JP5011010B2 - Ground improvement method - Google Patents

Description

  The present invention relates to a ground improvement method for performing ground improvement by stirring and mixing an original ground and a solidified material at an original position.

  The excavation shaft provided with the excavation blade portion formed at the tip portion and the stirring blade formed above the excavation blade portion is excavated by rotating the excavation shaft while rotating, and the solidified material and the excavation earth and sand There is a ground improvement method in which stirring and mixing are performed in situ.

As shown in FIGS. 5 (a) and 5 (b), such a conventional ground improvement method is such that the ground G by the excavation blade 120 is lowered by injecting the solidified material C while rotating the excavation shaft 110. While excavating, the excavated sediment and the solidified material C are agitated by the moving blade 121 and the agitating blade 122 to generate the primary improved sediment Dc ′. Next, after excavating to a predetermined depth, as shown in FIGS. 5 (c) and 5 (d), the solidified material C and the primary improved earth and sand are lifted by injecting the solidified material C while rotating the excavating shaft 2. The improved body Dc is constructed by further stirring with Dc ′ (see, for example, Patent Document 1). Here, FIG. 5 is a schematic diagram showing a conventional ground improvement method, in which (a) is a cross-sectional view showing the construction status of the excavation process, (b) is a cross-sectional view showing a soil state in the excavation process, (c) is sectional drawing which shows the construction condition of an improvement process, (d) is sectional drawing which shows the soil state in an improvement process.
The amount of the solidified material C injected during excavation is generally 50% of the total amount of the solidified material necessary for forming the improved body Dc, and the remaining 50% is generally injected when the excavation shaft 2 is lifted. It is.
JP 2004-204673 A ([0048] to [0049])

However, in the conventional ground improvement method, since the solidified material C injected during excavation progresses, the resistance when the excavating shaft 110 is lifted increases, which may affect workability. Moreover, since the primary improved earth and sand Dc ′ in which the solidification material C has been condensed is agitated again when the excavation shaft 2 is lifted, the improved body Dc having the planned strength may not be formed.
Therefore, there is a case where a retarder is injected for the purpose of delaying the start of the setting of the solidifying material C. However, the cost increases due to the material cost of the retarder, and there is a problem that it takes time and effort to introduce the retarder. It was.

Further, even during excavation, the solidified material C may condense, which may increase the resistance during excavation, and may require a device with a large excavation torque. Moreover, since the viscosity of the excavation groove (excavation hole) at the time of excavation increases due to the condensation of the solidified material C, it is necessary to increase the capacity of the injection pump, and the injection apparatus becomes large. Had.
Therefore, water / cement ratio may be increased for the purpose of reducing the viscosity of the solidified material C, but the amount of sludge increases due to an increase in the amount of the solidified material C, and the cost of disposal of residual soil, etc. It had the problem of being bulky.

  The present invention has been made to solve the above-mentioned problems, and provides a ground improvement method capable of improving workability and economy, and enabling production of a high-quality ground improvement body. The challenge is to propose.

In order to solve such a problem, the ground improvement method of the present invention includes a ground excavation shaft provided with a excavation blade portion at a tip and a moving blade directly above the excavation blade portion while being lowered while rotating. A ground improvement method for ground improvement by stirring and mixing the excavated sediment and solidified material using the excavation shaft, and excavating the ground while discharging only the excavated material; The solidification material is injected while rotating the excavation shaft and lifted up, and then the solidification material is pushed upward together with the excavation sediment by the excavation blade portion and the moving blade, and then dropped by gravity, the excavation sediment And an improvement step of stirring and mixing the solidified material.

  According to such a ground improvement method, since the solidification material is injected at the time of lifting after completion of excavation, there is no adverse effect on workability due to the progress of the solidification of the solidification material, and the workability is excellent. The apparatus can be miniaturized and is excellent in economic efficiency. Moreover, since the mixing | blending and injection amount of the solidification material according to a soil condition can be set, it becomes possible to form a high quality improved body. Further, since it is not necessary to introduce a retarder, it is excellent in economy and workability.

