JP2683753B2 - Muddy water pressure shield rig - Google Patents

Description

TECHNICAL FIELD The present invention relates to a muddy water pressure-type shield excavation device.

[Conventional technology]

The muddy water pressure shield excavation method used when constructing a tunnel in the ground is, as is well known, that the cutting part of the shield excavator is closed with a partition wall and the front surface of the partition wall is filled with muddy water containing only effective mud material such as bentonite. This mud pressure causes the shield excavator to proceed while stabilizing the face.

The muddy water sent to the face is usually carried out along with the excavated soil as earth and sand mixed muddy water to the ground outside the tunnel, and then solid matter such as earth and sand and gravel particles with relatively large particles by a muddy water treatment device installed on the ground. The muddy water is collected and sent again to the excavation section of the shield excavator.

As the sediment separating device, conventionally, constituted by a combination of a vibrating screen, a cyclone, an excess mud tank, a slurry tank, a coagulant supply tank, a filter press, etc., by these, the soil-mixed mud carried out from the shield excavator , Is processed as follows, for example.

First, the mud mixed with soil and sand discharged from the shield excavator is put on a vibrating screen to obtain large particles such as gravel (usually 1 to
20mm or more) After removing solids, hang on a cyclone.
In a cyclone, fine sand (particle size 74
Approximately half of the solids with a relatively small particle size up to (μm) minutes are removed. The solids removed by the vibrating screen and cyclone are transported to a predetermined place for disposal.

On the other hand, the muddy water that has passed through the cyclone is temporarily stored in the excess muddy water tank, and the muddy water with a large specific gravity is treated here.
Other mud and sand mixed mud water is sent to the slurry tank, where an appropriate agent such as an inorganic coagulant or an organic polymer coagulant filled in the coagulant supply tank is added to coagulate fine soil particles. , And promotes sedimentation or dehydration as large flocs of particles.

Next, the sediment-mixed mud water to which the coagulant has been added is dehydrated from the slurry tank by applying it to a filter press, which is a kind of pressure dehydrator. Then, after the water separated by this filter press is used as dilution water, it is mixed with the recovered muddy water having a larger muddy water specific gravity to adjust the specific gravity, and then supplied again to the excavating section of the shield excavator in the tunnel.

[Problems to be solved by the invention]

However, the above-mentioned method for treating muddy water has the following problems.

That is, in the process of removing solids with a particle size of 74 μm (fine sand) or more using a vibrating screen and a cyclone, the cyclone has a classification point of 74 μm (the classification point is the separated discharged solids side: underflow and discharge Fluid side: Both the overflow side and the solid matter of a certain diameter contained in
It is said that the particle size diameter is 50% each), and the removal of fine sand with a particle size of 74 μm cannot be completed completely. 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 water tank.

For this reason, the specific gravity of the soil-mixed mud water in the surplus mud tank tends to be large, and the amount of mud water discarded is large.
This is especially true when the ground to be excavated is soil consisting of fine soil particles such as silt or clay, or when the excavation propulsion speed is high and the amount of excavated sand per unit time is large,
Almost all of the fine soil particles pass through the cyclone and are transferred to the surplus mud tank.

As a result, a large-scale treatment device for surplus muddy water is required, and since the filter press has a small treatment capacity per unit, it is possible to cope with the treatment amount up to the previous process (process up to the slurry tank). It will be used more than once. Therefore, it is difficult to secure the installation space for the excess mud water treatment facility and the filter press.
This is a very serious problem especially in the case of construction on urban areas, coasts, seabeds or riverbeds. Further, if the filter press requires manpower for operation, it is necessary to secure such a large number of personnel, and if it is a fully automatic type, it requires equipment cost and causes a cost increase.

In addition, when the muddy water mixed with soil is transported to the ground, it is usually done with a pipe, but since the length of the pipe to the ground is long, the problem that the muddy water and excavated soil mix in this pipe and the sediment separation ability deteriorates. There is also.

The present invention has been made in view of the above circumstances, and can collect mud water used for mud pressure shield excavation effectively and at a high level, and realizes a narrowed equipment space. The purpose is to provide.

