Tunnel boring machine, method for modifying soil sludge

Abstract

To provide a tunnel boring machine that can reliably solidify the excavated mud. [Solution] The tunnel boring machine 100 comprises a body 11, an excavation section 12, a partition wall 13, a cutter chamber 14 partitioned by these, a discharge mechanism 30 for removing and discharging mud from inside the cutter chamber 14, and a belt conveyor 70 for transporting the mud discharged from the discharge mechanism 30 to the rear of the tunnel boring machine 100. In the mud transport path starting from inside the cutter chamber 14, the tunnel boring machine 100 has a first addition section for adding a first chemical agent to the mud in the transport path after the discharge mechanism 30, a first mixing section for mixing these, a second addition section for adding a second chemical agent to the mud after the first mixing section, and a second mixing section for mixing the mud before it reaches the tunnel entrance.

Description

Technical Field

[0001] The present invention relates to a tunnel boring machine and a method for modifying soil.

Background Art

[0002] Soil discharged from an operating tunnel boring machine can be used as embankment material, backfill material, etc. without becoming industrial waste if the cone index is 200 kN / m 2 or more. Therefore, attempts have been made to modify the soil as needed. For example, in Patent Document 1, in the earth pressure balance shield method, a method of modifying the cone index of soil (soil mixed with additive material) with increased plastic fluidity by mixing additive materials is disclosed. Specifically, two types of chemicals are added to the soil mixed with additive material in a screw conveyor in sequence or simultaneously to modify the soil mixed with additive material.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the method described in Patent Document 1 may result in insufficient modification due to various factors. Furthermore, while the mud generated during excavation of natural ground may contain heavy metals, the method described in Patent Document 1 does not take into account measures to prevent their leaching. Therefore, the present invention aims to provide a tunnel boring machine that can reliably solidify the discharged mud. Moreover, when the mud generated during excavation of natural ground contains heavy metals, the present invention aims to provide a tunnel boring machine that can reliably solidify the discharged mud and reduce the leaching of heavy metals. Furthermore, the present invention aims to provide a modification method that can reliably solidify mud. Moreover, when the mud generated during excavation of natural ground contains heavy metals, the present invention aims to provide a modification method that can reliably solidify the discharged mud and reduce the leaching of heavy metals. [Means for solving the problem]

[0005] According to the inventors' investigation, one possible reason for insufficient soil modification is that even when attempting to mix the added modifying agent using a screw conveyor transfer system, the mixing efficiency is low, resulting in insufficient mixing.

[0006] Therefore, the present invention provides a tunnel boring machine for excavating a tunnel, 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 wall provided inside 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 wall, into which the excavated soil from the excavation unit flows; a discharge mechanism for removing and discharging the soil from inside the cutter chamber; and a belt conveyor for transporting the soil discharged from the discharge mechanism to the rear of the tunnel boring machine, wherein the transport path of the soil starting from inside the cutter chamber includes: a first addition unit for adding a first chemical agent to the soil in the transport path after the discharge mechanism; a first mixing unit for mixing the soil to which the first chemical agent has been added; a second addition unit for adding a second chemical agent to the soil after the first mixing unit; and a second mixing unit provided in a location before the soil reaches the tunnel entrance for mixing the soil to which the second chemical agent has been added.

[0007] The present invention also provides a method for modifying soil inside a tunnel boring machine used to excavate a tunnel, wherein the tunnel boring machine comprises a body capable of supporting the inner wall of the ground, an excavation section attached to the body that excavates the ground by rotation, a partition wall provided inside 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 into which soil excavated by the excavation section flows, a discharge mechanism that removes and discharges soil from inside the cutter chamber, and a belt conveyor that transports the soil discharged from the discharge mechanism to the rear of the tunnel boring machine, and provides a method for modifying soil by adding and mixing a first agent to the soil discharged from the discharge mechanism, and then adding and mixing a second agent.

[0008] In the tunnel boring machine and modification method of the present invention, two types of chemicals necessary to achieve both solidification of the mud discharged from the operating tunnel boring machine and reduction of the leaching of heavy metals, etc., are added and mixed at different positions in the mud transport path. Moreover, since the first chemical and the second chemical are mixed in the first and second mixing sections provided in the transport path, the mixing efficiency with the mud is high, and they are thoroughly mixed.

