JP2017133235A - Soil improvement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a soil improvement body with a required sufficient diameter even in a narrow ground.SOLUTION: A mechanical agitation device 10 comprises a drilling blade 30 and an agitating blade 40 at the tip of a rod, and an improvement object ground is drilled by the drilling blade 30, and in-situ soil and a soil improvement material are mixed and agitated by the agitating blade 40 inserted in the improvement object ground so that a soil improvement body is established in the ground. The mechanical agitation device is separated from a ground surface part of the improvement object ground by a separation device comprising a bearing pile 60, a girder receiver 70, a rail 50 and others. A soil improvement body is established by steps of: implanting the bearing pile 60; laying the rail 50; installing the mechanical agitation device 10 and performing soil improvement; removing the mechanical agitation device 10; and removing separation equipment.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a ground improvement method, and more particularly, to a ground improvement method performed using a mechanical stirring device in a narrow area.

  In recent years, liquefaction damage due to earthquakes has occurred, and it is necessary to improve the ground for such soft ground. As such a ground improvement method, for example, a high-pressure jet stirring method and a mechanical stirring method are known. However, in areas where private houses are concentrated, ground improvement cannot be performed using a large ground improvement device, and ground improvement must be performed using a ground improvement device suitable for narrow areas.

  For this reason, a ground improvement device and a ground improvement method suitable for narrow areas have been proposed (see, for example, Patent Document 1). The technique described in Patent Document 1 relates to a ground improvement device used when performing ground improvement work for preventing liquefaction in a narrow residential area where various restrictions are imposed on the construction space. This ground improvement apparatus raises a rotational drive part and a rotational power apparatus only by a fixed stroke by a raising / lowering drive part. In addition, the rotary drive unit is moved downward while fixing and supporting the drive shaft by the rotary drive unit, and the ground improvement process of the mechanical stirring method by excavating the ground and injecting the solidified slurry is advanced downward.

  Then, when the elevating drive unit is lowered to the lower limit position, the fixing / supporting of the drive shaft by the rotation drive unit is once released, the rotation drive unit is lifted by a fixed stroke, and the drive shaft is fixed again by the rotation drive unit at the raised position. The ground improvement process step of supporting and rotating the rotary drive unit while rotating is repeatedly advanced to the target depth.

JP 2013-174094 A

  As described above, when it is necessary to perform ground improvement work without removing existing buildings in a residential area where houses are densely packed, a large ground improvement device cannot be introduced. The large ground improvement device has a large weight and can be constructed with its own weight as a reaction force when performing ground excavation, etc., but the small ground improvement device has its own weight as a small force. It is not possible to devise, and it is necessary to devise measures to take the reaction force.

  In this regard, the technique described in Patent Document 1 is a technique in which a moving table is placed on a rail laid on the ground surface, and a ground improvement device is installed on the moving table. The rail is configured to obtain a reaction force required for preventing excavation and a falling force by a fixture such as a pile driven into the ground or a screw pile screwed into the ground.

  However, in the ground improvement device described in Patent Document 1, since the rail must be laid in contact with the ground surface portion of the construction site, the ground surface portion of the construction site is narrowed by the amount of laying the rail. For this reason, the diameters of the excavation blades and the stirring blades are limited. In particular, when performing ground improvement in a narrow area, a ground improvement body having a necessary and sufficient diameter may not be formed.

  The present invention has been proposed in view of the above-described circumstances, and an object thereof is to provide a ground improvement method capable of forming a ground improvement body having a necessary and sufficient diameter even in a narrow area.

  The ground improvement method of the present invention has the following features in order to achieve the above-described object. That is, the ground improvement method of the present invention is provided with a drilling blade and a stirring blade at the tip of the rod, excavating the ground to be improved by the drilling blade, and the in-situ soil and the ground improvement material by the stirring blade inserted into the ground to be improved It is related with the ground improvement construction method using the mechanical stirring apparatus for mixing and stirring these, and creating a ground improvement body in the ground.

