JPH05202693A - Mechanical shield excavation method using foaming agent - Google Patents

Abstract

PURPOSE:To improve execution efficiency by foaming liquid containing foaming agent, feeding the bubble to a working face or a soil pressure chamber, stirring and mixing muck and the bubble, and drilling the working face against the soil pressure and the water pressure by the use of the muck containing the bubble. CONSTITUTION:Liquid containing foaming agent stored in a storage tank 11 is stirred together with air supplied from a compressor 14 in a forming device 13 so as to generate bubble. Next, this bubble is fed at least to either of the working face of a cutter head 2 or a soil pressure chamber 7 provided in a mechanical shield machine 1 through feed pipes 15, 16. Next, friction resistance between the cutter head 2 and the working place is reduced by lubricating action of the bubble, and the muck and the bubble taken into the soil pressure chamber 7 are stirred and mixed to be the muck. The working place is drilled with the cutter head 2 against the soil pressure of the working place and the underground water pressure by the use of the muck containing the bubble, and the muck is discharged. Hereby, cutter torque can be reduced.

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 mechanical shield excavation method.

[0002]

2. Description of the Related Art Conventionally, as a mechanical shield excavation method, a soil type of a type in which an open front end of a rotary driven screw conveyor is inserted into an earth pressure chamber defined between a cutter head and a partition wall has been generally used. Using a pressure shield machine, the shear excavated by the cutter head is taken into the earth pressure chamber to fill the earth pressure chamber with the shear, and then the screw conveyor discharges the shear to the outside. ..

[0003]

However, in the above-mentioned method, when excavating sandy ground or gravel ground that has stagnant water, a screw conveyor is used in a series of steps from excavation on the face to discharge of the shear. The water-stopping effect inside was not so expected, and the outflow of soil water sometimes induced the collapse of the face. In order to prevent this, if a valve is attached to the discharge port of the screw conveyor to try to squeeze out runoff water, an arching phenomenon will occur in the soil pressure chamber, making it impossible to discharge soil, and there will be insufficient torque on the cutter head. There was a problem.

Further, when excavating the cohesive ground, there is a problem that the cohesive soil adheres to the cutter head and the inner wall of the earth pressure chamber to increase the frictional resistance between the shield and the surrounding ground, which makes the excavation difficult. there were.

In order to solve such problems and improve the workability, sandy soil or gravel soil has conventionally been used in sandy soil or gravel soil by injecting bentonite or other mud soil material into the soil pressure chamber. Construction methods have been adopted to increase the fluidity of excavated slides and to improve the water cutoff at the same time. However, in order to impart fluidity and water shut-off to the excavation shear, a large amount of mud soil material must be injected, which requires the primary and secondary treatment of the discharged excavation shear. There was a problem in terms of efficiency. In addition, no effective measures have been found for the excavation of clayey ground.

The present invention has been made in view of the above problems, and it is an object of the present invention to reduce friction between a cutter head and a cutting face, and to improve fluidity and water stoppage during excavation shearing. The purpose of the present invention is to provide a mechanical shield excavation method which prevents the arching phenomenon in the earth pressure chamber by applying the above-mentioned method and which does not require the post-treatment of the discharged excavation shear and has good workability.

[0007]

To achieve the above object, the present invention provides a method of excavating a mechanical shield, comprising:
By agitating and mixing the step of supplying the air bubbles generated by foaming the liquid containing the foaming agent to at least one of the face face and the earth pressure chamber, and the excavation shear and the air bubbles taken into the earth pressure chamber. , A step of creating an excavation shear having a fluidity and a water stop including bubbles, a step of excavating the face of a face against the earth pressure and groundwater pressure of the face by the excavation shear including bubbles, And a step of discharging the excavated shear.

