Ground improvement device and ground improvement method

Abstract

To enable eccentricity of a rotary shaft of a ground improvement device to be favorably inferred during construction by a ground improvement method.SOLUTION: A ground improvement device (1) and a ground improvement method in which an agitation device (15) is provided at a bottom edge of a rotary shaft (14) being lifted up and down, and a ground (2) is improved by agitating and mixing sediment and a ground improving material in the excavated ground (2), measure displacement of the rotary shaft (14) from a reference position on the ground using GNSS (Global Navigation Satellite System) and notify when the displacement exceeds a specified value. The invention allows the reference position to be changed. The invention changes the specified value of the displacement depending on depth of the agitation device (15).SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a ground improvement device and a ground improvement method in which a mixing device is attached to the lower end of a rotating shaft that moves up and down, and which improves the ground by mixing and stirring soil and soil improvement materials in the excavated ground. [Background technology]

[0002] Conventionally, ground improvement has been carried out for the purpose of strengthening weak ground or purifying contaminated ground.

[0003] The ground improvement device used in this ground improvement is configured so that a rotating shaft has a hollow outer shaft arranged in a double-tube shape outside the inner shaft, to which is connected a stirring device having an excavation body connected to the inner shaft and an inner stirring blade and an outer stirring blade connected to the outer shaft, and the rotating shaft is rotated by a rotary drive device.

[0004] In a ground improvement method using a ground improvement device, the ground is excavated using an excavation device, and a ground improvement material (such as a solidification agent or a purification agent) is discharged into the excavated ground, and the ground improvement material and the soil and sand are stirred and mixed in the ground using a stirring device, thereby improving the ground (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-161843 Summary of the Invention [Problem to be solved by the invention]

[0006] In the conventional ground improvement method described above, the ground is excavated using a ground improvement device inside the ground, and then the excavated soil and soil improvement material are stirred and mixed to perform ground improvement, making it difficult to directly check the condition of the ground by visual inspection, etc. In particular, when excavating the ground, the rotating shaft of the ground improvement device and the excavation body of the mixing device attached to the bottom end of the rotating shaft must be lowered vertically downward, and if the rotating shaft becomes eccentric due to contact with underground obstacles such as gravel or boulders in the ground, there is a risk that the rotating shaft and other parts will be broken or damaged by loads that exceed their capacity.

[0007] Therefore, the eccentricity of the rotating shaft of the ground improvement device is managed using a measuring device to measure the eccentricity and tilt of the rotating shaft inside the ground, in order to prevent breakage or damage to the rotating shaft.

[0008] However, the measuring equipment required to measure the eccentricity and tilt of the rotation axis inside the ground is expensive, and since measurements are taken inside the ground, advanced technology is required, making maintenance during construction complicated.

[0009] Therefore, the present invention makes it possible to accurately estimate the eccentricity of the rotation axis of the ground improvement device during the execution of the ground improvement method. [Means for solving the problem]

[0010] In the present invention according to claim 1, a stirring device is provided at the lower end of a rotating shaft that moves up and down, and in the ground improvement device, the device improves the ground by stirring and mixing soil and soil improvement material in the excavated ground. The amount of displacement of the rotating shaft from a reference position on the ground is measured using GNSS (Global Navigation Satellite System), and an alert is issued when the amount of displacement exceeds a predetermined value.

[0011] In the present invention according to claim 2, in the present invention according to claim 1, the reference position is made changeable.

[0012] In addition, in the present invention according to claim 3, in the present invention according to claim 1 or claim 2, the predetermined value of the amount of displacement is changed according to the depth of the stirring device.

[0013] Furthermore, in the present invention according to claim 4, in a ground improvement method in which a stirring device is provided at the lower end of a rotating shaft that moves up and down, and soil and ground improvement materials are stirred and mixed in the excavated ground to improve the ground, the amount of displacement of the rotating shaft from a reference position on the ground is measured using GNSS (Global Navigation Satellite System), and an alert is issued when the amount of displacement exceeds a predetermined value.

[0014] Furthermore, in the present invention according to claim 5, in the present invention according to claim 4, when the displacement amount exceeds a predetermined value, the stirring device is pulled out from the ground, and then the excavation conditions are changed and the ground is excavated again. [Effects of the Invention]

[0015] The present invention provides the following effects.

