Ground improvement device and ground improvement method

Abstract

To provide an improved ground improvement device and ground improvement method. [Solution] A ground improvement device according to one embodiment includes a rod inserted into the ground, a monitor provided on the rod, a first supply passage that passes through the inside of the rod and delivers liquid to the monitor, and a second supply passage that passes through the inside of the rod and delivers powder to the monitor. Furthermore, the monitor includes a mixing unit that generates a hardening material by mixing the liquid delivered by the first supply passage and the powder delivered by the second supply passage, and a hardening material nozzle that sprays the hardening material generated by the mixing unit into the ground.

Description

Technical Field

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[0001] The present invention relates to a ground improvement device and a ground improvement method for improving the ground by constructing a ground improvement body in the ground.

Background Art

[0002] There are various conventional ground improvement methods. As an example, the high-pressure jet mixing method is known. In the high-pressure jet mixing method, the ground is cut using a high-pressure jet, and a ground improvement body is constructed in the space thus formed. For the high-pressure jet for cutting, sometimes the hardening material itself for constructing the ground improvement body is used, and sometimes a liquid such as water separate from the hardening material is used.

[0003] The hardening material is jetted from a monitor at the tip of a rod inserted into the ground. Generally, the hardening material is cement milk in which cement and water are mixed, and is sent to the monitor through a flow path in the rod.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described above, in conventional ground improvement methods such as the high-pressure jet mixing method, a hardening material such as cement milk is sent to the monitor. Therefore, it is necessary to arrange a plant (mixer) for generating the hardening material on the ground.

[0006] Because the hardening agent contains many particles such as cement, it has high viscosity, resulting in significant frictional losses when pumped to the monitor. This reduces the injection speed of the hardening agent from the nozzle on the monitor, which can lead to a decrease in cutting capacity when the hardening agent is used as a high-pressure jet for cutting the ground. On the other hand, in order to ensure sufficient cutting capacity, the hardening agent must be pumped in large quantities at high pressure, which necessitates a high-powered pump.

[0007] Furthermore, spraying a hardening agent containing numerous particles at high speed causes nozzle wear, necessitating frequent nozzle replacement. Nozzles are generally made of expensive special alloys, and replacement incurs significant costs. Moreover, frequent replacements drastically reduce work efficiency.

[0008] In addition to the above, conventional ground improvement methods have various problems. Therefore, one of the objectives of the present invention is to provide an improved ground improvement device and ground improvement method that can improve work efficiency and reduce costs related to ground improvement. [Means for solving the problem]

[0009] A ground improvement device according to one embodiment includes a rod inserted into the ground, a monitor provided on the rod, a first supply channel that passes through the inside of the rod and delivers liquid to the monitor, and a second supply channel that passes through the inside of the rod and delivers powder to the monitor. Furthermore, the monitor includes a mixing unit that generates a hardening material by mixing the liquid delivered by the first supply channel and the powder delivered by the second supply channel, and a hardening material nozzle that sprays the hardening material generated by the mixing unit into the ground.

[0010] For example, the mixing unit comprises a mixing chamber connected to the hardening agent nozzle and the second supply passage, and a mixing nozzle connected to the first supply passage for injecting the liquid into the mixing chamber. As the liquid is injected by the mixing nozzle, the pressure in the mixing chamber is reduced, drawing the powder from the second supply passage into the mixing chamber and mixing it with the liquid.

[0011] The mixing unit further comprises a depressurization chamber provided between the second supply passage and the mixing chamber, and the powder from the second supply passage may be drawn into the mixing chamber through the depressurization chamber.

[0012] The ground improvement device may further include a third supply channel that passes through the inside of the rod and sends gas to the monitor. In this case, the hardening material nozzle may inject the gas sent through the third supply channel together with the hardening material.

[0013] The ground improvement device may further include a fourth supply channel that passes through the inside of the rod and delivers liquid to the monitor. In this case, the monitor may further include a cutting nozzle that sprays the liquid delivered by the fourth supply channel to cut the ground.