  In this ground improvement method, a plurality of pairs of supporting piles having a predetermined width are driven into the ground to be improved so that the upper part protrudes from the ground to be improved, and the pair of supporting piles Crossing the girder between the upper parts, laying a pair of rails on the girder along the direction of formation of the ground improvement body, and placing a mechanical stirrer on the rails, set at predetermined intervals The process of ground improvement at each improved ground position, and when the ground improvement is completed over the entire area of the ground to be improved, the process of removing the mechanical agitation device from the rail, and dismantling the rails, girders and support piles And a step of removing.

  In the said ground improvement construction method, while making the opposing space | interval in the pile center reference | standard of a support pile used as a pair, and the excavation stirring diameter by a mechanical stirring apparatus into the same diameter in the range of 0.5-1.5m, adjacent ground improvement body It is preferable to construct a continuous wall-like improvement body by overlapping a part of the above.

  In the ground improvement method, along the ground portion of the support pile, the earth retaining plate may be installed in the direction in which the ground improvement body is formed, and the end of which is angled with respect to the formation direction of the ground improvement body. preferable.

  In the ground improvement construction method, excavation of the ground to be improved by the excavating blade and mixing and mixing of the in-situ soil and ground improvement material by the agitating blade are performed in a reciprocating process of inserting and removing the excavating blade and the stirring blade from the ground to be improved. It is preferable to do.

  In the ground improvement method, the upper end portion of each support pile is covered with a pile head cap that is tubular and has a heel portion at the top, and the heel portion and the girder are connected and fixed by a fixture. It is preferable to connect and fix a rail with a fixing tool.

  In the ground improvement method, the rod of the mechanical stirring device is detachably attached to the rod rotating device supported by the rod supporting device that moves up and down along the support column, and the excavation blade and the stirring blade are attached to the lower end portion of the rod. It is possible to adopt a configuration in which the improvement material discharge port is provided at the lower end portion of the rod.

  In the ground improvement method, the mechanical stirring device preferably includes a travel drive device for traveling along the rail.

  According to the ground improvement method of the present invention, since the base of the mechanical stirring device can be installed separately from the surface portion, the base and the surface portion of the mechanical stirring device are laid directly on the ground portion by laying rails or the like. It is possible to secure a range (width) of the ground that can be improved as compared with the case where and are close to each other.

The side view of the mechanical stirring apparatus used for the ground improvement construction method which concerns on embodiment of this invention. The top view of the mechanical stirring apparatus used for the ground improvement construction method which concerns on embodiment of this invention, a rear view, and a front view. The side view of the driving device of the support pile used for the ground improvement construction method which concerns on embodiment of this invention. The front view of the separation equipment used for the ground improvement construction method which concerns on embodiment of this invention. The top view and side view of the separation equipment used for the ground improvement construction method which concerns on embodiment of this invention. The side view which shows the state which fixes a girder to a support pile. The cross-sectional view which shows the state which fixes the earth retaining plate to a support pile. Explanatory drawing of the ground excavation process (at the time of excavation start) in the ground improvement construction method which concerns on embodiment of this invention. Explanatory drawing of the ground excavation process (at the time of completion | finish of excavation from the middle of excavation) in the ground improvement construction method which concerns on embodiment of this invention. Explanatory drawing of the ground improvement body formation process in the ground improvement construction method which concerns on embodiment of this invention.

  Hereinafter, an embodiment of a ground improvement method according to the present invention will be described with reference to the drawings. 1 to 10 illustrate a ground improvement method according to an embodiment of the present invention. FIG. 1 is a side view of a mechanical stirring device, FIG. 2 is a plan view, a rear view, and a front view of the mechanical stirring device. Is a side view of the driving device for the support pile, FIG. 4 is a front view of the separation facility, FIG. 5 is a plan view and a side view of the separation facility, and FIG. 6 is a side view showing a state where the girder is fixed to the support pile. Is a cross-sectional view showing a state in which the retaining plate is fixed to the support pile, FIG. 8 is an explanatory view of the ground excavation process (at the start of excavation), FIG. 9 is an explanatory view of the ground excavation process (at the end of excavation from the middle of excavation), FIG. 10 is an explanatory diagram of the ground improvement body forming step.

