JP6908433B2 - Drain material cutting device and drain material cutting method - Google Patents

Description

The present invention relates to a drain material cutting device and a drain material cutting method used in the shield method.

As a construction method to improve the soft ground containing water, a drain material with a hollow inside is provided so as to extend downward from the ground surface, and a construction method is used in which the moisture in the ground is discharged to the ground through this drain material. Has been done.
When digging a ground that has been improved by such a method with a shield excavator, if the drain material in the ground is caught with a cutter bit, the ground surface may collapse, so it is necessary to cut the drain material in advance. There is.

Patent Document 1 below discloses a method in which a cutting blade capable of applying vibration with high frequency or ultrasonic waves is provided on the cutter face plate of a shield excavator, and the drain material is cut by feeding the cutting blade forward. There is.

Japanese Unexamined Patent Publication No. 2012-219549

However, the invention described in Patent Document 1 has the following problems.
(1) A high-power oscillator must be adopted.
Under soil water pressure, the cutting blade comes into contact with water or soil (hereinafter, also referred to as "water or the like"), so that vibration is transmitted to water or the like and the vibration of the cutting blade is attenuated.
For this reason, it is necessary to adopt a high-power oscillator for the cutting blade in consideration of attenuation, which leads to an increase in cost.
(2) The penetration resistance of the cutting wave tends to increase.
Since the cutting blade using a high-power vibrator has a large size, the penetration resistance into the soil becomes large, and the workability is likely to be adversely affected. Further, if the vibrator becomes larger than the cutting edge size, it may not be possible to arrange the vibrator.

Therefore, one of the objects of the present invention is to provide a means for which the vibration of the cutting blade is less likely to be damped even in water or soil.

The first invention of the present application, which has been made to solve the above problems, is a drain material cutting device provided in a shield excavator for cutting a drain material embedded in a ground, and is provided on the front surface of the shield excavator. The drain cutter, which is configured to project more in the excavation direction than the provided excavation cutter and vibrates by high frequency or ultrasonic waves, and the drain cutter are arranged so as to sandwich the drain cutter in the radial direction of the shield excavator. It is characterized by including at least a gas layer forming means for locally forming a gas layer for cutting the drain material around the drain cutter when the drain material is cut.
Further, the second invention of the present application is characterized in that, in the first invention, the gas layer forming means moves together with the drain cutter .
Further, the third invention of the present application is characterized in that, in the first invention or the second invention, the gas layer forming means includes at least a means for sending compressed air or a foaming agent around the drain cutter. ..
Further, the fourth invention of the present application is a method for cutting a drain material embedded in a ground by a drain cutter provided in the shield excavator at the time of excavation of the ground . With the gas layer forming means arranged so as to sandwich the drain cutter in the radial direction, the drain cutter is vibrated by high frequency or ultrasonic waves while locally forming a gas layer for cutting the drain material around the drain cutter. This is characterized by cutting the drain material.

According to the present invention, at least the following effects are exhibited.
(1) By forming a gas layer around the drain cutter and making it difficult for the vibration of the drain cutter to be transmitted to the surrounding water or the like when cutting the drain material, it is possible to suppress the attenuation of the vibration of the drain cutter. Therefore, it is not necessary to make the vibrator used for the drain cutter have an unnecessarily high output.
(2) Since the size of the drain cutter is not excessively increased due to raising the standard of the vibrator, deterioration of workability can be avoided and it also contributes to saving the arrangement space.

The schematic diagram which shows the operation image of the drain lumber cutting apparatus.

Hereinafter, examples of the present invention will be described with reference to the drawings.

<1> Overall configuration FIG. 1 is a schematic functional diagram of a drain lumber cutting device according to this embodiment, (a) shows a state in which the drain lumber cutting device is stored in a shield excavator, and (b) a drain. It shows the state where the drain material is cut by the material cutting device.
The drain lumber cutting device A is a device provided on the front surface of a shield excavator that excavates the ground under soil water pressure, and is a gas layer forming means for forming a gas layer around the drain cutter 10 and the drain cutter 10. 20 and at least.
The details of each component will be described below.

<2> Drain cutter The drain cutter 10 is a device for cutting the drain material X embedded in the ground to be excavated by moving so as to project from the shield excavator in the excavation direction.
The drain cutter 10 is configured to project more freely in the excavation direction than the excavation surface Y of the excavation cutter used for excavating the ground.
The drain cutter 10 includes at least a vibrating blade 11 that vibrates with high frequency or ultrasonic waves, and a telescopic mechanism 12 for moving the vibrating blade 11 in the excavation direction.

<2.1> Vibrating blade The vibrating blade 11 is a member for cutting the drain material X.
In this embodiment, the vibrating blade 11 is interposed between the cutting edge 111 in contact with the drain material X, the vibrator 112 that vibrates the cutting edge 111 with high frequency or ultrasonic waves, and the cutting edge 111 and the vibrator 112. It is composed of a resonator 113 and the like.
Then, the drain material X is melt-cut by pressing the cutting edge vibrating with high frequency or ultrasonic waves against the drain material.
The vibrating blade 11 may appropriately select an optimum shape depending on the required performance of the vibrator 112, the material of the drain material X, and the like.
The term "ultrasonic wave" in the present specification means a type of high frequency sound wave having a frequency of about 20 kHz or more.

<2.2> Expansion / contraction mechanism The expansion / contraction mechanism 12 is a mechanism for making the vibrating blade 11 movable in the front-rear direction of excavation.
A known telescopic jack can be used for the telescopic mechanism 12, and the tip of the telescopic jack is connected to the vibrating blade 11 while fixing the rear end of the telescopic jack to an arbitrary floating position of the shield excavator.
By expanding and contracting the telescopic jack in this state, the vibrating blade 11 can be made movable in the front-rear direction of excavation.

