JPS62206194A - Shield type tunnel excavation method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Technical Field) The present invention aims to reduce the excavation resistance of the face ground to a rotary cutter or to impart fluidity and watertightness to the shear. This invention relates to a shield type tunnel excavation method that excavates while adding air bubbles to the shear in a pressure chamber.

(Prior art) - As one of the shield type tunnel excavation methods in which the tunnel is excavated while adding air bubbles to the face surface or the slide in the pressure chamber,
As described in Publication No. 8-47560, air bubbles obtained by foaming a foaming agent are sprayed onto the face surface,
There is an excavation method in which a pickpocket in a pressure chamber and air bubbles supplied to the pressure chamber are agitated. However, this excavation method requires a complicated, costly, and expensive foaming device for foaming the foaming agent in advance.

In addition, when this excavation method is applied to a rock with a high gravel weight ratio or a low uniformity coefficient, the porosity of the pickpocket in the pressure chamber increases, making it easier for the air bubbles in the pressure chamber to separate from the pickpocket. , the air bubbles cannot be maintained in shear.

(Objective of the invention) The present invention has high work efficiency, is inexpensive, does not require a complicated, large, and expensive foaming device, and is suitable for use in rock formations where the ratio of gravel weight is high or the uniformity coefficient is small. However, the bubbles can be maintained in the pickpocket. The purpose is to provide a shield type tunnel excavation method.

(Structure of the Invention) The shield type tunnel excavation method of the present invention stirs a mixed fluid containing a foaming agent, fine grain material, and water to foam a part of the foaming agent, and then foams a part of the foaming agent. The mixed fluid and compressed air are supplied to a pressure chamber in front of the partition wall, the foaming agent is stirred and foamed together with the slurry in the pressure chamber by a stirring means disposed in the pressure chamber, and then the foaming agent is foamed with a slurry containing air bubbles. This includes discharging the gas behind the bulkhead.

(Effects) The excavation method of the present invention foams a part of the foaming agent and supplies it to the pressure chamber, so that by simply stirring the foaming agent and the shear in the pressure chamber for a short time, the foaming agent can be fluidized. And the foaming agent can be foamed to a sufficient value to impart water-stopping properties. Therefore, according to the present invention, the work efficiency is high and the cost is low.

Moreover, in the excavation method of the present invention, since it is only necessary to foam a part of the foaming agent, a part of the foaming agent can be foamed by stirring the mixed fluid. Therefore, according to the present invention, there is no need for a complicated, large, and expensive foaming device.

Further, in the excavation method of the present invention, since the mixed fluid contains fine grain material, the porosity of the shear in the pressure chamber is reduced by the fine grain material and air bubbles. Therefore, according to the present invention, even if the rock has a large percentage of gravel weight or a rock with a small uniformity coefficient, the air bubbles will not separate from the pickpocket, and the bubbles can be maintained in the pickpocket. If the rock has a small weight ratio or a large uniformity coefficient, the air bubbles will be less likely to separate from the pickpocket, and the bubbles can be reliably maintained by the pickpocket.

Furthermore, since the fine-grained material is fed into the pressure chamber together with the foaming agent, water and air bubbles, there is no need to use a special feeding device for the fine-grained material.

(Example) Embodiments of the present invention shown in the drawings will be described below.

The so-called Tonosho balanced shield type tunneling machine IO shown in FIG. a cutter head 18, a rotation mechanism 20 such as a motor that rotates the cutter head, and a plurality of propulsion jacks 22 that move the entire excavator lO forward.
The propulsion jack 22 includes a zero rotation mechanism 20 whose reaction force is a segment 24 assembled on the inner peripheral surface of the tunnel at the rear of the shield body 12, and a zero rotation mechanism 20 that is supported on the shield body 12 by a support means (not shown). has been done.

The cutter head 18 is fixedly provided at the tip of a rotating shaft 26 that is rotatably supported by the partition wall 14 around the axis of the shield body 12. The cutter head 18 meshes with a gear 28 provided on the output shaft of the rotation mechanism 20 by the rotation mechanism 20, and engages with the gear 28, and engages with a gear 30 fixedly provided on the tip of the rotation shaft 26. It is rotationally driven via 26. , on the partition wall 14 side of the cutter head 18,
A plurality of stirring blades 32 are fixedly provided to stir the pickpockets placed in the pressure chamber 16 as the cutter head 18 rotates. In order to enhance the stirring effect of the stirring blades 32, a plurality of fixed blades 34 may be provided on the pressure chamber 16 side of the partition wall 14 at a position where they do not interfere with the stirring blades 32.

