JPH0218886B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field) Regarding a method for treating excavated soil in a shield tunnel excavation method, in particular, air bubbles are added to excavated soil in front of a partition wall of a shield body, and the excavated soil is discharged from the front of the partition wall to the rear. The present invention also relates to a method for treating excavated soil that eliminates air bubbles in the excavated soil discharged behind the partition wall.

(Prior art) One of the seed tunnel excavation methods involves supplying a foaming agent to the front of the bulkhead of the shield body in order to reduce the cutting resistance of the rotary cutter on the face ground or to provide fluidity and water sealing properties to the excavated soil. air bubbles are added to the ground or excavated soil to prevent the face from collapsing due to pressure drop in the pressurized area in front of the bulkhead. While considering
There is an excavation method that discharges water continuously or intermittently into the atmospheric pressure area behind the bulkhead.

Conventionally, excavated soil containing air bubbles in such excavation methods has been directly transported to an earth dumping site and discarded without removing the air bubbles. For this reason, the excavated soil deposited in the soil dumping site remains with air bubbles trapped therein. As described above, if air bubbles remain in the excavated earth and sand that has been deposited, the ground becomes soft due to the air bubbles, and the air bubbles also flow out into rivers, lakes, and marshes together with rainwater.

One of the processing methods to eliminate such defects is
There is a method of eliminating air bubbles in the earth and sand by adding an antifoaming agent to the aerated excavated earth and sand discharged behind the partition wall and stirring and mixing the earth and sand. However, this treatment method uses an air entraining agent such as a nonionic active agent such as a polyoxy compound or a sulfone compound as a foaming agent, and a surfactant such as ethyl alcohol as an antifoaming agent. Even if the bubbles are removed, the foaming agent and antifoaming agent remain in the soil without being decomposed, and the foaming agent and rainwater flow into rivers, lakes and marshes, causing natural destruction. There is a problem of causing serious pollution.

(Object of the invention) The present invention can reliably eliminate air bubbles,
Another object of the present invention is to provide a method for treating excavated soil that does not cause pollution due to the use of foaming agents and antifoaming agents.

(Structure of the Invention) The method for treating excavated soil of the present invention includes supplying air bubbles generated by a foaming agent decomposable by enzymes to the front of the partition wall of the shield main body to impart the air bubbles to the excavated earth and sand. is discharged behind the partition wall, and the enzyme that decomposes the foaming agent is added to the excavated soil discharged behind the partition wall to decompose the foaming agent.

As the foaming agent, hydrolyzed proteins or stearic acid-based fat-proofing agents can be used. Further, as the enzyme, protease can be used if the foaming agent is a hydrolyzed protein, and lipase can be used if the foaming agent is a stearic acid-based fat-proofing agent.

(Effects of the Invention) According to the present invention, since a foaming agent that can be decomposed by an enzyme is used and an enzyme that can decompose the foaming agent is used as an antifoaming agent, the foaming agent can be decomposed by the enzyme. Decomposition ensures that air bubbles are eliminated. In addition, the enzyme itself is a harmless substance and is decomposed into harmless substances by foaming agents and enzymes.
Foaming agents and antifoaming agents do not cause pollution.

(Example) Hereinafter, an example of the present invention shown in the drawings will be described.

The shield tunnel excavation device 10 shown in the figure is an earth pressure shield excavation machine, and has a cylindrical shield body 1.
2 and a plurality of jacks 14 for advancing the main body. The jack 14 has a segment 16 arranged behind the main body 12 as the tunnel is excavated.
obtains a reaction force. A partition wall 18 is provided within the main body 12, and the partition wall separates the interior of the main body 12 into a pressure region 20 in front of the partition wall and an atmospheric pressure region 22 behind the partition wall.

A cutter head 24 is rotatably supported on the partition wall 18. The cutter head 24 is rotated by a drive mechanism 26 to excavate a face 28. The earth and sand excavated by the cutting head 24 is discharged from the pressure area 20 to the atmospheric pressure area 22 by the earth and sand discharger 30.

In the illustrated example, the earth and sand discharger 30 includes a screw conveyor 32 and a drive mechanism 34 that drives this, and discharges excavated earth and sand at a speed that does not cause collapse of the face 28 due to a pressure drop in the pressure region 20. is discharged from the discharge port 36 onto the belt conveyor 38.
The excavated earth and sand discharged onto the belt conveyor 38 is further conveyed to the rear by the belt conveyor 38,
From the belt conveyor 38, it is transported to the ground by another transporting machine such as a slider.

The excavation device 10 also includes a bubble adding machine 40 that supplies bubbles to the front of the partition wall 18, and an antifoaming agent adding machine 42 that adds a defoaming agent to the excavated soil discharged to the rear of the partition wall 18. Also, Katsutahed 24
includes a hole 44 for supplying air bubbles, and a plurality of spout ports 46 that eject the air bubbles supplied to the hole toward the face;
It has stirring blades 48 that stir the excavated earth and sand to give fluidity to the excavated earth and sand.

The foam adding machine 40 includes a tank 4 that stores a foaming agent.
9, a foaming machine 50 that generates bubbles using the foaming agent supplied from the tank via a pipe 51 with compressed air, and a foam supply pipe 52, and a foaming machine 50 that generates bubbles in the foaming machine 50. The feed pipe 5
2 to the pressure region 20 and to the face 28 via the hole 44 in the cutter head 24.

