JP6918073B2 - Excavation stirrer - Google Patents

Description

The present application relates to an excavation agitator capable of efficiently implementing a ground improvement method for constructing a columnar improved body by injecting a binder into excavated soil and stirring and mixing while excavating a vertical hole in the ground.

When building a building on soft ground, inject a binder (solidifying material) such as cement milk into the excavated soil while excavating a vertical hole, and stir and mix the excavated soil and the binder to solidify them into columns. Therefore, a ground improvement method is known in which a columnar improved body called a "pile" is constructed in the ground to enhance the bearing capacity of the ground. Regarding such a ground improvement method, for example, because the soil of the ground is organic soil, the solidification strength of the agitated soil does not reach the required level, or because the site is small and only a small base machine can be introduced, a columnar improved body with a small diameter. In some cases, the support capacity of the columnar improved body cannot be sufficiently obtained due to circumstances such as the fact that it can only be constructed, or the stirring capacity of the base machine is low and the stirring soil is not uniformly solidified. In order to solve such a problem, Patent Document 1 additionally forms a core body made of only a binder in the central portion of a columnar improved body made of a solidified mixture of excavated soil and a binder to improve the columnar shape. A construction method for increasing the support strength of the body is disclosed. Furthermore, the applicants have also proposed in Patent Document 2 a construction method that is an improvement of the construction method described in Patent Document 1, and are trying to put it into practical use.

8 to 9 show an outline of the ground improvement method disclosed in Patent Document 2 and the excavation agitation device used in the method. In this ground improvement method, an excavation agitator 1 also called a "head" or a "bit" is attached to the tip of a rod 21 which is rotationally driven by an auger device (not shown) mounted on a base machine. While excavating the vertical hole, the excavated soil and the binder are agitated and mixed. As shown in FIG. 8, the excavation agitator 1 has a main body cylinder portion (“main body shaft portion” in Patent Document 2) 22 which is connected to the rod 21 and rotates integrally with the rod 21, and a lower end of the main body cylinder portion 22. The excavation blade 24 provided so as to project from the vicinity in the outer diameter direction of the main body cylinder portion 22, the stirring blade 26 provided above the excavation blade 24 in the main body cylinder portion 22, and the excavation blade 24 and the stirring blade 26. The ground is excavated by a plurality of excavation blades 241 projecting from the lower surface of the excavation wing 24, which is provided with a co-rotation prevention wing 25 provided so as to be rotatable relative to the main body cylinder portion 22. It is configured. A binder injection port (nozzle) 221 is provided laterally near the lower end of the main body cylinder portion 22, and the binder supplied through the flow path 220 formed inside the rod 21 is excavated from the binder injection port 221. It is discharged into the soil and mixed with the excavated soil by the rotation of the excavation blade 24 and the stirring blade 26.

FIG. 9 is a diagram showing steps in order when the ground improvement method is carried out using the excavation agitation device 1. The illustrated steps are carried out as follows.

[S1] The rod 21 to which the excavation agitator 1 is attached is installed vertically at a predetermined position, and is gradually lowered while rotating in the positive direction to start excavation of the ground 4.

[S2] As the excavation hole 40 is dug down, excavated soil remains inside the excavation hole 40. In parallel with this, a binder such as cement milk is injected into the excavation hole 40. The binder is discharged into the excavation hole 40 from the coupling material injection port 221 provided at the lower end of the excavation stirring device 1, and is agitated and mixed with the excavated soil by the rotation of the excavation blade 24 and the stirring blade 26. At this time, the co-rotation prevention blade 25, which is slightly longer than the excavation blade 24, has its tip bitten into the hole wall of the excavation hole 40, so that the rod moves to the deep part of the excavation hole 40 without rotating itself. It acts as a steady rest of the rotation of 21 and resists the excavated soil and binder and the excavation blades 24 and 26 from trying to rotate together, helping to mix them. In this way, the uncured mixture 5 is formed substantially uniformly in the excavation hole 40. When the excavation hole 40 reaches a predetermined depth, the descent of the excavation agitation device 1 is stopped.

