated soil generated by the construction of the structure is introduced into the casing from the casing head, Mixing and stirring with a stirring means while injecting a ground improvement material into the construction generated soil, pulling up the stirring means to the ground, and pulling up the casing to the ground with the mouth piece at the tapered tip end opened Therefore, it was decided to construct a columnar ground improvement body.

According to a third aspect of the present invention, in the mixing and stirring by the stirring means, the soil in the casing including the construction generated soil is moved upward in the casing shaft center portion and is moved downward in the casing wall portion. Thus, vertical convection from the tip of the casing to the upper part of the casing is generated, and the ground improvement material is injected into the soil in the convection at an upper position and a lower position of the casing. .
According to a fourth aspect of the present invention, the casing is pulled up while moving up and down simultaneously with the rotation.
According to a fifth aspect of the present invention, after the casing is excavated to a predetermined depth, the casing head protrudes from the ground surface when the construction-generated soil is introduced into the casing from the casing head. The top end of the construction-generated soil was positioned above the ground surface.
The invention according to claim 6 is the method for constructing the columnar ground improvement body according to claim 3, wherein the soil in the casing is moved upward in the casing shaft center portion by the positive rotation of a screw having a diameter smaller than the inner diameter of the casing. It moves and moves downward by free fall in the gap between the outer end of the screw and the inner wall of the casing, thereby generating convection in the vertical direction from the tip of the casing to the upper portion, and rotating the soil and the screw together. It was decided to stir in the horizontal direction within the range reaching the inner wall of the casing at the ground improvement material injection site.

According to the first aspect of the present invention, it is possible to utilize construction generated soil generated at a construction site of a structure as a constituent material of a columnar ground improvement body, and the generated amount of construction generated soil to be treated as industrial waste Can be reliably reduced.
Moreover, a high quality columnar ground improvement body with little mixing nonuniformity can be formed by stirring and mixing the soil and the ground improvement material in the casing.
Furthermore, the leaching of the ground improvement material to the surrounding ground can be reduced, groundwater contamination can be prevented as much as possible, and the usage volume of the used ground improvement material can be reduced. Since it can be consolidated, the improvement degree of the original ground can be remarkably improved.
Furthermore, since the casing and the stirring blade may be driven separately, it can be constructed using an inexpensive rotational drive device.
According to the second aspect of the present invention, since the excavated soil does not enter the casing, the pressure density of the original ground can be increased, and in particular, a new alluvium of a sedimentation age or a soft clay such as a secondary deposit. It is suitable for constructing a columnar ground improvement body in a soft raw ground such as a loose sand layer or a landfill layer that is not sufficiently managed.
According to the invention according to claim 3, since the soil of the original ground and the construction generated soil are stirred in the vertical direction of the columnar ground improvement body, and mixing and stirring with the ground improvement material is repeated, in the vertical direction A columnar ground improvement body with uniform strength can be constructed.
According to the invention of claim 4, when the soil quality of the excavated soil mixed and stirred with the ground improvement material in the casing is difficult to be discharged out of the casing when the casing is pulled up, it can be easily discharged. .

According to the invention according to claim 5, when the occupied volume of the casing and the stirring means is estimated in advance, the construction generated soil having a volume corresponding to the estimated volume is added, and the top end of the columnar ground improvement body lifts both. It can be made near the ground surface, and it can be made uniform from the tip to the top of the columnar ground improvement body. Moreover, the improvement performed to the ground surface vicinity by this method can be performed in a short time.
According to the invention of claim 6, the soil including the construction-generated soil in the casing is provided with a ground improvement material in the vertical and horizontal directions from the tip of the columnar ground improvement body to the head in a state in which co-rotation is prevented. Therefore, the entire columnar ground improvement body can be constructed uniformly.

  The present invention has an excavation head attached to the tip, and proceeds with excavation while rotating a casing composed of a tapered portion that is compacted by compacting the surrounding ground sideways and a cylindrical portion continuous thereto, After excavating to a predetermined depth with the casing head protruding from the ground surface, the construction generated soil generated by the construction of the structure from the casing head until the top surface is located above the ground surface. Columnar ground improvement by charging into the casing, mixing and stirring with a stirring blade while injecting a ground improvement material into the soil in the casing including the construction generated soil, and lifting the stirring blade and the casing to the ground It is a construction method of a columnar ground improvement body for constructing a body.