[0016] That is, in the present invention, a ground improvement device is provided at the lower end of a rotating shaft that moves up and down, and improves the ground by stirring and mixing soil and ground improvement materials in the excavated ground. The amount of displacement of the rotating shaft from a reference position on the ground is measured using GNSS (Global Navigation Satellite System), and an alert is issued when the amount of displacement exceeds a predetermined value. Therefore, the eccentricity of the rotating shaft inside the ground can be accurately estimated using GNSS, which is widely used in ground improvement methods that utilize ICT (Information and Communication Technology), without using any special equipment, and construction management of the ground improvement method can be easily carried out.

[0017] In particular, if the reference position can be changed, a position suitable for each construction site or construction environment can be selected as the reference position, allowing construction management to be carried out in a manner suitable for each construction site or construction environment.

[0018] Furthermore, if the specified value of the displacement amount is changed depending on the depth of the mixing device, the eccentricity of the rotation axis can be inferred depending on the depth, and construction management of the ground improvement method can be carried out more accurately.

[0019] Furthermore, in this invention, in a ground improvement method in which a stirring device is installed at the lower end of a rotating shaft that rises and falls, and soil and ground improvement materials are stirred and mixed in the excavated ground to improve the ground, the amount of displacement of the rotating shaft from a reference position on the ground is measured using GNSS, and an alert is issued when the amount of displacement exceeds a predetermined value.As a result, the eccentricity of the rotating shaft inside the ground can be accurately estimated using GNSS, which is widely used in ground improvement methods that utilize ICT, without the need for special equipment, and construction management of the ground improvement method can be easily carried out.

[0020] In particular, if the amount of displacement exceeds a predetermined value, and the mixing device is pulled out of the ground, and then the excavation conditions are changed and the ground is excavated again, the ground improvement method can be carried out smoothly and safely without damaging or damaging the rotating shaft, etc. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. [Figure 2] FIG. [Figure 3] Same plan view. [Figure 4] FIG. [Figure 5] FIG. 4 is an explanatory diagram showing the displacement amount of a rotation shaft. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, specific configurations of the ground improvement device and the ground improvement method according to the present invention will be described with reference to the drawings.

[0023] As shown in Figures 1 to 3, the ground improvement device 1 is a device for excavating the ground 2 and stirring and mixing the excavated soil and sand with a ground improvement material (solidification material) to improve the strength and properties of the ground 2. This ground improvement device 1 has a support 4 erected at the front end of a heavy machine 3, and a ground improvement mechanism 5 attached to this support 4 so that it can be raised and lowered. A ground improvement material supply mechanism 6 is connected to this ground improvement mechanism 5 via a swivel joint 7. The ground improvement material supply mechanism 6 is configured to connect a ground improvement material storage tank 8 and a water tank 9 to a ground improvement material mixing plant 10, and to connect a ground improvement material discharge pump 11 to the ground improvement material mixing plant 10, so that the ground improvement material is supplied to the ground improvement mechanism 5.

[0024] The ground improvement mechanism 5 has a lifting support 12 attached to the front side of the support 4 so that it can be raised and lowered freely, a driver 13 attached to this lifting support 12, the base end (upper end) of a rotating shaft 14 extending in the vertical direction attached to the driver 13, and an agitator 15 connected in tandem to the tip end (lower end) of the rotating shaft 14.

[0025] The driving body 13 has an inner shaft 16 and an outer shaft 17 that constitute the rotary shaft 14 , and a rotary drive device 18 connected to the inner shaft 16 and the outer shaft 17 via a reversing transmission 19 .

[0026] The rotating shaft 14 is composed of an inner shaft 16 and an outer shaft 17, with their central rotation axes arranged coaxially. The outer shaft 17, which is also hollow and cylindrical and extends vertically, is provided on the outside of the inner shaft 16, which is hollow and cylindrical and extends vertically, in a double-tube configuration. The tip of the inner shaft 16 of the rotating shaft 14 protrudes downward further than the tip of the outer shaft 17. When the rotary drive device 18 is driven, the inner shaft 16 and the outer shaft 17 rotate in relatively opposite directions due to the action of a reversing transmission 19. The hollow part of the inner shaft 16 is connected to the ground improvement material supply mechanism 6 and serves as a flow path for discharging the ground improvement material into the ground 2.

[0027] Agitator 15 is interlocked and connected to the tip (lower end) of rotating shaft 14 via a seal rod 20 for preventing soil and soil improvement material from flowing in between inner shaft 16 and outer shaft 17 of rotating shaft 14. This agitator 15 is composed of agitator blade body 21 for agitating and mixing soil and soil improvement material, and an excavator body 22 for excavating ground 2.