[S3] Next, the excavation stirring device 1 is gradually raised while rotating the rod 21 in the reverse direction. Even during this rise, the binder can be injected and stirred. Then, the excavation agitator 1 is once completely pulled up from the excavation hole 40, the excavation blade 24 is removed from the main body cylinder portion 22, and the excavation agitator 1 is replaced with the extension nozzle 27. As shown in FIG. 8, the extension nozzle 27 is a substantially cylindrical member having a flow path 270 of a binder inside, and the upper end thereof is connected to the lower end of the main body tubular portion 22. In order to enable this replacement, the excavation blade 24 is configured to be separable from the main body cylinder portion 22. The lower end of the extension nozzle 27 is opened downward, and when this opening becomes a new binder injection port 271, the injection position of the binder is substantially moved downward. The core bottom lid material 3 is engaged with the binder injection port 271 and temporarily fixed by an appropriate means.

[S4] The excavation agitator 1 to which the extension nozzle is attached is put into the excavation hole 40 again, and the rod 21 is lowered while rotating in the forward direction. The core bottom lid material 3 engaged with the lower end of the extension nozzle 27 is pushed into the uncured mixture 5 while rotating integrally with the extension nozzle 27. Then, when the lower end of the extension nozzle 27 reaches the vicinity of the bottommost portion 41 of the excavation hole 40, the descent of the excavation stirring device 1 is stopped.

[S5] The delivery of the binder is restarted at the stop position, and the binder is injected from the binder injection port 271 at the lower end of the extension nozzle 27 into the center of the uncured mixture 5. The excavation stirring device 1 is gradually raised by rotating the rod 21 in the reverse direction while injecting the binder. The core bottom lid material 3 is disengaged from the extension nozzle 27 when the discharge of the binder material is started, and is left in the vicinity of the bottommost portion 41 of the excavation hole 40. The additionally injected binder gradually forms an uncured core 6 consisting only of the binder in the center of the uncured mixture 5 from bottom to top. Since the height difference between the rotation position of the stirring blade 26 and the binder injection port 271 is generated by attaching the extension nozzle 27, the stirring blade 26 is rotated when the excavation stirring device 1 is raised. However, the binder discharged from the extension nozzle 27 is less affected by stirring, and the shape of the core portion 6 is preferably maintained.

[S6] After the excavation agitator 1 is pulled up, the uncured mixture 5 and the uncured core 6 are solidified after a predetermined curing period. Thus, a double-structured columnar improved body including a solidified mixture 50 formed in a columnar shape up to the bottom 41 of the excavation hole 40 and a core body 60 formed only of a binder formed in the central portion thereof is constructed. Will be done.

Japanese Unexamined Patent Publication No. 2016-20621 Japanese Patent No. 6216477

In the ground improvement method disclosed in Patent Documents 1 and 2, the first half steps ([S1] to [S3]) of producing an unsolidified mixture 5 in which the excavated soil and the binder are stirred and mixed in the excavation hole 40. ) And the latter half step ([S4] to [S5]) of additionally forming the core body 60 made of only the binder in the central portion of the mixture 5, the excavation agitator 1 is once inserted into the excavation hole 40. It is necessary to pull up from the digging blade 24, remove the excavation blade 24, and replace it with the extension nozzle 27. Since the weight of the member to be replaced is several tens of kilograms or more, this replacement work takes time and labor, and is also dangerous.

Therefore, the invention disclosed in the present application integrally integrates a prism made of a mixture of excavated soil and a binder and a core made of only a binder without pulling up from the excavation hole or replacing members. It is an object of the present invention to provide an excavation agitation device that can be constructed in Japan, thereby significantly improving the workability of the construction method.

The excavation agitation device of the invention disclosed in the present application for achieving the above-mentioned object has a main body cylinder portion connected in the axial direction of a rotary driven rod, and the main body cylinder portion from the vicinity of the lower end of the main body cylinder portion. An excavation blade that projects in the out-of-diameter direction, a stirring blade that projects in the out-of-diameter direction from a position above the excavation blade in the main body cylinder portion, and the main body cylinder portion between the excavation blade and the stirring blade. On the other hand, it is provided with a co-rotation prevention blade provided so as to be relatively rotatable, and while excavating the ground by the rotation of the excavation blade, a binder is discharged into the excavated soil from the vicinity of the lower end of the main body cylinder portion, and the stirring blade is provided. In an excavation agitator configured to agitate and mix the excavated soil and the binder by the rotation of the main body cylinder portion, the excavation agitator is housed inside the main body cylinder portion and advances and retreats in the axial direction of the main body cylinder portion. The hollow cylindrical core body construction inner cylinder that appears and disappears from the opening formed at the lower end is rotatably supported by the main body cylinder portion to connect the main body cylinder portion and the core body construction inner cylinder. According to the interference of the connecting shaft, a handle coupled to one end of said connecting shaft extending out to the outside of the main body tube portion, and the co-rotation preventing blade and the handle caused by rotation about the axis of the main body tube portion It is characterized as comprising a transmission mechanism that converts the rotational movement of the handle and the connecting shaft into the advancing / retreating movement of the core body construction inner cylinder.