Depending on the region, the nature of the ground to be excavated can vary widely, and it can be clay or gravel. Therefore, the ground improvement material to be injected, the excavated soil of the original ground flowing into the casing, and later The blending ratio with the construction generated soil to be input is appropriately adjusted according to these properties.
Moreover, as a ground improvement material, the component which has various portland cement as a main component and acts effectively on the solidification object is added.
There are various kinds of active ingredients to be added, such as slag, fly ash and other polyzone materials, alumina cement, strength enhancing materials such as jet cement, and hydration stimulating materials such as gypsum and sodium sulfate.
On the other hand, the amount of excavated soil flowing into the casing is determined by the excavating diameter of the excavating head attached to the tip of the casing, except for the invention according to claim 2.
For this reason, the volume of the space created by penetrating the casing into the raw ground is basically determined by the casing inner diameter and the excavation diameter of the excavation head.
The volume of this space is substantially equal to the total amount of construction-generated soil put into the casing and ground improvement material to be injected.

Hereinafter, the embodiment of the construction method of the columnar ground improvement object concerning the present invention is described in detail based on a drawing.
1 and 2 schematically show the construction procedure of the present invention 1 and the present invention 3, and FIG. 3 is an enlarged perspective view of the apparatus of FIG.
4 and 5 are diagrams showing an embodiment of a tapered portion formed at the tip of the casing.
FIG. 6 is a schematic view of the casing of the present invention 2 in which the tip portion is formed in the shape of a shed.
FIG. 7 is a view showing a co-rotation preventing mechanism in the casing.

Embodiment 1

Based on FIG. 1, the present invention 1 of the single-axis rotation system will be described in detail.
The method for constructing a columnar ground improvement body for constructing the columnar ground improvement body according to the first aspect of the present invention includes a taper-shaped portion 2 having a digging head 10 (see FIG. 5) attached to the tip, and compacting the peripheral ground laterally and compacting. The casing 1 constituted by the continuous cylindrical portion 3 is rotated while being rotated by a uniaxial rotation driving device (not shown), and the casing 1 is accommodated with the soil 4 of the original ground to a predetermined depth. Excavation / consolidation process for excavation, construction generated soil injection process for introducing the construction generated soil 6 generated from the head of the casing 1 with the construction of the structure into the gap 5 formed in the casing, and the occurrence of the construction The step of mixing and stirring the stirring blade 7 that is a stirring means by the rotational drive device while injecting the ground improvement material into the soil in the casing 1 containing the soil, and the stirring blade 7 and the casing 1 on the ground 4 steps of pulling up Consists of.

In the construction generated soil charging process in which the construction generated soil 6 generated by the construction of the structure from the head of the casing 1 following the excavation / consolidation process is input to the gap 5 formed in the casing 1, The excavation of the previous process is completed with the part protruding from the ground surface, and the top end surface of the construction-generated soil that has been injected, mixed with ground improvement material, and mixed and stirred is located above the ground surface. Adjust the amount of generated soil and the amount of soil improvement material injected.
By doing in this way, extra construction-generated soil and ground improvement material with a capacity corresponding to the total volume of the casing and stirring blades are added, the amount of them is optimized, and the strength of the top of the columnar ground improvement body is increased. The strength of the columnar ground improvement body below the top can be made equal, and the strength of the entire columnar ground improvement body can be homogenized.

  Further, in the step of mixing and stirring while injecting the ground improvement material into the soil 4 and 6 in the casing 1 including the construction generated soil 6, the stirring blade 7 is rotationally driven using the above-described uniaxial rotation driving device, and simultaneously stirred. Move the wing 7 up and down. Then, during the operation of the stirring blade 7, the ground improvement material is discharged and injected from the ground improvement material discharge hole 9 formed in the vicinity of the tip of the stirring blade 7, so that the mixing and stirring of the soil and the ground improvement material is made more homogeneous. As a result, it is possible to reduce the variation in the strength of the columnar ground improvement body as much as possible.