Further, in the ground improvement method, the drilling axis if it has a 撹拌wings, it is possible to perform the stirring and drilling soil and the solidifying material more effectively.

According to the ground improvement method of the present invention, the ground improvement can be performed with high quality by a method having excellent workability.
Furthermore, when the working time is limited, if the excavated material and the solidified material are injected simultaneously as in the prior art, the solidified material solidifies during the excavation, and the excavation work cannot be interrupted. If the entire work is not completed within the work time, the day must be changed. However, according to the method of the present invention, the work can be stopped even during excavation, and the work time can be effectively utilized.

DESCRIPTION OF EMBODIMENTS Preferred embodiments of the present invention will be described in detail with reference to the drawings.
Here, FIG. 1 is a side view showing a usage situation of the ground improvement device according to a preferred embodiment of the present invention. FIG. 2 is an enlarged front view showing a part of the ground improvement device shown in FIG. In the following description, the same reference numerals are used for the same elements, and duplicate descriptions are omitted.

  In the excavation method according to the present embodiment, the ground is excavated by lowering the excavation shaft having the excavation blade portion at the tip while rotating to a planned improvement depth, and the excavation shaft is used to return to the original position. The ground is improved by stirring and mixing the excavated soil and solidified material.

  In this embodiment, as shown in FIG. 1 and FIG. 2, a ground improvement device comprising a base machine 1 and three excavation shafts 2, 2, 2 supported by the base machine 1 so as to be movable up and down. Use A. In this embodiment, the three-axis ground improvement device A having three excavation shafts 2 is used. However, the number of excavation shafts 2 is not limited to this, and for example, a single shaft or Other multi-axis type ground improvement devices provided with two or four or more excavation shafts may be used.

  As shown in FIG. 1, the base machine 1 supports the excavation shafts 2, 2, 2 through a support member 11, and includes a drive motor 10 that applies a rotational force to the excavation shaft 2. Yes.

  As shown in FIGS. 1 and 2, the excavation shafts 2, 2, and 2 are supported so as to be able to rotate in a state where they are arranged in parallel with the base machine 1. The excavation shafts 2, 2, 2 are connected via connection members 40, 40 at two places, an upper portion and a lower portion of the columnar excavation shaft main body 20.

  As shown in FIG. 2, each excavation shaft main body 20 is formed with an excavation blade portion 30 for excavating the ground G at the tip (lower end), and above the excavation blade portion 30 by the excavation blade portion 30. A moving blade 21 and a stirring blade 22 or a stirring blade 23 for stirring the cut excavated earth and sand are formed.

  In the present embodiment, the excavation shaft main body 20 is formed of a steel pipe having a circular cross section. However, the material constituting the excavation shaft main body 20 is not limited, and may be appropriately selected from known materials. . Moreover, the cross-sectional shape of the excavation shaft main body 20 is not limited to a circular cross section, and can be set as appropriate.

  The excavation blade portion 30 includes an excavation blade 31 and a plurality of cutter bits 32, 32,... Arranged in parallel at the lower end of the excavation blade 31.

The excavation blade 31 is formed in a spiral shape in order to push up excavation earth and sand generated when excavating the ground G.
Further, the cutter bits 32, 32,... Are detachably arranged in parallel at the lower end of the excavating blade 31, and are appropriately replaced when the cutting function of the ground G is deteriorated due to wear or the like. The number, arrangement, interval, and the like of the cutter bits 32 are not limited, and may be set as appropriate according to the shape of the excavating blade 31 and the soil quality and strength of the ground G to be excavated.

In the present embodiment, the excavating blade portion 30 is configured by fixing an attachment to the lower end of the excavating shaft 2. This attachment is formed by integrally fixing an excavating blade 31 which is a steel plate processed into a spiral shape around the outer periphery of the blade body 33 formed in a substantially cylindrical shape.
In addition, you may form directly in the lower end part of the excavation axis | shaft 2, without attaching the excavation blade part 30. FIG. Moreover, the shape dimension of the excavation blade 31 is not limited, and is appropriately set according to the planned shape of the excavation groove M and the like.

