JPH0254092A - Liquid mud pressure-applying type shield excavating construction and its apparatus - Google Patents

Abstract

PURPOSE:To contrive effective collection by applying a specified low centrifugal force to liquid mud to separate the solid matter of sand or the like, after the solid matter of the gravels or the like of large grain size is removed from the liquid mud mixed with carried sediment, and by re-using the obtained liquid mud. CONSTITUTION:The title apparatus 1 is composed of a shield excavator 2, a rotary type sieve 3, a plurality of decanters 4 for applying the low centrifugal force of 30-400G to liquid mud mixed with sediment removing fine grain component, a liquid mud tank 5, a belt conveyor 6, and the like. After that, from the liquid mud mixed with sediment taken in a chamber 12, rough grain component is removed on the conveyor 6 by a sieve 18, and the liquid mud mixed with the sediment stored in a casing 17 is fed to each decanter 4. Then, a separated solid matter is dropped on the conveyor 6, and the liquid mud is stored in the tank 5, and after that, the liquid mud is fed as excavated liquid mud via a liquid mud feeding line 15. Accordingly, the liquid mud can be effectively collected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mud water pressurized shield drilling method and a drilling device used therein.

[Conventional technology]

As is well known, the mud pressurized shield excavation method used when constructing tunnels in the ground is to close the cutting part of the shield excavator with a bulkhead, and fill the front of the bulkhead with muddy water containing only effective muddy materials such as bentonite. This mud water pressure is used to stabilize the face while allowing the shield excavator to dig.

The mud sent to the face is usually carried out to the ground outside the tunnel as mud mixed with excavated soil, and then a mud water treatment device installed on the ground removes soil lines with relatively large particles. Solid matter and muddy water are separated, and the muddy water is collected and sent to the excavation section of the shield excavator again.

Conventionally, the earth and sand separator is composed of a combination of a vibrating screen, a cyclone, an excess mud tank, a slurry tank, a flocculant supply tank, a filter press, etc., and these devices separate the mud mixed mud water carried out from the shield excavator. For example, it is processed as follows.

First, the mud mixed with earth and sand discharged from the shield excavator is passed through a vibrating sieve to remove particles of large particle size (usually 1 to 2
After removing solid matter (0 mm or more), it is charred in a cyclone. The centrifugal action of the cyclone removes about half of the relatively small solids, including fine sand (particle size 74 μm). These solids removed by the vibrating sieve and cyclone are transported to a designated location and disposed of.

On the other hand, the muddy water that has passed through the cyclone is temporarily stored in a surplus muddy tank, and the muddy water whose muddy specific gravity has increased is treated there, and other mixed muddy water is sent to the slurry tank, where this muddy water is collected from the flocculant supply tank. A suitable agent such as an inorganic flocculant or an organic polymer flocculant filled in the supply tank is added to flocculate fine soil particles and promote sedimentation or dewatering as large flocs.

Next, the mixed mud water to which the flocculant has been added is dehydrated by applying it from the slurry tank to a filter press, which is a type of pressurized dewatering device. Then, the water separated by the filter press is used as dilution water, and then mixed with the recovered mud water whose specific gravity has increased to adjust the specific gravity, and then supplied again to the excavation section of the shield excavator in the tunnel.

[Problem to be solved by the invention]

However, the following problems occur in the muddy water treatment method described above.

In other words, in the process of removing solids with a particle size of 74 μm or more (fine sand) using a vibrating sieve and a cyclone, the cyclone has a classification point of 74 μm (the classification point refers to the separation of the separated discharged solids: underflow and discharge). This refers to the particle size when the solids of a certain particle size contained in the fluid side and the flow side are both 50%, and the removal of this fine sand with a particle size of 74 μm is complete. It is not something that is done to you. Therefore, as a matter of course, most of the fine soil particles having a particle size of 74 μm or less pass through the cyclone and are sent to the surplus mud tank.

For this reason, the specific gravity of the mixed mud in the surplus mud water tank tends to increase, resulting in a large amount of mud being disposed of. This is especially true when the excavated ground is soil made up of fine soil particles such as silt or clay, or when the excavation propulsion speed is high and the amount of excavated soil discharged per unit time is large, most of the fine soil particles are Everything passes through a cyclone and is transferred to a surplus mud tank.