  Further, in the step of pulling up the stirring blade 7 and the casing 1 to the ground, the stirring blade 7 and the casing 1 are pulled back and forth to the ground, so that both the stirring blade and the casing are moved up and down while rotating with a time difference. It is possible to complete the mixing of the soil and the ground improvement material, more smoothly discharge the internal soil from the casing tip, and construct a uniformly reinforced columnar ground improvement body.

  In the above description, as shown in FIG. 1, after the construction generated soil is put into the casing 1, the stirring blade 7 is inserted, and the soil including the construction generated soil and the ground improvement material are mixed and stirred. The blades 7 are inserted after the excavation work is completed, and the stirring blades 7 are first lifted while mixing and stirring the soil of the original ground and the ground improvement material, and then the ground is being lifted while moving the stirring blades 7 while moving up and down the construction generated soil. You may make it mix and stir with an improving material.

Next, embodiments of the tapered portion of the casing will be described.
The casing 1 having a taper at the tip is rotated by a rotary drive device while being pressed into the original ground to excavate the original ground.
At this time, the soil of the excavated raw ground can enter the casing 1 from the opening provided at the front end portion of the casing, and the surrounding soil is pushed sideways by the tapered portion of the casing 1 and consolidated. The
This consolidation action increases the density and strength of the original ground around the casing, and secures a space in the casing 1 where construction-generated soil can be introduced in a later process.
As the structure of the tapered portion at the tip of the casing, an appropriate one is selected according to the ground improvement condition and the ground condition.

On the other hand, the soil that has entered the casing 1 is mixed and stirred with the ground improvement material by the stirring blade 7 and is reinforced by the subsequent consolidation of the ground improvement material.
The opening at the front end of the casing serves as a mechanism for returning to the original ground the soil of the original ground that has been excavated and the construction generated soil that is input in a later step when the casing is pulled up.

As the most general structure of the tapered portion, there is the tapered portion 2 shown in FIG. 4A formed at the tip of the cylindrical portion 3.
Based on ground survey results such as N value for sandy soil and Qu (uniaxial compressive strength) for viscous soil, the ratio of the inner diameter of the tip opening to the casing outer diameter, D ₁ / D ₂ in the figure, is optimal. Can be made.
An appropriate taper angle θ can be determined based on the same index.

As shown in FIG. 5, an excavation head 10 having an excavation blade planted on a ring-shaped base is attached to the tip of the tapered portion.
Since this casing has the communication hole 14 formed in the tapered portion, when the casing is pulled up to the ground, the excavated soil in the casing can be easily discharged from the communication hole 14 formed in the tapered portion. it can.
In order to reliably prevent soil from entering the casing during excavation, a blocking plate 15 slightly larger than the communication hole 14 may be pivotally attached. The closing plate 15 is automatically closed by earth pressure when the casing is pressed, and is automatically opened by the weight of the earth when the casing is pulled up.
Further, a continuous or discontinuous spiral blade 16 may be formed on the outer peripheral surface of the casing 1. In this way, excavation while rotating the casing is performed while obtaining propulsive force by the spiral blades formed continuously or discontinuously, so that the driving force of the rotary drive device is reduced and stable. It can contribute to excavation work and energy saving.

  As another example of the tapered portion, there is a double tapered portion in which the tapered portion is formed in two stages at the tip of the casing cylindrical portion, as shown in FIG. According to the tapered portion, the surrounding soil is consolidated twice. In this case, since the surrounding soil is smoothly consolidated, it is effective for compacting soil that is difficult to compact.

  As still another example of the tapered portion, there is a case where a tapered portion is formed between a small-diameter cylindrical portion and a large-diameter cylindrical portion shown in FIG. 4C. In this case, the excavated soil can be guided smoothly into the casing 1.

Embodiment 2

Although it depends on the conditions of the ground, if you want to increase the compression ratio of the ground, close the casing tip as shown in Fig. 6 so that the soil of the original ground does not enter into the casing 1, It is good also as the invention 2 comprised only with the construction construction soil thrown in and the injected ground improvement material.
The closed tapered portion of the present invention is composed of a throat piece 11 obtained by dividing a conical tip portion of the casing into a plurality of circumferential directions, and the throat piece 11 does not have a special opening / closing mechanism, and is not soiled when the casing is press-fitted. It is automatically closed by pressure, and when the casing is pulled up, the tip of the stirring blade housed inside is protruded from the tip of the casing, so that it is opened without the need to provide a special mechanism. Of course, a drive opening / closing mechanism may be adopted.