[0028] The seal rod 20 is configured such that the outer side of the inner shaft 16, which protrudes from the lower end of the outer shaft 17, is covered at a distance by a pair of front and rear exterior bodies 23, 24 attached to the lower end of the outer shaft 17. A hollow space between the inner shaft 16 and the exterior bodies 23, 24 is provided with an inflow prevention body 25 for preventing the inflow of soil and soil improvement materials. The inflow prevention body 25 is formed by sandwiching grease-impregnated nonwoven fabric between multiple ring-shaped packings spaced apart vertically. The exterior bodies 23, 24 connected to the outer shaft 17 of the seal rod 20 rotate in the opposite direction relative to the inner shaft 16. At this time, the inflow prevention body 25 of the seal rod 20 functions as both a bearing and a seal.

[0029] The agitator blade body 21 has an inner blade shaft 26 interlocked with the inner shaft 16 of the rotating shaft 14, and an outer blade shaft 27 interlocked with the outer shaft 17 of the rotating shaft 14, with the central rotation axis arranged coaxially, and the hollow cylindrical outer blade shaft 27 extending vertically is provided outside the hollow cylindrical inner blade shaft 26 extending vertically in a double-tube shape. The hollow part of the inner blade shaft 26 is connected to the ground improvement material supply mechanism 6 via the inner shaft 16, and a discharge port for the ground improvement material is formed at the tip (lower end) of the inner blade shaft 26, etc., which serves as a flow path for discharging the ground improvement material into the ground 2.

[0030] The agitator blade body 21 also has an innermost agitator blade 28 that is arranged on the innermost side, an inner agitator blade 29 that is arranged on the outer periphery of that, and an outer agitator blade 30 that is arranged further on the outer periphery of that (outermost side).

[0031] The innermost agitating blade 28 has two flat innermost agitating blade pieces 31 attached to the outer peripheral surface of the tip of the outer blade shaft 27, facing radially outward at an interval of 180 degrees in the circumferential direction.

[0032] The inner agitator blade 29 has two inner agitator blade pieces 32 attached to the tip of the inner blade shaft 26 in a radial pattern facing outward at 180-degree intervals in the circumferential direction. Each inner agitator blade piece 32 is formed into a roughly U-shape in side view with the middle part bulging outward, consisting of an inner agitator blade upper piece 33 extending downward at an angle, an inner agitator blade middle piece 34 extending vertically downward, and an inner agitator blade lower piece 35 extending upward at an angle. The inner agitator blade lower piece 35 of each inner agitator blade piece 32 is attached to the tip of the inner blade shaft 26, and the inner agitator blade upper piece 33 is attached to an annular body 36, which is loosely fitted around the outer peripheral surface of the outer blade shaft 27 so as to be freely rotatable. Each inner agitating blade piece 32 has an agitating piece 37 attached to the outside of the inner agitating blade mid-portion piece 34 , and a connecting piece 38 attached between the inner agitating blade mid-portion piece 34 and the inner blade shaft 26 .

[0033] The outer agitator blade 30 has three outer agitator blade pieces 39 attached to the tip of the outer blade shaft 27 in a radial pattern facing outward at 120-degree intervals in the circumferential direction. Each outer agitator blade piece 39 is formed into a roughly U-shape in side view with the middle part bulging outward, consisting of an outer agitator blade upper piece 40 extending downward at an angle, an outer agitator blade middle piece 41 extending vertically downward, and an outer agitator blade lower piece 42 extending upward at an angle. The outer agitator blade upper piece 40 of each outer agitator blade piece 39 is attached to the base end of the outer blade shaft 27, and the outer agitator blade lower piece 42 is attached to an annular body 43, which is loosely fitted around the outer peripheral surface of the inner blade shaft 26 so as to be freely rotatable. Each outer agitating blade piece 39 has two agitating blades 44 attached inside the outer agitating blade mid-section piece 41, one above the other, sandwiching an agitating blade 37 attached outside the inner agitating blade mid-section piece 34 therebetween.

[0034] In the agitator blade body 21, the inner blade shaft 26 rotates as the inner shaft 16 of the rotating shaft 14 rotates, and the outer blade shaft 27 rotates in the opposite direction relative to the inner blade shaft 26 as the outer shaft 17 of the rotating shaft 14 rotates, and the inner agitator blade 29 rotates as the inner blade shaft 26 rotates, and the innermost agitator blade 28 and the outer agitator blade 30 rotate in the opposite direction relative to the inner agitator blade 29 as the outer blade shaft 27 rotates, and these innermost agitator blade 28, inner agitator blade 29 and outer agitator blade 30 agitate and mix the soil and ground improvement material inside the ground 2.