[0014] The ground improvement device may further include a fifth supply channel that passes through the inside of the rod and sends gas to the monitor. In this case, the cutting nozzle may inject the gas supplied by the fifth supply channel together with the liquid supplied by the fourth supply channel.

[0015] The monitor may further include a discharge port located at the lower end in the extending direction of the rod from which the liquid of the first supply passage is discharged, a drilling tool provided around the discharge port, and a valve that opens and closes the flow path from the first supply passage to the discharge port.

[0016] A ground improvement method according to one embodiment includes inserting the rod into the ground, rotating the rod while spraying the hardening material from the hardening material nozzle, and pulling up the rod to create a ground improvement body in which the hardening material has hardened in the ground. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide an improved ground improvement device and ground improvement method that can improve work efficiency and reduce costs related to ground improvement.

Brief Description of the Drawings

[0018] [Figure 1] FIG. 1 is a diagram showing a configuration example of a construction system for implementing a ground improvement method according to the first embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view showing the configuration of a monitor according to the first embodiment. [Figure 3] FIG. 3 is a diagram showing an example of a ground improvement method using a ground improvement device or a construction system according to the first embodiment. [Figure 4] FIG. 4 is a schematic cross-sectional view showing the configuration of a monitor according to the second embodiment. [Figure 5] FIG. 5 is a schematic cross-sectional view showing the configuration of a monitor according to the third embodiment. [Figure 6] FIG. 6 is a schematic cross-sectional view showing the configuration of a monitor according to the fourth embodiment. [Figure 7] FIG. 7 is a schematic cross-sectional view showing the configuration of a monitor according to the fifth embodiment. [Figure 8] FIG. 8 is a schematic cross-sectional view showing the configuration of a monitor according to the sixth embodiment. [Figure 9] FIG. 9 is a schematic cross-sectional view showing the configuration of a monitor according to the seventh embodiment.

Modes for Carrying Out the Invention

[0019] Some embodiments will be described with reference to the drawings. In each embodiment, an example in which the ground improvement method and the ground improvement device according to the present invention are applied to the high-pressure jet mixing method and the device for implementing the same is disclosed. However, the configurations disclosed in each embodiment can be appropriately modified and applied to other types of construction methods related to ground improvement and the like.

[0020] [First Embodiment] Figure 1 shows an example of the configuration of a construction system for implementing the ground improvement method according to the first embodiment. This construction system comprises a ground improvement device 1, a pump 2, and a silo 3.

[0021] The ground improvement device 1 comprises a rod 4 inserted into a hole H made in the ground, a monitor 5 provided at the tip of the rod 4 (lower end in the figure), and a work machine 6 that holds the rod 4. The work machine 6 is equipped with a linear motion mechanism for moving the rod 4 up and down, and a rotation mechanism for rotating the rod 4. The work machine 6 may further be equipped with a swinging mechanism for swinging the rod 4.

[0022] Pump 2 supplies water from a water source S, such as a water tank, to the rear end 7 of rod 4. Silo 3 contains cement powder. This powder is supplied to the rear end 7 of rod 4. In the example in Figure 1, a storage section 8 is provided at the rear end 7 for temporarily storing the powder supplied from silo 3. In another example, the powder may be supplied directly to the rear end 7 without going through the storage section 8.

[0023] The construction system may further include a powder supply device 9 for transporting the powder from silo 3 to storage section 8. The powder supply device 9 may, for example, be a belt conveyor, but is not limited to this example.

[0024] As will be explained in more detail later, the water and powder supplied to rod 4 are sent through the inside of rod 4 to monitor 5, where they are mixed. The hardening agent generated by this mixing is then sprayed laterally from monitor 5 in the ground at high pressure. As the hardening agent sprayed into the ground hardens, a ground improvement body G is created.