[Means for solving the problem]

The mud pressure type shield excavator of the present invention is provided with a shield excavator for advancing the ground, and a sediment-mixed mud carried out together with excavated soil from the excavation section of the shield excavator, and a particle diameter such as gravel from the sediment-mixed mud. As a primary treatment mechanism for removing large solids of soil, a sieve that separates the sediment-mixed mud into coarse-grained solids and mud is supplied with the sediment-mixed mud that has passed through this primary treatment mechanism, and the sediment-mixed mud is centrifuged. As a secondary treatment mechanism that separates muddy water containing only effective muddy water material such as bentonant and fine soil particles and solid matter such as sand by applying force, it has a cylindrical shape with one end narrowed. A rotary casing rotatably supported in one direction around the central axis, and a screw provided in the rotary casing and rotatably supported in another direction different from the rotary casing. And Nbeya, a hollow shaft which is penetrated from one end side of the rotating casing in the screw conveyor,
A feed tube connected to the hollow shaft is provided, and the rotary casing and the screw conveyor are rotated in different directions and jetted by a rotational force from the field tube into the rotary casing. A low-centrifugal separator that applies a low centrifugal force of 30 to 400 G to the sediment-mixed mud water separated from the solid matter to separate it into fine-grained solid matter and mud water, and is obtained by this primary treatment mechanism and secondary treatment mechanism. A muddy water collecting mechanism that collects muddy water in the drill hole and sends the muddy water to the drilling unit, and a solid matter unloading mechanism that carries out the solid matter separated by the primary treatment mechanism and the secondary treatment mechanism to the outside of the drill hole. And each of the above-mentioned mechanisms is installed inside an excavation hole that is excavated by the shield excavator.

[Action]

According to the present invention, since muddy water is treated inside the tunnel, for example, even if it is difficult to install a treatment device on the ground because it is an urban area, or if it is completely impossible, muddy water is treated without any problem. In addition to being able to secure a working space on the ground, the mud water discharged from the shield excavator is promptly processed in the tunnel without being lifted to the ground, so mud can be collected in a short time and effectively. And, it can be reused for excavation by shield excavator.

The muddy water is collected by a primary treatment mechanism such as a sieve and a secondary treatment mechanism consisting of a low-speed centrifuge.
By applying a centrifugal force of about 0 G, most of the fine soil particles, as well as the gravel and fine sand of 74 μm or more, are removed from the sediment-mixed mud, so the increase in the specific gravity of the mud is extremely low. The amount of surplus mud, that is, the amount of waste mud, will also be small.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral H is a starting shaft excavated in the ground L to a predetermined depth, 1 is a mud pressure shield excavator according to the present invention, and T is a lower end of the starting shaft H by the mud pressure shield excavator 1. It shows a tunnel being dug horizontally from.

The muddy water pressure type shield excavator (hereinafter simply referred to as excavator) 1 includes a shield excavator 2 and coarse excavated earth and sand containing mud discharged from the shield excavator 2, that is, coarse particles in a mud mixed with earth and sand. In this case, a rotary sieve (primary treatment mechanism) 3 for removing a particle diameter of 10 mm or more) and a sediment-mixed mud from which the coarse particles have been removed by the rotary sieve 3 are supplied. Obtained from a plurality of decanters 4 (in this case, three units are set according to the flow rate of muddy water) that give a low centrifugal force of 400 G (low-speed centrifuge: secondary treatment mechanism). The mud tank 5 for temporarily storing the collected mud water, a belt conveyor (solid material carrying-out mechanism) 6 for carrying solid matter other than the mud discharged from the rotary sieve 3 and the decanter 4 to the rear of the tunnel T, and The conveyor type mixer (solid material unloading mechanism) 7 and the solid material supply tank 8 are arranged in series behind the belt conveyor 6.

As shown in FIGS. 1 and 2, each of the constituent elements 2 to 8 of the excavation device 1 is fixed to a carriage D that travels on two sets of rails RR laid on the bottom of the tunnel T. As is clear from the above, all of the excavation device 1 is installed inside the tunnel T along with the truck D so as to be movable along the rails RR.