That is, in this excavation and stirring device, the main body cylinder portion provided with the excavation blade, the stirring blade and the co-rotation prevention blade, and the inner cylinder for building the core body housed inside the main body cylinder are connected via a connecting shaft, and the main body cylinder is connected. When the part rotates around its axis, the handle connected to one end of the connecting shaft interferes with the co-rotation prevention blade, and the reaction causes the inner cylinder for core body construction to move in the axial direction of the main body cylinder part via the transmission mechanism. It is configured to advance and retreat to. If such a mechanism is adopted, the entire excavation agitator is simply rotated in either the forward or reverse direction in the same manner as in a normal excavation process, and is housed in the main body cylinder without using a special driving force or the like. The inner cylinder for building the core body can be stretched or shortened.

In this excavation agitator, the handle is provided with a plurality of arms extending radially, and the tip of the arm interferes with the co-rotation prevention blade one by one, so that the handle is coupled to the handle. It is preferred that the connecting shaft be configured to rotate intermittently around its axis. By increasing the number of arms of the handle, it is possible to improve the smoothness of the movement of the inner cylinder for building the core body to move forward and backward.

Further, in this excavation agitation device, a groove hole extending in the axial direction is formed in the inner cylinder for building the core body, and the connecting shaft is inserted into the groove hole to form the main body cylinder portion and the inner cylinder for building the core body. It is preferable that the transmission mechanism is formed by a meshing mechanism between a rack gear arranged in the radial direction of the cylinder and formed on the side edge of the groove and a pinion gear formed on the connecting shaft. If a rack and pinion mechanism having such a relatively simple structure is adopted, operation troubles due to soil clogging or the like are less likely to occur even if the rack and pinion mechanism is driven in excavated soil or a binder.

Further, in this excavation agitation device, it is more preferable that non-meshing portions without the rack gear are formed at the upper end and the lower end of the groove hole, and the pinion gear of the connecting shaft idles at the non-meshing portion. According to this, since the pinion gear provided on the connecting shaft idles at the extension limit position and the shortening limit position of the core body construction inner cylinder, it is provided in the groove hole of the pinion gear and the core body construction inner cylinder. It is possible to avoid applying an excessive force to the meshing mechanism with the rack gear.

Further, it is more preferable that the upper end and the lower end of the groove hole are interposed with an urging member that pushes the connecting shaft back from the non-meshing portion to the rack gear side. According to this, the start operation when the inner cylinder for building the core body is shortened from the stretching limit position and when the core body construction inner cylinder is stretched from the shortening limit position becomes smooth.

Further, in this excavation agitation device, it is preferable that the connecting shaft is arranged between the excavation blade and the co-rotation prevention blade. According to this, it is possible to secure the maximum advance / retreat stroke of the inner cylinder for building the core body.

In the excavation agitation device according to the invention disclosed in the present application, when the main body cylinder portion is rotated around its axis, the inner cylinder for core body construction appears and disappears from the lower end of the main body cylinder portion according to the direction of the rotation. By extending the inner cylinder for building the core body downward, the binder can be injected at a position lower than that of the excavation blade and the stirring blade. Therefore, if this excavation agitator is used, a step of injecting a binder while digging a drill hole to a predetermined depth to agitate and mix the excavated soil and the binder (the ground described in Patent Document 2 described in the background technology column). Following the step (S2) in the improved construction method (FIG. 9), the inner cylinder for core body construction is extended near the lowest part of the excavation hole, and the binder is injected from the lower end to the center of the uncured mixture. The step of raising the excavation agitator to form the core portion made of only the binder (the step of [S5]) can be continuously carried out. Since it is possible to save the trouble of pulling up the excavation agitator from the excavation hole and replacing the members, the construction efficiency of the ground improvement method for constructing a columnar improved body having a core body consisting only of a binder in the central portion is remarkably improved.