  An injection port 34 for discharging the drilling fluid (digging material) S to the ground G is formed at the center of the lower end of the drilling blades 30 and 30 of the drilling shafts 2a and 2c arranged at both ends (left and right). .

  The injection port 34 is in communication with a transportation device (not shown) including a pump or the like disposed on the ground part via a transportation pipeline that passes through the inside of the excavation shaft 2. And the excavation material S pumped (transported) from the transport device is discharged (injected) toward the ground G. In addition, the pressure at the time of discharge of the excavation material S is appropriately set to a pressure that can be injected (injected) into the ground G according to the soil condition and the like.

  As shown in FIG. 2, the excavating shafts 2a and 2c arranged on the left and right sides (both ends) are arranged directly above the excavating blade part 30 and move up the excavated earth and sand cut by the excavating blade part 30 upward. 21 and a stirring blade 22 that is disposed above the moving blade 21 and stirs the excavated earth and sand pushed upward. In addition, a moving blade 21 is further disposed above the stirring blade 22 so that the excavated soil is efficiently stirred in the excavation groove M.

The moving wing 21 is a plate member that is spirally wound around the digging shaft 2, similarly to the digging wing 31. Although the moving blade 21 according to the present embodiment is integrally fixed to the excavation shaft 2 by welding or the like, the fixing method of the moving blade 21 is not limited and may be appropriately performed by a known method. The moving blade 21 has an outer diameter (width) dimension equal to or less than the outer diameter (width) dimension of the excavating blade 31, and can agitate the entire excavated earth and sand cut by the excavating blade portion 30. It is configured.
The excavated earth and sand in the excavated trench M is pushed upward by the moving blade 21 and then agitated in the vertical direction by dropping by gravity.

The stirring blades 22 are a pair of plate members that project outwardly around the outer periphery of the excavation shaft 2 and are disposed so as to face each other with the excavation shaft 2 interposed therebetween. The stirring blade 22 is disposed so that each plate material is inclined with respect to the rotation direction of the excavation shaft 2.
Each agitating blade 22 has a full width of a pair of plates to the extent that it does not come into contact with other adjacent excavating shafts 2 so as to agitate the entire excavated sediment in the excavation groove M cut by the excavating blade 30. Is configured to have approximately the same outer diameter (width) dimension of the excavating blade 11. In the present embodiment, the excavating shafts 2a and 2c are each provided with two stages of the stirring blades 22 respectively. In addition, the shape dimension and arrangement number of the stirring blade 22 are not limited.

  On the excavation shaft 2b disposed at the center, stirring blades 23, 23,... Are formed at locations corresponding to the stirring blades 22, 22 of the excavation shafts 2a, 2c at both ends.

The agitating blades 23 are a pair of plate members projecting outwardly around the outer periphery of the excavating shaft 2b, like the agitating blades 22 formed on the excavating shafts 2a and 2c at both ends, and sandwiching the excavating shaft 2b. It arrange | positions so that it may oppose. The stirring blades 23 are arranged so that each plate material is inclined with respect to the rotation direction of the excavation shaft 2b.
Each agitating blade 23 is not in contact with the other adjacent excavation shafts 2a and 2c so that the entire inside of the excavation groove M cut by the excavation blade 30 can be agitated. Is configured to have approximately the same outer diameter (width) dimension of the excavating blade 11. In the present embodiment, the stirring blades 23 are formed in three stages. In addition, the shape dimension, arrangement number, etc. of the stirring blade 23 are not limited.

In addition, the stirring blades 23 formed on the central excavation shaft 2b and the stirring blades 22 and 22 formed on the left and right (both ends) excavation shafts 2a and 2c are mutually in the height direction so as not to contact each other. It is formed at a shifted position.
As the stirring blades 22 and 23 rotate, the excavated earth and sand moving up and down by the moving blade 21 are stirred in the horizontal direction.