As a result, a large-scale equipment for processing surplus muddy water is required, and since the processing capacity of each filter press is small, the process up to the pre-process (up to the slurry tank) is necessary.
Multiple systems will be used to handle the amount of processing required. For this reason, it is difficult to secure installation space for equipment for treating surplus muddy water and a filter press, and this is a very serious problem, especially when construction is carried out in urban areas, on the coast, on the seabed, or on the ocean floor. Furthermore, if a filter press requires manpower to operate, it will require a large number of personnel, and if it is a fully automatic type, equipment costs will be high, leading to an increase in recycling costs.

In addition, when transporting muddy water mixed with earth and sand to the ground, it is usually carried out using pipes, but since the length of the pipe to the ground becomes long, there is a problem that the mixing of muddy water and excavated earth and sand progresses in this vibrator, worsening the earth and sand separation ability. There is also.

The present invention has been made in view of the above circumstances, and is a muddy water pressurized shield excavation method that enables effective and high-level recovery of muddy water used in muddy water pressurized shield excavation, and also realizes a reduction in equipment space. The purpose is to provide such equipment.

[Means to solve the problem]

In the mud pressurized shield excavation method of the present invention, the mud mixed mud that is carried out together with the excavated soil from the excavation part of the shield excavator is supplied to the inside of the excavation hole dug by the shield excavator, and from this mud mixed mud. A primary treatment mechanism such as a sieve for removing solids with large particle sizes such as sand and gravel, and the mixed mud water that has passed through this primary treatment mechanism are supplied, and a low centrifugal force of 30 to 400 G is applied to the mixed mud water. Therefore, we installed a secondary treatment mechanism consisting of a low-speed centrifuge that separates muddy water containing only effective muddy materials such as bentonite and fine soil particles from other solids such as sand. The muddy water obtained is collected in the excavation hole and sent to the excavation section, while the solids separated by the secondary treatment mechanism are carried out of the excavation system.

The equipment includes a shield excavator that excavates the ground, and mud mixed with earth and sand that is carried out together with the excavated soil from the excavation part of the shield excavator. A primary treatment mechanism such as a sieve for removal is supplied, and the mixed mud that has passed through this primary treatment mechanism is supplied with a
A secondary treatment mechanism consisting of a low-speed centrifugal separator that separates muddy water containing only effective muddy materials such as bentonite and fine soil particles from other solids such as sand by applying a low centrifugal force of 00G; a muddy water recovery mechanism that collects the muddy water obtained by the secondary treatment mechanism in the excavation hole and sends it to the excavation section; and an object carrying-out mechanism, and each of the above-mentioned mechanisms is characterized in that it is installed inside the excavation hole dug by the shield excavator.

[Effect]

According to the present invention, muddy water is treated inside the tunnel, so even if the ground is in an urban area and it is difficult or impossible to install a treatment device, the muddy water can be treated without any problems. In addition, the work space on the ground can be secured, and the muddy water mixed with earth and sand discharged from the shield excavator is quickly processed in the tunnel without being lifted to the ground, so the muddy water can be collected quickly and effectively. , and can be reused for excavation by shield excavators.

In addition, muddy water is recovered using a primary treatment mechanism such as a sieve, and a secondary treatment mechanism consisting of a low-speed centrifugal separator.
By applying a centrifugal force of about 00 G, most of the fine soil particles as well as gravel and fine sand bones of 74 μm or more are removed from the mixed mud, and the rise in the specific gravity of the mud is extremely low. The amount of surplus muddy water, that is, waste muddy water, will also be reduced.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral H indicates a starting shaft excavated to a predetermined depth in the ground, ■ indicates a muddy water pressurized shield drilling device according to the present invention, and T indicates the lower end of the starting shaft H drilled by the muddy water pressurized shield drilling device 1. It shows a tunnel being excavated horizontally.

