JP2678563B2 - Detection system of harmful gas in the face of shield method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for detecting harmful gas generated from the ground in a shield mine.

[0002]

2. Description of the Related Art Today, the shield construction method is widely used to install tunnels such as subway lines, water and sewage systems, and power communication cables in underground spaces of cities. The shield construction method constructs a vertical shaft, inserts a strong steel shell called a shield into the ground from the vertical shaft, excavates the natural ground in front of the space protected by the shield, and assembles segments at the rear part. This is a method to build a tunnel by advancing the shield while applying reaction force to the segment.

The underground where the above-mentioned shield method is constructed is under conditions where it is difficult to supply outdoor fresh air sufficiently. Therefore, especially when harmful gas such as combustible gas such as methane gas is generated from the ground, it is possible to promptly detect the harmful gas and inform the user that there is a risk of oxygen deficiency or explosion. Is essential.

Accordingly, a method has been adopted in which a check boring is performed from the ground before a shield reaches above a route where a tunnel is to be constructed by a shield method. In addition, a method of installing a gas detector inside the shield machine and measuring the gas concentration is also adopted.

[0005]

However, the check boring method has a problem in that it is not possible to grasp in real time the harmful gas generation state at the face where the construction is actually being performed. Further, since only a few places are checked, the inspection method is incomplete, and there is a problem that a boring cost is required.

Further, the method of measuring the gas concentration by the gas detector installed in the shield machine is such that the danger is detected only after the harmful gas is introduced even to the rear of the bulkhead of the shield machine. It is hard to say that this is a completely safe method for humans working in the mine, because it is not possible to grasp in real time the state of harmful gas generation at the face.

[0007] Therefore, an object of the present invention is to provide a system capable of promptly detecting harmful gas generated from the ground in a mine where the above shield construction method is applied.

[0008]

According to the present invention, in the shield construction method, a sampling chamber divided into an upper chamber and a lower chamber by an air permeable layer is provided inside the bulkhead that separates the soil chamber from the underground. A shield construction method in which a pipe for circulating mud in a soil chamber is connected to the lower chamber of the sampling chamber and a water supply port is provided, and a harmful gas detection sensor is disposed in the upper chamber of the sampling chamber. Provided is a system for detecting harmful gas in the face of a sword.

The detection system further has the following features. -The harmful gas is methane gas.・ The sampling chamber has a double structure consisting of an outer cylinder and an inner cylinder. The lower part of the outer cylinder is closed, the upper part of the outer cylinder is open, and the lower part of the inner cylinder and the inner part of the inner cylinder are separated by an air permeable layer. The upper part of the inner cylinder is closed, and the inner cylinder is vertically slidable along the inner surface of the outer cylinder.・ A mud suction port and a mud discharge port are formed in the bulkhead, and a pipe for introducing mud from the suction port to the lower chamber of the sampling chamber and a pipe for discharging the mud from the lower chamber of the sampling chamber to the discharge port. There must be a road. -A check valve must be provided at the mud discharge port formed on the bulkhead to prevent mud from entering the soil chamber.

[0010]

[Function] The gas generated at the face enters the soil chamber together with the mud excavated by the face, and is carried into the lower chamber of the sampling chamber through the pipeline. At the same time, water is supplied to the lower chamber of the sampling chamber from the supply port, and the lower chamber of the sampling chamber is filled with mud and water. As a result, the gas carried in together with the mud floats above the lower chamber of the sampling chamber due to the difference in specific gravity, and the gas further permeates the air permeable layer and enters the upper chamber of the sampling chamber. When harmful gas is present, it is detected as dangerous by a sensor arranged in the upper chamber of the sampling chamber. On the other hand, the water and mud in the lower chamber of the sampling chamber cannot permeate the air permeable layer, and then are transported to the soil chamber again through the pipeline. In this way, the mud excavated by the cutting face is constantly circulated to the lower chamber of the sampling chamber to detect the generation of toxic gas such as methane gas in the cutting face in real time and avoid the danger.

[0011]

[Embodiment] Hereinafter, a system for detecting harmful gas such as methane gas generated at a face will be described with respect to a shield method of earth pressure system. First, the earth pressure shield method will be described with reference to FIGS. 1 and 2. A cutter 2 is installed in front of the shield machine 1, and a soil chamber 3 is provided behind the cutter 2. Further, an earth discharging conveyor 4 having an outlet at the tail portion of the shield machine 1 is provided at substantially the center of the soil chamber 3. The soil chamber 3 and the mine are blocked by a bulkhead (partition wall) 5. The bulkhead 5 is a facility that shuts off the pressure side of the face and the atmosphere side of the mine.

