JP3502958B2 - Ground improvement method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for carrying out a hardening treatment by stirring and mixing original ground soil while discharging and filling a ground hardening agent into soft ground.

[0002]

2. Description of the Related Art When constructing a soil improvement method in which a slurry-type ground hardening agent such as cement milk is filled and mixed with soft soil, depending on the soil quality of the original ground, the filling of the hardening agent increases the volume of the soil. And ground rise phenomenon,
Lateral movement of the soil may occur and may seriously affect existing surrounding structures.

Therefore, as an effective means for solving this, for example, as described in Japanese Examined Patent Publication No. 4-57805, there is a method of pre-discharging an amount of raw ground soil corresponding to the discharge amount of the curing agent. Recently proposed. However, this method discharges the soil before injecting the hardener, so that the soft soil around the soil is drawn into the soil, causing displacement to the surrounding ground, which also has an adverse effect on the surrounding existing structures. Become.

[0004]

DISCLOSURE OF THE INVENTION The present invention proposes a method which solves the problems in the conventional soil improvement type ground improvement method and enables the earth to be discharged without affecting the surrounding soft ground. To do.

[0005]

SUMMARY OF THE INVENTION The present invention does not discharge the soil before pouring the curing agent, but simultaneously pours the curing agent and discharges the soil. It is made adjustable so that a suitable amount of soft soil can be discharged. For this purpose, the Japanese Patent Publication 6 previously proposed by the applicant.
A device obtained by modifying the inner and outer triple pipe type ground improvement device described in JP-A-4-11771 is used.

That is, according to the present invention, the rotating shaft body is configured as a triple tube of an inner tube, a middle tube, and an outer tube, each of which can be changed in an arbitrary rotation direction and number of revolutions. Shorter, lower digging and stirring blades and upper tier stirring blades are attached to the lower ends of the inner and middle pipes, respectively, and a spiral blade for earth removal is formed on the outer periphery of the outer pipe, and a slurry is formed at the lower end. After the upper outlet of the hardening agent is provided and the lower end of the inner tube serves as the lower outlet of the slurry-like hardening agent, the rotary shaft of the soil improvement apparatus is rotated and after penetrating to a predetermined depth of the soft ground. , While gradually discharging the hardening agent from the upper outlet of the outer tube and reversely rotating the outer tube, gradually pulling out the entire rotary shaft body from the ground, mixing and stirring the hardening agent with the soft soil, and excluding the system of the soft soil. Ground improvement method that simultaneously removes In addition, immediately before the rotary shaft penetrates the bottom of the soft ground to reach a predetermined depth, the curing agent is discharged from the lower discharge port of the inner pipe when leaving the space between the upper and lower stirring blades. The hardener and the surrounding soil are mixed and stirred up to the bottom. Further, when the rotary shaft is pulled out, the rotation speed of the outer tube is adjusted according to the soil quality of the soft soil so that the soil is discharged in an amount corresponding to the discharge amount of the curing agent. Examples of the method of the present invention will be described below with reference to the drawings.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of a ground improvement device used in the method of the present invention. As in Japanese Patent Publication No. 64-11771, an inner tube having a rotating shaft as a center 1, an intermediate middle tube 2, and an outer outer tube. 3, the lower ends of the middle pipe 2 and the outer pipe 3 are sequentially made shorter than the inner pipe 1, and the inner pipe 1 has no lower end port 4 with the lower discharge port 4 of a slurry-like hardening agent such as cement milk. A lower stage excavating and stirring blade 5 is attached to the lower end of the inner pipe 1, and an upper stage stirring blade 6 is attached to the lower end of the middle pipe 2. Also, the outer tube 3
A spiral blade 7 for soil removal is formed on the outer periphery of the outer pipe 3, and an upper discharge port 8 for the slurry-like hardening agent is also provided at the lower end of the outer pipe 3. Each of the pipes 1, 2 and 3 is configured so that the rotation direction and the rotation speed thereof can be arbitrarily converted by a prime mover 9 installed above.

[0008] First, when the device is positioned at a predetermined position on the soft ground 10 to be improved, the prime mover 9 is driven to rotate the inner pipe 1 in the forward direction, and the lower surface excavating blade 5a of the excavating and stirring blade 5 at the lower end thereof. While excavating the ground 10 by
Also, the outer tube 3 is also rotated forward at the same time, and penetrates to a predetermined depth a without discharging the earth (FIG. 2 (a)).

Immediately before the bottom blade 5 leaves a space f between the upper blade 6 and the bottom blade 5 at a predetermined depth a, a slurry-like hardening agent such as cement milk is discharged from the discharge port 4 at the lower opening of the inner pipe 1. It is discharged, and the hardening agent and the surrounding soil are mixed and agitated to the bottom by rotating the lower blade 5 (Fig. 2).
(B)).

When the lower blade 5 reaches a predetermined depth a, the discharge of the curing agent from the inner pipe 1 is stopped, and this time, the upper discharge port 8 provided at the lower end of the outer pipe 3 is passed through the inner side of the outer pipe 3 as well. While the outer tube 3 is rotated in the reverse direction, and the inner tube 2 and the inner tube 1 are rotated in opposite directions, the entire rotary shaft bodies 1 to 3 are gradually pulled out (FIG. 2).
(C)).