The antifoaming agent addition machine 42 includes a tank 54 that stores the antifoaming agent, and a sprayer 56 that sprays the antifoaming agent.
The antifoaming agent in the tank 54 is supplied to the sprayer 56 via a pipe 58. The spreader 56 is disposed above the conveyance end portion of the belt conveyor 38 and sprays an antifoaming agent onto the excavated soil conveyed by the belt conveyor 38. Since the antifoaming agent can be supplied to the excavated soil discharged to the rear of the bulkhead, the soil discharging machine 3
Excavated soil during discharge by 0, belt conveyor 3
It may be added to any of the excavated soil that is being transported to the ground by 8 or other conveying devices such as a sliding trolley, or to the excavated soil that has been transported to the ground.

The foaming agent stored in the tank 49 is one that can be decomposed by enzymes, such as hydrolyzed proteins and stearic acid-based fat-proofing agents. The water-soluble foaming agent is dissolved in water and stored in the storage tank 49, and the water-insoluble foaming agent is dispersed in water and stored in the storage tank 49.
It is stored in 9.

The antifoaming agent stored in the tank 54 is an enzyme that decomposes the foaming agent, such as protease or lipase. Since these antifoaming agents are water-soluble, they are dissolved in water and stored in the tank 54.

During excavation, the drilling rig 10 excavates the face 28 with the cutter head 24 while supplying bubbles generated by the liquid containing the foaming agent to the pressure region 20 and the face 28 from the bubble adding machine 40. Therefore, the excavated earth and sand is stirred by the rotation of the stirring blade 48 in conjunction with the rotation of the cutter head 24, and the above-mentioned air bubbles are added to the excavated earth and sand.

The excavated soil to which air bubbles have been added is transported to the soil ejector 30.
is discharged from the pressure region 20 to the atmospheric pressure region 22,
The belt conveyor 38 further conveys it to the rear.

A liquid containing the enzyme as an antifoaming agent is sprayed onto the excavated earth and sand conveyed by the belt conveyor 38 by an antifoaming agent sprayer 42 . As a result, the foaming agent in the excavated soil is decomposed by the enzyme, so that the air bubbles in the excavated soil are eliminated.

Hydrolyzed proteins used as foaming agents include the trade name "Telfoomer 55" (manufactured by Delnight Co., Ltd.). This Telfomer 55 is water-soluble and its properties are as follows.

Main ingredient: Animal hydrolyzed protein (raw material is cow hoof horn powder) Appearance: Dark brown liquid Specific gravity: 1.16 PH: Neutral Enzymes that decompose Telfhomer 55 are available under the trade names ``Biobrase'' and ``Denapsin'' (Nagase Sangyo Co., Ltd.) Co., Ltd.). These are water-soluble and their main component is protease.

When the above-mentioned enzyme is sprayed on the excavated soil to which air bubbles have been added using Telfoomer 55, the protein in the foaming agent is decomposed by the enzyme and converted into amino acids, and the amino acids are further decomposed by bacteria in the excavated soil to form ammonia, Water becomes carbon dioxide gas. In addition, air bubbles in excavated soil disappear during the process in which proteins are decomposed by enzymes and converted into amino acids.

For fatty acids as a foaming agent, use the product name ``Nopco DC''.
-100-A” (manufactured by San Nopco Co., Ltd.). This Nopco DC-100-A is an aqueous ammonium stearate dispersion, and its properties are as follows.

Main ingredient: Ammonium stearate (raw material is beef tallow) Appearance: White liquid Solid content: 33% Viscosity: 50 cPs (25 degrees C) As an enzyme that decomposes Nopco DC-100-A,
The product names are "Lipase AP" and "Lipase M-AP" (manufactured by Amano Pharmaceutical Co., Ltd.). These are water-soluble and their main component is lipase.

When the enzyme is sprayed on excavated soil to which air bubbles have been added using Nopco DC-100-A, the lipase decomposes ammonia stearate and eliminates air bubbles.

By using the above-mentioned foaming agent and enzyme, air bubbles in excavated soil can be effectively eliminated, and since the foaming agent is decomposed into harmless substances by enzymes and bacteria in excavated soil, foaming Foaming agents and antifoaming agents do not cause pollution.

[Brief explanation of drawings]

The figure is a sectional view showing an embodiment of an excavation device implementing the present invention. 12: Shield main body, 20: Partition wall, 24: Cut head, 40: Foam adding machine, 42: Antifoaming agent spraying machine.

Claims (1)

[Scope of Claims] 1. Supplying air bubbles generated by a foaming agent decomposable by enzymes to the front of the partition wall of the shield body to impart the air bubbles to the excavated earth and sand, and discharging the excavated earth and sand behind the partition wall, A method for treating excavated soil, comprising adding the enzyme that decomposes the foaming agent to the excavated soil discharged behind the partition wall to decompose the foaming agent. 2. Claim 1, wherein the foaming agent is a hydrolyzed protein, and the enzyme is a protease.
The method for treating excavated soil as described in section. 3. The method for treating excavated earth and sand according to claim 1, wherein the foaming agent is a stearic acid-based fatty acid, and the enzyme is lipase.