[0008]

According to the present invention having the above-described structure, the bubbles generated by foaming the foaming agent are supplied to at least one of the face face in front of the cutter head of the earth pressure shield machine and the earth pressure chamber. Therefore, it is possible to reduce the frictional resistance between the cutter head and the face to reduce the cutter torque. In addition, the excavation shear that contains air bubbles and is rich in fluidity and waterproofness is created in the soil pressure chamber to counteract the earth pressure and groundwater pressure of the face and prevent the arching phenomenon of the excavation shear in the soil pressure chamber. It becomes possible to do. Further, since the excavated shear including air bubbles fills the earth pressure chamber and is then smoothly taken into the screw conveyor, the water stoppage in the screw conveyor can be enhanced, resulting in extremely good construction efficiency. In addition, the bubbles in the excavation discharged from the screw conveyor gradually disappear over time and return to the original excavation containing no bubbles. Unlike excavated shear containing mud material,
No primary or secondary treatment is required for excavation shear after unloading.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a cross-sectional view of a hollow cylindrical earth pressure shield machine used in the method of the present invention, and FIG. 2 shows a front view thereof. This earth pressure shield machine 1 has a cutter head 2 for excavation at the front end thereof. The cutter head 2 is supported by a support girder 3 on its back surface, and is rotationally driven by a drive motor 5 via a transmission mechanism 4. A partition wall 6 is provided behind the cutter head 2, and an earth pressure chamber 7 is defined between the partition wall 6 and the cutter head 2. Reference numeral 8 is a screw conveyor that is rotationally driven by a drive motor (not shown), and the tip portion thereof penetrates the partition wall 6 and opens in the earth pressure chamber 7. The support girder 3 also has a function of a stirring blade as described later. As shown in FIG. 2, the front surface of the cutter head 2 is composed of three spokes 9, and a plurality of cutter bids 19 are fixed to each spoke. In addition, a slit opening 10 is formed between the spokes 9 for taking in the excavated shear.

A liquid storage tank 11 in which a liquid containing a foaming agent is stored is provided behind the partition wall 6, and an injection pump 12 arranged in front of the liquid storage tank 11 supplies a desired amount of the liquid in the tank 11 to the foaming device 13. Supplied. The foaming device 13 contains a plurality of resistors (not shown) for foaming the liquid containing the foaming agent that has been pumped by the air from the compressor 14 to generate bubbles. The generated bubbles are sent to the face face and the earth pressure chamber 7 via the supply pipes 15 and 16, respectively. As shown in the drawing, a supply branch pipe 16a having a diameter smaller than that of the supply pipe 16 is branched from the supply pipe 16 opening on the front surface of the cutter head 2 to the peripheral side portion 2a of the cutter head 2. There is.

In the figure, reference numeral 17 is a shield propelling jack, 18 is a segment, 20 is a universal joint, and 21 is a valve.

Next, a description will be given of an implementation point of the method of the present invention. First, the earth pressure shield excavator 1 applies a reaction force to the segment 18 assembled in the rear of the earth pressure shield excavator 1 and is propelled toward the face by the shield propulsion jack 17 having one end fixed to the excavator 1. In parallel with this, the foaming agent previously diluted to an arbitrary concentration with water and stored in the liquid storage tank 11 is pressure-fed to the foaming device 13 by the injection pump 12. The liquid containing the foaming agent is agitated together with the air from the compressor 14 by the plurality of resistors incorporated in the foaming device 13, is converted into shaving foam-like fine bubbles, and is pumped to the supply pipes 15 and 16, respectively. To be done. The bubbles fed under pressure are supplied toward the inside of the earth pressure chamber 7 from the open end of the supply pipe 15, and the supply pipes 16, 16
It is supplied from the opening end of a toward the face of the face and the peripheral side portion 2a of the cutter head 2, respectively. This reduces the frictional resistance between the front surface of the cutter head 2 and the face of the cutting face, and between the skin plate of the shield machine 1 and the surrounding ground. When the surrounding ground is made of cohesive soil, the cohesive soil is prevented from adhering to the cutter head 2 or the skin plate, so that the friction resistance is more significantly reduced.