[0009] In the tunnel boring machine and modification method of the present invention, both the first agent and the second agent may be liquids.

[0010] The tunnel boring machine of the present invention may further include a crushing mechanism for crushing the mud discharged from the discharge mechanism, and a feeder mechanism for discharging the mud crushed by the crushing mechanism toward a belt conveyor. In this case, the crushing mechanism may be the part that receives the first chemical agent from the first additive section, and the feeder mechanism may be the first mixing section.

[0011] The tunnel boring machine of the present invention may further include a second crushing mechanism for further crushing the mud transported by a belt conveyor, and a second feeder mechanism for discharging the mud crushed by the second crushing mechanism. In this case, the second crushing mechanism may be a part that receives a second chemical agent from a second additive section, and the second feeder mechanism may be a second mixing section.

[0012] In the tunnel boring machine and modification method of the present invention, the mud removed from the cutter chamber has a water content of 10 to 70%, the first agent may be a liquid mixture of alkali silicate composed of alkali oxide and silicon dioxide, and water, and the second agent may be an aqueous solution or suspension of water containing a substance that produces trivalent iron ions. [Effects of the Invention]

[0013] According to the present invention, the discharged mud can be reliably solidified. Furthermore, if the mud generated from excavating the ground contains heavy metals, etc., the leaching of heavy metals, etc. can be reduced. [Brief explanation of the drawing]

[0014] [Figure 1] This is a side view of a shield tunneling machine according to an embodiment of the present invention. [Figure 2] This is a magnified view of the storage chamber of a shield tunneling machine. [Modes for carrying out the invention]

[0015] The present invention relates to a tunnel boring machine and a method for modifying soft, high-water-content mud (hereinafter simply referred to as "mud") generated during tunnel excavation. Specifically, two types of chemicals may be added to the mud at time intervals from each other, with the aim of granulating and solidifying the mud to increase the cone index and further reducing the leaching of heavy metals, etc. In this specification, "heavy metals, etc." refers to cadmium, hexavalent chromium, cyanide, mercury, selenium, lead, arsenic, fluorine, boron, and compounds thereof, which are classified as Class II specified hazardous substances under the Soil Contamination Countermeasures Act. Therefore, "heavy metals, etc." is a concept that also includes cyanide, arsenic, fluorine, and boron. Preferred embodiments of the present invention will be described in detail below with reference to the drawings.

[0016] <Shield tunneling machine> In this embodiment, we will describe the case where the tunnel boring machine is a shield tunneling machine 100 used in the shield tunneling method. Furthermore, the shield tunneling machine 100 is a slurry pressure type shield tunneling machine used in the slurry pressure shield tunneling method. As shown in Figure 1, the shield tunneling machine 100 excavates underground (natural ground) to form an excavation hole 1, and constructs a tunnel T by assembling a segment ring 10 (lining) to cover the inner wall of the excavation hole 1.

[0017] In Figure 1, the direction in which the shield tunneling machine 100 moves, the tunnel face side (left side in the figure), is referred to as "forward," and the opposite direction, the tunnel entrance side, is referred to as "rear." In the following, "up" and "down" refer to vertical up and down. In this embodiment, the up and down direction in Figure 1 corresponds to the vertical direction. Note that when comparing multiple processing stages along the transport path, the one located on the tunnel entrance side may be referred to as the "later stage."

[0018] The shield tunneling machine 100 includes a skin plate 11 as a cylindrical body that extends along the axial direction of the tunnel T and can support the inner wall of the excavation pit 1, and a cutter head 12 as an excavation part that is rotationally driven in front of the skin plate 11. Further, the shield tunneling machine 100 includes a partition wall 13 provided in the skin plate 11 and arranged to face the cutter head 12 in the axial direction of the tunnel T, that is, arranged on a plane perpendicular to the axial direction of the tunnel T, and a cutter chamber 14 into which the earth and sand excavated by the cutter head 12 flows and stays. On the rear side inside the skin plate 11, the segment ring 10 is sequentially constructed as the shield tunneling machine 100 advances.