It is a side view (a) and the front view (b) of the excavation agitation apparatus which concerns on one Embodiment of the invention disclosed in this application, and is the figure which shows the state which houses the inner cylinder for core body construction. Similarly, it is the side view (a) and the front view (b) of the excavation agitator, and is the figure which shows the state which stretched the inner cylinder for core body construction. It is explanatory drawing which shows the connection between the main body cylinder part and the core body construction inner cylinder in the state of FIG. It is a cross-sectional view in the direction orthogonal to the axis (AA) which shows the connection around the connecting shaft. It is explanatory drawing which shows the connection between the main body cylinder part and the core body construction inner cylinder in the state of FIG. It is explanatory drawing which shows the action which the handle interferes with the co-rotation prevention blade by the rotation of the main body cylinder part. It is a process explanatory drawing of the ground improvement method using the excavation agitation device which concerns on the invention disclosed in this application. It is a front view of the excavation agitator used in the ground improvement construction method disclosed in Patent Document 2. It is a process explanatory drawing of the ground improvement method disclosed in Patent Document 2.

Hereinafter, embodiments of the invention disclosed in the present application will be described with reference to the drawings. In the following description, when specifying the positional relationship of parts / members and the direction of movement, the vertical direction and the horizontal direction are specified with reference to the usage mode in which the ground is excavated. Further, the components having the same function or action as the conventional excavation agitation device shown in FIGS. 8 to 9 and the ground improvement method using the device are designated by a common reference numeral to simplify their description.

1 to 6 show an excavation agitator according to an embodiment of the invention disclosed in the present application. The excavation agitation device 10 is configured by attaching an excavation blade 24, a co-rotation prevention blade 25, a stirring blade 26, and the like around a hollow cylindrical main body cylinder portion 22. The upper end of the main body cylinder 22 is connected to the rod 21 (see FIG. 8) and is rotationally driven by an auger device or the like. A flow path of the binder is formed inside the main body cylinder portion 22, and the lower end of the main body cylinder portion 22 is opened downward.

The excavation blade 24 is provided so as to project from the vicinity of the lower end of the main body cylinder portion 22 in the out-of-diameter direction of the main body cylinder portion 22, and rotates integrally with the main body cylinder portion 22. A plurality of excavation blades 241 for excavating the ground are projected on the lower surface of the excavation blade 24. The stirring blade 26 is provided so as to project from the vicinity of the middle of the main body cylinder 22 and the vicinity of the upper end in the outer diameter direction of the main body 22 and rotates integrally with the main body 22. The rotating diameter of the stirring blade 26 is substantially the same as the rotating diameter of the excavating blade 24.

The co-rotation prevention blade 25 is arranged between the excavation blade 24 and the lower stirring blade 26, and between the lower stirring blade 26 and the upper stirring blade 26, respectively, in the out-of-diameter direction of the main body cylinder portion 22. Overhanging. The co-rotation prevention blade 25 is formed so that its rotation diameter is slightly larger than the rotation diameter of the excavation blade 24 and the stirring blade 26, and is attached so as to be able to rotate (idle) relative to the main body cylinder portion 22.

In the illustrated embodiment, the co-rotation prevention blade 25 and the stirring blade 26 are provided in two stages each, but in the present invention, the number of these stages is not particularly limited. Further, the detailed shapes of the excavation blade 24 and the excavation blade 241 are not particularly limited.

Inside the opening formed at the lower end of the main body cylinder portion 22, the core body construction inner cylinder 23 is inserted from below. The inner cylinder 23 for building the core body has a hollow cylindrical shape having a diameter slightly smaller than that of the main body cylinder portion 22, and the upper end thereof opens upward and communicates with the flow path in the main body cylinder portion 22. The practical length of the core body construction inner cylinder 23 is about the same as or slightly longer than the rotating diameter of the excavation blade 24. In the exemplary embodiment, the lower end of the core body construction inner cylinder 23 is projected in an inverted conical shape, and a binder injection port 231 that opens laterally is formed on the conical surface thereof. The lower end of the core body construction inner cylinder 23 is opened downward like the extension nozzle 27 in the excavation stirring device 1 described in Patent Document 2, so that the core bottom lid material 3 is engaged and disengaged from the opening. It may be.