Regarding the timing of loading the construction generated soil and inserting the stirring blade 7, the stirring blade is inserted prior to the construction generated soil, and the construction generated soil and ground are improved while pulling up the stirring blade while introducing the construction generated soil. If the materials are mixed and stirred, it is advantageous for a short and efficient mixing and stirring.
In addition, when the construction generated soil is put in before the stirring blade is inserted, mixing and stirring may be performed while moving the stirring blade up and down and entering the casing.
Furthermore, since the press-fitting of the casing 1 and the insertion of the stirring blade 7 and the pulling-up of the stirring blade 7 and the casing 1 are not performed at the same time, it may be performed using a uniaxial rotating device.
According to this invention, since the excavated soil of the original ground is not allowed to enter the casing, the soil around the casing can be strongly consolidated, and no excavated soil exists in the casing. Since a large amount of soil can be treated and the casing tip can be opened, the soil can be smoothly discharged when the casing is pulled up.

Embodiment 3

As an example of a stirring method using a stirring blade, there is a method of stirring excavated soil three-dimensionally.
Specifically, there is a method of stirring by a three-dimensional stirring mechanism including a rotating device that rotates a stirring blade around a rotating shaft and a vertical moving device that moves the rotating shaft up and down simultaneously.
In addition, a rotating device that rotates the stirring blade around the rotation axis and two support members that are orthogonal to the rotation axis are fixed, and a ring having 3 to 4 stirring rods planted on the surface is rotated around the support member. There is a method of stirring by a three-dimensional stirring mechanism that is pivotally mounted.
According to these methods, the mixing and stirring of the soil and the ground improvement material can be made uniform over the entire columnar ground improvement body, and as a result, a columnar ground improvement body having a uniform strength can be constructed and created.

  Furthermore, in order to make the strength more uniform in the horizontal and depth directions from the tip to the head of the columnar ground improvement body, the soil in the casing including the construction generated soil is moved upward in the axial center portion. The method of the invention 3 in which convection in the axial direction of the casing of the soil is generated by moving downward in the wall portion, and the ground improvement material is injected into the soil in the convection at an upper position and a lower position of the casing and stirred. There is.

This method is carried out using the stirring device 20 shown in FIGS.
The rod 17 that is rotationally driven by a driving device (not shown) is provided with a screw 18 having a diameter of about half of the casing inner diameter as a stirring means. The vicinity of the terminal edge of the screw 18 is a flat portion where no twisting of the screw is formed, and the terminal edge is formed along a line inclined rearward from the radial direction of the rod 17.
The soil in the casing moves upward along the rod 17 by the screw 18 and is guided in the wall direction from the position near the casing axis by the guide plate 19 formed at the terminal end edge of the screw 18.
As shown in FIG. 3, the guide plate 19 is a plate in which a screw terminal edge inclined backward from the radial direction of the flat portion is bent in the rod 17 direction. The soil or the like is guided between the casing and the screw, that is, in the direction of the casing wall without being dropped. As a result, the upward flow of the soil in the axial center portion of the casing is changed to a downward flow that freely falls due to the weight of the soil in the vicinity of the upper end of the casing.
On the other hand, since the soil is moved upward along the rod 17 of the screw 18 at the casing tip position, a cavity is formed at a position near the casing axial center, and the soil at the peripheral portion descending from above is supplied to the cavity. Will be.
Thereby, the convection of the up-down direction of the soil in the casing from the casing tip part to the vicinity of the upper end part is generated.

Reference numeral 9 denotes a ground improvement material discharge hole provided near the upper end and the tip of the rod 17.
If the discharge hole is provided only near the lower end, soil that has been fluidized by ground improvement material has a higher specific gravity and tends to accumulate at the lower end in the casing, so that vertical convection does not occur up to the upper end in the casing. There is sex. On the contrary, when the discharge hole is provided only in the vicinity of the upper end, it is conceivable that soil or the like is not rotated and mixed and stirred between the casing and the screw near the lower end of the casing.
Therefore, in the present embodiment, in consideration of these, the discharge hole 9 and the stirring blade 7 are provided in the vicinity of the minimum upper end and lower end.