[0035] The excavating body 22 has two flat excavating wings 45 attached radially outward at an interval of 180 degrees in the circumferential direction to the outer peripheral surface of the tip of the inner blade shaft 26, and a plurality of excavating bits 46 detachably attached at intervals on the left and right to the lower part of each excavating wing 45. In the excavating body 22, the excavating wings 45, 45 rotate as the inner blade shaft 26 (inner shaft 16) rotates, and the excavating bits 46 excavate the ground 2.

[0036] In the ground improvement method using the above-mentioned ground improvement device 1, the ground improvement device 1 is moved to a predetermined position on the ground 2, the ground improvement mechanism 5 is lowered, and the excavation body 22 of the mixing device 15 excavates the ground 2 to a predetermined depth, and then the ground improvement material is discharged from the ground improvement material supply mechanism 6 into the ground 2, and the mixing blade body 21 of the mixing device 15 mixes and stirs the ground improvement material and the excavated soil and sand while the ground improvement mechanism 5 is raised and lowered, thereby creating an improved body inside the ground 2.

[0037] In the present invention, as shown in Figure 4, the above-mentioned ground improvement device 1 is provided with a control device (computer) 47 for controlling the ground improvement mechanism 5 (e.g., rotary drive device 18, etc.) and the ground improvement material supply mechanism 6 (e.g., ground improvement material discharge pump 11, etc.), and the control device 47 appropriately drives and controls them.

[0038] This control device 47 is connected to various driving mechanisms such as the rotary drive device 18 and the ground improvement material discharge pump 11, as well as various measuring mechanisms such as a depth gauge 48 for measuring the stirring / mixing position (depth), a flow meter 49 for measuring the discharge amount of ground improvement material, and an ammeter 50 for measuring the load current flowing through the rotary drive device 18 so as to confirm that it has reached the supporting layer, etc. Various control signals such as a switching signal 51 for switching the rotation speed of the rotary drive device 18 are also connected, and a display device 52 for displaying various information and an alarm means 54 such as a speaker 53 for generating sound are also connected.

[0039] Furthermore, in the present invention, in order to carry out a ground improvement method using ICT (Information and Communication Technology), antennas 55-57 and receivers 58-60 (GNSS receiving means 61) for GNSS (Global Navigation Satellite System) are mounted on the ground improvement device 1 as a navigation system, and are connected to the control device 47. Note that at least one of the antennas 55-57 and receivers 58-60 is sufficient, but more accurate position measurement can be achieved by providing multiple units and performing relative positioning rather than performing single positioning with one unit.

[0040] In the ground improvement device 1, the current value of the load current flowing through the rotary drive device 18, which is measured using an ammeter 50, can be used to confirm that the supporting layer has been reached, and the stirring / mixing position (depth) and penetration / pulling speed (change in depth per unit time) can be measured using a depth meter 48, and the discharge amount of the ground improvement material can be measured using a flow meter 49, making it possible to confirm (manage) the state of the inside of the ground (degree of ground improvement) from the depth and flow rate.

[0041] Furthermore, the ground improvement device 1 not only uses the GNSS receiving means 61 to navigate and manage the construction position of the ground improvement device 1, but also uses a depth meter 48 to measure the stirring and mixing position of the stirring device 15 (depth: vertical distance from the surface of the ground 2), and also uses the GNSS receiving means 61 to measure the displacement of the rotating axis 14 from a reference position on the ground (the horizontal distance on the surface of the ground 2 from the reference position set at the start of construction to the center position of the rotating axis 14 (stirring device 15) during construction), and infers the degree of eccentricity of the rotating axis 14 from these depths and displacements, and if necessary, uses the notification means 54 to notify the operator, manager, etc.

[0042] That is, in the ground improvement device 1, a reference position (reference point) on the ground is determined in advance, as shown schematically in Fig. 5. This reference point can be a position registered in coordinates as the center position of the regular improved body when the ground improvement method is performed, a position set (recorded) as the center position of the improved body at the start of the ground improvement method by moving the ground improvement device 1 when the ground improvement method is performed, or the center position of the agitator 15 (agitator blade body 21) at the start of the ground improvement method, or it can be determined by selecting from these positions.