Groove holes 232 extending in the axial direction are formed at two side surfaces facing each other with the axial center of the core body construction inner cylinder 23 interposed therebetween. The length of the groove hole 232 extends to 80 to 90% of the total length of the inner cylinder 23 for building the core body. The two facing groove holes 232 have the same length and width, and a rack gear 233 is provided on one side edge of each groove hole 232. The rack gear 233 is provided so that the inner cylinder 23 for building the core body is on the same side on the front side and the back side when viewed from the front side of one groove hole 232. The rack gear 233 is interrupted near the upper end and the lower end of the groove hole 232, and non-meshing portions 234 without the rack gear 233 are formed at the upper end and the lower end, respectively.

A connecting shaft 28 is inserted through these groove holes 232 in the horizontal direction. The connecting shaft 28 is formed with a pinion gear 281 that meshes with a rack gear 233 formed in each groove 232. The connecting shaft 28 is also inserted into bearing holes 222 formed at two side surfaces facing each other with the axial center of the main body cylinder 22 interposed therebetween. The bearing hole 222 is provided between the excavation blade 24 and the lower co-rotation prevention blade 25. As a result, the connecting shaft 28 is attached to the main body cylinder 22 side so as to penetrate the main body cylinder 22 and the core body construction inner cylinder 23 in the radial direction, and is rotatably supported in the bearing hole 222.

A handle 29 for applying a rotational force to the connecting shaft 28 is integrally coupled to the connecting shaft 28 at one end of the connecting shaft 28 extending to the outside of the main body cylinder portion 22. The handle 29 is arranged between the excavation blade 24 and the lower co-rotation prevention blade 25. The handle 29 has a plurality of arms 291 (six in the exemplary embodiment) extending radially in the radial direction of the connecting shaft 28, and the lengths of the arms 291 are all equal. At the other end of the connecting shaft 28, a large diameter portion 282 is provided to prevent the connecting shaft 28 from coming off.

An engaging piece 251 that interferes with the tip of the arm portion 291 of the handle 29 is attached to the lower edge of the lower co-rotation prevention wing 25. When the main body cylinder 22 rotates around its axis due to the rotational drive of the rod or the like, the handle 29 of the connecting shaft 28 also rotates around the main body cylinder 22 integrally with the main body cylinder 22. However, since the co-rotation prevention wing 25 does not rotate, as shown in FIG. 6, the tip of the arm portion 291 of the handle 29 interferes with the engaging piece 251 attached to the co-rotation prevention wing 25. Each time the main body cylinder 22 makes one rotation, the arm 291 of the handle 29 interferes with the co-rotation prevention wing 25 twice on the front side and the back side. This reaction pushes the handle 29 little by little, causing the connecting shaft 28 to rotate intermittently around its axis. Then, the inner cylinder 23 for building the core body advances and retreats along the axial direction of the main body cylinder portion 22 via the meshing mechanism between the pinion gear 281 provided on the connecting shaft 28 and the rack gear 233 provided on the groove hole 232. do. When the main body cylinder 22 is rotated in the opposite direction, the direction in which the co-rotation prevention blade 25 and the handle 29 interfere with each other is also opposite, and the connecting shaft 28 is rotated in the opposite direction. It will move forward and backward in the direction.

In this way, the inner cylinder 23 for building the core body advances and retreats with respect to the main body cylinder portion 22 with a predetermined stroke, but since the non-meshing portion 234 without the rack gear 233 is formed at the upper end and the lower end of the groove hole 232, the core body The engagement between the pinion gear 281 and the rack gear 233 is released at the extension limit position and the shortening limit position of the inner cylinder 23 for construction. Therefore, even if the main body cylinder 22 continues to rotate and the handle 29 and the co-rotation prevention blade 25 repeatedly interfere with each other, the connecting shaft 28 idles at the extension limit position and the shortening limit position of the core body construction inner cylinder 23. Therefore, it is possible to avoid excessive force acting on the rack and pinion mechanism.

Further, at the upper and lower ends of the groove holes 232, an urging member that pushes the connecting shaft 28 located at the non-meshing portion 234 at the extension limit position and the shortening limit position of the core body construction inner cylinder 23 back to the rack gear 233 side. 235 is intervened. A coil spring, a leaf spring, or the like is used for the urging member 235. When such an urging member 235 is attached, the meshing of the rack and pinion mechanism is smoothly restarted when the inner cylinder 23 for building the core body is shortened from the extension limit position and when the core body construction inner cylinder 23 is extended from the shortening limit position. NS.