A cutter bit is attached to the front surface of the cutter 2, and the cutter 2 is rotated to cut the ground, and the mud is taken into the soil chamber 3. Then, while using this cut mud to counter the pressure of the face, the belt conveyor 6 continuously supplies the earth discharging conveyor 4 provided in the soil chamber 3 with an amount of mud that balances with the amount of propulsion of the shield machine 1. The basic principle is to propel the shield machine 1 while stabilizing the face by removing soil.

In the earth pressure system shield construction method described above, the sampling chamber 7 is provided inside the mine of the bulkhead 5 which separates the earth chamber 3 from the mine. As shown in FIG. 3, the sampling chamber 7 has a double structure including an outer cylinder 8 and an inner cylinder 9. The lower part of the outer cylinder 8 is closed and the upper part of the outer cylinder 8 is open. On the other hand, the inner cylinder 9
The inside of the inner cylinder 9 is partitioned by an air permeable layer 10, and the upper part of the inner cylinder 9 is closed by a top plate 11. Inner cylinder 9
Is vertically slidable along the inner surface of the outer cylinder 8. Thus, inside the sampling chamber 7, the upper chamber 12 which is the inner space of the inner cylinder 9 and the lower chamber 13 which is the inner space of the outer cylinder 8 are separated by the air permeable layer 10.
Is formed. The air permeable layer 10 is from the lower chamber 13 to the upper chamber 12
It is a layer that allows gas to pass through but does not allow liquid or solid (including powder and fluid) to pass.

The top plate 11 of the inner cylinder 9 is provided with a sensor 14 for detecting harmful gas inside the upper chamber 12 of the sampling chamber 7. The sensor 14
When a harmful gas is present inside the upper chamber 12 of the sampling chamber 7, the display device 15 is connected to a display device 15 provided outside the sampling chamber 7 by a bus 16, and the display device 15 displays a light or the like and sirens. It is configured to issue an alarm such as.

Water supply lines 17, 17 are provided on both sides of the air permeable layer 10, and these water supply lines 17, 1 are provided.
Water is supplied to the lower chamber 13 of the sampling chamber 7 from the supply ports 18 formed at the lower end of the sampling chamber 7.

As shown in FIGS. 2 and 4, the bulkhead 5 is provided with a suction port 20 for mud and a discharge port 21 for mud. The suction port 20 is provided behind the bulkhead 5. Lower chamber 13 of sampling chamber 7
A pipe line 22 for carrying in the mud is provided, and a pipe line 23 for carrying out the mud from the lower chamber 13 of the sampling chamber 7 to the discharge port 21 is provided. These pipelines 22
The pipe 23 and the pipe 23 are each provided with a conveying means such as a snake pump, and the lower chamber 13 of the sampling chamber 7 is supplied with the mud in the soil chamber 3 in a circulating manner by the pipes 22 and 23.

As shown in FIG. 5, a check valve 25 is provided at the mud discharge port 21 formed in the bulkhead 5 to prevent the mud from entering the mud chamber 3. . Lower chamber 13 of sampling chamber 7 as shown
A backup plate 26 is provided in the vicinity of the outlet of the pipeline 23 for discharging the mud from the inside, and the mud carried out in the pipeline 23 passes through the gaps 27, 27 formed around the backup plate 26. And is discharged from the discharge port 21 into the soil chamber 3. A check valve main body 28 is provided around the discharge port 21, and rubber sheets 29, 29 fixed by the check valve main body 28 are arranged so as to close the gaps 27, 27 by its elasticity. Then, the mud in the pipeline 23 is constantly carried out through the gaps 27, 27, so that the rubber sheets 29, 29 are driven by the force.
Is bent as shown by the solid line in the figure, but the soil chamber 3
When the pressure of the mud inside becomes high, it is pressed down to the position indicated by the alternate long and short dash line 29 'in the figure to close the gaps 27, 27 around the backup plate 26, so that the mud inside the soil chamber 3 is closed. Is prevented from flowing back and trying to enter the pipeline 23.

In the detection system of the embodiment of the present invention described above, the harmful gas generated in the face is taken into the soil chamber 3 together with the mud excavated by the face,
The muddy soil suction port 20 formed in the bulkhead 5 enters the conduit 22. The mud that has entered the conduit 22 in this way is carried into the lower chamber 13 of the sampling chamber 7 by the operation of a transporting means such as a snake pump. As described above, the mud that has passed through the conduit 22 is vigorously carried into the lower chamber 13 of the sampling chamber 7. However, as described above, the inner cylinder 9 is configured to be vertically slidable inside the outer cylinder 8. Since the inner cylinder 9 rises when the mud is carried into the lower chamber 13 of the sampling chamber 7 and absorbs the supply pressure of the mud, the wall surface of the sampling chamber 7, the air permeable layer 10, etc. There is no harmful effect such as damage to the.