[0043] During the construction of the ground improvement method, the ground improvement device 1 excavates the ground 2 with the excavation body 22 of the mixing device 15 while lowering the rotation axis 14 with the lifting support 12, and at that time, the control device 47 measures the depth using the depth meter 48 and measures the position of the center of the rotation axis 14 on the ground (the surface of the ground 2: the earth's surface) using the GNSS receiving means 61.

[0044] During construction, a force that causes the rotating shaft 14 to become eccentric may be applied due to contact between the agitator 15 and underground obstacles such as gravel or boulders inside the ground 2. When an external force is applied to the rotating shaft 14 in this way, the position of the center of the rotating shaft 14 on the ground moves (displaces) in one direction or another. Although the direction and amount of displacement of the rotating shaft 14 do not necessarily coincide with the direction and amount of eccentricity of the rotating shaft 14, at least when the amount of displacement of the rotating shaft 14 is large, it is considered that an external force has been applied to the rotating shaft 14, causing it to become eccentric.

[0045] Therefore, when the displacement amount in the X direction and the Y direction from the reference point is within a first displacement range from the reference point to less than the first predetermined displacement (shown as points P1 and P2 in FIG. 5) within a first depth range from the surface of the ground 2 to less than the first predetermined depth set in advance, the displacement amount is displayed on the display device 52 with a mark (circle in FIG. 5) indicating that the depth is within the first depth range.

[0046] Thereafter, if the displacement amount exceeds the first displacement range within the first depth range (indicated by point P3 in Figure 5), it is assumed that a large force is acting to eccentricate the rotation axis 14, and time is measured. Once a predetermined time has elapsed, the displacement amount is displayed on the display device 52 with a mark indicating that the device is within the first depth range (circle in Figure 5), and an alarm is emitted from the speaker 53, which is the notification means 54, or a warning is displayed on the display device 52 to notify the worker, etc. (which may also include the manager, etc.).

[0047] Similarly, when the displacement amount in the X direction and Y direction from the reference point is within a second depth range from the first predetermined depth to less than the second predetermined depth, and the displacement amount is within a second displacement range from the first predetermined displacement to less than the second predetermined displacement (indicated by points P4 and P5 in Figure 5), the displacement amount is displayed on display device 52 with a mark (● in Figure 5) indicating that the displacement is within the second depth range, and when the displacement amount exceeds the second displacement range within the second depth range (indicated by point P6 in Figure 5), after a predetermined time has passed, the displacement amount is displayed on display device 52 with a mark (● in Figure 5) indicating that the displacement is within the second depth range, and an alarm is generated from speaker 53, which is notification means 54, or a warning is displayed on display device 52 to notify the operator, etc.

[0048] Furthermore, when the displacement amount in the X direction and Y direction from the reference point is within a third depth range from the second predetermined depth to less than the third predetermined depth, and the displacement amount is within a third displacement range from the second predetermined displacement to less than the third predetermined displacement (indicated by points P7 and P8 in Figure 5), the displacement amount is displayed on display device 52 with a mark (□ in Figure 5) indicating that the displacement is within the third depth range, and when the displacement amount exceeds the third displacement range within the third depth range (indicated by point P9 in Figure 5), after a predetermined time has passed, the displacement amount is displayed on display device 52 with a mark (□ in Figure 5) indicating that the displacement is within the third depth range, and an alarm is generated from speaker 53, which is notification means 54, or a warning is displayed on display device 52 to notify the operator, etc.

[0049] When the displacement of the rotating shaft 14 exceeds a predetermined value and an alarm is issued, the worker raises the rotating shaft 14 using the lifting support 12 and pulls out the agitator 15 from the ground 2, then changes the excavation conditions such as the descent speed and rotation speed of the agitator 15, and then re-excavates the ground 2 with the agitator 15. If the worker or the like performs a confirmation operation after the alarm is issued, the alarm is canceled and will not be issued again within a preset time, so that repeated alarms will not be issued while the worker is making corrections such as re-excavating.

[0050] As described above, the ground improvement device 1 is a device that has a stirring device 15 attached to the lower end of a rotating shaft 14 that moves up and down, and that improves the ground 2 by stirring and mixing soil and soil improvement material in the excavated ground 2.The device is configured to measure the amount of displacement of the rotating shaft 14 from a reference position on the ground using GNSS, and to issue an alert when the amount of displacement exceeds a predetermined value.

[0051] Therefore, with the ground improvement device 1 configured as described above, the eccentricity of the rotating shaft 14 inside the ground 2 can be accurately estimated using GNSS, which is widely used in ground improvement methods that utilize ICT, without using any special equipment, thereby preventing damage or breakage to the stirring device 15 of the ground improvement device 1, etc., and making it easy to manage the construction of the ground improvement method.

