Slurry type tunnel drilling machine and method for drilling tunnel

Abstract

To reduce drilling torque in slurry type tunnel drilling machines.SOLUTION: A slurry type shield drilling machine 100 comprises a skin plate 11 capable of supporting an inner wall of rock mass, a cutter head 12 mounted on the skin plate 11 and drilling the rock mass by rotation, a bulkhead 13 provided in the skin plate 11 and positioned opposite the cutter head 12 in an axial direction of a tunnel T, a cutter chamber 14 which is divided by the skin plate 11, the cutter head 12, and the bulkhead 13, and into which sediment drilled by the cutter head 12 flows, a mud feed pipe 41 supplying mud to the cutter chamber 14, a mud drain pipe 46 discharging mud from the cutter chamber 14, and a first bubble injection pipe 51 that is attached to the cutter head 12 and injects bubbles between the cutter head 12 and a working face 2 of the rock mass or into the cutter chamber 14.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a slurry tunnel boring machine and a tunnel excavation method. [Background technology]

[0002] Patent Document 1 discloses a muddy water shield method in which a tunnel face is filled with muddy water and excavated using a shield machine. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-266031 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a muddy tunnel boring machine such as that disclosed in Patent Document 1, muddy water is supplied to a cutter chamber formed on the back of a cutter head that excavates natural ground through a mud supply pipe and discharged through a mud discharge pipe. The pressure of the face acting on the cutter head is supported by the pressure of the muddy water in the cutter chamber. The cutter head and the face are connected to the cutter chamber, and the excavated soil is led into the cutter chamber and discharged through the mud discharge pipe.

[0005] In recent years, tunnel construction has become larger in cross section and longer in distance. When the tunnel construction becomes larger in cross section or longer in distance, the excavation torque of the tunnel boring machine increases, which may reduce the excavation speed.

[0006] An object of the present invention is to reduce the excavation torque in a mud type tunnel boring machine. [Means for solving the problem]

[0007] The present invention is a mud water tunnel boring machine comprising a body capable of supporting the inner wall of the ground, an excavation unit attached to the body and excavating the ground by rotation, a partition provided within the body and positioned opposite the excavation unit in the axial direction of the tunnel, a cutter chamber partitioned by the body, the excavation unit and the partition and into which soil excavated by the excavation unit flows, a mud supply pipe for supplying mud water into the cutter chamber, a mud discharge pipe for discharging mud water from within the cutter chamber, and an air bubble injection pipe attached to the excavation unit for injecting air bubbles between the excavation unit and the face of the ground or into the cutter chamber.

[0008] The present invention also relates to a mud water tunnel boring machine comprising a body capable of supporting the inner wall of the ground, an excavation section attached to the body and excavating the ground by rotation, a partition provided within the body and positioned opposite the excavation section in the axial direction of the tunnel, a cutter chamber partitioned by the body, the excavation section and the partition and into which soil excavated by the excavation section flows, a mud supply pipe for supplying mud water into the cutter chamber, a mud discharge pipe for discharging mud water from within the cutter chamber, and an air bubble injection pipe provided in the body for injecting air bubbles between the excavation section and the face of the ground or into the cutter chamber.

[0009] The present invention also relates to a mud water tunnel boring machine comprising a body capable of supporting the inner wall of the ground, an excavation section attached to the body and excavating the ground by rotation, a partition wall provided within the body and positioned opposite the excavation section in the axial direction of the tunnel, a cutter chamber partitioned by the body, the excavation section and the partition wall and into which soil excavated by the excavation section flows, a mud supply pipe for supplying mud water into the cutter chamber, a mud discharge pipe for discharging mud water from within the cutter chamber, and an air bubble injection pipe provided in the partition wall for injecting air bubbles between the excavation section and the face of the ground or into the cutter chamber. Effect of the Invention