The mud water pressurizing type shield drilling equipment (hereinafter simply referred to as the drilling equipment) 1 includes a shield excavator 2 and a coarse particle content in the excavated earth and sand, that is, the earth and sand mixed mud containing the mud water discharged from the shield excavator 2. A rotary sieve primary treatment mechanism (3) for removing coarse grains (if the particle size is 13 mm or more) is supplied, and the mixed mud from which the coarse particles have been removed is supplied to the rotary sieve 3. 40
A plurality of decanters 4 (low-speed centrifugal separators: secondary treatment mechanism) that provide a low centrifugal force of 0G (three in this case; the number of installations is set according to the flow rate of muddy water), and these decanters 4, A mud tank 5 temporarily stores the muddy water obtained from the rotary sieve 3 and the decanter 4, and a belt conveyor (solids transport system) that transports the solids other than the muddy water discharged from the rotary sieve 3 and the decanter 4 to the rear of the tunnel T. 6, a conveying mixer (solid material conveying mechanism) 7 connected to the rear of the belt conveyor 6, and a solidification material supply tank 8.

As shown in FIGS. 1 and 2, each of the components 2 to 8 of the excavation device 1 is fixed to a bogie that runs on two sets of rails R-R laid at the bottom of the tunnel T. As is clear, the entire excavation device 1 is installed movably along the rail RR together with the truck inside the tunnel T.

The shield excavator 2 includes a cylindrical skin plate 9, a cutter 10 and its rotational drive mechanism 11, and a cutter 1.
The cutter 10 is equipped with a partition plate 13 forming a chamber 12 behind the cutter 10, and a jack 14 as an advancing means, which stabilizes the excavation face T by the water pressure of muddy water supplied to the front surface of the cutter 10, and rotates it. While excavating the face T with the cutter 10 rotated by the drive mechanism 11, the jack 14
Move forward in the excavation direction (in Figure 1, move to the left)
It is configured to do this.

The muddy water is supplied to the front surface of the cutter 10 by a muddy water supply line 15 piped from above ground into the tunnel T,
In addition, the tunnel T excavated by the shield excavator 1
The peripheral wall surface of the shield excavator 2 is covered with segments S by an erector 16 installed at the rear of the shield excavator 2, thereby providing a primary lining. The jack 14 is adapted to move the shield excavator 2 forward by applying a reaction force to the segment S.

As described above, the earth and sand excavated by the shield excavator 2 is mixed with muddy water to become a mixed muddy water, and this mixed muddy water is taken into the chamber 12 and then passed through the rotary sieve 3 and each decanter 4. ... is used to separate muddy water and other solids, and the muddy water is reused for excavation by the shield excavator 2.

As shown in FIG. 3, the rotary sieve 3 includes a cylindrical casing 17 having a supply port 17a for earth and sand mixed mud water at the top and a discharge port 17b for coarse particles on the side wall, and an interior of the casing 17. The upper part is composed of an umbrella-shaped sieve 18 that sieves coarse particles, and a motor 18a that rotates the sieve 18, which rotates the muddy water mixed with earth and sand that has been put into the casing 17 from the supply port 17a. After removing coarse particles through a sieve 18, the casing 17
The coarse particles are stored inside and the coarse particles are discharged from the discharge port 17b. The coarse particles discharged from the discharge port 17b fall onto the belt conveyor 6, and are transported by this belt conveyor.
Sent to the back of tunnel T.

The mixed mud water separated by the rotary sieve 3 and stored in the casing 17 is transferred to each of the decanters 4...
The slurry is then separated into muddy water and other solids such as sand.

As shown in FIG. 4, the decanter 4 includes a cylindrical rotating casing sink 9 with a slight space at one end, a screw conveyor 20 provided in the rotating casing 19, and a screw conveyor 20 from one end of the rotating casing 19. conveyor 20
It includes a hollow shaft 21 penetrated therein, and a feed tube 22 connected to the hollow shaft 21. The rotating casing 19 and the hollow shaft 21 are integrally connected, and the motor 23
In conjunction with these, the screw conveyor 20 rotates in the same direction as the rotating casing 19 via the gear box 24 and at a slightly lower speed than the rotating casing 19. .

This decanter 4 transports the mixed mud water supplied into the hollow shaft 21 from the feed tube 22 to the rotating casing 19.
By applying centrifugal force to the soil mixed mud by ejecting it by rotational force, solids such as sand contained therein are ejected and deposited on the inner wall of the rotating casing 19, and the solids and effective mud are Separate into muddy water containing only the material. The solids are discharged from one end of the rotary casing 19 by the screw conveyor 20, while the muddy water is discharged from the other end of the rotary casing 19.