As described above, the excavation agitation device 10 according to the invention disclosed in the present application is provided at one end of the connecting shaft 28 that penetrates the main body cylinder portion 22 and the core body construction inner cylinder 23 when the main body cylinder portion 22 rotates. When the handle 29 interferes with the co-rotation prevention blade 25, the connecting shaft 28 rotates, and the inside of the core body is constructed via a rack and pinion mechanism provided between the connecting shaft 28 and the inner cylinder 23 for building the core body. Since the cylinder 23 is configured to move forward and backward, the entire excavation stirring device 10 is simply rotated in either the forward or reverse direction in the same manner as in the normal excavation process, and no special driving force or the like is required. The core body construction inner cylinder 23 housed in the main body cylinder portion 22 can be stretched or shortened. As a result, the inner cylinder 23 for building the core body is extended below the main body cylinder portion 22 at an arbitrary depth of the excavation hole, and the height difference between the stirring blade 26 or the excavation blade 24 and the coupling material injection port 231 is increased. Can be secured.

FIG. 7 shows the process of the ground improvement method carried out by using the excavation agitation device 10. This step is carried out as follows.

[S10] The rod 21 to which the excavation agitator 10 is attached is installed vertically at a predetermined position, and is gradually lowered while rotating forward to start excavation of the ground. At this time, the core body construction inner cylinder 23 is housed in the main body cylinder portion 22 and held at the shortening limit position.

[S20] While rotating the excavation agitator 10 in the forward direction to dig down the excavation hole 40, a binder is injected into the excavation hole 40 from the lower end of the core body construction inner cylinder 23, and the excavated soil and the binder are agitated and mixed. Then, the unsolidified mixture 5 is formed in the excavation hole 40. During this time, the handle 29 that swivels around the main body cylinder 22 continues to interfere with the co-rotation prevention blade 25, but the rack and pinion mechanism idles, so that the core construction inner cylinder 23 is accommodated in the shortening limit position. Will remain. When the excavation hole 40 reaches a predetermined depth, the excavation stirring device 10 is rotated in the forward direction and slightly moved up and down a plurality of times to perform bottom treatment, and then the rotation and the up and down movement are stopped. The first half steps up to this point are substantially the same as the steps [S1] to [S2] in the ground improvement method (FIG. 9) described in Patent Document 2 described in the background technology column.

[S30] Subsequently, the excavation stirring device 10 is switched to reverse rotation and gradually raised. Then, the rack and pinion mechanism meshes with each other, and the inner cylinder 23 for building the core body begins to stretch. When the core body construction inner cylinder 23 is appropriately stretched after a predetermined number of rotations, the injection of the binder is restarted, and the excavation agitator 10 is pulled up at a substantially constant speed while rotating in the reverse direction. The binder additionally injected from the lower end of the core body construction inner cylinder 23 gradually forms an unsolidified core portion 6 composed of only the binder from the bottom to the top in the center of the uncured mixture 5. To go. Since the inner cylinder 23 for building the core body is stretched when ascending, a height difference is generated between the rotation position of the stirring blade 26 and the binder injection port 231. Therefore, the additionally injected binder is used for stirring. The shape of the core portion 6 is preferably maintained because it is less affected.

[S40] After the excavation agitator 10 is pulled up, the uncured mixture 5 and the uncured core 6 are solidified after a predetermined curing period. Thus, a double-structured columnar improved body including a solidified mixture 50 formed in a columnar shape up to the bottom 41 of the excavation hole 40 and a core body 60 formed only of a binder formed in the central portion thereof is constructed. Will be done. This latter half step is substantially the same as the steps [S5] to [S6] in the ground improvement method (FIG. 9) described in Patent Document 2 described in the background technology column.

