JP2011137358A - Device and method for constructing ground improving body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and method for constructing a ground improving body, capable of setting, in construction of the ground improving body, the improving body having constant strength by sufficiently kneading and stirring excavated earth in tunnelling with a solidifying agent. <P>SOLUTION: The device for constructing a ground improving body configured to construct a pile foundation by injecting a solidifying agent while tunnelling a ground includes: a rod 14 disposed in a rotatable manner, an excavating bit 16 provided at a lower portion of the rod 14, a spiral stirring blade 18 attached to an upper position of the bit 16, and a rod 14 rotatably disposed, and cutout portions 20A-20C provided at a part of the stirring blade 18 to vertically move the earth and sand in excavation. The ground is excavated by the bit 16 at the tip by rotating the rod 14 while inputting the solidifying agent to the excavated hole, the excavated earth is kneaded with the solidifying agent with stirring according to the rotation of the spiral stirring blade 18, and the earth and sand are moved through the cutout portions 20A-20C of the stirring blade 18 to apply a vertical shearing force to the earth and sand. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a construction device for a ground improvement body and a method for constructing the ground improvement body, and particularly relates to a construction device and a construction method suitable for improvement of soft ground.

Generally, buildings constructed on soft ground are supported by pile foundations, and measures against soft ground of buildings depend on various pile foundations. However, in soft ground, the depth of burial of piles becomes deep, so when the scale of the building is small, it may be more cost effective to use the ground improvement method than to use the pile foundation.

Conventionally, as such a ground improvement method, a method of injecting a solidifying material such as cement milk at the time of excavation and mechanically mixing the soil and the solidifying material with a stirring blade to construct a column-shaped improved body is known. ing. As an example of such a construction method, the invention described in JP-A-2008-127812 (Patent Document 1) is known.
FIG. 7 is a diagram showing a main part of the ground improvement device described in the same document. As shown in the figure, the ground improvement device according to the invention described in the same publication includes a hollow rod 100 provided with a discharge port for a solidifying material, an excavation blade 102 rotating with the hollow rod 100, and stirring blades 104 and 106. It is provided with co-rotation prevention blades 108 and the like that are rotatably attached to the hollow rod 100. When excavating cohesive soil with high adhesive strength such as a clay layer, the excavated soil also tries to rotate with the rotation of the stirring blades 104 and 106.

On the other hand, since the co-rotation prevention blade 108 described in Patent Document 1 is rotatably attached to the hollow rod 100, it does not rotate together with the stirring blades 104 and 106, and the co-rotation prevention blade 108 is Since it is in a state of biting into the ground during excavation, it does not rotate at the same time as the excavated soil, and the excavated soil can be divided vertically during excavation by the co-rotation prevention blade 108 to reduce the mass of the excavated soil. It is possible. As a result, it is possible to knead and stir the solidified material and the excavated soil more uniformly, and it is said that the ground improvement work can be performed efficiently.

Japanese Unexamined Patent Publication No. 2008-127812

In the invention relating to the "ground improvement device" described in Patent Document 1 described above, it is true that when the co-rotation prevention blade 108 is press-fitted into the ground, the excavated soil is dug while being divided in the excavation direction, so that the excavated soil is made finer to some extent. It is possible to perform stirring work while doing so.
However, in the ground where there are many clay layers and organic substances, it is still difficult to sufficiently knead and stir the solidified material with the excavated soil, and it cannot be said that it is perfect to use the divided excavated soil as a component of the foundation pile. ..

In other words, when the surrounding ground is used as a part of the structure of the ground improvement body during excavation, the strength of the pile body that becomes the ground improvement body is increased by sufficiently kneading and stirring the earth and sand with the solidifying material. Although it is required to secure it, the ground improvement device described in Patent Document 1 contains a large amount of organic matter even if it can be divided in the excavation direction when the constituents in the ground and the solidifying material are kneaded. In cohesive soil such as a peat layer, there is a problem that it is difficult to uniformly mix the solidified material with the solidified earth and sand because the agglomerated earth and sand rotate together with the rotation of the stirring blades 104 and 106.

Further, in the case of the "ground improvement device" described in Patent Document 1, since it is not possible to remove defective earth and sand such as peat, which is unsuitable as the earth and sand constituting the earth improvement body, sufficient strength of the improved body to be constructed is secured. There was a problem that it was difficult to do so and the applicable ground was limited.