<Outline of ground improvement method>
In the ground improvement method according to the embodiment of the present invention, a mechanical agitation device is placed on a rail installed separately from the ground surface portion of the improvement target ground so as to form a continuous ground improvement body in the improvement target ground. This is a construction method. As a basic process, in order to separate the mechanical stirrer from the ground surface, a support pile is driven into the ground, a girder is placed over the support pile, a rail is laid on the girder, and the machine is placed on the rail. A stirrer is placed, a continuous ground improvement body is formed, and when the ground improvement is completed over the entire ground to be improved, the mechanical stirrer, rail, girder, and support pile used are removed.

<Mechanical stirring device>
As shown in FIGS. 1 and 2, the mechanical agitation device 10 used in the ground improvement method of the present invention includes a drilling blade 30 and a stirring blade 40 at the tip of the rod 20. A ground improvement body is formed in the ground by mixing and stirring the in-situ soil and the ground improvement material by agitating blades 40 excavated and inserted into the improvement target ground. In the present embodiment, in consideration of use in a narrow area, the excavation stirring diameter is a small size of 0.5 to 1.5 m.

  The mechanical stirring device 10 includes a base 11 placed on a rail 50, a rod support device 13 installed on a support column 12 provided on the base 11, and a rod rotation device 14 supported by the rod support device 13. Is a basic component. Further, the rod 20 is provided with an improvement material delivery pipe 21 for delivering the ground improvement material to the tip of the rod 20, and the front end of the improvement material delivery pipe 21 is connected to the improvement material discharge port 22. The rod 20 is detachably attached to a rod rotating device 14 supported by a rod supporting device 13 that moves up and down along the support column 12. The excavation blade 30 and the stirring blade 40 are detachably attached to the lower end portion of the rod 20.

  On the base 11, a tiltable support column 12, a hoisting cylinder 15 for hoisting the support column 12 in the front-rear direction with respect to the base 11, and a tilt in the left-right direction of the support column 12 with respect to the base 11. A left / right adjustment cylinder 16 for adjustment, a travel drive device 17 for traveling the mechanical stirring device 10 on the rail 50, and a hydraulic unit 18 are mounted. Power is supplied from the hydraulic unit 18 to the hoisting cylinder 15, the left / right adjustment cylinder 16, and the travel drive device 17, but another power source (for example, an air pump) is used instead of the hydraulic unit 18 in accordance with the type of driving force. Or a generator). In the present embodiment, the hydraulic unit 18 serves as a balance weight. When the hydraulic unit 18 is provided separately from the mechanical stirring device 10 (for example, when power is supplied from a power shovel), a balance weight may be mounted instead of the hydraulic unit 18.

  Below the base 11, a plurality of wheels 19 a and traveling wheels 19 b to which power is supplied from the traveling drive device 17 are attached. The traveling wheel 19b is preferably made of synthetic resin or rubber in order to increase the frictional force against the rail 50. Further, it is preferable to provide a brake device (not shown) for preventing the mechanical stirring device 10 from traveling between the base 11 and the rail 50. The brake device may be a bolt and a nut spanned between the base 11 and the rail 50, or may be a device that prevents the rotation of the wheel 19a.