The stirring mechanism 21 constituting the stirring means is provided between the screw 18 provided at the rod front end and the rod upper end so as to be orthogonal to the rod 17 in a stepwise manner and has a length that substantially reaches the inner wall of the casing. It is comprised from the stirring blade 7 of this book, and the 2-4 stirring rod 22 planted by the two places of the surface.
Corresponding to the stirring mechanism 21, 23 is a co-rotation preventing tool attached to the upper and lower surfaces of the screw 18 at a desired position between the two stirring rods 22 in the axial direction of the stirring blade 7 and extending in the rod direction.
The stirring mechanism 21 and the co-rotation prevention tool 23 are arranged in the vicinity of the tip end and upper end of the rod 17 so that the soil and the screw are sandwiched between the screws 18 by the cooperative operation of the stirring rod 22 and the co-rotation prevention tool 23. While preventing co-rotation, the soil in the casing and the ground improvement material are mixed and stirred in the horizontal direction while crushing the clod.

The stirring rod 22 described above can be supported by three methods: a method of fixing to the stirring blade 7, a method of pivoting and pivoting, and a method of rotational driving.
However, the viscous soil or the like adheres to the screw 18, the stirring blade 7, and the like, which enlarges, and the stirring blade 7, the stirring rod 22, and the co-rotation prevention tool 23 may be integrated, and stirring may be hindered. In addition, forcible stirring is also effective and desirable for crushing a lump of viscous soil or the like.
Therefore, in this embodiment, the rotational drive type is adopted.

A driving mechanism for rotationally driving the stirring rod 22 is not shown, but the rod 17 is an inner / outer double tube, the inner tube is a fixed tube, and the outer tube to which the screw 18 is fixed is rotated.
A rack is formed on the surface of the non-rotating inner tube, a pinion is disposed on the inner surface of the rotating outer tube, and the driving force transmitted to the pinion may be used for the rotation of the stirring rod 22.
Specifically, a structure is adopted in which the pinion is fixed to the proximal end portion of the stirring blade 7 to which the stirring rod 22 is attached, and the stirring blade is inserted through a sleeve formed to project from the rod outer tube.
The slurry transport pipe (not shown) for supplying the ground improvement material to the upper and lower discharge holes 9 may be fixed to the inner surface of the outer pipe.

It is important that the stirring with the stirring blade is performed while preventing the excavated soil from rotating together with the stirring blade.
As another co-rotation preventing mechanism, it is composed of a fixed wing fixed to a rotating shaft and a free wing pivotally mounted coaxially, and as shown in FIG. A material 12, for example, a rubber material, is attached, and the rubber material is slidably contacted with the inner wall of the casing 1 (FIG. 7A), or the free wing is brought into contact with a stopper 13 provided in the casing, There is also a method for preventing the rotation of excavated soil by restricting the rotation of the free wing (FIG. 7B).
Alternatively, the co-rotation prevention mechanism consists of a forward rotating blade that rotates in the forward direction in the inward direction and a reverse rotating blade that rotates in the reverse direction in the outward direction, and prevents the rotation of the excavated soil by rotating the forward rotating blade and the reverse rotating blade. You can also
If it does in this way, mixing and stirring with the soil and ground improvement material in a casing can be performed efficiently.

Furthermore, the mixing and agitation of the construction generated soil and the ground improvement material is carried out after being put into the casing, but it is also possible to previously mix and agitate both on the ground.
At this time, when the construction generated soil is softened until it is fluidized on the ground, after the fluidization treatment is performed, the ground improvement material discharged from the head of the casing 1 to the rotating shaft of the hose or the stirring means inserted into the casing is discharged. It may be injected from the hole 9.
By doing in this way, a columnar ground improvement body with higher quality can be constructed.