The present invention has been proposed to deal with such circumstances, and is constant by sufficiently kneading and stirring the excavated soil generated during excavation and the solidifying material when constructing the ground improvement body. It is an object of the present invention to provide a ground improvement body construction device and a construction method capable of constructing a pile-shaped or rapple-shaped improvement body having the above strength.
In addition, it is an object of the present invention to provide a construction device capable of promptly replacing defective soil such as cohesive soil.

In order to achieve the above object, the invention according to claim 1 is a ground improvement body construction device that improves the ground by injecting a solidifying material while excavating the ground, and is rotatably arranged. A rod is provided, a bit for excavation is provided at the bottom of the rod, and a spiral stirring blade is attached to the rod at a position above the bit so that the earth and sand at the time of excavation can be moved up and down on a part of the stirring blade. The ground is excavated by the bit at the tip by rotating the rod, and the solidifying material is put into the excavation hole, and the excavated soil is excavated by the rotation of the spiral stirring blade. It is characterized in that it is kneaded with a solidifying material while stirring, and the earth and sand are moved from the notch portion of the stirring blade to apply a shearing force in the vertical direction to the earth and sand.

The invention according to claim 2 is characterized in that, in the above paragraph 1, a single or a plurality of small holes are formed in the stirring blade in addition to or in place of the notch.

The invention according to claim 3 is a method for constructing a ground improvement body that improves the ground by using the construction device according to the above paragraph 1 or 2, and excavates a target ground for ground improvement. The excavated soil is agitated and kneaded with the solidifying material by repeating the vertical movement while rotating the stirring blade while throwing the solidifying material from the head of the excavation hole, and the stirring blade of the stirring blade. A digging and stirring process that moves the earth and sand from the notch and applies a shearing force in the vertical direction to the earth and sand.
It is characterized by having a finishing step of repeating the vertical movement of the bit and the stirring blade up to the tip of the ground improvement body after excavating to the excavation depth in the excavation hole.

The invention according to claim 4 is a test moat in which a test moat for confirming the condition of the ground is performed in the above paragraph 3, and when defective earth and sand are found in the test moat, the defective earth and sand are lifted and removed by the stirring blade. It is characterized by adding a process.

As described above, according to the invention described in each claim, the excavated soil is kneaded with the solidifying material while being agitated by the excavating blade in the excavation hole, and the earth and sand are moved up and down from the notch portion of the stirring blade. The ground improvement body is constructed while applying the shear force in the direction to the earth and sand. Therefore, the excavated soil and the solidifying material can be sufficiently agitated and kneaded, and when constructing the ground improvement body, it is possible to construct a uniform and constant strength improvement body. In addition, the co-rotation prevention blade is not required, and the structure of the entire device can be simplified.

It is a perspective view which shows the schematic structure of the construction apparatus of the ground improvement body which concerns on 1st Embodiment of this invention. Similarly, it is an enlarged perspective view of a stirring blade which is a main part of the construction apparatus of the ground improvement body which concerns on 1st Embodiment of this invention. Similarly, it is explanatory drawing which shows the state in the excavation hole of the stirring blade which is the main part of the construction apparatus of the ground improvement body which concerns on 1st Embodiment of this invention. Similarly, it is explanatory drawing which shows the construction procedure in the case of constructing a column-shaped pile foundation by the construction apparatus of the ground improvement body which concerns on 1st Embodiment of this invention. Similarly, it is explanatory drawing which shows the outline of the operation of the stirring blade or the like in the case of constructing a column-shaped pile foundation by the construction apparatus of the ground improvement body which concerns on 1st Embodiment of this invention. Similarly, it is explanatory drawing which shows the stirring and kneading state of excavated soil by the stirring blade which is the main part of the construction apparatus of the ground improvement body which concerns on 1st Embodiment of this invention. It is a figure which showed the main part of the conventional ground improvement apparatus.

Hereinafter, a preferred embodiment of the ground improvement body construction device according to the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a perspective view showing a schematic configuration of a ground improvement body construction device according to the first embodiment of the present invention, and FIG. 2 is a main part of the ground improvement body construction device according to the first embodiment of the present invention. It is a perspective view of the main part which shows a certain stirring blade in an enlarged manner. As shown in FIG. 1, the construction device 10 of the ground improvement body includes a backhoe 12, a rod 14, a bit 16, a stirring blade 18, and the like.