[0019] A jack 20 is fixed to the skin plate 11. The jack 20 obtains a reaction force from the segment ring 10 and propels the skin plate 11 forward, pressing the cutter head 12 against the ground. When the skin plate 11 is propelled and the segment ring 10 exits from the skin plate 11, a backfill material (not shown) is filled between the outer peripheral surface of the segment ring 10 and the inner wall of the excavation pit 1.

[0020] 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 ground, the ground is excavated by the cutter bits 12a and the excavation pit 1 is formed. The outer diameter of the cutter head 12 is substantially equal to the outer diameter of the skin plate 11, and the ground is excavated with an inner diameter substantially equal to the outer diameter of the skin plate 11. The earth and sand excavated by the cutter head 12 is guided to the rear of the cutter head 12 through openings such as cutter slits (not shown) provided in the cutter head 12 and stays in the cutter chamber 14.

[0021] The cutter chamber 14 is formed by being partitioned by the skin plate 11, the cutter head 12, and the partition wall 13. In the cutter chamber 14, the excavated earth and sand and groundwater flow in, and they stay as muddy soil. By filling the cutter chamber 14 with muddy soil and applying the pressure of the muddy soil in the cutter chamber 14 to the cutter head 12, the earth pressure and groundwater pressure of the face can be suppressed by the cutter head 12 and the face can be stabilized.

[0022] The partition wall 13 is arranged to face the cutter head 12 in the axial direction of the tunnel T, and the rotary drum 26 is rotatably supported with respect to the partition wall 13. The cutter head 12 is connected to the rotary drum 26 via a connecting rod 27 and can rotate together with the rotary drum 26. The rotary drum 26 is connected to an electric motor 25 via a speed reduction mechanism (not shown), and by driving the electric motor 25, the rotary drum 26 and the cutter head 12 rotate with respect to the skin plate 11. By controlling the operation of the electric motor 25, it is possible to control the rotation direction and rotation speed of the cutter head 12.

[0023] As shown in FIGS. 1 and 2, the shield tunneling machine 100 includes a screw conveyor 30 (discharge mechanism) that discharges the muddy soil in the cutter chamber 14 to the rear of the shield tunneling machine 100, a first storage chamber 40 in which the muddy soil discharged from the screw conveyor 30 is stored, a first crushing mechanism 50 that crushes the muddy soil discharged from the screw conveyor 30, a first screw feeder 60 (first feeder mechanism, first mixing section) that discharges the muddy soil crushed by the first crushing mechanism 50, and a first belt conveyor 70 that transfers the earth and sand discharged by the screw conveyor 30 further rearward of the shield tunneling machine 100. In addition, a first additive supply mechanism 80 (first adding section) is provided on the wall of the first storage chamber 40.

[0024] The screw conveyor 30 is installed so as to face the cutter chamber 14 through an opening in the partition wall 13. The screw conveyor 30 has a cylindrical case 31 and an auger 32 incorporated inside the case 31. The screw conveyor 30 is configured to discharge excavated soil from the cutter chamber 14 by rotating the auger 32 with a motor (not shown) acting as a drive unit. The front side of the case 31 is an inlet for soil connected to the cutter chamber 14, and the rear side has an outlet 31a which serves as the soil outlet.

[0025] The first storage chamber 40 is a hopper composed of a box-shaped body having openings at the top and bottom (hereinafter referred to as "upper opening 40a" and "lower opening 40b," respectively), as shown in Figure 2. The first storage chamber 40 has a sloping section that widens towards the top, and the mud discharged from the discharge port 31a of the screw conveyor 30 is supplied to the first storage chamber 40 through the upper opening 40a. In this way, the upper opening 40a functions as a supply port at the top of the hopper. Although not shown in the figure, the first storage chamber 40 may also have a lid that opens and closes the upper opening 40a.

[0026] Furthermore, the first storage chamber 40 is provided with a sampling port 40c for sampling a portion of the soil supplied to the first storage chamber 40. Mud in its state before being crushed by the first crushing mechanism 50 can be sampled through the sampling port 40c. The sampling port 40c is also provided in the first storage chamber 40 so that soil in its state before additives are supplied by the first additive supply mechanism 80 can be sampled. By measuring the properties of the soil sampled through the sampling port 40c, the properties of the soil in the cutter chamber 14 can be determined.

