JPH03281819A - Ground improvement method - Google Patents

Abstract

PURPOSE:To make it possible to improve the ground with a small scaled device without requiring any specialized machine by making a mixing and stirring device having a motor, stirring wing and hardener discharge ports on the front end part of a shaft excavate in the ground while rotating the stirring wing only. CONSTITUTION:A mixing and stirring device 2 having a motor 22, stirring wing 21 and fixed wing 23 is provided to the front end part of a shaft 3 provided with a fluid passage 7. The stirring wing 21 is only rotated and, at the same time, the mixing and stirring device 2 is excavated in the ground while discharging a liquid hardener from a plurality of discharge ports 25 provided to the fixed wing 23. Then, after it is excavated to a specific depth, the stirring wing 21 is reversed, and the mixing and stirring device 2 is drawn by pulling capacity from the earth to solidify a soil stirred portion.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention improves the ground, especially at a depth of about 20 m or less from the ground surface, by mechanically mixing and solidifying soft soil and a solidifying agent. It's about how to do it.

[Prior Art] Conventionally, as a method for improving the ground, there has been a method of providing a cylindrical anchor unit in soft soil. One method was to drive concrete cylinders into the ground, but this method is gradually being avoided because it involves driving long concrete columns by impact, which causes problems such as cost and noise, and because it does not pass through urban areas at all. .

The first method to solve this problem is to use a drilling machine to make a hole in the ground, then pour concrete into the hole and harden it (cast-in-place concrete pile method). With this method, the soil is pulled up while excavating and concrete is placed, which means that the pouring equipment is rather large, and in geological conditions where the walls of the hole are prone to collapsing, bentonite walls may be used as the inner walls. It is necessary to prevent collapse by inserting a recasing.

Taking these points into consideration, recently, an excavation shaft equipped with stirring blades is rotated by an excavation mechanism installed on the ground, and the solidification material is fed through a fluid passage provided in the excavation shaft without pulling up the soil, and is used during excavation or extraction. At times, a type of injection method in which the solidifying material is discharged from a discharge port near the tip and mixed and stirred has come to be widely adopted.

[Problems to be Solved by the Invention] However, this method also has some drawbacks. One of these is that conventional equipment requires an excavation shaft that is longer than the mixing depth, so if it is necessary to mix the ground below the middle layer, the height of the equipment inevitably increases. be. This is because in conventional equipment, the excavation shaft itself is rotated, and the rotational force is applied to the upper end of the shaft.
This was also to support the vicinity of the upper end of the shaft of the excavation device with a special machine, and to install a heavy driving machine above the upper end position. Basically, what supports this drive machine is the above-mentioned special-purpose machine, and even if a tower or the like is used to support it, the special-purpose machine has to be tall and large. Ta. In addition, it has a fluid passage for the solidifying material, and it is extremely difficult to connect short length shafts because it has a twist or groove structure to rotate the shaft.

Applying a rotational force to the upper end position to rotate the shaft also means that as the stirring depth increases, a larger rotational force is required, and corresponding noise becomes a problem.

Furthermore, the need for specialized machines and the large size of the equipment also increase the cost of construction, and the industry is no longer requiring specialized machines. There was a great deal of hope for the emergence of a ground improvement method that does not require large equipment, is noiseless, and does not vibrate.

[Means for Solving the Problems] Therefore, in view of the above points, the present inventor has finally completed the method of the present invention as a result of intensive research, and its feature is that soft soil and solidification material are mechanically mixed. A method for improving the ground by solidifying and solidifying the ground, the method comprising: a shaft having a fluid passage inside which sends out a liquid solidifying material; a motor fixed to the tip of the shaft; and a motor installed at the most extreme position of the shaft. and a fixed blade having a maximum width not exceeding the stirring diameter of the stirring blade provided on the shaft and having a plurality of discharge ports for discharging the liquid solidified material from the fluid passage in the shaft. The mixing and stirring device is dug into the ground by rotating only the stirring blades and simultaneously discharging the liquid solidified material from the discharge port. After digging to a predetermined depth, the stirring blades are rotated in the opposite direction, and the stirring blades are rotated in the ground. The purpose is to pull up the mixing and stirring device by pulling it further and solidify the soil stirring portion.