[0010] According to the present invention, the excavation torque can be reduced in a slurry tunnel boring machine. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a shield machine according to an embodiment of the present invention. [Diagram 2] 1 is a block diagram showing a configuration of a shield tunneling machine according to an embodiment of the present invention. FIG. [Diagram 3] FIG. 2 is a schematic diagram showing a specific configuration of an air bubble liquid supply unit of a shield machine according to an embodiment of the present invention. [Figure 4] FIG. 2 is a schematic diagram showing a first modified example of a shield machine according to an embodiment of the present invention. [Diagram 5] FIG. 11 is a schematic diagram showing a second modified example of a shield machine according to an embodiment of the present invention. [Figure 6] FIG. 11 is a schematic diagram showing a third modified example of a shield machine according to an embodiment of the present invention. [Figure 7] FIG. 11 is a schematic diagram showing a fourth modified example of a shield machine according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] A tunnel boring machine according to an embodiment of the present invention will be described below with reference to the drawings. In the following, a case will be described in which the tunnel boring machine is a shield machine 100 used in a shield construction method. The shield machine 100 excavates the ground (natural ground) to form an excavation hole 1, and constructs a tunnel T by assembling segment rings 10 (lining) to cover the inner wall of the excavation hole 1. Note that the present invention can also be applied to tunnel boring machines other than the shield machine 100, for example, an excavation machine installed at the tip of a jacking pipe in a jacking construction method.

[0013] In the following description, the tunnel face side, which is the direction in which the shield machine 100 advances, is referred to as the "front," and the tunnel mouth side, which is the opposite direction, is referred to as the "rear."

[0014] The shield machine 100 of this embodiment is a slurry shield machine used in a slurry shield tunneling method.

[0015] 1, the shield machine 100 comprises a skin plate 11 as a cylindrical body extending along the axial direction of tunnel T and capable of supporting the inner wall of excavation hole 1, a cutter head 12 as an excavation section that is rotationally driven in front of the skin plate 11, a partition wall 13 provided within the skin plate 11 and arranged facing the cutter head 12 in the axial direction of tunnel T, a cutter chamber 14 into which earth and sand excavated by the cutter head 12 flows, and a mud water supply and discharge section 30 that supplies and discharges mud water into and from the cutter chamber 14. On the rear side inside the skin plate 11, segment rings 10 are constructed successively as the shield machine 10 advances.

[0016] The body of a jack 20 is fixed to the skin plate 11. The jack 20 receives a reaction force from the segment ring 10 to propel the skin plate 11 forward and press the cutter head 12 against the natural ground. When the skin plate 11 is propelled and the segment ring 10 comes out of the skin plate 11, a backfilling material (not shown) is filled between the outer circumferential surface of the segment ring 10 and the inner wall of the excavation hole 1. The jack 20 is also provided with a speed measuring unit 21 (see FIG. 2) for measuring the excavation speed of the shield machine 100. The speed measuring unit 21 is, for example, a stroke sensor that measures the amount of movement of the jack 20, and the measurement results of the speed measuring unit 21 are input to a control unit 70 described later.

[0017] The cutter head 12 is a so-called face plate type cutter head 12. The cutter head 12 is provided with a plurality of cutter bits 12a that protrude forward. When the cutter head 12 rotates while being pressed against the natural ground, the natural ground is excavated by the cutter bits 12a to form the excavation hole 1. The outer diameter of the cutter head 12 is approximately equal to the outer diameter of the skin plate 11, and the natural ground is excavated with an inner diameter approximately equal to the outer diameter of the skin plate 11. The soil excavated by the cutter head 12 is guided to the rear of the cutter head 12 through openings such as slits (not shown) provided in the cutter head 12, and is retained in the cutter chamber 14.

[0018] The cutter chamber 14 is partitioned by the skin plate 11, the cutter head 12, and the partition wall 13. Mud water is supplied into the cutter chamber 14 from a mud water supply and discharge section 30. By filling the cutter chamber 14 with mud water and causing the pressure of the mud water in the cutter chamber 14 to act on the cutter head 12, the earth pressure and groundwater pressure at the face 2 can be suppressed by the cutter head 12, and the face 2 can be stabilized.

[0019] The partition 13 is disposed opposite the cutter head 12 in the axial direction of the tunnel T, and a rotating drum 26 is rotatably supported relative to the partition 13. The cutter head 12 is connected to the rotating drum 26 via a connecting rod 27 and can rotate together with the rotating drum 26. The rotating drum 26 is connected to an electric motor 25 via a reduction mechanism (not shown), and the rotating drum 26 and the cutter head 12 rotate relative to the skin plate 11 when driven by the electric motor 25. The rotation direction and rotation speed of the cutter head 12 can be controlled by controlling the operation of the electric motor 25.

[0020] The muddy water supply and discharge section 30 has a storage section 31 located on the ground for storing muddy water, a supply line 40 for supplying muddy water from the storage section 31 to the cutter chamber 14, and a discharge line 45 for discharging muddy water from the cutter chamber 14 to the storage section 31.