A hydraulic motor or an electric motor is mounted on the backhoe 12 as a drive source for rotationally driving the rod 14, and the rod 14 vertically erected on the backhoe 12 can be rotated. In the present embodiment, the backhoe 12 is used as the construction machine for excavating work, but the backhoe 12 is not limited to this, and a construction machine such as a pillar car, a rough terrain crane, or a small crawler can also be used.

As shown in FIG. 2, a bit 16 is installed at the lowermost portion of the rod 14, and the bit 16 excavates the ground by rotating the rod 14.
A spiral stirring blade 18 (18A, 18B, 18C ...) Is attached to the rod 14 above the bit 16, and the stirring blade 18 has notches 20A, 20B, 20C formed in a part thereof. Has been done. Further, the stirring blade 18E is provided with a small window-shaped small hole 21.

FIG. 3 is an explanatory view showing a state of the stirring blade 18 inserted into the excavation hole 22, and as shown in the figure, the stirring blade 18 is formed by attaching a spiral blade to a rod 14 and having a tip. Two spiral stirring blades 18A and 18B are continuously formed from the bit 16 to form a shape that also serves as an excavation bit. Further, it has three stirring blades 18C, 18D, 18E above the bit 16 and has a total of five blades. As the excavation is carried out by these stirring blades 18, it is possible to dig while guiding the excavated soil upward.

Further, the notch portions 20A, 20B, 20C provided in the stirring blade 18 forcibly move and pass the excavated soil generated during excavation upward from the notch portions 20A, 20B, 20C inside the excavation hole. .. As a result, in addition to the rotational force, a vertical shearing force is applied to the excavated soil, and the synergistic effect of both the rotational force and the shearing force results in excavation while finely grinding the excavated soil. During excavation, a solidifying material such as cement milk is supplied into the excavation hole 22 from a slurry mixing plant (not shown) to knead and stir the solidifying material and the excavated soil, and the foundation pile, which is a ground improvement body, is formed in the excavation hole 22. Is constructed together with excavation work.

Further, it is possible to promote the passage of the excavated soil and the solidifying material upward or downward from the small hole 21, and to promote kneading and stirring by the shearing force as in the cutout portions 20A, 20B and 20C. When the small holes 21 are provided in the stirring blade 18 in place of the notches 20A, 20B, 20C and only a single or a plurality of small holes 21, the single or a plurality of small holes 21 are provided in the notches 20A, 20B. When it is provided together with 20C, there are three possible cases where only one or a plurality of small holes 21 are provided. When only the small holes 21 are provided, the rigidity of the stirring blade 18 can be ensured.

Next, a method of constructing the ground improvement body using the construction device of the ground improvement body of the present embodiment configured as described above will be described.
FIG. 4 is an explanatory diagram showing a construction procedure when a column-shaped pile foundation is constructed by the construction device 10 of the ground improvement body, and FIG. 5 is an explanatory diagram showing an outline of the operation of the stirring blade 18 and the like in the excavation hole 22; Is an explanatory diagram showing the stirring / kneading state of the excavated soil by the stirring blade 18.

The method for constructing the ground improvement body by the ground improvement body construction device 10 of the present embodiment is basically a soil removal step, a slurry discharge / excavation / vertical repeated stirring step (hereinafter, abbreviated as “drilling stirring step”), and a method of constructing the ground improvement body. It consists of five stages: finishing process, pulling process, and improved body head processing process.

In the explanatory views of FIGS. 4 and 5, the horizontal axis indicates time and the vertical axis indicates the depth at the time of excavation. As shown in FIG. 4, in the soil removal process (preceding digging), the topsoil of the ground to be constructed is removed, and the ground is excavated to the planned height of the ground improvement body by the bit 16 and the stirring blade 18, and the stirring blade 18 is used. Remove the earth and sand by. Then, after centering and adjusting the angle of the rod 14, the process proceeds to the excavation stirring step.