Next, the ground improvement method according to the present embodiment will be described with reference to the drawings.
Here, FIG. 3 is a schematic diagram showing the ground improvement method according to the present embodiment, where (a) is a cross-sectional view showing the construction status of the excavation process, and (b) is in the soil during construction of (a). Sectional drawing which shows a state, (c) is sectional drawing which shows the condition at the time of completion | finish of an excavation process, (d) is sectional drawing which shows the soil state in (c). Moreover, FIG. 4 is a schematic diagram showing the ground improvement method according to the present embodiment, where (a) is a cross-sectional view showing the construction status of the improvement process, and (b) is the soil state at the time of construction of (a). (C) is sectional drawing which shows the condition at the time of completion | finish of an improvement process, (d) is sectional drawing which shows the soil state in (c).

  The ground improvement method according to the present embodiment includes a drilling step of excavating the ground while discharging only the drilling material S to a predetermined improvement depth, and injecting the solidified material C while being lifted while rotating the drilling shaft 2. It consists of an improved process of stirring and mixing the excavated earth and sand and the solidified material C.

In the excavation process, as shown in FIGS. 3A and 3C, the excavation material 2 is discharged from the tips of the excavation shafts 2a and 2c to the ground, and the excavation shafts 2a, 2b and 2c are lowered while rotating. In this step, the excavation groove M having a predetermined depth is formed in the ground G.
Here, the material used as the excavation material S is not limited, but in this embodiment, bentonite liquid is used.

  The excavation of the ground G is performed by cutting the ground G softened by the excavation material S by the cutter bits 32, 32,... In the excavation groove M, the natural ground G is disrupted by being cut, but as shown in FIGS. 3B and 3D, the excavation material is excavation soil mixed with the excavation material S. The groove wall surface of the excavation groove M is held by the pressure of the mixed earth and sand Ds.

When drilling of the ground G is completed, as shown in FIG. 3 (d), the entire drilling groove M is filled by excavated material mixed soil D _S.

  As shown in FIGS. 4A to 4D, the improvement process is a process performed after excavation of the excavation groove M to a predetermined depth is completed by the excavation process, and the pulling of the excavation shafts 2a, 2b, 2c is performed. Excavated by the excavating blade 31, the moving vane 21, and the stirring vanes 22, 23 while injecting the solidified material C into the excavating material mixed soil Ds from the inlets 34, 34 formed at the tips of the excavating shafts 2 a, 2 c along with the frying. This is a step of forming the improved body Dc by stirring and mixing the material mixing soil Ds and the solidifying material C.

  The solidified material C injected from the tips of the excavating shafts 2a and 2c is pushed upward together with the excavating material mixed earth and sand Ds by the excavating blade 31 and the moving blade 21, and then stirred with the excavated material mixed earth and sand Ds by the agitating blade 22. By repeatedly falling downward due to gravity, the excavated material mixed earth and sand Ds is evenly mixed.

  In the improvement step, the solidification material C and the excavation material mixed earth and sand Ds may be more effectively stirred and mixed by repeatedly moving the excavation shafts 2, 2 and 2 as needed.

  Here, the material used as the solidifying material C is not limited, and is appropriately selected from known materials according to the condition of the ground G to be improved, the required strength of the improved body Dc, and the like. In this embodiment, a cement-based solidifying material is used.

  Moreover, the improvement body Dc which consists of desired intensity | strength is formed by setting the injection amount and mixing | blending of the solidification material C for every soil according to the natural ground condition grasped | ascertained with the excavation process.

  When the lifting of the excavating shafts 2, 2 and 2 is completed by the improvement process, as shown in FIG. 4 (d), the excavated material mixed soil Ds (excavated sediment) and the solidified material C are evenly mixed inside the excavated groove. As a result, a high-quality improved body Dc is formed.

  As described above, according to the ground improvement method of the present embodiment, the solidification material C is injected when the excavation shafts 2, 2, and 2 are lifted after excavation. Since it can be set, there is no difference in strength due to changes in the formation in the depth direction of the improved body Dc, and a high-quality improved body can be formed.