<3> Gas layer forming means The gas layer forming means 20 is a device for forming a gas layer around the drain cutter 10 when cutting the drain material X.
The gas constituting the gas layer 22 is not limited to air, and any kind of gas can be used alone or in combination.

<3.1> Method of forming a gas layer As a method of forming a gas layer 22 by the gas layer forming means 20, a pipeline in which a discharge port is located is provided around the drain cutter 10, and a conduit is provided through this conduit from a compressor. The method of sending the compressed gas of the above to mix the bubbles 21 into the water Z around the drain cutter 10 or by injecting the bubble agent into the water Z around the drain cutter 10 from the tank connected to the pipeline with a pump. There are a method of generating 21 and a mode in which these methods are appropriately combined.

<3.2> Gas layer formation location The gas layer 22 formation location may be around the drain cutter 10 (cutting work area) in a state where the drain cutter 10 is projected for cutting the drain material X. ..
Therefore, the gas layer forming means 20 is an embodiment in which the gas layer 22 is always formed at a position (cutting work area) where the drain cutter 10 is located when the drain cutter 10 is extended while being fixed to the shield excavator. Alternatively, the gas layer 22 may be formed around the drain cutter 10 by moving together with the drain cutter 10 protruding in the excavation direction.
In this embodiment, as in the former case, a mode in which the discharge port of the pipeline constituting the gas layer forming means 20 is fixed is adopted.

<3.3> Reason for providing a gas layer The energy loss due to the transmission of ultrasonic waves between media in contact with each other is determined by the magnitude of the difference in acoustic impedance between the media.
That is, if the difference in acoustic impedance between the media is small, the ultrasonic waves are more transmitted, so that the vibration of the vibrating blade 11 is easily transmitted to the surroundings and the energy loss is large. On the other hand, the larger the difference in acoustic impedance between the media, the more the ultrasonic waves are reflected, so that the vibration of the vibrating blade 11 is less likely to be transmitted to the surroundings and energy loss is less likely to occur.

<3.3.1> Acoustic impedance This acoustic impedance is obtained by ^{the product [kg / m 2 s] of the density [kg / m 3} ] of the medium and the speed of sound [m / s].
Since gases such as air have a much lower acoustic impedance than water, soil, and metals, the difference in acoustic impedance from the metal materials that make up the vibrating blade is naturally large. Become.
For example, when the vibrating blade 11 is made of aluminum, the acoustic impedance of aluminum is 17.3 × 10 ⁶ [kg / m ² s], and the acoustic impedance of water (25 ° C) is 1.5 × 10 ⁶ [kg / m ² s]. , The acoustic impedance of air (1 ° C, 1 atm) is 428 [kg / m ² s].
As described above, when the periphery of the vibrating blade 11 is covered with water or the like Z and when it is covered with the gas layer 22, the difference in acoustic impedance is larger in the latter case, so that the vibrating blade 11 Energy loss is less likely to occur.

<3.4> Usage procedure While proceeding with the excavation work by the excavation cutter provided in the shield excavator, if the drain material X to be cut approaches forward, it is cut by the gas layer forming means 20. With the gas layer 22 formed in the work area, the drain cutter 10 is moved forward of the excavation surface Y of the excavation cutter to cut the drain material X.
At this time, the space around the drain cutter 10 is in a state where water and soil are removed more than the other spaces by the gas layer 20 locally formed in the cutting work area.
Due to the presence of the gas layer 22, the drain material X can be cut without the vibration of the vibrating blade 11 of the drain cutter 10 coming into contact with water or the like and being attenuated.

<4> Summary As described above, according to the drain material cutting device A according to the present embodiment, the gas layer 22 is formed around the drain cutter 10, and the vibration of the drain cutter 10 is caused by the vibration of the drain cutter 10 when the drain material X is cut. By making it difficult for water or the like to be transmitted to Z, it is possible to suppress the damping of the vibration of the drain cutter 10. Therefore, it is not necessary to make the vibrator 112 used for the drain cutter 10 have an unnecessarily high output.

A Drain material cutting device 10 Drain cutter 11 Vibrating blade 111 Blade tip 112 Oscillator 113 Resonant body 12 Expansion and contraction mechanism 20 Gas layer shaping means 21 Bubbles 22 Gas layer X Drain material Y Digging surface Z Water, etc.

Claims (4)

It is a drain material cutting device installed in a shield excavator to cut the drain material embedded in the ground.
A drain cutter that is configured to project in the excavation direction and vibrates by high frequency or ultrasonic waves, rather than the excavation cutter provided on the front surface of the shield excavator.
A gas layer is formed by arranging the drain cutter in the radial direction of the shield excavator so as to sandwich the drain cutter and locally forming a gas layer for cutting the drain material around the drain cutter when cutting the drain material. Means and
It is characterized by having at least
Drain material cutting device. The gas layer forming means moves together with the drain cutter.
The drain material cutting device according to claim 1. The drain material cutting apparatus according to claim 1 or 2 , wherein the gas layer forming means includes at least a means for sending compressed air or a foaming agent around the drain cutter. It is a drain material cutting method that cuts the drain material embedded in the ground when digging the ground with a drain cutter installed in the shield excavator.
With the gas layer forming means arranged so as to sandwich the drain cutter in the radial direction of the shield excavator, the drain cutter is subjected to high frequency or high frequency while locally forming a gas layer for cutting the drain material around the drain cutter. The drain material is cut by vibrating with ultrasonic waves.
Drain lumber cutting method.

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