In addition, before the excavation stirring step, a test moat step may be added in which a test moat is performed to a predetermined depth where the ground improvement body is supported and the state of the stratum is confirmed. In this case, for example, when defective ground containing organic substances such as peat layers, cohesive soil, etc. is found in the ground in the middle, the earth and sand are lifted by hooking the earth and sand on the spiral stirring blade 18 of the construction device 10. After removing the defective earth and sand, the process proceeds to the next step, the excavation stirring step. By removing defective earth and sand that hinder the hydration reaction with cement milk, it is possible to construct a ground improvement body made of a uniform and uniform material.

In the excavation stirring step, cement milk, which is a solidifying material, is poured from the slurry mixing plant separately installed from the head of the excavation hole 22. Cement milk is added while supplying a specified amount as needed according to the progress of the excavation stirring process.
During the excavation stirring process, the inside of the excavation hole 22 is maintained in a state of being filled with cement milk, and the inside of the excavation hole 22 is always filled with low-viscosity cement milk as compared with the case of discharging from the tip of a conventional bit. It becomes possible to hold. As a result, it is possible to improve the stirring efficiency of the earth and sand and the cement milk by the stirring blade 18.

In the excavation stirring step, as shown in FIG. 4, while rotating the rod 14 in the normal direction (clockwise), vertical stirring and excavation every 1 m are standard, and the vertical movement is repeated several times in the excavation hole 22. , Mix and stir the excavated soil and solidifying material. In this step, vertical stirring is repeated three times, and as a result, the excavated soil is finely ground and excavated by the synergistic effect of both the rotational force and the shearing force.
Specifically, as shown in FIG. 6A, at the time of excavation in which the rod 14 is lowered, the excavated soil is moved upward by the stirring blade 18, and the excavated soil is formed by the cutout portions 20A, 20B, 20C. It is made finer by applying a shearing force.

Then, as shown in FIG. 6 (b), when the rod 14 during the kneading work is raised, the cement milk (solidifying material) and the excavated soil are mixed and sheared and dropped to the lower end portion, and also in FIG. 6 (b). When lowering the rod 14 as shown in c), the cement milk and the excavated soil are mixed and sheared and raised in the excavation hole 22. In short, by repeating stirring and mixing three times each in the excavation hole 22, the excavated soil and the solidifying material are sufficiently kneaded, and sand and clay are sufficiently mixed to make the excavated soil uniform and uniform. I try to build a ground improvement body.
The number of vertical iterations is not limited to three, and can be changed as appropriate depending on the ground conditions and the like. In principle, the water-cement ratio (W / C) of cement milk, which is a solidifying material, is in the range of 60% to 100%.

In the improved device 10 of the present embodiment, the operator can visually check the state inside the excavation hole 22 and perform the construction while grasping the mixing / stirring state of the solidifying material and the excavated soil, so that mixing / stirring is not possible. It is possible to prevent it from becoming sufficient. As a specific standard, it is visually confirmed that the improved slurry does not have a lump of about 5 cm or more. It is not necessary to check the status of the improved body constructed by this with an inspection jig or the like, and it is possible to reduce the labor.

The management items for the construction of the ground improvement body are the excavation depth, the integrated flow rate (total discharge amount) of the solidified material, and the number of blade cuttings. Of these, the number of blade cuttings (R) is calculated by the following formula.
R ＝ N × n ÷ L ～ (1)
N: Total rotation speed of rod (rotation speed x stirring time)
n: Number of blades
L: Improved length

As described above, in the present embodiment, the stirring blade 18 has a total of 5 blade blades (n), and the number of blade cuttings (R) per 1 m, which is our construction standard, is 350 times. An example of the stirring time and the number of rotations according to 1) is shown below.
Stirring time = number of blade cuttings (R) 350 ÷ 5 sheets = 70 (rotation / minute)
Rotation speed = 30 (rotation / minute)

In the finishing step, as shown in FIGS. 5 and 6, after repeating up and down repetition from the G level to the tip of the improved body, the process proceeds to the pulling step.
In the pulling step, the rod 14 is pulled out from the excavation hole 22 while being pulled forward or reversed at a pulling speed of 2 (m / min). Then, the height of the head of the improved body is adjusted to be approximately plus or minus 20 mm by the improved body head processing step, and a series of construction work is completed.