The cutter head 18 is also formed with a liquid supply path 36 that opens toward the face surface to eject a mixed fluid, which will be described later, toward the face surface. The liquid supply path 36 is communicated with a pump 42 via a supply path 38 formed in the rotating shaft 26 and a vibrator 40 .

Behind the excavator 10, for example on the ground, as shown in FIG. 2, there is installed an additive supply device 44 that reduces the excavation resistance of the face ground against the rotary cutter and imparts fluidity and water-stopping properties to the pickpocket. There is.

In the illustrated example, the additives include a foaming agent, a fine granule material that reduces the porosity of the pickpocket in the pressure chamber, and a thickener that acts as a foam strengthening agent to prevent the disappearance of the foam created by the foaming agent. It is a mixed fluid of water and fresh water.

A predetermined amount of the foaming agent is supplied from the foaming agent tank 46 to the mixer 52 via the scale 48 and the hopper 50, and a predetermined amount of the fine granule material is supplied from the fine granule material tank 54 to the mixer 52 via the scale 56 and the hopper 50. The thickener is stored in the thickener tank 58.
From there, a predetermined amount is supplied to the mixer 52 via a measuring device 60 and a hopper 50. Further, a predetermined amount of fresh water is supplied from the vibro 2 to the mixer 52 via the water meter 64 and the hopper 50.

The mixed fluid supplied to the mixer 52 is agitated and mixed in the mixer 52, whereby a portion of the foaming agent is foamed.

The mixed fluid containing air bubbles stirred and mixed by the mixer 52 is supplied to a tank 66, and further supplied by a pressure pump 68 via a pipe 70' to an in-house tank 72 provided in the excavator IO. The amount of foaming of the foaming agent by the mixer 52 varies depending on the soil type to be excavated, but the volume of the mixed fluid containing bubbles is 1.5 to 2.0 times, and the specific gravity of the mixed fluid containing bubbles is 0.7 to 0. It is about 8. If the specific gravity is less than 0.7, air bubbles will separate from the liquid in the tank 66 or the underground tank 72, which is undesirable.

Also on the ground, as shown in Figure 2, is a compressor 74.
is installed. Compressed air from compressor 74 is supplied to pressure chamber 16 via air pipes 76, 78 and flow regulating valve 80.

The excavator 10 also removes the shear in the pressure chamber 16 from the pressure chamber 16.
A pickpocket discharge device 82 for discharging from the rear of the partition wall 14
The evacuation device 82 is a known one in which a screw conveyor is disposed within a pipe extending from the pressure chamber 16 to the rear of the partition wall.

As the foaming agent, for example, a surfactant sold under the trade name Hozolith #505 by Pozolith Bussan Co., Ltd. or a foaming agent obtained by hydrolyzing protein can be used.

The fine grain material may be any material that reduces the porosity of the pickpocket, and examples of such fine grain materials include fine sand, silt,
Clay 5 coal ash can be used.

The thickener is preferably water-soluble. Examples of such thickeners include natural thickeners belonging to vegetable sources such as gum arabic, gum togand, and cornstarch alginate, and animal-based thickeners such as gelatin and casein. A natural thickener belonging to the soluble starch.

Processed and modified starch thickeners such as cationic starch, semi-natural thickeners such as carboxycellulose (CMC) and hydroxyethyl cellulose (HEC), polyvinyl alcohol (PVC), polyvinylhydrin (P
Thickeners belonging to the vinyl family such as VP), polyethylene oxide (PES), and thickeners such as Boron #II Ichibue can be used.

During excavation, the tunnel boring machine IO mixes the mixed fluid with the mixer 50.
A part of the foaming agent is foamed by stirring and mixing, and the mixed fluid in the tank 66 containing air bubbles is supplied to the underground tank 72 by the pump 70. Therefore, there is no need for a complicated, large, and expensive foaming device.