The shield excavator 2 has a cylindrical skin plate 9
A cutter 10 and its rotation driving mechanism 11, a partition plate 13 forming a chamber 12 behind the cutter 10, and a jack 14 as a forward means, and the excavation unit is driven by the water pressure of the muddy water supplied to the front surface of the cutter 10. The construction in which the cutting face T ₁ is stabilized and the cutting face T ₁ is excavated by the cutter 10 which is rotated by the rotary drive mechanism 11 and is moved forward in the excavation direction by the jack 14 (moves leftward in FIG. 1). Has become.

The muddy water is supplied to the front surface of the cutter 10 by a muddy water supply line 15 piped from the ground L ₁ into the tunnel T, and the peripheral wall surface of the tunnel T excavated by the shield excavator 1 is located behind the shield excavator 2. Erecta installed in
The segment S is stretched by 16 and the primary lining is performed. The jack 14 moves the shield excavator 2 forward by receiving a reaction force on the segment S.

The earth and sand excavated by the shield excavator 2 is mixed with the mud as described above to become the earth and sand mixed mud, and the earth and sand mixed mud is taken into the chamber 12, and then the rotary sieve 3 and each decanter 4 ... Thus, the muddy water is separated into solid matter and the other solid matter, and the muddy water is reused for excavation by the shield excavator 2.

As shown in FIG. 3, the rotary sieve 3 has an earth and sand mixed mud water supply port 17a at its upper portion and a coarse grain discharge port 1 at its side wall.
A cylindrical casing 17 provided with 7b, an umbrella-shaped sieve 18 for sieving coarse particles provided inside the casing 17 and a motor 18a for rotating the sieve 18, and the supply The earth and sand mixed muddy water put in the casing 17 through the port 17a is stored in the casing 17 after removing coarse particles by the rotating sieve 18, and the coarse particles are discharged through the discharge port 17b. The coarse particles discharged from the discharge port 17b fall on the belt conveyor 6 and are sent to the rear of the tunnel T by this belt conveyor.

The earth and sand mixed muddy water separated by the rotary sieve 3 and stored in the casing 17 is supplied to each of the decanters 4 ..., Where it is separated into muddy water and other solid matter such as sand. Has become.

As shown in FIG. 4, the decanter 4 includes a cylindrical rotary casing 19 with one end side slightly narrowed, a screw conveyor 20 provided in the rotary casing 19, and a screw conveyor from one end side of the rotary casing 19. A hollow shaft 21 penetrating into the hollow shaft 20 and a feed tube 22 continuous with the hollow shaft 21 are provided. Rotating casing 19 and hollow shaft
It is connected integrally with 21 and is rotated by a motor 23.Also, in conjunction with these, the screw conveyor 20 is in the same direction as the rotary casing 19 via the gear box 24, and more than the rotary casing 19. It is designed to rotate at a slightly low speed.

The decanter 4 gives a centrifugal force to the sediment-mixed mud by ejecting the sediment-mixed mud supplied from the hollow shaft 21 into the rotary casing 19 from the feed tube 22 by a rotational force, so that the sand content By ejecting and depositing such solid matter on the inner wall of the rotary casing 19, the solid matter and muddy water containing only effective mud material are separated. Then, the solid matter is discharged from one end of the rotating casing 19 by the screw conveyor 20, while the muddy water is rotated.
It is designed to discharge from the other end of 19. The solid matter discharged from the decanter 4 is 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 soil-and-sand mixed muddy water jetted from the feed tube 22 to the inner wall of the rotary casing 19, and the muddy water discharge amount, which is its processing capacity, is about 360. It has a capacity of ~ 400m ³ / h.

