JPH0449399A - Stabilization of working face in mud pressure shield driving method - Google Patents

Abstract

PURPOSE:To stabilize a working face in a soil pressure shield process, by adding a slurry material to the soil excavated by a shield machine to knead it for fluidizing and pressing it to resist the earth pressure and further, by feeding the compressed air into the chamber. CONSTITUTION:The soil excavated by the cutter 11 of a shield machine 10 is mixed with the slurry material from a feed pipe in a chamber 12 to fluidize it with plasticity by agitation thereof. Next, the soil is pressurized by a shield jack 14 to resist the earth pressure. During mixture, compressed air is conducted through an air duct 15 from a plurality of places to the chamber 12. Next, at the same time, the residual soil within the chamber 12 is discharged from a screw conveyor 17 and discharged to the ground level by a belt conveyor 18. And underground water is discharged by the compressed air pressure to prevent inflow into the chamber 12. In this way, breaking down of facing site can be securely prevented and the treating cost of residual soil can be reduced.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for stabilizing a face in a mud pressure shield construction method.

[Conventional technology]

The mud pressure soil method adds additives to the earth and sand excavated by a shield excavator, mixes and fluidizes it in the shield excavator's chamber, and stabilizes the face by pressurizing it and pushing it against the ground. There are two typical conventional methods, depending on how additives are used. (1) Mud pressurized shield construction method As shown in Figure 2, this construction method applies clay-based slurry material to the earth and sand that has been cut by the cutter 2 of the shield excavator 1 in accordance with the grain size characteristics of the ground. The slurry material is injected into the chamber 4 through the slurry injection pipe 3, stirred and kneaded to form plastic fluidized sand, and this is pressurized by the sealing machine 5 to counteract the ground, thereby stabilizing the face. The remaining soil from the screw conveyor 6 is discharged by the screw conveyor 6, and while a predetermined pressure is maintained, the remaining soil from the screw conveyor 6 is carried outside the mine by the held conveyor 7. (2) Cellular sole construction method This construction method involves mixing independent air bubbles with the excavated soil as an additive to turn the excavated soil into fluidized soil in a chamber, which is then pressurized in the same manner as above, and the remaining soil is discharged. It is.

[Section B that the invention will solve]

In both conventional methods, additives are added to the excavated soil to make it plastically fluid, and the face is stabilized simply by pressurizing this with a shield jack, which results in the following problems: there were. That is, especially when excavating sandy or highly viscous strata,
Excavated soil solidifies in the chamber, making it difficult to take in new excavated soil into the chamber, increasing thrust and cutter pressure, and reducing excavation speed. In addition, the plastically fluidized earth and sand in the chamber is an incompressible semi-solid, and if it is not discharged by a screw conveyor to prevent volume changes within the chamber, pressure fluctuations will occur within the chamber. As the fluctuations occur, groundwater flows into the chamber, making the face unstable. However, it is difficult to accurately link the shield excavation speed and the earth removal action of the screw conveyor due to changes in the physical properties of the earth and sand. Therefore, if the amount of soil discharged by screw con-hair is greater than the amount of excavated soil, Channo\
A void is created in the upper part of the tank, creating negative pressure and allowing groundwater to flow in. The inflowing groundwater changes the physical properties of the earth and sand, which changes the discharge efficiency of the screw container. This makes the amount of earth and sand discharged by the screw conveyor unstable, which further worsens the situation inside the chamber. As a result, there were the following drawbacks. ■ The face is more likely to collapse. ■ The earth and sand discharged from the screw conveyor becomes overflowing mud, making workability difficult. In other words, the overflowing mud flows down from the heldcon 7 into the mine, and it takes time to clean it up.Also, the hetonite in the slurry remains in the discharged soil, so it is treated as industrial waste and cannot be used with a vacuum truck or the like. It requires transportation, drying, or dewatering, which increases the cost of disposing of the remaining soil. An object of the present invention is to solve the above-mentioned problems caused by the conventional mud pressure Nordwe method.

[Means to solve the problem]

In the method according to the present invention, compressed air is forced into a chamber where excavated earth and sand and additives are mixed, thereby stabilizing the face.