[0052] Moreover, the ground improvement device 1 is configured so that the reference position can be changed.

[0053] Therefore, in the ground improvement device 1 configured as described above, a position suitable for each construction site and construction environment can be selected as the reference position, and construction management suitable for each construction site and construction environment can be performed.

[0054] Moreover, the above-mentioned soil improvement device 1 is configured such that the predetermined value of the amount of displacement (first to third displacement ranges) is changed according to the depth of the agitator 15 (first to third depth ranges).

[0055] Therefore, the eccentricity of the rotation axis 14 can be estimated depending on the depth, and construction management of the ground improvement method can be carried out more accurately.

[0056] In addition, the above-mentioned ground improvement method is configured to provide a stirring device 15 on a rotating shaft 14 that moves up and down, and to improve the ground 2 by stirring and mixing the soil and ground improvement material in the excavated ground 2, and to measure the amount of displacement of the rotating shaft 14 from a reference position on the ground using GNSS, and to issue an alert when the amount of displacement exceeds a predetermined value.

[0057] Therefore, in the ground improvement method configured as described above, the eccentricity of the rotating shaft 14 inside the ground 2 can be accurately estimated using GNSS, which is widely used in ground improvement methods that utilize ICT, without using any special equipment, which makes it possible to prevent damage to the stirring device 15 of the ground improvement device 1, etc., and also makes it easy to manage the construction of the ground improvement method.

[0058] Furthermore, the above-described ground improvement method is configured such that, when the amount of displacement exceeds a predetermined value, the agitator 15 is pulled out from the ground 2, and then the excavation conditions are changed and the ground 2 is excavated again.

[0059] Therefore, in the ground improvement method having the above configuration, the ground improvement method can be carried out well and safely without damaging or breaking the rotating shaft 14 and the like. [Explanation of symbols]

[0060] 1 Soil improvement equipment 2 Soil 3 Heavy equipment 4 Posts 5 Ground improvement mechanism 6 Ground improvement material supply mechanism 7 Swivel joint 8 Ground improvement material storage tank 9 Water tank 10 Ground improvement material mixing plant 11 Ground improvement material discharge pump 12 Lifting support 13 driving body 14 rotating shaft 15 Stirring device 16 Inner shaft 17 outer shaft 18 rotary drive device 19 Reverse transmission 20 Seal rod 21 agitating blade body 22 excavation body 23,24 Exterior body 25 Inflow prevention body 26 Inner wing shaft 27 Outer wing shaft 28 Innermost stirring blade 29 Inner stirring blade 30 outer stirring blade 31 innermost stirring blade piece 32 Inner stirring blade piece 33 Inner stirring blade upper piece 34 Inner stirring blade middle piece 35 Inner stirring blade lower piece 36 Ring body 37 Stirring piece 38 Connecting piece 39 Outer stirring blade piece 40 Upper part of outer stirring blade 41 Midway part of outer stirring blade 42 outer stirring blade lower piece 43 annular body 44 stirring piece 45 excavation blade 46 Drilling bit 47 Control device 48 Depth gauge 49 Flow meter 50 Ammeter 51 Switching signal 52 Display device 53 Speaker 54 Notification means 55-57 Antenna 58~60 Receiver 61 GNSS receiving means

Claims

1. A ground improvement device is provided with a mixing device at the bottom end of a rotating shaft that moves up and down, and improves the ground by mixing and stirring soil and ground improvement materials in the excavated ground. A ground improvement device that measures the displacement of the rotation axis from a reference position on the ground using GNSS (Global Navigation Satellite System) and issues an alert when the displacement exceeds a predetermined value.

2. 2. The soil improvement device according to claim 1, wherein the reference position is changeable.

3. 3. The soil improvement device according to claim 1, wherein the predetermined value of the amount of displacement is changed depending on the depth of the mixing device.

4. This is a ground improvement method in which a mixing device is installed at the bottom of a rotating shaft that moves up and down, and the soil and soil improvement material are mixed in the excavated ground to improve the ground. A ground improvement method characterized by measuring the displacement of the rotation axis from a reference position on the ground using GNSS (Global Navigation Satellite System) and issuing an alert when the displacement exceeds a predetermined value.

5. 5. The ground improvement method according to claim 4, wherein when the displacement amount exceeds a predetermined value, the stirring device is pulled out from the ground, and then the excavation conditions are changed and the ground is excavated again.

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