On the other hand, the shear generated by the rotating cutter head 2 excavating the face face flows into the earth pressure chamber 7 through the slit opening 10 together with the bubbles. Earth pressure chamber 7
Inside, the support girder 3 rotating together with the cutter head 2 mixes and agitates the excavation shearing and air bubbles to create a bubbled excavation shearing which is rich in fluidity and water shutoff. The excavation sheared with air bubbles filled in the earth pressure chamber 7 resists the earth pressure and the groundwater pressure of the face due to the earth pressure.
It moves inside, is taken into the opening of the screw conveyor 8, and is carried out of the earth pressure chamber 7. Screw conveyor 8
The excavated excavation sheared with air bubbles discharged from the mine is carried out of the mine by a conveyor (not shown) such as a belt conveyor, a truck, a pressure pump, and a pipeline. The bubbles in the excavation carried out to the outside of the mine gradually disappear with the passage of time, and the excavation returns to the state before the bubbles were added.

The foaming agent used in the method of the present invention includes:
Protein type foaming agents and surfactants are suitable. Examples of protein-based foaming agents include non-toxic animal hydrolyzed proteins. This has an excellent foaming action, and the obtained bubbles are stable. Examples of the surfactant include higher alkyl ether sulfate ester salts which are anionic surfactants. In particular, sodium lauryl ether sulfate has an excellent foaming action. In addition to this, an aqueous solution of a water-soluble polymer substance such as water-soluble cellulose ether may be used as a foaming agent. For example, a mixed solution of methyl cellulose as a water-soluble polymer and a super absorbent resin is suitable as a foaming agent.

In addition, particularly when excavating water-bearing gravel ground where bubbles are easily defoamed, bubbles having a tough film can be obtained by adding an aqueous dispersion of a superabsorbent resin to a foaming agent.

Further, when excavating the clay ground,
It is preferable to use an aqueous solution of benzalkonium chloride or an aqueous solution of dodecyltrimethylammonium chloride. Also,
A mixed solution obtained by adding a water-soluble polymer substance such as methylcellulose to these aqueous solutions may be used.

In the embodiment described above, the infusion pump 12 and the foaming device 13 are constructed so that the operator can manually control them based on the progress of the shield. However, it is also possible to configure the computer incorporated in the shield machine 1 to automatically control the injection amount and the injection pressure of the bubbles.

That is, the shield machine is provided with a cutter torque detecting means and an earth pressure detecting means in the earth pressure chamber 7 as an input for grasping the excavation state of the shield. The measured values of the cutter torque and earth pressure sent from these detecting means in real time are input to the control means including a CPU, a memory, an input / output interface and the like. The control means calculates the rotational speed of the screw conveyor 8 that carries out the excavation shear in the earth pressure chamber 7 and injects bubbles into the face and the earth pressure chamber 7 in accordance with a program stored in advance in the memory. The operation speeds of the injection pump 12 and the foaming device 13 for controlling the amount and the injection pressure are calculated. Based on these calculation results, the screw conveyor 8, the injection pump 12, and the foaming machine 13 are controlled via the output interface so that excavation is performed while maintaining the cutter torque and earth pressure at proper values.

[0019]

As described above in detail with reference to the embodiments, according to the present invention having the above-mentioned structure, at least one of the face face in front of the cutter head of the earth pressure shield machine and the earth pressure chamber, Since the bubbles generated by foaming the foaming agent are supplied, it is possible to reduce the frictional resistance between the cutter head and the face surface and reduce the cutter torque.

In addition, an excavating shear containing air bubbles, which is rich in fluidity and waterproofness, is created in the earth pressure chamber to counteract the earth pressure and groundwater pressure of the face by the earth pressure, and arching of the excavation shear in the earth pressure chamber It is possible to prevent the phenomenon.