[For production]

When compressed air is injected into a chamber where excavated soil and additives are mixed and fluidized, even if a void is created in the upper part of the chamber due to excessive or insufficient discharge of soil, the compressed air will fill the void. This momentarily expands and compensates for the pressure, preventing groundwater from flowing into the chamber. In addition, air enters between the excavated soil particles, reducing the friction between the soil particles, improving the fluidity of the soil, and preventing the soil from consolidating in the chamber even in sandy layers or strata with high viscosity. Therefore, the earth and sand can be smoothly discharged from the chamber, the thrust force and the rotational force of the cutter are reduced, and the excavation speed is increased.

【Example】

Hereinafter, one embodiment of the present invention will be described based on the drawings. In the first round, the excavated soil excavated by the cutter 11 of the shield excavator 10 is transferred to the chamber 1 of the shield excavator 10.
2, the slurry material is mixed with the slurry material from the slurry material injection pipe 13, and is plastically fluidized by being agitated by an agitator (not shown). The fluidized earth and sand is pressurized by the sandstone 14 and counteracts the ground. While the excavated earth and sand are being mixed with the slurry material, compressed air is forced into the chamber 12 from a plurality of locations through the air pipe 15. The air pressure is slightly higher than the underground water pressure of the ground (e.g. 0.2 kg/cd
(moderately high) pressure. In order to set the pressure, a pressure setting device and a receiver tank (not shown) are placed in the middle of the air pipe 15. Compressed air is press-fitted continuously or intermittently through holes provided in a plurality of locations in the partition wall 16. On the other hand, at the same time, the remaining soil in the chamber 12 is discharged by the screw con-hair 17, and then the con-hair 1
8 to take it out of the mine. As mentioned above, if compressed air is injected into the mix between the excavated earth and sand and the slurry material in the chamber 12, even if a void is created in the upper part of the chamber 12 due to excess or insufficient amount of earth and sand discharged, the compressed air will fill the void. enters and expands instantaneously to compensate for the pressure, and since the compressed air pressure is higher than the groundwater pressure, the groundwater in the face is also removed, and groundwater is reliably prevented from flowing into the chamber 12. Therefore, since the remaining soil is discharged from the chamber 12 in a dehydrated state, the remaining soil can be disposed of as general construction surplus soil in an ordinary dump trunk.Moreover, the remaining soil does not flow down into the mine, so the remaining soil disposal work is easy. becomes very easy. In addition, in the slurry material injected into the chamber 12, only the moisture is released into the ground by compressed air, and only the binder remains and acts against the ground, so the soil is stable and there is no over-digging, and it also causes pollution. There is no problem with occurrence. In addition, air enters between the excavated soil particles, reducing friction between the soil particles and improving the fluidity of the soil. Therefore, even in sandy or highly viscous strata, the chamber 1
2, it will not be difficult to take newly excavated earth into the chamber 12 due to consolidation of earth and sand, and the earth and sand will be taken into the screw container 17 smoothly. The force decreases and the digging speed increases.

【Effect of the invention】

According to the present invention, there are the following effects. ■ Since the pressure inside the chamber can be maintained in a stable state at all times, collapse of the face can be accurately prevented. ■ The moisture content of excavated soil is lowered, making it easier to dispose of it, and the remaining soil can be disposed of as 11% construction surplus rather than industrial waste, which reduces disposal costs and eliminates the problem of pollution. It also disappears. ■ Since air enters between the soil particles in the chamber, the friction between the soil particles is reduced and the fluidity of the soil is improved, and even with sandy layers and highly viscous strata, the chamber does not become clogged, so the soil and sand can be easily removed from the chamber. Ejection becomes smoother, the thrust force and rotational force of the cutter are reduced, and the excavation speed is increased.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention, and FIG. 2 is an explanatory diagram of a conventional example. lO...Shield excavator, 11...Canter, 12...Chamber, 13...Sludge material injection pipe, 14...Shield gear Tsuki, 15
...Air pipe. Figure 7 Figure 2 Figure 8

Claims (1)

[Claims] 1. In the mud pressure shield method, which adds additives such as slurry to the earth and sand excavated by the shield excavator, mixes and fluidizes it in the chamber of the shield excavator, and pressurizes it to counteract the ground. A method for stabilizing a face in a mud pressure shield method, characterized by injecting compressed air into the chamber where earth and sand and additives are mixed.