[0021] The storage section 31 has a sediment separation section 32 that separates sediment from the muddy water discharged from the cutter chamber 14, and an adjustment section 33 that adds an adjuster to the muddy water supplied from the sediment separation section 32 to adjust the properties of the muddy water and store it.

[0022] The sediment separation section 32 is composed of, for example, a cyclone or a vibrating screen, and separates sediment and muddy water (clay water) from each other based on the difference in specific gravity. The separated muddy water is supplied to the adjustment section 33. The muddy water containing a large amount of excavated soil particles discharged from the discharge line 45 has the excavated soil particles separated and removed by the sediment separation section 32, and the muddy water containing less excavated soil particles is supplied through the supply line 40. That is, the sediment separation section 32 adjusts the specific gravity of the muddy water. The specific gravity of the transported muddy water is preferably 1.10 or more and 1.25 or less, and the specific gravity of the discharged muddy water is preferably 1.20 or more and 1.35 or less. Although detailed explanation and illustration are omitted, the sediment separation section 32 is provided with a filter press (not shown) that presses the excess muddy water generated by adjusting the muddy water to produce a dehydrated cake (secondary treated soil).

[0023] In the adjustment section 33, fresh water is supplied to the muddy water stored in the adjustment tank 34 (storage tank) by the fresh water supply section 35a, or an adjuster is added by the adjuster supply section 35b. This adjusts the specific gravity or viscosity (viscosity) of the muddy water. Although detailed illustration is omitted, the adjuster supply section 35b has, for example, an addition section that adds an adjuster to the muddy water in the adjustment tank 34, and a supply section that is a supply source such as a pump that supplies the adjuster to the addition section. The adjuster is, for example, an additive that adjusts viscosity, such as bentonite, a polymer surfactant, or a polymer flocculant. This adjusts the muddy water supplied to the cutter chamber 14 to the desired properties.

[0024] The supply line 40 has a mud transport pipe 41 that connects the storage section 31 and the cutter chamber 14 and supplies mud water into the cutter chamber 14, and a mud transport pump 42 that sucks mud water from the storage section 31 and discharges it toward the cutter chamber 14. The supply line 40 is also provided with a mud transport amount measuring section 43 (see FIG. 2) that measures the amount of mud transported.

[0025] The mud transport pipe 41 is attached to the partition wall 13 and faces the inside of the cutter chamber 14. The mud transport pipe 41 is attached, for example, so as to open into the cutter chamber 14 above the center of the cutter chamber 14 in the vertical direction. One or more mud transport pumps 42 are provided throughout the mud transport pipe 41 to achieve the desired supply capacity. The mud transport amount measurement unit 43 is, for example, a flow meter provided in the mud transport pipe 41.

[0026] The discharge line 45 has a sludge discharge pipe 46 that connects the cutter chamber 14 and the storage section 31 and discharges the muddy water in the cutter chamber 14, and a sludge discharge pump 47 that sucks the muddy water from the cutter chamber 14 and discharges it toward the storage section 31. In addition, the discharge line 45 is provided with a sludge amount measuring section 48 (see FIG. 2) that measures the amount of sludge discharged.

[0027] The sludge discharge pipe 46 is attached to the partition wall 13 and faces the inside of the cutter chamber 14. The sludge discharge pipe 46 is attached, for example, so as to open into the cutter chamber 14 below the center of the cutter chamber 14 in the vertical direction. One or more sludge discharge pumps 47 are provided throughout the sludge discharge pipe 46 so as to achieve the desired discharge capacity. Note that only a single sludge feed pump 42 and a single sludge discharge pump 47 are shown in the drawings. The sludge discharge amount measurement unit 48 is, for example, a flow meter provided in the sludge discharge pipe 46.

[0028] As shown in Figures 1 and 2, the shield tunneling machine 100 further includes an air bubble injection unit 50 that injects air bubbles into the mud water circulated between the cutter chamber 14 and the storage unit 31, an air bubble removal unit 60 that removes air bubbles from the mud water, and a control unit 70 that controls the operation of the air bubble injection unit 50 and the air bubble removal unit 60.

[0029] In this embodiment, the amount of air bubbles contained in the muddy water can be adjusted for each specific section on the circulation path by the air bubble injector 50 and the air bubble remover 60.