Here, "soft soil" means soil that forms a ground that requires improvement, and the soil quality is not particularly limited.

The "solidifying material" used in the method of the present invention is in liquid form. As for its material, any conventional material may be used; cement milk is suitable for boat fishing. Other methods used include emulsions made by adding water to bitumen, silicate-based chemicals made by adding sodium aluminate, sodium bicarbonate, calcium chloride, etc. to sodium silicate, and chemicals made by adding catalysts necessary for polymerization to calcium acrylate. It will be done.

The "mixing and stirring device" is essential for carrying out the method of the present invention, and its greatest feature is that the motor that rotates the stirring blade is located on the tip side of the excavation shaft. In other words,
It does not have a structure in which the excavation shaft itself rotates. The structure of the stirring blade is not particularly limited, but since it is preferable to dig under its own weight, it is preferably an auger blade. The liquid solidifying material is sent from a separately installed solidifying material plant through a fluid passage provided in the shaft, and is discharged from the discharge port. The excavation axis has been patched.

It may be possible. When adding the joint 7, since the shaft 1 does not rotate, there is no need to worry about the screw 1/ at the connection part, and the connection work is relatively easy. Further, this mixing and stirring device is provided with fixed blades on its shaft. The method of attachment is to install it so that it does not rotate with the soil that comes up when the stirring blade rotates (it is also possible to install it with some play).
If play is provided, the effect will be that if soil that has come up is caught between the motor and the fixed blade, the fixed blade will swing due to its own vibration and remove the soil. Further, a passage for the liquid solidified material and an opening thereof are provided in the fixed blade. This opening is a discharge port 7 through which the solidifying material is discharged. Although the number of discharge ports is not limited, it is better to have a larger number from the viewpoint of mixing.

Such an IT-made mixing and stirring device is installed on the ground surface using a backhoe or the like. A special machine is not required for installation; something like a puncture hoe is sufficient. In addition, there is no need to support the vicinity of the upper end of the mixing/stirring device as in the conventional case, so there is no need for a large device near the top, and it is sufficient to simply hang a wire for hanging it down. Therefore, the tip of the backhoe boom is sufficient.

The mixing and stirring device can be moved up and down using a lifting wire and lowered using its own weight, or in addition to this hanging wire, a chain can be installed on the shaft and the chain can be moved up and down using a separately installed motor. good. Knead is suitable for ground that is difficult to excavate under its own weight. Of course, ranks and binions can be used instead of chains. The shaft of the mixing and stirring device may be supported at a relatively low position in order to vertically lower the mixing and stirring device and to prevent lateral vibration.

Further, for the rotation of the tip motor, a hydraulic motor such as a Huckhou motor that uses hydraulic pressure is convenient, but it may also be driven electrically by drawing a conductor inside the shaft.

Next, after installing in this manner, the stirring blades of the mixing and stirring device are rotated. The rotation causes the device to try to dig under its own weight. Note that, as described above, a pressing force may be applied auxiliary from the outside.

The liquid solidified material is discharged from the discharge port of the fixed blade when digging begins. The discharge time does not have to be at the same time as the rotation of the stirring blade, and may continue until after the excavation is completed and the extraction has begun; in short, it is sufficient that the soil is mixed with the solidification material. It is.

The extraction is carried out by rotating the stirring blade in the opposite direction and suspending the device. All you have to do is leave it alone and wait for the solidifying material to solidify.

[Example] The method of the present invention will be explained in more detail below based on the drawings.

FIG. 1 shows an example of soil improvement equipment 1 used in the method of the present invention. As is clear from the figure, the shaft 3 of the mixing and stirring device 2 having the stirring blade 21 at the tip is connected to the backhoe 4.
It is hung vertically. The length of the mixing and stirring device 2 itself is about 8 m, and the support portion 5 supports the mixing and stirring device at a relatively low position.

In the shaft 3 of the mixing and stirring device 2, a hydraulic piping 6 for a motor and a fluid passage 7 for sending out a liquid solidification material are provided, which communicate with the hydraulic line of the pack hoe and the solidification material plant 9, respectively.