As a result, the hardening agent discharged from the upper discharge port 8 is effectively mixed and stirred with the surrounding soil by the upper and lower blades 6 and 5, and the improved pile 11 is formed, and at the same time, the outer pipe is formed. 3 By the rotation of the spiral blade 7 on the outer periphery, the soft soil above the improved pile 11 being constructed is sent upward and is gradually discharged 12 onto the upper surface of the ground 10 (Fig. 2 (d)).

When pulling out this device from the ground 10,
The rotation speeds of the pipes 1 to 3 do not have to be the same, and the ground 1
The soil 12 is discharged in an amount commensurate with the amount of the hardening agent injected into 0, the rotation speed of the outer tube 3 is adjusted according to the soil quality of the soft soil, and the extraction speed of the device is also adjusted according to the discharged amount. In some cases, the extraction may be temporarily stopped and the soil removal and the hardening agent may be stirred and mixed. Also, the outer tube 3
Depending on the amount of soil discharged, the rotation itself is sometimes controlled by temporarily stopping the rotation or returning it to the normal rotation, and the amount of soil discharged is adjusted appropriately so as not to affect the surrounding ground.

As described above, during the formation of the improved pile 11, the lower blades 5 and the upper blades 6 are made to have different rotational directions and rotational speeds from each other so that they are agitated and kneaded so that soil does not adhere to both blades and between them. A uniform and highly accurate pile body 11 is created over the entire area of the pile body 11.

Moreover, during the construction of the pile 11, the untreated soil on the upper side is sequentially discharged out of the system by an amount commensurate with the discharge filling amount of the hardening agent by the rotation of the spiral blade 7 provided on the outer pipe 3. Therefore, the volume of the ground 10 does not increase and the surrounding ground is not displaced.

[0015]

As described above, the present invention eliminates the original ground soil in anticipation of the amount corresponding to the filling amount of the hardening agent in advance when the rotary shaft penetrates the ground, as in the conventional soil-removal type ground improvement method. Unlike the one that is performed, the soil of the soft soil around the soil is discharged in an area where the soil is gradually discharged in an amount commensurate with the discharge amount of the curing agent at the same time as the curing agent is discharged and the mixing and stirring process is performed when the rotary tube is pulled out. There is no adverse effect on the surrounding ground by pulling in.

In addition, the apparatus used in this method is constituted by a triple pipe, and a stirring blade is attached to the lower end of each of the outer pipes having a spiral blade formed on the outer circumference and a hardening agent discharge port provided at the lower end. Since the pipes and inner pipes are projected, by setting the rotation direction and number of rotations of each pipe as desired, it is possible to mix and stir with the curing agent discharged on the lower side when pulling out the equipment and to discharge the soil on the upper side. In addition, the amount of soil discharged can be adjusted freely, and there is no concern that the discharged curing agent will be discharged outside the system together with the discharged soil.

[Brief description of drawings]

FIG. 1 is an explanatory view of an apparatus used for a ground improvement method according to the present invention.

FIG. 2 is an explanatory view showing a construction process of the ground improvement method according to the present invention.

[Explanation of symbols]

1-inner tube 2- Middle tube 3-Outer tube 4- Lower curing agent outlet 5-Lower stage excavation and stirring blade 6- Upper stirring blade 7-Soil removal spiral blade 8-Upper curing agent outlet 9-Motor 10-soft ground 11-Improved pile 12-discharging

Front page continuation (72) Inventor Hitofumi Matsushima 3-8-15 Kaigan, Minato-ku, Tokyo Kokuso Shibaura Building National Land Construction Co., Ltd. (56) Reference JP-A-3-125712 (JP, A) JP-A-63-300110 (JP, A) JP-B 4-57805 (JP, B2) JP-B 64-11771 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) E02D 3/12

Claims (2)

(57) [Claims] 1. A rotary shaft is composed of a triple pipe of an inner pipe, a middle pipe, and an outer pipe, each of which can be changed in an arbitrary rotation direction and number of revolutions, and the lower ends of the middle pipe and the outer pipe are sequentially made shorter than the inner pipe, A lower stage excavating and stirring blade and an upper stage stirring blade are attached to the lower ends of the inner pipe and the middle pipe, respectively, and a spiral blade for earth removal is projectingly formed on the outer periphery of the outer pipe, and a slurry hardening agent is formed at the lower end. The upper discharge port is provided and the lower end port of the inner pipe serves as the lower discharge port of the slurry-like hardening agent.The rotary pipe of the soil improvement device is rotated to penetrate the soft ground to a predetermined depth, and then the outer pipe. While gradually discharging the hardening agent from the upper discharge port and rotating the outer tube in reverse, the entire rotary shaft is gradually pulled out from the ground, and the hardening agent is mixed and stirred with the soft soil and the soft soil is removed from the system. It is a ground improvement method that is performed simultaneously with Immediately before the rotary shaft penetrates to the specified depth of soft ground and reaches the bottom, the curing agent is discharged from the lower discharge port of the inner pipe where there is left the gap between the upper and lower stirring blades, and the curing agent reaches the bottom. A ground improvement method characterized by mixing and stirring the soil and surrounding soil. 2. The ground according to claim 1, wherein when the rotary shaft is pulled out, the rotation speed of the outer pipe is adjusted in accordance with the soil quality of the soft soil so that the soil is discharged in an amount commensurate with the discharge amount of the hardening agent. Improved construction method.