  Further, even when the excavation takes a long time because the improved range is deep or when the excavation is interrupted for some reason during excavation, the solidification material C does not proceed with condensation, which adversely affects workability. I will not bring you. Moreover, since it is not necessary to use a retarder, it is economical.

In addition, since the excavation material S and the solidification material C are separately injected, the viscosity of these injection materials can be kept low, so that the workability is excellent and the injection device (pump, etc.) is downsized. This makes it possible to improve economy.
In addition, for the purpose of reducing the viscosity of the solidified material C, it is not necessary to increase the water-cement ratio as in the conventional ground improvement method, so that the amount of residual soil disposal can be minimized.

As mentioned above, although preferred embodiment was described about this invention, this invention is not limited to the said embodiment, A design change is possible suitably in the range which does not deviate from the meaning of this invention.
For example, in the embodiment, the excavation material and the solidification material are injected into the ground using the same injection port, but the excavation material and the solidification material are injected from injection ports provided at different positions. It is good.

In the above embodiment, the case where the solidification material is injected from the tip (lower end) of the excavation shaft has been described, but the position of the injection port for injecting the solidification material is not limited to the lower end of the excavation shaft, For example, you may arrange | position just above a stirring blade.
In the embodiment, the drilling material or the solidified material is injected from the drilling shafts at both ends. Needless to say, the drilling material or the solidified material may be injected from all the drilling shafts. The excavation axis on which is formed is not limited.

  Moreover, in the said embodiment, about the case where the three-axis type excavation apparatus provided with the excavation blade part rotated in the horizontal direction with the rotation of the excavation shaft forms a planar excavation groove in which three circles are connected. Although explained, it goes without saying that the shape of the excavation groove is not limited to this. For example, if a single-axis ground improvement device is used, a drilling hole having a circular cross section is formed.

  In the embodiment, the excavation shaft includes the moving blade and the stirring blade. However, only one of the moving blade or the stirring blade may be provided.

It is a side view which shows the use condition of the ground improvement apparatus which concerns on the best embodiment of this invention. It is an enlarged front view which shows a part of ground improvement apparatus shown in FIG. It is a schematic diagram which shows the ground improvement method which concerns on the best embodiment of this invention, Comprising: (a) is sectional drawing which shows the construction condition of an excavation process, (b) shows the soil state at the time of construction of (a). Sectional drawing, (c) is a sectional view showing the situation at the end of the excavation process, (d) is a sectional view showing the soil state in (c). It is a schematic diagram which shows the ground improvement method which concerns on the best embodiment of this invention, Comprising: (a) is sectional drawing which shows the construction condition of an improvement process, (b) shows the soil state at the time of construction of (a). Sectional drawing, (c) is a sectional view showing the situation at the end of the improvement process, (d) is a sectional view showing the soil state in (c). It is a schematic diagram which shows the conventional ground improvement method, (a) is sectional drawing which shows the construction condition of an excavation process, (b) is sectional drawing which shows the soil state in an excavation process, (c) is construction of an improvement process Sectional drawing which shows a condition, (d) is sectional drawing which shows the state in the soil in an improvement process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base machine 2 Excavation axis 30 Excavation blade part A Ground improvement device G Ground M Excavation groove

Claims (2)

The excavation shaft provided with the excavation blade portion at the tip and provided with the moving blade directly above the excavation blade portion is excavated by rotating the excavation shaft while rotating, and the excavation soil and the solidified material are collected using the excavation shaft. A ground improvement method for ground improvement by stirring and mixing,
A drilling process for excavating the ground while injecting only the drilling material;
The solidification material is injected while rotating the excavation shaft and lifted up, and then the solidification material is pushed upward together with the excavation sediment by the excavation blade portion and the moving blade, and then dropped by gravity, the excavation sediment A ground improvement method comprising: an improvement step of stirring and mixing the solidified material and the solidified material. The ground improvement method according to claim 1 , wherein the excavation shaft includes a stirring blade.

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