Further, since the excavated shear containing air bubbles fills the earth pressure chamber and is then smoothly taken into the screw conveyor, the water stoppage in the screw conveyor can be enhanced, so that the construction efficiency becomes extremely good. ..

In addition, the air bubbles in the excavation shear discharged from the screw conveyor have the property of gradually disappearing with the passage of time and returning to the original excavation shear without bubbles, so that a large amount of conventional bentonite is produced. Unlike other excavations that contain mud soil materials, 1 against the excavations that have been carried out
Various excellent effects are achieved, such as the need for secondary and secondary processing.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an earth pressure shield excavator used for carrying out the method of the present invention.

2 is a front view of the excavator shown in FIG. 1. FIG.

[Explanation of symbols]

 1 Earth Pressure Shield Machine 2 Cutter Head 7 Earth Pressure Chamber 8 Screw Conveyor 11 Liquid Storage Tank 13 Foamer 14 Compressor 15,16 Supply Pipe 16a Supply Branch Pipe

Claims (13)

[Claims] 1. A method of excavating a mechanical shield, comprising the steps of supplying air bubbles generated by foaming a liquid containing a foaming agent to at least one of a face face and an earth pressure chamber, and incorporating it into the earth pressure chamber. A step of creating a drilling shear having a fluidity and a water stop including bubbles by agitating and mixing the drilled shear and the bubbles, and the earth pressure and the groundwater pressure of the face are counteracted by the drilling shear containing bubbles. A mechanical shield excavation method using a foaming agent, which comprises a step of excavating a cutting face and a step of discharging excavation shear from the earth pressure chamber. 2. A method for excavating an earth pressure shield machine, wherein bubbles generated by agitating a liquid containing a foaming agent stored in a liquid storage tank in advance with air supplied from a compressor in a foaming machine. Supplying at least one of the face of the cutter head and the earth pressure chamber via a supply pipe, and stirring the excavated shear and air bubbles taken into the earth pressure chamber from the slit opening formed in the cutter head. A step of creating a drilling shear having a fluidity and a water stop containing bubbles by mixing, and a cutting head is drilled by a cutter head while counteracting earth pressure and groundwater pressure of the face by the drilling shear containing bubbles A mechanical shield digging using a foaming agent, which comprises a process and a process of discharging the digging shear from the earth pressure chamber by a screw conveyor. Method. 3. The foaming agent comprises a protein-based foaming agent,
A mechanical shield excavation method using the foaming agent according to claim 1. 4. The mechanical shield excavation method using a foaming agent according to claim 1, wherein the foaming agent contains a surfactant. 5. The foaming agent includes a water-soluble polymer substance,
A mechanical shield excavation method using the foaming agent according to claim 1. 6. The mechanical shield excavation method using a foaming agent according to claim 5, wherein the water-soluble polymer substance is water-soluble cellulose ether. 7. The mechanical shield excavation method using a foaming agent according to claim 6, wherein the water-soluble cellulose ether is methyl cellulose. 8. The mechanical shield excavation method using a foaming agent according to claim 6, wherein the water-soluble cellulose ether is ethyl cellulose. 9. The mechanical shield excavation method using a foaming agent according to claim 1, wherein the foaming agent contains a highly water-absorbent resin. 10. The mechanical shield excavation method using a foaming agent according to claim 1, wherein the foaming agent contains benzalkonium chloride. 11. The mechanical shield excavation method using a foaming agent according to claim 1, wherein the foaming agent contains dodecyltrimethylammonium chloride. 12. A mechanical shield excavation method using a foaming agent according to claim 1, further comprising a step of supplying the bubbles so as to be interposed between an outer peripheral side portion of the shield and a surrounding ground. . 13. The supply amount and supply pressure of the bubbles are
The mechanical shield excavation method using a foaming agent according to claim 1, which is automatically controlled by a control means attached to the shield.