[0030] The air bubble injection section 50 has a first air bubble injection pipe 51 (air bubble injection pipe) attached to the cutter head 12 and injecting air bubbles into the mud water in the space between the cutter head 12 and the face 2 (hereinafter also referred to as the "face space 3"); a second air bubble injection pipe 52 (air bubble injection pipe) attached to the skin plate 11 and injecting air bubbles into the mud water in the face space 3; and an air bubble liquid supply section 53 that supplies air bubble liquid to the first air bubble injection pipe 51 and the second air bubble injection pipe 52. Note that the face 2 and the face space 3 are shown in FIG. 1 as a schematic diagram.

[0031] The first air bubble injection pipe 51 is connected to a supply passage 12b formed in the center of the circular cross section of the cutter head 12 and communicating with the face space 3, and is attached to the cutter head 12 via a bearing (not shown). As a result, the air bubbles introduced by the first air bubble injection pipe 51 are supplied to the face space 3 through the supply passage 12b.

[0032] The second air bubble injection pipe 52 is attached to the skin plate 11 along the axial direction of the tunnel T, and faces the face space 3 through a gap between the outer periphery of the cutter head 12 and the inner periphery of the excavation hole 1. A plurality of second air bubble injection pipes 52 may be provided in the circumferential direction of the cutter head 12.

[0033] The air bubbles introduced by the second air bubble injection pipe 52 are supplied to the face space 3 through the gap between the outer periphery of the cutter head 12 and the inner periphery of the excavation hole 1. In other words, the air bubbles are injected into the face space 3 from the outer periphery side of the cutter head 12 by the second air bubble injection pipe 52.

[0034] The first air bubble injection pipe 51 and the second air bubble injection pipe 52 are provided with valves (not shown) for controlling the flow of the air bubbles (air bubble liquid) passing through them. By opening and closing the valves, the flow rates of the air bubbles introduced by the first air bubble injection pipe 51 and the second air bubble injection pipe 52 can be controlled.

[0035] The air bubble liquid supply unit 53 is a supply source that supplies air bubble liquid to the first air bubble injection pipe 51 and the second air bubble injection pipe 52. Air bubbles are contained in the muddy water by injecting the air bubble liquid into the muddy water through the first air bubble injection pipe 51 and the second air bubble injection pipe 52. As shown in Fig. 3, the air bubble liquid supply unit 53 has a foaming agent solution supply unit 54 that supplies a foaming agent solution obtained by diluting a foaming agent stock solution (foaming agent stock solution), an air supply unit 57 that supplies air to the foaming agent solution, and a foaming unit 58 that foams the foaming agent solution to which air has been supplied.

[0036] The foaming agent solution supply section 54 has a foaming agent solution tank 55a into which the foaming agent concentrate is guided from the concentrate tank 55b and water is guided from the fresh water tank 55c, and inside which the foaming agent concentrate is diluted with water, and a foaming agent solution pump 56 that sucks the foaming agent solution from the foaming agent solution tank 55a and supplies it to the foaming section 58.

[0037] The air supply unit 57 is a compressor that supplies compressed air to the foaming unit 58 .

[0038] The foaming unit 58 is a foaming gun that mixes and stirs the supplied foaming agent solution and air to generate and discharge foam liquid. By controlling the operation of the foaming agent solution pump 56 of the foaming agent solution supply unit 54 (and thus the supply amount of foaming agent solution) and the operation of the air supply unit 57 (and thus the supply amount of air), foam liquid with any foaming ratio can be generated.

[0039] The foam liquid, which is a solution containing air bubbles, is produced by diluting the foaming agent stock solution with water, for example, 15 to 20 times to prepare a foaming agent solution, and then foaming the foaming agent solution to a volume of 5 to 30 times the foaming ratio. The foaming agent is, for example, an anionic surfactant. Anionic surfactants are excellent in terms of resistance to defoaming, chemical stability, foaming ability, etc. The foaming agent is not limited to anionic surfactants, and may be other types such as protein-based foaming agents and nonionic surfactants.

[0040] The amount of bubbles in the foam liquid is calculated from the volume of the foaming agent solution and the foaming ratio relative to the volume. For example, the foaming agent solution, which is obtained by diluting the foaming agent stock solution with water, is supplied to the foaming section 58 by the foaming agent solution supply section 54 with a volume L of 1 liter [l], and air is injected into the foaming section 58 by the air supply section 57 so that the foaming ratio N becomes 10 times (N=10). As a result, the foaming agent solution is foamed 10 times and 10 liters (L×N) of foam liquid is generated. In this case, the amount of bubbles is calculated to be 9 liters (L×(N-1)). Since the amount of bubbles in the foam liquid, which is a solution containing bubbles, cannot be measured directly, the amount of bubbles in the foam liquid (i.e., the amount of bubbles supplied to the muddy water) is calculated by design from the process of generating the foam liquid in this way, that is, it is specified by the volume of the foaming agent solution and the foaming ratio.