[0025] Figure 2 is a schematic cross-sectional view showing the configuration of the monitor 5 according to this embodiment. The monitor 5 includes a first supply channel P1, a second supply channel P2, a mixing section 10, and a hardening material nozzle 20.

[0026] The first supply channel P1 and the second supply channel P2 extend through the inside of the rod 4 to the rear end 7. High-pressure water is supplied to the first supply channel P1 from the pump 2 to the rear end 7. Powder is supplied to the second supply channel P2 from the silo 3 to the storage section 8.

[0027] The mixing unit 10 generates a hardening material by mixing water supplied through the first supply channel P1 with powder supplied through the second supply channel P2. The hardening material nozzle 20 sprays the hardening material generated by the mixing unit 10.

[0028] In this embodiment, the mixing unit 10 comprises a mixing chamber 11 and a mixing nozzle 12. The mixing chamber 11 is connected to a hardening agent nozzle 20 and a second supply passage P2. The mixing nozzle 12 is connected to a first supply passage P1 and sprays water supplied by the first supply passage P1. This forms a water jet W in the mixing chamber 11.

[0029] The water jet W is mixed with powder C supplied from the second supply channel P2 to the mixing chamber 11. The mixture of water and powder C generated in the mixing chamber 11 corresponds to the hardening agent in this embodiment. In this embodiment, mixing in the mixing section 10 does not necessarily mean that the water jet W and powder C are uniformly mixed, as in cement milk. That is, in the mixing section 10, it is sufficient that powder C is added to the water jet W.

[0030] The hardening agent nozzle 20 is positioned opposite the mixing nozzle 12 via the mixing chamber 11. Therefore, the jet W containing the powder C, i.e., the jet M of the hardening agent, is ejected from the hardening agent nozzle 20 to the side of the monitor 5. The direction of the jet M may be horizontal, perpendicular to the extension direction of the rod 4, or it may be inclined with respect to the horizontal.

[0031] A jet W can be used as the power source to draw the powder C into the mixing chamber 11. That is, as the jet W passes through the mixing chamber 11, the mixing chamber 11 becomes a vacuum. As a result, the powder C is drawn into the mixing chamber 11 from the second supply passage P2. Here, "vacuum" means a state in which the pressure in the second supply passage P2 is reduced to the extent that the powder C is drawn into the mixing chamber 11. Note that the method of sending the powder C into the mixing chamber 11 is not limited to drawing it in using the jet W described here. As another example, the powder C may be sent into the mixing chamber 11 by pressurized transport using a gas such as air.

[0032] If the water in the jet W accumulates in the mixing chamber 11, a vacuum cannot be formed, and the powder C will not be drawn into the mixing chamber 11. Therefore, it is preferable that the curing material nozzle 20 has a larger diameter than the mixing nozzle 12 so that all of the curing material, which is a mixture of the water in the jet W and the powder C, is discharged from the mixing chamber 11.

[0033] In this embodiment, the "mixing chamber" refers to the area where the water in the jet W and the powder C in the second supply channel P2 are mixed. It does not necessarily have to be a space where the width in the extension direction (vertical direction in the figure) or horizontal direction (lateral direction in the figure) of the rod 4 is larger than the diameter of the first supply channel P1 or the second supply channel P2, as shown in Figure 2. For example, the mixing chamber 11 may be a frustoconical space that extends from the tip of the mixing nozzle 12 to the hardening material nozzle 20.

[0034] Figure 3 shows an example of a ground improvement method using the ground improvement device 1 or construction system according to this embodiment. When improving the ground, first a small-diameter hole H is formed in the ground as shown in Figure 3(a). Furthermore, a rod 4 is inserted into the hole H. In addition, if a cutting tool is provided at the lower end of the monitor 5, as in the seventh embodiment described later, the hole H may be formed by drilling with the rod 4 and the monitor 5.