The solids discharged from the decanter 4 are conveyed to the rear of the tunnel T by the belt conveyor 6.

In the decanter 4, a low centrifugal force of about 30 to 400 G is applied to the mixed mud water ejected from the feed tube 22 onto the inner wall of the rotating casing 19, and the discharge amount of mud water, which is the processing capacity of the decanter 4, is approximately 360 G. ~400
It has a capacity of m'/h.

Such ability can be achieved under the above-mentioned low centrifugal force by appropriately setting the differential speed between the rotating casing 19 and the screw conveyor 20, the gap between them, and the shape of the screw conveyor 20. increased throughput and large particle size (maximum diameter 20 mm in the example)
) This realizes the separation of solids. Thus, the classification point of the decanter 4 is 6 to 10 μm, and the removal rate is 100% for solids of 174 μm or more, and the processing capacity is 360 to 400 m 3 /h as described above.

The muddy water obtained by each of the decanters 4 is supplied to the muddy water tank 5, where it is temporarily stored, and then sent to the muddy water supply line 15 via a collection line (muddy water collection mechanism) 25. It has become.

Note that the recovery line 25 is connected to an excess muddy water recovery line 26 for recovering excess muddy water.

On the other hand, the solids discharged from the rotary sieve 3 and each decanter 4 and transported to the rear of the tunnel T by the belt conveyor 6 are supplied into the transport mixer 7. A solidification material is quantitatively supplied into the mixer 7 from the solidification material supply tank 8 provided above the mixer 7 via a quantitative feeder 8a, and after the solids are solidified, the solidification material is be discharged.

The above solidifying materials include cement, gypsum, super absorbent resin,
There is dry ash or a special assimilation material for the pond, for example, if the material has a high water content such as silt or clay, a material with high water absorption is used.
It is preferable to select and use them appropriately depending on the water content and the like.

The solidified solids discharged from the mixer 7 are transferred to a trolley (solids transport mechanism) 27 that can run on the rail R.
It is transported to the rear of the tunnel T and temporarily stored in a pit H1 dug at the lower end of the starting shaft H.

The solids disposed of in the pit H1 are then conveyed to the ground level L1 by a vertical belt conveyor (solids conveyance mechanism) 28 installed in the starting shaft H.

In this belt conveyor 28, as the belt 28a rotates, a large number of shovels 28b fixed to the outer surface of the belt 28a sequentially scoop up solid matter in the pit t(+) and raise it to the ground. Part 28
When the shovel 28b descends through point c, the solid matter inside the shovel 28b is dropped from the shovel 28b.

In this case, the solid material that has fallen from the shovel 28b is collected in a hopper 29 installed on the ground, and is further loaded from this hopper 29 onto the dump truck C.
will be transported to an appropriate location and disposed of.

Next, the operation of the excavating device 1 with the above configuration will be explained.

The excavated earth and sand excavated by the shield excavator 2 and taken into the chamber 12 of the shield excavator and the muddy water contained therein, that is, the earth and sand mixed muddy water, are fed through the supply port 17a provided in the casing 7 of the rotary sieve 3. It is supplied into the casing 17. Note that the muddy water is supplied at the initial stage via the muddy water supply line 15 from above ground.

The coarse particle content (particle size IQm
m or more) is a sieve 18 rotated by a motor 18a.
The remaining mud mixed with earth and sand passes through the sieve 18 and is temporarily stored in the casing 17.

The coarse particles remaining on the sieve 18 fall onto the belt conveyor 6 from the outlet 17b of the casing 17, and are sent to the rear of the tunnel T by the belt conveyor 6.

On the other hand, the mixed mud water stored in the casing 17,
It is separated and supplied to each decanter 4.

That is, it is supplied into the hollow shaft 21 of each decanter 4....

The mixed muddy water supplied into the hollow shaft 21 is moved from the feed tube 22 into the rotating casing 19 by a centrifugal force of 30 to 4
It is ejected by a centrifugal force of about 00 G, and solid matter such as sand contained in the mixed mud is deposited on the inner wall of the rotating casing 19 and separated into the solid matter and the muddy water.