[0027] In the first additive supply mechanism 80, a first chemical agent, which is a type of additive, is injected into the first crushing mechanism 50 through an inlet provided in the first storage chamber 40. Although not shown in the diagram, the first chemical agent is stored in a chemical tank installed above ground, and is supplied to the first additive supply mechanism 80 after being temporarily stored in an underground chemical tank by extending piping into the excavated shaft 1. Here, if the chemical agent is a liquid, it may be stored directly in a chemical tank installed above ground. If it is transported as a powder for economic reasons, it may be dissolved in a liquid and then stored in a chemical tank installed above ground. Details of the first chemical agent will be described later. When the chemical agent is a liquid, the first additive supply mechanism 80 includes piping through which the chemical agent flows to the inlet, a pump for pressurizing the chemical agent, and a flow rate control device for controlling the flow rate of the liquid fluid flowing through the piping.

[0028] The first crushing mechanism 50 crushes or breaks the mud supplied into the first storage chamber 40 from the upper opening 40a. The first crushing mechanism 50 has a pair of rods 51 (crushing section) provided in the first storage chamber 40 that come into contact with the mud in the first storage chamber 40 and crush the mud, and an electric motor (not shown) that rotates the pair of rods 51 around their axis.

[0029] A pair of rods 51 are installed in the first storage chamber 40 so as to extend horizontally (perpendicular to the plane of the paper) perpendicular to the axial direction of the tunnel T. Each of the pair of rods 51 has blade sections 52 on its outer circumference, which are provided parallel to each other and crush the mud. The blade section 52 is composed of a plurality of protrusions 52a that project radially outward from the outer circumference of the cylindrical rod 51. For example, the blade section 52 is composed of a pair of cylindrical protrusions 52a that are spaced 180° apart in the circumferential direction of the rod 51, and are arranged continuously with a 90° offset and spaced apart in the axial direction of the rod 51. The pair of rods 51 are installed with a gap between them so that the trajectories of the blade section 52 due to the rotation of the rod 51 do not overlap (the trajectories do not intersect) in an axial view of the rod 51. Therefore, the blade sections 52 of the pair of rods 51 are configured so as not to interfere with (contact with) each other as the rod 51 rotates.

[0030] Columbs of soil (soil, rock) with a particle size larger than the distance between the blades 52 of the pair of rods 51 are crushed into smaller particle sizes by the rotating blades 52 of the pair of rods 51. Columbs of soil (mud) with a particle size smaller than the distance between the blades 52 of the pair of rods 51 are broken down by collision with the rotating blades 52 of the pair of rods 51. In this way, the first crushing mechanism 50 breaks down relatively large particle sizes of soil and mud into finer particles, making the size of the excavated soil uniform overall. The particle size after crushing is preferably 20 mm or less. The soil crushed by the first crushing mechanism 50 passes through the pair of rods 51 and is guided to the lower opening 40b provided at the bottom of the first storage chamber 40. The lower opening 40b functions as an outlet for the mud supplied to the upper opening 40a of the hopper.

[0031] The first screw feeder 60 is installed at the bottom of the first storage chamber 40. As a result, the first screw feeder 60 is supplied with mud that has been crushed by the first crushing mechanism 50 in the first storage chamber 40. The first screw feeder 60 discharges the mud led from the first crushing mechanism 50 toward the first belt conveyor 70.

[0032] The first screw feeder 60 includes a pair of augers 61 arranged parallel to each other and having helical blades on their outer circumferences, a case 62 that houses the pair of augers 61, and an electric motor 63 (not shown) that rotates the pair of augers 61 in the axial direction.

[0033] Case 62 has a supply port 62a for guiding soil supplied from the first storage chamber 40 into Case 62, and a discharge port 62b for discharging soil transported by a pair of augers 61 inside Case 62. Case 62 is attached to the lower part of the first storage chamber 40 such that the supply port 62a faces the lower opening 40b of the first storage chamber 40. Soil in the first storage chamber 40 is guided into Case 62 from the lower opening 40b of the first storage chamber 40 through the supply port 62a of Case 62.

[0034] A pair of augers 61 are positioned below the supply port 62a of the case 62, with their base ends facing each other, and are installed inside the case 62. The pair of augers 61 extend horizontally (towards the front in the illustration) parallel to the pair of rods 51 of the first crushing mechanism 50. The soil introduced into the case 62 is transported toward the tip of the augers 61 by the rotating pair of augers 61 and discharged outside the case through the discharge port 62b. During this discharge process, the mud and the first chemical agent are thoroughly mixed in the first screw feeder 60. A chute 65 is provided at the discharge port 62b of the case 62.