[0035] Next, by driving pump 2, high-pressure water is supplied to monitor 5. Furthermore, the work machine 6 moves upward while rotating rod 4. At this time, as shown in Figure 3(b), a jet of hardening material M is ejected from monitor 5. This jet M cuts the ground forming the wall surface of hole H, and the resulting space is filled with the hardening material. The mud (a mixture of soil and hardening material) generated by the cutting is discharged to the ground through the gap between rod 4 and hole H.

[0036] Subsequently, as Rod 4 is further pulled up, the space filled with the hardening material grows vertically, as shown in Figure 3(c). As the hardening material in this space hardens, a cylindrical ground improvement body G is formed.

[0037] According to the above embodiment, it is possible to provide an improved ground improvement device and ground improvement method that can improve work efficiency and reduce costs related to ground improvement.

[0038] In other words, in conventional construction methods, a hardening agent (cement milk) is generated on the ground by mixing cement powder and water, and this hardening agent is then pumped to monitor 5 through a rod. In this case, it is necessary to place a mixer or measuring device on the ground to mix the cement powder and water.

[0039] In contrast, in this embodiment, the cement powder and water are sent separately to the monitor 5 and mixed in the mixing section 10 of the monitor 5. With this configuration, there is no need to place a mixer or weighing equipment on the ground, and the work efficiency and cost of ground improvement work can be greatly improved.

[0040] Furthermore, in this embodiment, the powder C is supplied to the mixing chamber 11 by reducing the pressure in the mixing chamber 11 with the jet W from the mixing nozzle 12. With this configuration, a mechanism for sending the powder C to the mixing unit 10 becomes unnecessary.

[0041] Furthermore, since water is to be pumped from the ground to monitor 5, frictional losses within rod 4 are extremely small compared to pumping hardening agents such as cement grout. Therefore, it becomes possible to use a low-volume pump 2, and further cost reductions can be expected.

[0042] Since the mixing nozzle 12 sprays water, wear on the mixing nozzle 12 is extremely minimal. Therefore, the frequency of replacing the mixing nozzle 12 is less than that of the nozzle that sprays the hardening agent in conventional construction methods. As a result, the time and cost required to replace the mixing nozzle 12 are negligible compared to the overall construction work.

[0043] Furthermore, although a hardening agent mixture of cement powder and water is sprayed from the hardening agent nozzle 20, its flow velocity is lower than that of the water sprayed from the mixing nozzle 12 because it passes through the mixing chamber 11. Therefore, wear on the hardening agent nozzle 20 is suppressed. As a result, the work time and cost required to replace the hardening agent nozzle 20 are also reduced. In addition to what has been described herein, various other desirable effects can be obtained from this embodiment.

[0044] The following discloses other configurations applicable to Monitor 5 as second to seventh embodiments. Configurations and effects not specifically mentioned in each embodiment are the same as in the first embodiment.

[0045] [Second Embodiment] Figure 4 is a schematic cross-sectional view showing the configuration of monitor 5 according to the second embodiment. In addition to the elements shown in Figure 2, monitor 5 according to this embodiment further includes a third supply path P3.

[0046] The third supply channel P3 extends to the rear end 7 through the inside of the rod 4 shown in Figure 1. High-pressure air is supplied to the third supply channel P3 from the rear end 7. The pump for generating this high-pressure air is located on the ground at the construction site and forms part of the construction system according to this embodiment.

[0047] Furthermore, the third supply channel P3 is connected to the hardening agent nozzle 20 inside the monitor 5. In this embodiment, the hardening agent nozzle 20 is a double nozzle, with an annular nozzle for injecting air from the third supply channel P3 around the nozzle for injecting the hardening agent.

[0048] In this configuration, an air jet Am is formed around the hardening material jet M. As a result, the reach of the jet M is increased when excavating the ground, as shown in Figures 3(b) and 3(c). Consequently, a large-diameter ground improvement body G can be formed. Alternatively, the capacity of the pump 2 can be reduced compared to the case where the monitor 5 according to the first embodiment is used.