[0041] As shown in Figures 1 and 2, the air bubble removal section 60 has a first defoaming agent injection section 61 (defoaming agent injection section) that injects defoaming agent into the muddy water discharged from the cutter chamber 14 and passing through the mud discharge pipe 46, and a second defoaming agent injection section 62 (defoaming agent injection section) that injects defoaming agent into the muddy water in the adjustment tank 34 of the storage section 31.

[0042] Although detailed illustration is omitted, the first defoaming agent injection section 61 and the second defoaming agent injection section 62 each have a nozzle section for injecting a defoaming agent and a supply section such as a pump for supplying a defoaming agent to the nozzle section. The first defoaming agent injection section 61 is attached to the sludge discharge pipe 46 and injects the defoaming agent into the sludge discharge pipe 46 from an injection port provided in the sludge discharge pipe 46. The first defoaming agent injection section 61 is configured to inject the defoaming agent into the sludge discharge pipe 46 between at least one sludge discharge pump 47 and the cutter chamber 14. The second defoaming agent injection section 62 is attached to the adjustment tank 34 and injects the defoaming agent into the adjustment tank 34. The defoaming agent is, for example, a silicone-based defoaming agent.

[0043] The control unit 70 is configured by a computer including a CPU (Central Processing Unit) that executes a control program and the like, a ROM (Read-Only Memory) that stores the control program executed by the CPU, a RAM (Random Access Memory) that stores the results of CPU calculations and the like, a communication device, etc. The control unit 70 executes various functions of the control unit 70 described in this specification by loading the control program stored in the ROM into the RAM and executing it on the RAM by the CPU. The control unit 70 may be configured by one computer, or may be configured by multiple microcomputers and configured to distribute the various controls among the multiple computers.

[0044] The control unit 70 acquires the excavation speed of the tunnel T by the cutter head 12, the amount of mud water (mud feed amount) supplied to the cutter chamber 14, and the amount of mud water (mud discharge amount) discharged from the cutter chamber 14. The excavation speed is calculated from the movement amount (stroke amount) of the jack 20 measured by the speed measurement unit 21. The mud feed amount and the mud discharge amount are acquired by utilizing the measurement values ​​of the mud feed amount measurement unit 43 and the mud discharge amount measurement unit 48, respectively.

[0045] The control unit 70 controls the operation of the air bubble injection unit 50 (more specifically, the air bubble liquid supply unit 53) based on the excavation speed of the tunnel T and the amount of mud sent to the cutter chamber 14. The control unit 70 may be used in common with other controllers that control components other than the air bubble injection unit 50 and the air bubble removal unit 60 in the shield tunneling machine 100, or may be provided separately from the other controllers.

[0046] When the shield machine 100 excavates the tunnel T, the face space 3 between the cutter head 12 and the face 2 is filled with muddy water mixed with excavated earth and sand and groundwater from the natural ground. Since the face space 3 is connected to the cutter chamber 14, the muddy water in the cutter chamber 14 is also led to the face space 3. In this manner, with the face space 3 filled with muddy water, the cutter head 12 rotates to excavate the natural ground. In the tunnel excavation method using the shield machine 100 of this embodiment, the tunnel T is excavated while air bubbles are injected into the muddy water in the face space 3 by the air bubble injection unit 50.

[0047] The amount of air bubbles injected into the mud (amount of air bubbles per unit time) is determined based on the amount of mud sent to the cutter chamber 14 (amount of mud sent per unit time), i.e., the amount of mud sent measured by the mud sent amount measuring unit 43. Specifically, when the outer diameter of the cutter head 12 is less than 8 m, the amount of air bubbles injected into the mud is set so that the volume ratio to the amount of mud sent is 0.2% or more and 10.0% or less, preferably 0.2% or more and 7.5% or less, and more preferably 0.2% or more and 5.0% or less. When the outer diameter of the cutter head 12 is 8 m or more, the amount of air bubbles injected into the mud is set so that the volume ratio to the amount of mud sent is 0.2% or more and 8.0% or less, preferably 0.2% or more and 6.0% or less, and more preferably 0.2% or more and 4.0% or less.