[0035] As shown in Figure 1, the first belt conveyor 70 is installed along the excavation shaft 1 from below the discharge port 62b of the first screw feeder 60 toward the rear, and receives the soil discharged from the first screw feeder 60 and transports it toward the rear.

[0036] Downstream of the first belt conveyor 70, there is a second storage chamber 40' for storing the mud transported by the first belt conveyor 70, a second crushing mechanism 50' for crushing the mud transported by the first belt conveyor 70, a second screw feeder 60' (second feeder mechanism, second mixing section) for discharging the mud crushed by the second crushing mechanism 50', and a second belt conveyor 70' for transporting the mud discharged by the first belt conveyor 70 further behind the shield tunneling machine 100. In addition, a second additive supply mechanism 80' (second additive section) is provided on the wall of the second storage chamber 40'.

[0037] The structure and function of the second storage chamber 40', the second crushing mechanism 50', the second screw feeder 60', the second belt conveyor 70', and the second additive supply mechanism 80' are the same as those of the first storage chamber 40, the first crushing mechanism 50, the first screw feeder 60, the first belt conveyor 70, and the first additive supply mechanism 80, respectively.

[0038] In the second additive supply mechanism 80', a second chemical agent, which is a type of additive, is injected into the second crushing mechanism 50' through an inlet provided in the second storage chamber 40'. Although not shown in the diagram, the second chemical agent is stored in a chemical tank installed above ground, and is supplied to the second additive supply mechanism 80' after being temporarily stored in an underground chemical tank by extending piping into the excavated shaft 1. Here, if the chemical agent is a liquid, it may be stored directly in the chemical tank installed above ground. If it is transported as a powder for economic reasons, it may be dissolved in a liquid and then stored in the chemical tank installed above ground. Details of the second chemical agent will be described later. When the chemical agent is a liquid, the second additive supply mechanism 80' includes piping through which the chemical agent flows to the inlet, a pump for pressurizing the chemical agent, and a flow rate control device for controlling the flow rate of the liquid fluid flowing through the piping.

[0039] The mud crushed by the second crushing mechanism 50' is then supplied to the second screw feeder 60', which discharges the mud toward the second belt conveyor 70'. During this discharge process, the mud and the second chemical are thoroughly mixed within the second screw feeder 60'.

[0040] Behind the second belt conveyor 70', although not shown in the diagram, there is a hopper to receive the mud transported by the second belt conveyor 70', and a transport vehicle to receive the mud via the hopper is waiting below it. Here, the mud modification is completed while the mud mixed with the second chemical is being transported by the second belt conveyor 70', or at the latest while the mud is stored in the hopper.

[0041] <Sludge, additives> The mud and additives (first chemical agent, second chemical agent) in this embodiment will be described in detail below.

[0042] The mud targeted by the shield tunneling machine 100 of this embodiment is mud with a water content of 10-70%. This water content may also be 15-65% or 20-60%. To this target mud, as described above, the first chemical agent is first added and mixed, and then the second chemical agent is added and mixed.

[0043] The pH of the target soil is preferably between 5.0 and 9.0. If the pH of the target soil is not within the range of 5.0 to 9.0, an appropriate pH adjuster may be added before adding the first chemical to adjust the pH to 5.0 to 9.0.

[0044] The first agent is a liquid mixture of alkali silicate, composed of alkali oxide and silicon dioxide, and water. Alkali silicate is generally represented by the chemical formula X₂O·nSiO₂ (where X represents an alkali metal and n is a positive number representing the molar ratio (SiO₂ / X₂O)). The alkali silicate used in this embodiment has a molar ratio of silicon dioxide to alkali oxide (i.e., "n") of 2.4 to 4.1. n may also be 2.7 to 4.0, 3.1 to 3.9, or 3.1 to 3.2.

[0045] The second agent contains a substance that dissolves in water to produce trivalent iron ions. Examples of such substances include iron(III) sulfate (ferric sulfate), polyferric sulfate, and ferric chloride. These substances may also be in hydrate form.