As described above, by using the excavation stirring device 10 according to the invention disclosed in the present application, following the first half step of injecting a binder while digging a drill hole to a predetermined depth and stirring and mixing the excavated soil and the binder, The inner cylinder 23 for building the core is extended near the lowest part of the excavation hole, and the excavation agitator 10 is raised while injecting the binder from the lower end into the center of the uncured mixture to form the core composed of only the binder. The latter half step of forming can be continuously carried out without interruption. Since it is possible to save the trouble of pulling up the excavation agitator 10 from the excavation hole and replacing the members (steps [S3] to [S4] in the ground improvement method (FIG. 9) described in Patent Document 2), only the binder is provided in the central portion. The construction efficiency of the ground improvement method for constructing a columnar improved body having a core body made of the above is significantly improved. In particular, when a plurality of columnar improved bodies are continuously constructed together, the effect of reducing man-hours becomes remarkable.

The technical scope of the present invention should not be construed in a limited manner by the illustrated embodiments, but should be conceptually interpreted based on the description of the claims. In carrying out the present invention, for example, the type and composition of the binder, the detailed shape of the construction machine and the excavation agitator, etc., may be appropriately adjusted according to the construction environment, etc. , Can be modified. It is also possible to slightly modify the detailed ascending / descending operation of the excavation agitator and the timing of injecting the binder.

10 Excavation agitator 21 Rod 22 Main body cylinder 220 Flow path 222 Bearing hole 23 Core body construction inner cylinder 231 Coupling material injection port 232 Groove hole 233 Rack gear 234 Non-meshing part 235 Biasing member 24 Excavation blade 241 Excavation blade 25 Co-rotation Prevention wing 251 Engagement piece 26 Stirring wing 28 Connecting shaft 281 Pinion gear 282 Large diameter part 29 Handle 291 Arm part 4 Ground 40 Drilling hole 41 Bottom part 5 Unsolidified mixture 50 Solidified mixture 6 Unsolidified core 60 Core body

Claims (6)

The main body cylinder that is connected in the axial direction of the rod that is driven to rotate,
An excavation blade protruding from the vicinity of the lower end of the main body cylinder portion in the outer diameter direction of the main body cylinder portion,
A stirring blade protruding outward from a position above the excavation blade in the main body cylinder portion,
A co-rotation prevention blade provided so as to be rotatable relative to the main body cylinder portion between the excavation blade and the stirring blade is provided.
While excavating the ground by the rotation of the excavation blade, the binder is discharged into the excavated soil from the vicinity of the lower end of the main body cylinder portion, and the excavated soil and the binder are agitated and mixed by the rotation of the stirring blade. In the excavation stirrer
A hollow cylindrical core body construction inner cylinder housed inside the main body cylinder portion, advancing and retreating in the axial direction of the main body cylinder portion, and appearing and disappearing from an opening formed at the lower end of the main body cylinder portion.
A connecting shaft that is rotatably supported by the main body cylinder portion and connects the main body cylinder portion and the core body construction inner cylinder,
A handle coupled to one end of the connecting shaft extending to the outside of the main body cylinder,
A transmission mechanism that converts the rotational movement of the handle and the connecting shaft due to the interference between the handle and the co-rotation prevention blade caused by the rotation of the main body cylinder portion around the axial center into the advancing / retreating movement of the inner cylinder for building the core body. ,
An excavation agitation device characterized by being provided with. In the excavation agitator according to claim 1,
The handle comprises a plurality of arms extending radially.
An excavation agitation device characterized in that the connecting shaft coupled to the handle rotates intermittently around its axis when the tip of the arm portion interferes with the co-rotation prevention blade one by one. In the excavation agitator according to claim 1 or 2.
A groove extending in the axial direction is formed in the inner cylinder for building the core body.
The connecting shaft is inserted into the groove and arranged in the radial direction of the main body cylinder portion and the core body construction inner cylinder.
An excavation agitation device characterized in that the transmission mechanism is formed by a meshing mechanism between a rack gear formed on a side edge of the groove and a pinion gear formed on the connecting shaft. In the excavation agitator according to claim 3,
Non-meshing portions without the rack gear are formed at the upper end and the lower end of the groove, respectively.
An excavation agitation device characterized in that the pinion gear formed on the connecting shaft idles at the non-meshing portion. In the excavation agitator according to claim 4,
An excavation agitation device characterized in that an urging member for pushing the connecting shaft back from the non-meshing portion to the rack gear side is interposed at the upper end and the lower end of the groove hole. In the excavation agitator according to any one of claims 1 to 5,
An excavation agitation device characterized in that the connecting shaft is arranged between the excavation blade and the co-rotation prevention blade.

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