[0048] The control unit 70 controls the operation of the air bubble liquid supply unit 53 (foaming agent solution supply unit 54, air supply unit 57, foaming unit 58) (supply amount of foaming agent solution) so that the amount of air bubbles injected into the muddy water is the amount of air bubbles set as described above. In other words, the supply amount of air bubble liquid is set so that the volume ratio of air bubbles to the muddy water volume measured per unit time is the above-mentioned ratio. The supply amount of air bubble liquid can be calculated from the volume of the foaming agent solution and the foaming ratio. The ratio of the amount of air bubble liquid introduced from the first air bubble injection pipe 51 to the amount introduced from the second air bubble injection pipe 52 can be set arbitrarily.

[0049] The control unit 70 also controls the operation of the air bubble injection unit 50 so as to increase the amount of air bubbles (amount of air bubble liquid supplied) injected as the tunneling speed of the shield tunneling machine 100 increases and decrease the amount of air bubbles injected as the tunneling speed decreases, within a range in which the amount of air bubbles injected into the muddy water is set to a set amount. The tunneling speed of the shield tunneling machine 100 is preferably set to a lower limit of 0.010 m / min or more and an upper limit of 0.050 m / min or less, and more preferably set to a lower limit of 0.020 m / min or more and an upper limit of 0.040 m / min or less, and tunneling is continued continuously within this tunneling speed range.

[0050] In this way, by injecting air bubbles into the mud water in the face space 3, the lubricating effect of the air bubbles in the mud water reduces the frictional resistance between the face 2 and the cutter head 12. This reduces the excavation torque of the shield machine 100. Furthermore, as the excavation torque is reduced, it is possible to increase the excavation speed and reduce power consumption.

[0051] On the other hand, an increase in the air bubble content in the muddy water may make it easier for cavitation to occur in the mud feed pump 42 or the mud discharge pump 47. For this reason, in this embodiment, the air bubble removal section 60 removes air bubbles from the muddy water passing through the mud discharge pipe 46 and the muddy water stored in the adjustment tank 34.

[0052] By removing the air bubbles from the muddy water passing through the sludge discharge pipe 46, the air bubble content in the muddy water sucked into the sludge discharge pump 47 is reduced, so that the occurrence of cavitation in the sludge discharge pump 47 can be suppressed.

[0053] By removing the air bubbles from the muddy water stored in the adjustment tank 34, the air bubble content of the muddy water sucked into the mud feed pump 42 decreases, thereby suppressing the occurrence of cavitation in the mud feed pump 42.

[0054] In this way, by reducing the air bubble content of the mud sucked in by the mud feed pump 42 and the mud discharge pump 47 using the bubble removal section 60, the occurrence of cavitation in the mud feed pump 42 and the mud discharge pump 47 can be suppressed even if air bubbles are injected into the face space 3 and the air bubble content of the mud increases.

[0055] In addition, by removing air bubbles from the muddy water stored in the adjustment tank 34, the squeezing efficiency (the efficiency of producing dehydrated cake) of the filter press that produces secondary treated soil from the excess muddy water can be improved.

[0056] According to the above embodiment, the following advantageous effects are achieved.

[0057] In this embodiment, air bubbles are injected into the face space 3 between the face 2 and the cutter head 12, so that air bubbles are contained in the muddy water containing the excavated soil between the face 2 and the cutter head 12. This reduces the frictional resistance between the face 2 and the cutter head 12 due to the lubricating effect of the air bubbles. This makes it possible to reduce the excavation torque in the shield tunneling machine 100. The reduced excavation torque makes it possible to accommodate larger cross-sections and longer distances in shield construction work.

[0058] This embodiment also includes a bubble removal section 60 that removes air bubbles from the mud water in the mud discharge pipe 46 and the adjustment tank 34 of the reservoir 31. This allows air bubbles to be injected into the mud water in the face space 3 to reduce the drilling torque, while suppressing the air bubble content in the mud water sucked in by the mud discharge pump 47 and the mud feed pump 42, thereby suppressing the occurrence of cavitation.

[0059] Next, modified examples of this embodiment will be described. The following modified examples are also within the scope of the present invention. It is also possible to combine the configuration shown in the modified example with the configuration described in the above embodiment, or to combine the configurations described in the different modified examples below.

[0060] In the above embodiment, the air bubble injection unit 50 injects air bubbles into the face space 3 between the cutter head 12 and the face 2. In contrast, the air bubble injection unit 50 (first air bubble injection pipe 51 and second air bubble injection pipe 52) may be configured to inject air bubbles into the muddy water in the cutter chamber 14. Since the muddy water in the cutter chamber 14 is also led to the face space 3, even if the air bubble injection unit 50 is configured to inject air bubbles into the muddy water in the cutter chamber 14, the same effect as in the above embodiment can be achieved.