[0046] The second drug may be an aqueous solution or a suspension of water.

[0047] The lower limit of the time interval between adding the first agent to the target soil and adding the second agent is preferably at least 5 seconds, more preferably 8 seconds, and even more preferably 10 seconds. The upper limit of this time interval may be 20 seconds, 30 seconds, or 60 seconds. By adding the second agent after the first agent has been thoroughly mixed with the target soil and the buffering effect of the target soil has settled, the effects of both agents can be fully exerted. Furthermore, it is preferable to mix the second agent for at least the above-mentioned time after adding it. If the time interval is shorter than the lower limit or longer than the upper limit, the effect will be reduced. In this regard, in the shield tunneling machine 100 of this embodiment, the above-mentioned time interval can be obtained because the first screw feeder 60 and the first belt conveyor 70 are passed between leaving the first storage chamber 40 where the first agent is added and entering the second storage chamber 40' where the second agent is added. In other words, it is preferable to set the transport capacity of the first screw feeder 60 and the first belt conveyor so that the above-mentioned time interval is ensured for the movement time of the target mud from the first storage chamber 40 to the second storage chamber 40'.

[0048] The pH of the soil after adding and mixing the second agent is preferably 5.0 to 9.0, more preferably 5.5 to 8.8, and even more preferably 5.8 to 8.6.

[0049] The cone index of the soil after adding and mixing the second chemical agent should be 200 kN / m³, considering that it should be accepted as construction-generated soil and also for ease of transportation. 2 Preferably, it should be 300 kN / m 2 It is more preferable that the value be greater than or equal to 400 kN / m 2 It is even more preferable that the above conditions are met.

[0050] <Effects> In the shield tunneling machine 100 of this embodiment, the first chemical agent is added to the target soil whose particle size has been reduced in the first crushing mechanism 50, resulting in high mixing efficiency and thorough mixing. Then, when the second chemical agent is added and mixed in the second crushing mechanism 50', the target soil solidifies (or granulates and solidifies), and the fluidity of the soil decreases. The pH of the soil is adjusted to an appropriate range by the appropriate mixing ratio of the first and second chemical agents. At the same time, the insolubilization of heavy metals progresses due to the action of trivalent iron ions generated from the second chemical agent.

[0051] As a result, the cone index of the target soil before the addition of the first agent was 200 kN / m³. 2 Even if it is less than 200 kN / m³, granulation solidification can convert it to 200 kN / m³. 2 It can be increased to the above, and furthermore to 400 kN / m 2 The above is also possible. Once granulation and solidification are complete, the modified soil can be transported and used without requiring a curing period.

[0052] In the shield tunneling machine 100 of this embodiment, the mud modification can be completed in the mud transport path starting from inside the cutter chamber 14, before the mud reaches the tunnel entrance T. Therefore, there is no need to install large-scale equipment such as modification facilities and soundproof houses on the surface.

[0053] Furthermore, regarding the suppression of the leaching of heavy metals, the leaching of arsenic and hexavalent chromium is particularly suppressed.

[0054] The pH of modified soil is typically between 5.0 and 9.0, making it easy to handle afterward.

[0055] In this embodiment, since the first agent is a liquid, it is easily mixed with the target soil. Similarly, if the second agent is also a liquid, it is easily mixed with the target soil.

[0056] Although preferred embodiments of the present invention have been described above, the present invention is not limited in any way to the above embodiments. For example, in the above embodiments, the first agent was added from the first additive supply mechanism 80, but instead, the first agent may be dripped or flowed in from above the first storage chamber 40 toward the first crushing mechanism 50.

[0057] Furthermore, in the above embodiment, the first additive supply mechanism 80 corresponds to the first additive section, the first screw feeder 60 corresponds to the first mixing section, the second additive supply mechanism 80' corresponds to the second additive section, and the second screw feeder 60' corresponds to the second mixing section. However, the first additive section, the first mixing section, the second additive section, and the second mixing section may be in other configurations. For example, the second chemical agent may be added to the mud being transported by the second belt conveyor 70'. In this case, the second belt conveyor 70' corresponds to the second additive section.