This decanter 4 has a capacity of 30% for the supplied earth and sand mixed muddy water.
Since it provides a low centrifugal force of ~400G, the classification point is 6 to 10 μm, and even fine soil particles such as fine sand are removed from the solids contained in the mud mixed mud. Furthermore, effective mud materials such as solids contained as fine colloids, such as bentonite and fine soil particles, are not separated, and the specific gravity is 1.2, which is the most effective mud water.
Some degree of muddy water can be obtained.

The centrifugal force applied to the muddy water by the decanter 4 is 30
This is because the centrifugal force is 30G.
If it is less than 400G, fine sand or fine soil particles with small particle size will not be separated sufficiently, while if it is more than 400G, effective muddy water materials such as bentonite and fine soil particles necessary to form muddy water will not be separated. This is because there is a possibility that they may be separated. Therefore, considering both separation ability and processing efficiency, the centrifugal force of the decanter 4 is 200~
It is more desirable to set it to around 300G, and furthermore, it is preferable to set it appropriately depending on the geology of the excavated soil.

Of the solids and muddy water separated by each decanter 4, the solids are dropped onto a belt conveyor 6 and conveyed to the rear of the tunnel T, while the muddy water is temporarily transferred to the muddy water tank 5. After being stored, it is sent to the muddy water supply line 15 via the recovery line 25. Since the muddy water sent to the recovery line 25 usually has a higher specific gravity than a predetermined specific gravity, dilution water is sent from the muddy water supply line 15 at an appropriate flow rate and mixed with the muddy water to adjust its specific gravity, and then the shield excavator 2
Drilling mud is supplied to the front surface of the cutter 10 through a mud water supply line 15. Additionally, surplus muddy water generated in the muddy water tank 5 is sent to the ground via a surplus muddy water recovery line 26 and treated appropriately.

If solid matter such as slum settles in the muddy tank 5, it is removed from the bottom of the muddy tank 5 or scooped out with a grab or the like.

On the other hand, the solids discharged from the rotary sieve 3 and each decanter 4 and transported to the rear of the tunnel T by the belt conveyor 6 are supplied into the transport mixer 7 and are solidified in this mixer 7. Assimilation materials are quantitatively supplied from the material supply tank 8 via a quantitative feeder 8a in accordance with the components contained in the solids and the water content. The solids are thereby solidified and then discharged from the mixer 7.

The solidified solids discharged from the mixer 7 are transported to the rear of the tunnel T by a trolley 27 that can run on rails R, and are temporarily stored in a pit H1.

Next, the solids stored in this pit H are brought to the ground by a belt conveyor 28 installed in the starting shaft H,
and temporarily stored in the hopper 29. When a suitable amount of solid matter has accumulated in this hopper 29, the solid matter is loaded from the hopper 29 onto a dump truck C, and transported by this dump truck C to a suitable location for disposal.

However, according to the excavation method using the excavation device 1 as described above, since muddy water is treated inside the tunnel T, for example, since the above ground L1 is in an urban area, it is difficult to install treatment equipment. Even if this is not possible, muddy water can be treated without any problems, and a work space on the ground L1 can be secured. In addition, since the mixed muddy water discharged from the shield excavator 2 is immediately treated in the tunnel T without being lifted up to the ground L1, the muddy water can be collected effectively in a short time, and the muddy water can be collected by the shield excavator 2.
Can be reused for excavation.

In addition, collecting muddy water is achieved by processing it with two devices: a rotary sieve 3 and each decanter 4. Since most of the soil particles are removed, the increase in the specific gravity of the muddy water is extremely low, and therefore the amount of surplus muddy water, that is, the amount of waste muddy water is also small.

Therefore, as in the past, devices for removing fine solids such as filter presses and equipment for treating surplus muddy water are not required, or even if they are necessary, the number of them is significantly reduced. Installation space can be reduced. This allows the excavation device I to be easily installed inside the tunnel T.

In the above embodiment, the decanter 4 is improved by mixing an appropriate amount of a dispersant that effectively disperses the muddy water and other solids into the mixed muddy water stored in the casing 17 of the rotary sieve 3. Separation power can be further improved.