[0061] In the above embodiment, the air bubble injection section 50 has a first air bubble injection pipe 51 and a second air bubble injection pipe 52 as air bubble injection pipes. This allows air bubbles to be injected uniformly throughout the mud water in the tunnel face space 3. In contrast, the shield machine 100 may be configured to have only the first air bubble injection pipe 51 as shown in Fig. 4, or may be configured to have only the second air bubble injection pipe 52 as shown in Fig. 5.

[0062] In addition, as shown in FIG. 6, the shield machine 100 may have a third air bubble injection pipe 59a that is connected to the sludge discharge pipe 46 and injects air bubbles into the muddy water passing through the sludge discharge pipe 46. In this case, the injection of the defoaming agent from the first defoaming agent injection section 61 of the air bubble removal section 60 is stopped. As described above, if the muddy water in the sludge discharge pipe 46 contains a large amount of air bubbles, cavitation may occur in the sludge discharge pump 47. On the other hand, if cavitation does not occur, it is better for the muddy water to contain a certain amount of air bubbles in order to reduce friction between the sludge discharge pipe 46 and the muddy water, and to improve the life of the sludge discharge pump 47 and the sludge discharge pipe 46. Therefore, when the muddy water in the sludge discharge pipe 46 contains a small amount of air bubbles and there is little risk of cavitation, it is also possible to improve the life of the sludge discharge pump 47 and the sludge discharge pipe 46 by injecting air bubbles into the muddy water in the sludge discharge pipe 46 from the third air bubble injection pipe 59a.

[0063] 7, the air bubble injection section 50 may have a fourth air bubble injection pipe 59b attached to the partition wall 13 as an air bubble injection pipe, instead of or in addition to the first air bubble injection pipe 51 and the second air bubble injection pipe 52 of the above embodiment. In this case, as shown in FIG. 7, air bubbles may be injected into the cutter chamber 14 through the fourth air bubble injection pipe 59b, or, although not shown, air bubbles may be injected into the face space 3 (between the cutter head 12 and the face 2) through the gap between the outer periphery of the cutter head 12 and the inner periphery of the excavation hole 1.

[0064] In the above embodiment, the cutter head 12 has a supply passage 12b formed in the center of the circular shape, and air bubbles are supplied from the first air bubble injection pipe 51 to the face space 3 through the supply passage 12b. In contrast, the configuration of the supply passage 12b is not limited to that of the above embodiment. For example, in addition to the supply passage 12b in the above embodiment, the cutter head 12 may have one or more outer supply passages that communicate with the supply passage 12b and open to the face space 3 on the outer periphery side of the cutter head 12 relative to the supply passage 12b. Air bubbles guided from the first air bubble injection pipe 51 are guided to the outer supply passage in addition to the supply passage 12b, so that air bubbles can be injected into the mud water in the face space 3 from the outer periphery side of the cutter head 12. This allows air bubbles to be injected more uniformly throughout the mud water in the face space 3.

[0065] In the above embodiment, the amount of air bubbles injected into the muddy water is set based on the amount of muddy water supplied (amount of mud sent) to the cutter chamber 14. Alternatively, the amount of air bubbles injected into the muddy water may be set based on the amount of mud discharged from the cutter chamber 14.

[0066] When the amount of air bubbles injected into the mud is set based on the amount of sludge discharged per unit time from the cutter chamber 14, i.e., the amount of sludge measured by the sludge amount measuring unit 48, the amount of air bubbles injected into the mud is set so that the volume ratio to the amount of sludge discharged is 0.2% or more and 10.0% or less, preferably 0.2% or more and 7.5% or less, and more preferably 0.2% or more and 5.0% or less, when the outer diameter of the cutter head 12 is less than 8 m, as in the case of being based on the amount of sludge fed. When the outer diameter of the cutter head 12 is 8 m or more, the amount of air bubbles injected into the mud is set so that the volume ratio to the amount of sludge discharged is 0.2% or more and 8% or less, preferably 0.2% or more and 6.0% or less, and more preferably 0.2% or more and 4.0% or less. Even in this case, the amount of air bubbles to be supplied is set and controlled in the same manner as in the case of being based on the amount of sludge fed.