[0049] [Third Embodiment] Figure 5 is a schematic cross-sectional view showing the configuration of the monitor 5 according to the third embodiment. In addition to the elements shown in Figure 2, the monitor 5 according to this embodiment further includes a fourth supply path P4 and a cutting nozzle 30 connected to the fourth supply path P4.

[0050] The fourth supply channel P4 extends to the rear end 7 through the inside of the rod 4 shown in Figure 1. High-pressure water is supplied to the fourth supply channel P4 from the rear end 7. This water may be supplied by pump 2, or by a pump other than pump 2.

[0051] The cutting nozzle 30 is located on the side of the monitor 5, above the hardening agent nozzle 20. The cutting nozzle 30 injects water supplied by the fourth supply channel P4. This forms a jet E for cutting the ground. The direction of the jet E may be horizontal, perpendicular to the extension direction of the rod 4, or it may be inclined with respect to the horizontal.

[0052] When using the monitor 5 according to this embodiment, the ground is cut by the jet E when forming the ground improvement body G, as shown in Figures 3(b) and 3(c). In other words, the hardening material nozzle 20 can be used mainly for discharging the hardening material, which increases the design flexibility of the mixing nozzle 12 and the hardening material nozzle 20.

[0053] Furthermore, in the configurations according to the first and second embodiments, the ground is cut by a jet M of hardening material, resulting in mud mixed with hardening material and soil being discharged to the surface. In contrast, when the ground is cut by a jet E from the cutting nozzle 30, as in this embodiment, mainly mud mixed with water and soil is discharged to the surface. Therefore, it is possible to suppress the discharge of mud mixed with hardening material.

[0054] [Fourth Embodiment] Figure 6 is a schematic cross-sectional view showing the configuration of the monitor 5 according to the fourth embodiment. In addition to the elements shown in Figure 5 according to the third embodiment, the monitor 5 according to this embodiment further includes a fifth supply path P5.

[0055] The fifth supply channel P5 extends to the rear end 7 through the inside of the rod 4 shown in Figure 1. High-pressure air is supplied to the fifth supply channel P5 from the rear end 7. The pump for generating this high-pressure air is located on the ground at the construction site and forms part of the construction system according to this embodiment.

[0056] Furthermore, the fifth supply channel P5 is connected to the cutting nozzle 30 inside the monitor 5. In this embodiment, the cutting nozzle 30 is a double nozzle, with an annular nozzle for injecting air from the fifth supply channel P5 surrounding a nozzle for injecting high-pressure water.

[0057] In this configuration, an air jet Ae is formed around the cutting jet E. This increases the reach of the jet E when cutting the ground. As a result, a large-diameter ground improvement body G can be formed. Alternatively, compared to using the monitor 5 according to the third embodiment, the capacity of the pump for supplying high-pressure water to the fourth supply channel P4 can be reduced.

[0058] [Fifth Embodiment] Figure 7 is a schematic cross-sectional view showing the configuration of the monitor 5 according to the fifth embodiment. In addition to the elements shown in Figure 6 in the fourth embodiment, the monitor 5 according to this embodiment further includes the third supply path P3 shown in Figure 4 in the second embodiment.

[0059] In other words, in this embodiment, a jet of hardening material M and a jet of air Am are injected from the hardening material nozzle 20. Furthermore, a jet of cutting material E and a jet of air Ae are injected from the cutting nozzle 30. With this configuration, the effects described above in the second and fourth embodiments can be obtained.

[0060] [Sixth Embodiment] Figure 8 is a schematic cross-sectional view showing the configuration of the monitor 5 according to the sixth embodiment. The configuration of the mixing unit 10 in the monitor 5 according to this embodiment differs from that shown in Figure 2 in the first embodiment.

[0061] In other words, the mixing unit 10 further includes a depressurization chamber 13 (preliminary depressurization chamber). The depressurization chamber 13 is connected to the second supply passage P2 and also to the mixing chamber 11 through a connecting passage 14. In Figure 8, the diameter of the connecting passage 14 is smaller than the diameter of the second supply passage P2, but this is not the only example.