Such ability, by appropriately setting the differential speed between the rotary casing 19 and the screw conveyor 20 and a gap between them, and further, the shape of the screw conveyor 20 and the like, under the above low centrifugal force. It realizes an increase in throughput and separation of solid particles having a large particle size (maximum diameter of 20 mm in the example). Thus, the decanter 4 has a classification point of 6 to 10 μm, and a removal rate for solids of 74 μm or more.
100%, and the processing capacity is such that a value of 360 to 400 m ³ / h can be obtained as described above.

The muddy water obtained by each of the decanters 4 ... Is supplied to the muddy water tank 5, temporarily stored therein, and then sent to the muddy water supply line 15 via a recovery line (muddy water recovery mechanism) 25. ing. In addition, in the recovery line 25,
An excess mud water recovery line 26 for recovering excess mud water is connected.

On the other hand, the solid matter discharged from the rotary sieve 3 and the decanters 4 ... And conveyed to the rear of the tunnel T by the belt conveyor 6 is supplied into the conveyer mixer 7. Solidified material is quantitatively supplied into the mixer 7 from the solidified material supply tank 8 provided above the mixer 7 through a constant quantity feeder 8a, whereby the solid matter is solidified, and
It is discharged from the mixer 7.

Examples of the solidifying material include cement, gypsum, superabsorbent resin, dry ash, and other special solidifying materials.For example, in the case of silt having a high water content, clay, etc., a material having high water absorbing property is used. As described above, it is preferable to appropriately select and use the composition of the solid matter, the water content, and the like.

The solidified solid matter discharged from the mixer 7 is a truck (solid matter carry-out mechanism) 27 that can travel on the rail R.
Is transported to the rear of the tunnel T and temporarily stored in the pit H ₁ dug at the lower end of the starting shaft H.

Next, the solid matter discarded in the pit H ₁ is conveyed to the ground L ₁ by a vertical belt conveyor (solid matter discharge mechanism) 28 installed in the starting shaft H.

The belt conveyor 28 includes a large number of shovels 2 fixed to the outer surface of the belt 28a as the belt 28a rotates.
8b sequentially scoops up the solid matter in the pit H ₁ and raises it to the ground L ₁ and drops the solid matter in the shovel 28b from the shovel 28b when descending via the bent portion 28c at the upper end.

In this case, the solid matter dropped from the shovel 28b is stored in the hopper 29 installed on the ground, and the hopper 29 is further
It is mounted on the dump truck C from 29 and is transported to an appropriate place by the dump truck C and disposed of.

 Next, the operation of the excavation device 1 having the above configuration will be described.

The excavated earth and sand excavated by the shield excavator 2 and taken into the chamber 12 of the shield excavator and the mud contained in the excavated earth, that is, the mud mixed with earth and sand, are supplied from the supply port 17a provided in the casing 17 of the rotary sieve 3 to the casing. Supply within 17 The muddy water in the initial stage is supplied from the ground L ₁ through the muddy water supply line 15.

Sediment-mixed mud contains coarse particles (particle size 10 mm
The above) remains on the sieve 18 which is rotated by the motor 18a, and the other sediment-mixed muddy water passes through the sieve 18 and is temporarily stored in the casing 17.

The coarse particles remaining on the sieve 18 are discharged from the outlet of the casing 17.
From 17b, it falls on the belt conveyor 6, and it is sent to the back of the tunnel T by this belt conveyor 6.

On the other hand, the soil-sand mixed mud stored in the casing 17
It is supplied after being separated into each decanter 4. That is, it is supplied into the hollow shaft 21 of each decanter 4.

The sediment-mixed mud water supplied into the hollow shaft 21 is ejected from the feed tube 22 into the rotary casing 19 by a centrifugal force of about 30 to 400 G, which causes the sand content contained in the sediment-mixed mud water to be included. Solid matter such as rotating casing 19
It accumulates on the inner wall and is separated into this solid matter and muddy water.

The decanter 4 is 30 for the supplied mud and sand mixture.
Since it gives a low centrifugal force of ~ 400G, the classification point is 6
It is up to 10 μm, and even fine soil particles such as fine sand are excluded from the solid matter contained in the soil-mixed mud water, but solid matter contained as a finer colloid than that, that is, bentonite, fine soil particles, etc. The effective mud material of is not separated, and the most effective mud with specific gravity of 1.2 is obtained.