When the mud is carried into the lower chamber 13 of the sampling chamber 7 as described above, water is simultaneously supplied to the lower chamber 13 of the sampling chamber 7 from the supply port 18 via the supply pipe line 17. Thus, the lower chamber 13 of the sampling chamber 7 is filled with mud and water. As a result, the gas carried in together with the mud floats upward in the lower chamber 13 of the sampling chamber 7 due to the difference in specific gravity thereof, and the gas is further absorbed in the air permeable layer 10.
To penetrate into the upper chamber 12 of the sampling chamber 7.

Thus, when harmful gas is generated in the face, the harmful gas is promptly brought into the upper chamber 12 of the sampling chamber 7 through the process described above, and the top plate 11 of the inner cylinder 9 is carried out. Its presence is immediately detected by the sensor 14 arranged at. Then, the display device 15 displays a light or the like, and an alarm such as a siren is issued to inform the worker or the like in the shield pit of the danger.

On the other hand, the lower chamber 1 of the sampling chamber 7
Since the water and mud in 3 cannot pass through the air permeable layer 10,
After being discharged from the discharge port 21 through the duct 23, the soil chamber 3 is again discharged.
To be carried out. As described in FIG. 5, the outlet 2
Since the check valve 25 is provided in No. 1, even if the pressure of the mud in the soil chamber 3 becomes high, the mud in the soil chamber 3 does not flow backward and there is no concern that the pipe line 23 is clogged.

As described above, in the detection system according to the embodiment of the present invention, the mud excavated by the cutting face is circulated and supplied to the lower chamber 13 of the sampling chamber 7 to prevent the generation of toxic gas such as methane gas at the cutting face. Real-time detection can be done to avoid danger.

Although the embodiment of the detection system of the present invention has been described with respect to the earth pressure type shield construction method, the present invention can be applied to other shield construction methods such as a muddy water shield construction method.

[0024]

According to the present invention, the harmful gas generated from the ground in the mine where the shield method is applied can be detected promptly, and a safe and hygienic working environment can be provided.

[Brief description of the drawings]

[Fig. 1] Illustration of earth pressure shield method

[Figure 2] Front view of the shield machine

FIG. 3 is a vertical sectional view of a sampling chamber.

FIG. 4 is an explanatory view showing a pipeline for circulating mud in a soil chamber in a lower chamber of a sampling chamber.

FIG. 5 is an enlarged cross-sectional view of a mud discharge port formed on a bulkhead.

[Explanation of symbols]

 3 Soil chamber 5 Bulkhead 7 Sampling chamber 10 Air permeable layer 12 Upper chamber 13 Lower chamber 14 Sensor 18 Water supply port 22, 23 Pipe line

Claims (5)

(57) [Claims] 1. A sampling chamber, which is divided into an upper chamber and a lower chamber by an air permeable layer, is provided inside the mine of the bulkhead that separates the soil chamber from the mine in the shield method.
In the lower chamber of the sampling chamber, a pipe for circulating mud in the soil chamber is connected and a water supply port is provided.
A system for detecting harmful gas in a face of a shield construction method, wherein a sensor for detecting harmful gas is provided in the upper chamber of the sampling chamber. 2. The harmful gas detection system in the face of the shield construction method according to claim 1, wherein the harmful gas is methane gas. 3. The sampling chamber has a double structure consisting of an outer cylinder and an inner cylinder. The lower part of the outer cylinder is closed, the upper part of the outer cylinder is opened, and the lower part of the inner cylinder and the inner part of the inner cylinder are permeable to air. The face of the shield construction method according to claim 1 or 2, wherein the inner cylinder is divided into layers and the upper part of the inner cylinder is closed, and the inner cylinder is vertically slidable along the inner surface of the outer cylinder. Gas detection system in Japan. 4. A mud suction port and a mud discharge port are formed in the bulkhead, and a pipe line for introducing mud into the lower chamber of the sampling chamber from the suction port and a lower chamber of the sampling chamber from the discharge port. 4. A system for detecting harmful gas in a face of a shield construction method according to claim 1, wherein a pipe line for carrying out mud is provided. 5. The check valve according to claim 4, wherein a check valve for preventing the mud in the soil chamber from entering is provided at the mud discharge port formed in the bulkhead. Detection system of harmful gas in the face of shield method.