In this example, a chain 10 is provided on the shaft 3 and is interlocked with a motor 11 provided on the support portion 5. A suspension wire 12 for the pack hoe 4 is fixed to the top of the shaft 3. This allows the mixing and stirring device 2 to be suspended, excavated,
Performs control during work such as pulling out.

Basically, the mixing and stirring device 2 starts digging under its own weight when the stirring blades 21 start rotating.

However, if the ground is hard or the digging force of the stirring blade is small, the motor 11 is driven to push the shaft 3 downward.

FIG. 2 shows the main parts of the mixing and stirring device 2, in which a motor 22 and stirring blades 21 are provided at the tip.

The motor 22 is fixed to the shaft 3 of the device 2, so when the motor 22 is driven, only the stirring blade 21 portion rotates.

The stirring blade 21 is an auger blade. Fixed wings 23 are also scattered on the shaft 3. The fixed blades 23 are provided to ensure that the excavated soil is sufficiently stirred without rotating together, and are fixedly installed on the shaft 3. It has a certain amount of play so that if the soil is removed by vibration or the like, and a blade is provided that faces the soil that has risen. Furthermore, a fluid passage 24 communicating with the fluid passage 7 in the shaft 3 of the mixing/stirring device 2 is provided in the fixed blade 23, and a discharge port 25, which is an opening thereof, opens downward. The liquid solidified material is discharged from the discharge port 25, and this may be performed not only during excavation but also during extraction.

[Effects of the Invention] As explained in detail above, the ground improvement method according to the present invention is a method for improving the ground by mechanically mixing and solidifying soft soil and a solidifying agent, It has a stirring blade at its tip that is rotated by the motor, and a shaft to which the motor is fixed is provided with a fluid passage for delivering the liquid solidified material, and the shaft has a maximum width that does not exceed the excavation diameter of the stirring blade. A mixing and agitating device having a fixed blade fixedly installed therein, the fixed blade having a plurality of discharge ports for discharging the liquid solidified material from the fluid passage in the shaft, is installed in the ground by rotating only the stirring blade, and at the same time. Digging is performed while discharging liquid solidification material from the discharge port, and after digging to a predetermined depth, the stirring blades are rotated in the opposite direction and the mixing and stirring device is pulled up from the ground to solidify the soil stirring portion. This is a highly advanced invention that has the following effects.

■ Since it rotates only the tip of the shaft, and the motor is located at the tip, there is no need to support the upper end of the shaft or install a drive device at the upper end, as in the conventional case. No equipment required.

■ Unlike conventional methods, the mixing and stirring device does not move by rotating the shaft, but only the tip is rotated, so less energy is required.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view showing an example of equipment used in the method of the present invention. FIG. 2 is a partially sectional front view showing the main parts of the mixing and stirring device which is part of the equipment. 1...Soil improvement equipment 2...Mixing stirring device 21-...Stirring blade 22...Motor 23...Fixed blade 24...Fluid passage 25...Discharge port 3 ...Shaft 4 ... Backhoe 5 ... Support part 6 ... Hydraulic piping 7 ... Fluid passage 9 ... Solidification Material tank 10... Chain 11... Motor 12... Hanging wire

Claims (1)

[Claims] 1. A method for improving the ground by mechanically mixing and solidifying soft soil and a solidification material, comprising: a shaft having a fluid passageway for delivering a liquid solidification material therein; a motor fixed to the tip of the shaft, a stirring blade provided at the most extreme position of the shaft, and a fluid passage within the shaft having a maximum width not exceeding the stirring diameter of the stirring blade provided on the shaft. A mixing and stirring device consisting of a fixed blade having a plurality of discharge ports for discharging the liquid solidified material from the ground is excavated into the ground while rotating only the stirring blades and simultaneously discharging the liquid solidified material from the discharge ports. After digging to a deep depth, the stirring blades are rotated in the opposite direction,
A soil improvement method characterized by: pulling the mixing and stirring device up from the ground and solidifying the soil stirring portion. 2. The ground improvement method according to claim 1, wherein the stirring blade of the mixing and stirring device is an auger blade.