[0058] Furthermore, although the above embodiment described the case in which the tunnel boring machine is a shield tunneling machine 100 used in the shield tunneling method, the present invention is also applicable to tunnel boring machines other than the shield tunneling machine 100, for example, boring machines installed at the tip of a jacking pipe in the pipe jacking method. [Industrial applicability]

[0059] This invention can be used for on-site treatment of soft, highly water-containing mud generated during civil engineering works. [Explanation of Symbols]

[0060] 1…Excavation pit, 10…Segment ring, 11…Skin plate (body), 12…Cutter head (excavation section), 12a…Cutter bit, 13…Bulkhead, 14…Cutter chamber, 20…Jack, 25…Electric motor, 26…Rotating drum, 27…Connecting rod, 30…Screw conveyor (discharge mechanism), 31…Case, 31a…Discharge port, 32…Auger, 40…First storage chamber, 40'…Second storage chamber, 40a…Upper opening, 40b…Lower opening, 40c…Collection port, 50…First crushing mechanism, 50'…Second crushing Mechanism, 51...Rod (crushing section), 52...Blade section, 60...First screw feeder (first feeder mechanism, first mixing section), 60'...Second screw feeder (second feeder mechanism, second mixing section), 61...Auger, 62...Case, 62a...Supply port, 62b...Discharge port, 65...Cute, 70...First belt conveyor, 70'...Second belt conveyor, 80...First additive supply mechanism (first additive section), 80'...Second additive supply mechanism (second additive section), 100...Shield tunneling machine, T...Tunnel.

Claims

1. A tunnel boring machine for excavating tunnels, A body capable of supporting the inner wall of the natural ground, An excavation unit attached to the aforementioned body, which excavates 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 is partitioned by the aforementioned body, the aforementioned excavation section, and the aforementioned bulkhead, into which the soil excavated by the excavation section flows, A discharge mechanism for removing and discharging mud from inside the cutter chamber, The system includes a belt conveyor that transports the mud discharged from the discharge mechanism to the rear of the tunnel boring machine, In the mud transport path starting from inside the cutter chamber, A first addition section for adding a first chemical agent to the mud in a transfer path downstream of the discharge mechanism, A first mixing unit for mixing the mud to which the first chemical agent has been added, A second addition section, after the first mixing section, adds a second chemical agent to the mud, A tunnel boring machine having a second mixing section provided at a location before the mud reaches the tunnel entrance, to which the mud to which the second chemical has been added is mixed.

2. The tunnel boring machine according to claim 1, wherein both the first and second agents are liquids.

3. A crushing mechanism for crushing the mud discharged from the aforementioned discharge mechanism, The system further comprises a feeder mechanism that discharges the mud crushed by the crushing mechanism toward the belt conveyor, The crushing mechanism is the part that receives the first drug by the first additive section, The tunnel boring machine according to claim 1, wherein the feeder mechanism is the first mixing unit.

4. A second crushing mechanism further crushes the mud transported by the belt conveyor, The system further comprises a second feeder mechanism for discharging the mud broken down by the second crushing mechanism, The second disintegration mechanism is the part that receives the second drug by the second additive section, The tunnel boring machine according to claim 3, wherein the second feeder mechanism is the second mixing section.

5. A method for modifying soil inside a tunnel boring machine used to excavate a tunnel, The aforementioned tunnel boring machine, A body capable of supporting the inner wall of the natural ground, An excavation unit attached to the aforementioned body, which excavates the ground by rotation, A partition wall is provided within the body and is positioned opposite the excavation section in the axial direction of the tunnel, A cutter chamber is partitioned by the aforementioned body, the aforementioned excavation section, and the aforementioned bulkhead, into which the soil excavated by the excavation section flows, A discharge mechanism for removing and discharging mud from inside the cutter chamber, The system includes a belt conveyor that transports the mud discharged from the discharge mechanism to the rear of the tunnel boring machine, A method for modifying soil, comprising adding and mixing a first chemical agent to the mud discharged from the discharge mechanism, and then adding and mixing a second chemical agent.

6. The modification method according to claim 5, wherein both the first agent and the second agent are liquids.

7. The mud removed from the cutter chamber has a water content of 10-70%. The first agent is a liquid mixture of alkali silicate, which is composed of alkali oxide and silicon dioxide, and water. The modification method according to claim 5, wherein the second agent is an aqueous solution or suspension of water containing a substance that produces trivalent iron ions.

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