[0062] In the monitor 5 according to this embodiment, as the mixing chamber 11 is depressurized by the jet W from the mixing nozzle 12, the depressurization chamber 13 is also depressurized. The powder C from the second supply passage P2 is first drawn into the depressurization chamber 13, and then drawn into the mixing chamber 11 through the connecting passage 14.

[0063] For example, in configurations where the second supply channel P2 and the mixing chamber 11 are directly connected, as in the embodiments described above, if the fluidity of the powder C is low, the powder C may be drawn into the mixing chamber 11 intermittently as clumps. In contrast, with the configuration of this embodiment, even if the fluidity of the powder C is low, the powder C in the second supply channel P2 is first drawn into the depressurization chamber 13 and loosened, and then supplied to the mixing chamber 11. Therefore, the powder C can be supplied to the mixing chamber 11 stably at a constant pace.

[0064] In this embodiment, we have illustrated the case where a depressurization chamber 13 is provided in the monitor 5 with the configuration shown in the first embodiment, but a similar depressurization chamber 13 can also be provided in the monitor 5 shown in the second to fifth embodiments.

[0065] [Seventh Embodiment] Figure 9 is a schematic cross-sectional view showing the configuration of the monitor 5 according to the seventh embodiment. In addition to the elements shown in Figure 2 according to the first embodiment, the monitor 5 according to this embodiment further includes a drilling fluid discharge port 41, a drilling tool 40, and a valve 50.

[0066] The discharge port 41 is located at the lower end of the monitor 5 and communicates with the first supply passage P1. The drilling tool 40 is, for example, a metal blade provided to surround the discharge port 41.

[0067] The valve 50 opens and closes the flow path from the first supply passage P1 to the discharge port 41. In the example shown in Figure 9, the valve 50 includes a valve seat 51 provided at the lower end of the first supply passage P1 and a metal ball 52 that can be inserted into the first supply passage P1.

[0068] The monitor 5 according to this embodiment can also be used to form a hole H for inserting a rod 4 into the ground. That is, the ground is excavated by the drilling tool 40 by lowering the rod 4 while rotating it with the work machine 6. During this excavation, the metal ball 52 is not introduced. Therefore, water sent from the pump 2 is discharged from the discharge port 41. By using this water as the drilling fluid, smooth drilling and soil removal become possible.

[0069] After the hole H is formed, a metal ball 52 is introduced into the first supply channel P1. The valve seat 51 receives the metal ball 52, thereby blocking the flow path from the first supply channel P1 to the discharge port 41. In this state, similar to the monitor 5 according to the first embodiment, water from the first supply channel P1 is injected into the mixing chamber 11 through the mixing nozzle 12, the powder C is mixed into this jet W, and a jet M of hardening material is injected from the hardening material nozzle 20. Therefore, by pulling up the rod 4 while rotating it as shown in Figure 3, a ground improvement body G can be formed in the ground.

[0070] In this embodiment, an example was given in which the monitor 5 with the configuration shown in the first embodiment is provided with a discharge port 41, a drilling tool 40, and a valve 50. However, the same configuration can be applied to the monitor 5 shown in the second to sixth embodiments.

[0071] The present invention is not limited to the configurations of the first to seventh embodiments described above, and can be modified in various ways.

[0072] For example, in each embodiment, the cases in which the powder and liquid for generating the hardening agent are cement and water, respectively, were illustrated. However, the powder for generating the hardening agent is not limited to cement, as long as it is a material capable of solidifying or strengthening the ground. Also, the liquid for generating the hardening agent is not limited to water, as long as it does not contain solid particles that cause significant wear of the nozzle and has low viscosity (low friction loss). Furthermore, the gas for forming the jets Am and Ae disclosed in the second embodiment (Figure 4), the fourth embodiment (Figure 6), and the fifth embodiment (Figure 7) is not limited to air, and various gases can be used depending on the situation.