As described above, according to the construction device 10 of the ground improvement body of the present embodiment, the co-rotation prevention blade required in the conventional improvement device becomes unnecessary, and the structure of the entire device can be simplified. It became. In addition, the excavated soil generated during excavation and the solidifying material can be sufficiently kneaded and agitated, and a uniform and uniform ground improvement body having a certain strength or higher can be constructed.

As described above, according to the present invention, the excavated soil is kneaded with the solidifying material while being agitated by the spiral stirring blade in the excavation hole, and the earth and sand are moved up and down from the notch portion of the stirring blade. The shearing force in the direction is applied to the earth and sand. Therefore, the excavated soil and the solidifying material can be sufficiently agitated and kneaded, and when constructing the ground improvement body, it is possible to construct a uniform and constant strength improvement body.

10 Construction equipment for ground improvement body
12 backhoe
14 rod
16 bit
18 18A 18B 18C 18D 18E Stirring blade
20A 20B 20C Notch
21 small hole
22 Drilling hole

In order to achieve the above object, the invention according to claim 1 is a ground improvement body construction device that improves the ground by injecting a solidifying material while excavating the ground, and is rotatably arranged. A rod is provided, a bit for excavation is provided at the lower part of the rod, and a spiral stirring blade continuously formed from the bit is attached to a position above the bit, and a part of the stirring blade at the time of excavation is attached. A notch that allows the earth and sand to move up and down is provided, or a single or multiple small holes are drilled in addition to or in place of the notch, and the rod is rotated to cause the ground by a bit at the tip. Is excavated and the solidifying material is put into the excavation hole, and the excavated soil is kneaded with the solidifying material while stirring with the rotation of the spiral stirring blade, and among the notches and small holes of the stirring blade. It is characterized in that the earth and sand are moved from either or both sides to apply a vertical shearing force to the earth and sand.

The invention according to claim 2 is a method for constructing a ground improvement body for improving the ground by using the construction device according to the above paragraph 1, and excavates a target ground for ground improvement to form an excavation hole. At the same time, the excavated soil is stirred and kneaded with the solidifying material by repeating the vertical movement while rotating the bit and the stirring blade in the normal direction while throwing the solidifying material from the head of the excavation hole, and the stirring blade of the stirring blade. A digging and stirring step in which the earth and sand are moved from the notch to apply a shearing force in the vertical direction to the earth and sand, and after digging to the excavation depth in the excavation hole, the bit and the tip of the ground improvement body are reached. It is characterized by having a finishing process in which the vertical movement of the stirring blade is repeated .

According to the third aspect of the present invention, in the above two paragraphs, after the finishing step is completed, the bit and the stirring blade are pulled out from the drilling hole while rotating the bit and the stirring blade in the forward or reverse direction. It is a feature .

Claims (4)

An apparatus for constructing a ground improvement body that improves the ground by injecting solidification material while excavating the ground,
It has a rod arranged rotatably, and a drilling bit is provided at the lower part of the rod, and a spiral stirring blade is attached to the rod above the bit, and a part of the stirring blade is used for excavation. A notch that allows the earth and sand to move up and down is provided, and by rotating the rod, the ground is excavated by a bit at the tip, and a solidified material is introduced into the excavation hole, and the spiral stirring blade A ground improvement body characterized in that the excavated soil is agitated with rotation while being kneaded with the solidified material, and the earth and sand are moved from the notch of the agitating blade to apply a vertical shearing force to the earth and sand. Construction equipment. The ground improvement body construction apparatus according to claim 1, wherein a single or a plurality of small holes are formed in the stirring blade in addition to or instead of the notch. A construction method of a ground improvement body for improving the ground using the construction device according to claim 1,
The excavated soil is stirred by excavating the target ground for ground improvement to form a drilling hole, and by repeating the vertical movement while rotating the stirring blade while feeding the solidification material from the head of the drilling hole. An agitation and agitation step of performing agitation and agitation to knead with the solidified material and move the earth and sand from the notch of the agitation blade to apply a vertical shear force to the earth and sand,
A method for constructing a ground improvement body comprising: a finishing step of repeating the vertical movement of the bit and the stirring blade after reaching the excavation depth in the excavation hole to the tip of the ground improvement body. A test pit for confirming the state of the ground is performed, and when a defective soil is discovered by the test pit, a test digging step for adding and removing the defective soil by the stirring blade is added. The construction method of the ground improvement body of description.

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