The centrifugal force applied to the mud mixed with soil by the decanter 4 is 30
However, if the centrifugal force is 30 G or less, equal separation of fine sand or fine soil particles with a small particle size is not sufficiently performed, while if it is 400 G or more, muddy water is established. This is because the necessary mud materials such as bentonite and fine soil particles may be separated. Therefore, in consideration of both the separation ability and the treatment efficiency, it is more preferable to set the centrifugal force of the decanter 4 to around 200 to 300 G, and further it is preferable to set it appropriately according to the geology of the excavated soil.

Of the solid matter and muddy water separated by each decanter 4, ..., the solid matter is dropped onto the belt conveyor 6 and conveyed by the belt conveyor 6 to the rear of the tunnel T.
The muddy water is temporarily stored in the muddy water tank 5, and then sent to the muddy water supply line 15 via the recovery line 25. Since the muddy water sent to the recovery line 25 is usually higher than a predetermined specific gravity, the dilution water is sent from the muddy water supply line 15 at an appropriate flow rate to be mixed with the muddy water to adjust its specific gravity, and then the shield excavator 2 Cutter 10
It is supplied as drilling mud to the front side through a mud supply line 15. In addition, surplus mud water generated in the mud tank 5 is sent to the ground through the surplus mud recovery line 26 and appropriately treated.

When solid matter such as slum settles in the muddy water tank 5, it is extracted from the bottom of the muddy water tank 5, or
Try to scoop up with a grab.

On the other hand, the solid matter discharged from the rotary sieve 3 and the decanters 4 ... And conveyed to the rear of the tunnel T by the belt conveyor 6 is supplied into the conveyer mixer 7 and the solidifying material is also supplied into the mixer 7. A solidifying material is quantitatively supplied from the tank 8 via the constant quantity feeder 8a in accordance with the solid content and the water content. As a result, the solid matter is solidified and then discharged from the mixer 7.

The solidified solid matter discharged from the mixer 7 is transferred to the rail R
It is transported to the rear of the tunnel T by the trolley 27 that can run above, and is temporarily stored in the pit H ₁ . Next, the solid matter stored in the pit H ₁ is conveyed to the ground L ₁ by the belt conveyor 28 installed in the starting shaft H and is temporarily stored in the hopper 29. Then, when an appropriate amount of solid matter is accumulated in the hopper 29, the solid matter is loaded from the hopper 29 to the dump truck C, and is transported to an appropriate place by the dump truck C for disposal.

However, according to the excavation method using the excavation device 1 as described above, muddy water is treated inside the tunnel T. For example, it is difficult to install a treatment facility because the ground L ₁ is in the city area. Or, even if it is not possible at all, muddy water can be treated without any problems and a working space on the ground L ₁ can be secured. Moreover, since the mud water mixed with soil and sand discharged from the shield excavator 2 is promptly processed in the tunnel T without being lifted to the ground L ₁ , the mud water can be recovered in a short time and effectively, and Can be reused for drilling.

Further, in order to collect the muddy water, it is realized by treating with two devices of the rotary sieve 3 and each decanter 4, ... The decanter 4 is not only fine gravel and fine sand of 74 μm or more, but also fine soil particles. Since most of the muddy water is 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 muddy waste water is also small.

Therefore, as in the conventional case, a device for removing fine solid matter such as a filter press and a treatment facility for excess mud water are unnecessary, or the number thereof is drastically reduced even if necessary. Installation space can be reduced. This allows the excavator 1 to be easily installed in the tunnel T.

In the above embodiment, the decanter 4 of the decanter 4 was prepared by mixing an appropriate amount of a dispersant that effectively disperses the mud water and other solid matter into the mud water containing earth and sand stored in the casing 17 of the rotary sieve 3. The resolution can be further improved.

Further, solid matter such as sand content separated and discharged by each decanter 4 ... May be separately collected and used as a backfill material for resource reuse. Further, a solidifying material is mixed with the solid material conveyed by the belt conveyor 6 for disposal, and this step is
It can be omitted depending on the type of solid matter, water content, and the like.