[0067] Although the embodiments of the present invention have been described above, the above-mentioned embodiments merely show some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above-mentioned embodiments. [Explanation of symbols]

[0068] 100 Shield tunneling machine (tunnel boring machine) 2. Face 11 Skin plate (torso) 12 Cutter head (excavation section) 13 Bulkhead 14 Cutter chamber 34 Adjustment tank (storage tank) 41 Sludge pipe 46 Sludge drainage pipe 51 First air bubble injection pipe (air bubble injection pipe) 52 Second air bubble injection pipe (air bubble injection pipe) 59b Fourth air bubble injection pipe (air bubble injection pipe) 61 First defoamer injection section (defoamer injection section) 62 Second defoamer injection section (defoamer injection section) T-Tunnel

Claims

1. A mud tunnel boring machine for excavating a tunnel, comprising: A body capable of supporting an inner wall of the ground; An excavation unit that is attached to the body and excavates the natural ground by rotation; A bulkhead provided within the body and arranged opposite the excavated portion in the axial direction of the tunnel; a cutter chamber partitioned by the body, the excavation section, and the partition, into which soil excavated by the excavation section flows; A mud pipe for supplying mud water into the cutter chamber; A mud drain pipe for draining muddy water from within the cutter chamber; and an air bubble injection pipe attached to the excavation section for injecting air bubbles between the excavation section and the face of the natural ground or into the cutter chamber. Tunnel boring machine.

2. A mud tunnel boring machine for excavating a tunnel, comprising: A body capable of supporting an inner wall of the ground; An excavation unit that is attached to the body and excavates the natural ground by rotation; A bulkhead provided within the body and arranged opposite the excavated portion in the axial direction of the tunnel; a cutter chamber partitioned by the body, the excavation section, and the partition, into which soil excavated by the excavation section flows; A mud pipe for supplying mud water into the cutter chamber; A mud drain pipe for draining muddy water from within the cutter chamber; and an air bubble injection pipe attached to the body for injecting air bubbles between the excavation section and the face of the natural ground or into the cutter chamber. Tunnel boring machine.

3. A mud tunnel boring machine for excavating a tunnel, comprising: A body capable of supporting an inner wall of the ground; An excavation unit that is attached to the body and excavates the natural ground by rotation; A bulkhead provided within the body and arranged opposite the excavated portion in the axial direction of the tunnel; a cutter chamber partitioned by the body, the excavation section, and the partition, into which soil excavated by the excavation section flows; A mud pipe for supplying mud water into the cutter chamber; A mud drain pipe for draining muddy water from within the cutter chamber; and an air bubble injection pipe attached to the bulkhead for injecting air bubbles between the excavation section and the face of the natural ground or into the cutter chamber. Tunnel boring machine.

4. A tunnel boring machine according to any one of claims 1 to 3, Further provided is a defoaming agent injection unit that injects a defoaming agent into the muddy water in the sludge discharge pipe to defoam air bubbles in the muddy water. Tunnel boring machine.

5. A tunnel boring machine according to any one of claims 1 to 3, A storage tank for storing mud water supplied to the cutter chamber through the mud pipe and discharged from the cutter chamber; Further provided is a defoaming agent injection unit that injects a defoaming agent into the muddy water in the storage tank to defoam air bubbles in the muddy water. Tunnel boring machine.

6. A mud tunnel excavation method performed by a tunnel boring machine according to any one of claims 1 to 3, comprising the steps of: The volume ratio of the amount of air bubbles injected between the excavation section and the face of the natural ground to the amount of mud water supplied to the cutter chamber through the mud transport pipe is 0.2% or more and 10% or less. Tunnel excavation methods.

7. A tunnel excavation method performed by a tunnel excavation machine according to any one of claims 1 to 3, comprising the steps of: The volume ratio of the amount of air bubbles injected between the excavation section and the face of the ground to the amount of mud water discharged from the cutter chamber through the mud discharge pipe is 0.2% or more and 10% or less. Tunnel excavation methods.

8. 7. A tunnel excavation method according to claim 6, comprising the steps of: increasing the amount of air bubbles to be injected as the tunnel boring machine's excavation speed increases, and decreasing the amount of air bubbles to be injected as the tunnel boring machine's excavation speed decreases. Tunnel excavation methods.

9. 8. A tunnel excavation method according to claim 7, comprising the steps of: increasing the amount of air bubbles to be injected as the tunnel boring machine's excavation speed increases, and decreasing the amount of air bubbles to be injected as the tunnel boring machine's excavation speed decreases. Tunnel excavation methods.

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