It is a schematic process drawing which shows typically the process of the construction method of the columnar ground improvement object of the present invention 1. It is a schematic process drawing which shows typically the process of the construction method of the columnar ground improvement object of the present invention 2. FIG. 3 is an enlarged perspective view of FIG. 2. It is a schematic diagram which shows the structural example of a casing front-end | tip part, (a) is a general casing in which the taper-shaped part was formed in the front-end | tip of a cylindrical part, (b) is a cylindrical part of the small diameter of a taper-shaped part at the front-end | tip part of a casing, and A casing formed between the large-diameter cylindrical portions, (c) is a casing having a double tapered portion in which the tapered portion is formed in two steps at the tip of the cylindrical portion. FIG. 5 is an enlarged perspective view of FIG. It is a schematic diagram of the casing of this invention 3 in which the front-end | tip part was formed in the shape of a shed. It is a figure which shows the co-rotation prevention mechanism in a casing. It is explanatory drawing of the prior art described in patent document 1. FIG. It is an image figure of the conventional deep ground improvement construction method which blows off the powdery ground improvement material and air from the rod tip, mechanically stirs with the ground using a stirring rod with a stirring blade, and discharges air. It is an image figure of the deep-layer ground improvement construction method which ejects the conventional slurry-like ground improvement material from the rod front-end | tip, and mechanically stirs with the ground using the stirring rod with a stirring blade. It is an image figure of the deep ground improvement construction method which discharges a slurry-like ground improvement material at a high pressure from the tip of a thin hollow rod, rotates the rod, and jets and stirs the ground.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Casing 2 Tapered part of casing 3 Cylindrical part of casing 4 Soil of original ground 5 Cavity 6 Construction generated soil 7 Stirring blade 8 Drilling bit 9 Ground improvement material discharge hole 10 Drilling head 11 Tail piece 12 Material having a large friction coefficient (rubber Material)
DESCRIPTION OF SYMBOLS 13 Stopper 14 Communication hole 15 Blocking plate 16 Spiral blade 17 Rod 18 Screw 19 Guide plate 20 Stirrer 21 Stirrer mechanism 22 Stirrer bar 23 Corotation prevention tool

Claims (6)

  The excavation head is attached to the tip, and the excavation is carried out while rotating the casing composed of a tapered part that is compacted by compacting the surrounding ground to the side and a cylindrical part that continues to it, and excavation to a predetermined depth After that, the construction generated soil generated by the construction of the structure from the casing head is put into the casing, and the ground improvement material is injected into the soil in the casing including the construction generated soil and mixed by the stirring means. A method for constructing a columnar ground improvement body, wherein the columnar ground improvement body is constructed by stirring, lifting the stirring means to the ground, and then lifting the casing to the ground.   With a plurality of tapered taphole pieces closed, press-fitting is advanced while rotating a casing composed of a tapered tip portion that is compacted by compacting the surrounding ground laterally and a cylindrical portion continuous therewith. After press-fitting to the depth, the construction generated soil generated by the construction of the structure from the casing head is put into the casing, and the ground improvement material is injected into the construction generated soil in the casing and mixed by the stirring means. A method for constructing a columnar ground improvement body, wherein the columnar ground improvement body is constructed by stirring, lifting the stirring means to the ground, and lifting the casing to the ground in a state in which the mouth piece of the tapered tip portion is opened.   The mixing stirring by the stirring means moves the soil in the casing including the construction-generated soil upward in the casing axial portion and downward in the casing wall portion, so that the casing of the soil is moved. A convection in the vertical direction from the tip end to the upper part is generated, and a ground improvement material is injected into the soil in the convection at an upper position and a lower position of the casing. The construction method of the columnar ground improvement body which builds the columnar ground improvement body described in any one of 2.   The method for constructing a columnar ground improvement body according to any one of claims 1 to 3, wherein the casing is pulled up while moving up and down simultaneously with rotation. After the casing is excavated to a predetermined depth, the casing head protrudes from the ground surface at the time when the construction generated soil is introduced into the casing from the casing head.
The method for constructing a columnar ground improvement body according to any one of claims 1 to 4, wherein the top end of the construction-generated soil that has been input is located above the ground surface.   The soil in the casing is moved upward in the casing axial center by a positive rotation of a screw having a diameter smaller than the inner diameter of the casing, and is moved downward by a free fall at a gap between the screw outer end and the casing inner wall. By this, the vertical convection from the tip of the casing to the upper part is generated, and the stirring is performed in the horizontal direction within the range reaching the inner wall of the casing at the ground improvement material injection site while preventing co-rotation of the soil and the screw. The construction method of the columnar ground improvement body which builds the columnar ground improvement body described in Claim 3 characterized by the above-mentioned.

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