Next, the tunnel excavating machine 10 blows the mixed fluid containing air bubbles in the underground tank 72 onto the face surface from the liquid supply path 36 using the pump 42, and supplies compressed air to the pressure chamber 16 using the compressor 74.
8 is rotated by the rotating mechanism 16 to dig, and the excavated pickpockets are discharged from the pressure chamber 16 to the rear of the partition 914 by the discharge device 82.

As a result, the mixed fluid containing air bubbles is sprayed onto the face, so that the excavation resistance of the face against the cutter head 18 is reduced. Further, as the cutter head 18 rotates, the mixed fluid is stirred by the stirring blade 32 together with the pickpocket in the pressure chamber 16 to generate bubbles, so that fluidity and water-stopping properties are imparted to the pickpocket in the pressure chamber. Furthermore, since the mixed fluid contains fine-grained material, the porosity of the shear within the pressure chamber 16 is reduced by the fine-grained material, thus ensuring that air bubbles are maintained in said shear.

According to the above-described tunneling method using the tunnel excavator 10, in order to foam a part of the foaming agent and supply it to the pressure chamber together with air bubbles, the foaming agent and the pickpocket in the pressure chamber are simply stirred for a short time. The foaming agent can be foamed to a value sufficient to reduce the excavation resistance of the face ground against the rotary cutter, and to a value sufficient to provide fluidity and water-stopping properties to the cut, thus increasing work efficiency. It becomes expensive and cheap. In addition, since a part of the foaming agent is foamed by stirring the mixed fluid with the mixer 66, there is no need for a complicated, large, and expensive foaming device. Or, even if the rock has a small uniformity coefficient, if the air bubbles do not separate from the shear and can be maintained in the shear, and if the rock has a small gravel weight ratio or a rock that has a large uniformity coefficient, The bubbles are less likely to separate from the shear, the bubbles can be maintained reliably by the shear, and there is no need to use a special feeding device for fine granule material. Furthermore, since the additive supply device 44 and the compressor 74 are installed on the ground, the present invention can also be applied to small-diameter shield type tunnel boring machines.

(Example of construction) External diameter of shield body = 2680 mm Amount of excavated soil per excavation distance in = 5.64 m3 soil Purchase = sandy soil (uniformity coefficient = 5 ~ 8 ° 10% particle size = 0.3 mm) Mixed fluid formulation Proportion (per 1 batch) Fine grain material (local sauce) = 80Kg Water = 50% Thickener (CMCTE-V15 solution) = 5-pronged foaming agent (Hozolith #505) = 0.3cm - Next foaming foaming Magnification = approx. 1.7 0.15 mm3 per batch 0.2 m3 per 1 m3 of excavated soil
was injected into the pressure chamber at a rate of 2:2. Also.

The amount of compressed air supplied to the pressure chamber was adjusted by the flow rate adjustment valve 80 according to the condition of the discharged sediment (injection pressure = internal indenter of the pressure chamber, 1Kg/cm2), and under these conditions, the flow rate was 4.0 c/min.
I was able to dig m.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing one embodiment of a tunnel boring machine used for implementing the present invention, and FIG. 2 is a diagram showing a ground device. 12: Shield main body, 14: Partition wall, 16: Pressure chamber, 18 Two cuff heads, 32: Stirring blade, 36: Liquid supply path. 52: Mixer, 74: Compressor. Agent Patent Attorney Nobuyuki Matsunaga Figure 1

Claims (4)

[Claims] (1) After stirring a mixed fluid containing a foaming agent, fine grain material, and water to foam a part of the foaming agent, the mixed fluid containing air bubbles and compressed air are pumped to the pressure in front of the partition wall. A shield type method comprising supplying the foaming agent to a chamber, stirring the foaming agent together with shear in the pressure chamber by a stirring means disposed in the pressure chamber to foam, and then discharging the shear containing air bubbles to the rear of the partition wall. Tunnel digging method. (2) The shield type tunnel excavation method according to claim (1), wherein the mixed fluid contains a thickener. (3) The shield type tunnel excavation method according to claim (1), wherein the mixed fluid and the compressed air are supplied to the pressure chamber through separate pipe lines. (4) The shield type tunnel excavation method according to claim (1), wherein the mixed fluid and the compressed air are combined near the pressure chamber and supplied to the pressure chamber.