[0073] In the third to fifth embodiments (Figures 5 to 7), the first supply path P1 and the fourth supply path P4 of the monitor 5 may form a single common flow path in at least a portion of the interior of the rod 4 and the monitor 5. Similarly, in the fifth embodiment (Figure 7), the third supply path P3 and the fourth supply path P4 of the monitor 5 may form a single common flow path in at least a portion of the interior of the rod 4 and the monitor 5.

[0074] Each embodiment of the monitor 5 may include two or more hardening agent nozzles 20. In this case, the monitor 5 may include a number of mixing units 10 corresponding to each hardening agent nozzle 20. Similarly, in the third to fifth embodiments (Figures 5 to 7), the monitor 5 may include two or more cutting nozzles 30. [Explanation of symbols]

[0075] 1...Ground improvement device, 2...Pump, 3...Silo, 4...Rod, 5...Monitor, 6...Working machine, 10...Mixing section, 11...Mixing chamber, 12...Mixing nozzle, 20...Hardening material nozzle, 30...Cutting nozzle, 40...Drilling tool, 41...Discharge port, 50...Valve section, P1...First supply channel, P2...Second supply channel, P3...Third supply channel, P4...Fourth supply channel, P5...Fifth supply channel, C...Powder, M...Hardening material jet, G...Ground improvement body.

Claims

1. A ground improvement device for creating a ground improvement body, A rod inserted into the ground, A monitor provided on the aforementioned rod, A first supply path that passes through the inside of the rod and sends liquid to the monitor, A second supply path that passes through the inside of the rod and sends the powder to the monitor, Equipped with, The aforementioned monitor is A mixing unit that produces a hardening material by mixing the liquid supplied by the first supply channel and the powder supplied by the second supply channel, A hardening material nozzle for spraying the hardening material generated by the mixing unit into the ground, A ground improvement device equipped with [specific features / features].

2. The mixing section is The mixing chamber connected to the curing material nozzle and the second supply passage, A mixing nozzle connected to the first supply path and for injecting the liquid into the mixing chamber, Equipped with, As the mixing chamber is depressurized by the injection of the liquid by the mixing nozzle, the powder in the second supply passage is drawn into the mixing chamber and mixed with the liquid. The ground improvement device according to claim 1.

3. The mixing unit further comprises a pressure reduction chamber provided between the second supply passage and the mixing chamber, The powder in the second supply channel is drawn into the mixing chamber through the reduced pressure chamber. The ground improvement device according to claim 2.

4. The system further comprises a third supply path that passes through the inside of the rod and delivers gas to the monitor, The curing agent nozzle injects the gas supplied by the third supply path together with the curing agent. The ground improvement device according to claim 1.

5. The rod further comprises a fourth supply path that passes through the inside of the rod and delivers liquid to the monitor, The monitor further comprises a cutting nozzle that cuts the ground by injecting the liquid delivered by the fourth supply channel. The ground improvement device according to claim 1.

6. The system further comprises a fifth supply path that passes through the inside of the rod and sends gas to the monitor, The cutting nozzle injects the gas supplied by the fifth supply passage together with the liquid supplied by the fourth supply passage. The ground improvement device according to claim 5.

7. The aforementioned monitor is Located at the lower end in the extending direction of the rod, and having a discharge port from which the liquid of the first supply passage is discharged, A drilling tool provided around the discharge port, A valve unit that opens and closes the flow path from the first supply passage to the discharge port, It also has, The ground improvement device according to claim 1.

8. A ground improvement method using a ground improvement device according to any one of claims 1 to 7, Insert the rod into the ground, By rotating the rod while spraying the hardening material from the hardening material nozzle, and by pulling up the rod, a ground improvement body in which the hardening material has hardened is created in the ground. A ground improvement method that includes the following.

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