Further, solid matter such as sand separated and discharged by each decanter 4 may be separately collected and used as a backfilling material to reuse resources. Also,
A solidification material is mixed and solidified with the solids to be transported and disposed of by the belt conveyor 6, but this process
It can be omitted depending on the type of solid material, moisture content, etc.

Furthermore, in the above embodiments, the low-speed centrifugal separator was explained as the decanter, but the low-speed centrifuge in the present invention refers to one that continuously performs separation treatment of solids with a centrifugal force in the above range, and It is not limited to decanters.

〔Effect of the invention〕

As explained above, according to the present invention, muddy water is treated inside the excavation hole, so even if it is difficult or impossible to install equipment on the ground because it is in an urban area, there will be no problem. Not only can muddy water be treated without problems, work space on the ground can be secured, and
Shield m The muddy water mixed with earth and sand discharged from the excavator is immediately treated inside the excavation hole without being lifted to the ground, so the muddy water can be collected quickly and effectively and reused for excavation by the shield excavator. .

In addition, muddy water is recovered by processing it using a primary treatment machine groove such as a sieve and a low-speed centrifugal separator as a secondary treatment mechanism. By applying a certain degree of centrifugal force, most of the fine soil particles as well as gravel and fine sand with a diameter of 74 μm or more are removed from the mixed mud, so that the increase in the specific gravity of the mud is extremely low (therefore, The amount of surplus muddy water, that is, waste muddy water, will also be reduced.

Therefore, as in the past, devices for removing fine solids such as filter presses and equipment for treating surplus muddy water are not required, or even if they are necessary, the number of them is significantly reduced. Reduced installation space,
Costs can be reduced both by reducing the number of workers.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is an overall schematic diagram showing a muddy water treatment facility suitable for implementing the method of the present invention, Fig. 2 is a view taken along the line ■-■ in Fig. 1,
FIG. 3 is a longitudinal sectional view showing the structure of a rotary sieve, and FIG. 4 is a sectional view showing the structure of a decanter. 1... Mud water pressurized shield drilling equipment, 2...
Shield excavator, 3...Rotary sieve (primary treatment mechanism), 4...
...decanter (low-speed centrifuge, secondary treatment mechanism),
6.28...Belt conveyor (solid material delivery mechanism), 7...Transportation mixer, 25...Recovery line (muddy water collection mechanism), 27.
...Trolley (solid material transport mechanism), L...
・Ground, T...Tunnel (excavation hole), T1...Face. Outsourcer Shimizu Construction Co., Ltd.

Claims (2)

[Claims] (1) The earth and sand mixed mud that is carried out together with the excavated earth and sand from the excavation part of the shield excavator is supplied to the inside of the excavated hole dug by the shield excavator, and solids with large particle diameters such as sand and gravel are extracted from this earth and sand mixed mud. A primary treatment mechanism such as a sieve is used to remove sand and mud that has passed through this primary treatment mechanism.
It consists of a low-speed centrifugal separator that applies a low centrifugal force of 30 to 400 G to this mixed muddy water to separate it into muddy water containing only effective muddy materials such as bentonite and fine soil particles, and other solids such as sand. a secondary treatment mechanism is installed, the muddy water obtained by the secondary treatment mechanism is collected inside the excavation hole and sent to the excavation part, and the solids separated by the secondary treatment mechanism are This is a pressurized mud water shield drilling method that is characterized by carrying mud out of the excavation hole. (2) A shield excavator that excavates the ground, and mud mixed with earth and sand that is carried out with excavated soil from the excavation part of this shield excavator is supplied, and solids with large particle sizes such as sand and gravel are removed from this mud mixed with earth and sand. A primary treatment mechanism such as a sieve is provided, and the mixed mud water that has passed through this primary treatment mechanism is supplied.
It consists of a low-speed centrifugal separator that applies a low centrifugal force of 30 to 400 G to this mixed muddy water to separate it into muddy water containing only effective muddy materials such as bentonite and fine soil particles, and other solids such as sand. a secondary treatment mechanism; a muddy water recovery mechanism that collects the muddy water obtained by the secondary treatment mechanism in the excavation hole and sends it to the excavation section; A mud water pressurizing shield drilling device, comprising: a solid matter transporting mechanism for transporting solid matter out of the drilling hole, wherein each of the above mechanisms is installed inside the drilling hole excavated by the shield drilling machine.