Furthermore, in the above embodiment, the low-speed centrifuge was described as the decanter, but the low-speed centrifuge in the present invention refers to one that continuously carries out the separation treatment of the solid matter with the centrifugal force in the above range, It is not limited to the decanter.

〔The invention's effect〕

As described above, according to the present invention, since muddy water is processed inside the drill hole, for example, even if it is difficult to install the device because the city is on the ground, or even if it is impossible at all, no matter what. The mud can be treated without problems, a working space on the ground can be secured, and the mud containing soil and sand discharged from the shield excavator is quickly processed inside the excavation hole without being lifted to the ground. Muddy water can be effectively collected and reused for excavation by a shield excavator.

The muddy water is collected by treating it with a primary treatment mechanism such as a sieve and a low-speed centrifuge as a secondary treatment mechanism. The low-speed centrifuge is about 30 to 400 G for mud mixed with sediment. By applying the centrifugal force of, the sediment-mixed mud removes most of the fine soil particles as well as gravel and fine sand of 74 μm or more, so the specific gravity of the mud is extremely low, and therefore the excess mud That is, the amount of waste mud is also small.

Therefore, as in the conventional case, a device for removing fine solid matter such as a filter press and a treatment facility for excess mud water are unnecessary, or the number thereof is drastically reduced even if necessary. Cost reduction can be realized from both aspects of installation space reduction and labor reduction.

[Brief description of the drawings]

1 is an overall schematic view showing a muddy water treatment facility suitable for carrying out the present invention, FIG. 2 is a view taken along the line II-II in FIG. 1, and FIG.
FIG. 4 is a vertical sectional view showing the structure of the rotary sieve, and FIG. 4 is a sectional view showing the structure of the decanter. 1 …… Muddy water pressure shield excavator, 2 …… Shield excavator, 3 …… Rotary sieve (primary treatment mechanism), 4 …… Decanter (low-speed centrifuge: secondary treatment mechanism), 6, 28 …… Belt conveyor (solids unloading mechanism), 7 ... transport mixer, 25 ... collection line (muddy water recovery mechanism), 27 ... truck (solids unloading mechanism), L ... ground, T ... tunnel (drilling hole) ), T ₁ …… Face.

Claims (1)

(57) [Claims] 1. A shield excavator for digging into the ground, and sediment-mixed mud carried out together with excavated soil from the excavation section of the shield excavator, from which solid matters having a large particle size such as gravel are removed. As a primary treatment mechanism, a sieve for sieving the sediment-mixed mud to separate it into large-particle-sized solids and mud, and the sediment-mixed mud that has passed through this primary treatment mechanism is supplied.
A secondary treatment mechanism that separates muddy water containing only effective muddy water materials such as bentonants and fine soil particles and fine solid particles with a small particle size such as sand by applying centrifugal force to this muddy water As a rotating casing having a cylindrical shape with one end narrowed and rotatably supported in one direction around the central axis, and provided in the rotating casing so as to rotate in another direction different from the rotating casing. A supported screw conveyor, a hollow shaft that penetrates into the screw conveyor from one end side of the rotating casing, and a feed tube that is connected to the hollow shaft, and separates from coarse solids by the primary treatment mechanism. The soil-mixed muddy water is rotated by rotating the rotary casing and the screw conveyor in different directions to generate a rotational force from the field tube into the rotary casing. A low-centrifugal separator that separates coarse particles into solids and mud separated by the primary treatment mechanism to give a low centrifugal force of 30 to 400 G to separate small particles into solids and mud. And a muddy water collecting mechanism that collects the muddy water obtained by the primary treatment mechanism and the secondary treatment mechanism in the excavation hole and sends the muddy water to the excavation section, while separating the muddy water by the primary treatment mechanism and the secondary treatment mechanism. And a solid material carrying-out mechanism for carrying out the solid material to the outside of the drilling hole, wherein each mechanism is installed inside the drilling hole driven by the shield drilling machine. .