<Support pile>
Further, as shown in FIGS. 1 and 5, a plurality of sets of support piles 60 having a predetermined width are driven into the improvement target ground. As for this support pile 60, the upper part protrudes from the improvement object ground. Further, a girder 70 is spanned between the upper portions of the paired support piles 60. A pair of rails 50 are laid on the girder 70 along the formation direction of the ground improvement body. By placing the mechanical stirring device 10 on the top, the mechanical stirring device 10 is separated from the ground surface portion. The distance between the ground surface portion and the base 11 is about the width of the ground to be improved (for example, 1.5 m).

  The support pile 60 is a member for separating the base 11 of the mechanical agitation device 10 from the surface portion, and a screw pile is used in this embodiment. Although not shown in detail, the screw pile is provided with a spiral protrusion on the outer peripheral surface of a cylindrical pile body. This spiral protrusion is provided from the lower end portion of the pile body to the middle portion. In addition, a cutting blade for cutting the ground when rotationally press-fitting into the ground to be improved is provided at the lower end of the spiral ridge. Moreover, it is preferable to make the excavation stirring diameter by the mechanical stirring apparatus 10 into the range of 0.5-1.5 m which is the same diameter as the opposing space | interval in the pile center reference | standard of the support pile 60 used as a pair. By making the excavation stirring diameter by the mechanical stirring device 10 and the opposing distance in the pile center reference of the paired support pile 60 the same diameter, appropriate ground improvement can be performed in a narrow area.

<Support pile driving device>
In this embodiment, a crawler traveling type mini earth auger 80 is used as a device for driving the support pile 60. As shown in FIG. 3, the crawler traveling mini-earth auger 80 is provided with a bending / extending arm 82 upward from a vehicle main body provided with a crawler 81, and a support pile 60 around the axis at the tip of the bending / extending arm 82. A rotating device 83 for rotating is provided. The rotating device 83 is provided with a cylindrical holding portion 84 having an opening downward to hold the support pile 60. By inserting the upper end portion of the support pile 60 into the holding portion and bolting, The support pile 60 can be rotatably held at the tip of the bending / extending arm 82.

<Procedure for ground improvement>
Next, a procedure for performing ground improvement using the mechanical stirring device 10 described above will be described. The ground improvement method of the present invention includes a driving pile 60 driving step, a rail 50 laying step, a mechanical stirring device 10 installation and ground improvement step, a mechanical stirring device 10 removal step, and a separation facility removal step. Contains. In addition, a separation facility is the rail 50, the girder 70, the support pile 60, and these incidental devices, and is a facility for separating the mechanical stirring apparatus 10 from the ground surface part of the improvement target ground.

<Support pillar driving process>
The drive-in process of the support pile 60 is a process for installing the separation facility together with the laying process of the rail 50 following the process. In the step of driving the support pile 60, a plurality of pairs of support piles 60 having a predetermined width are driven into the improvement target ground so that the upper portion protrudes from the improvement target ground.

  In order to drive the support pile 60, first, the upper end portion of the support pile 60 is inserted into the holding portion 84 provided in the rotating device 83 of the crawler traveling mini-earth auger 80 and bolted. Then, while the support pile 60 is rotated by the rotating device 83, the bending arm 82 is driven to drive the support pile 60 into the ground to be improved. The support pile 60 has a total length of about 2 m, for example, and protrudes an upper portion of about 0.3 to 0.7 m from the ground surface portion. Moreover, the opposing space | interval of the support pile 60 used as a pair can perform an appropriate ground improvement in a narrow area by setting it as 0.5-1.5m on a pile center reference | standard.

  In addition, when the opposing space | interval of the support pile 60 is too narrow, a ground improvement area will become narrow and effective liquefaction prevention cannot be performed. Furthermore, if the spacing between the support piles 60 is narrowed, the spacing between the rails 50 is also narrowed, and the mechanical agitator placed on the rails 50 must be miniaturized. In the stirring device 10, a large rotational load reaction force cannot be received by the separation facility when excavating and stirring the ground. On the other hand, if the facing distance between the support piles 60 is too wide, the ground cannot be improved due to the spatial restriction due to the structure close to the improvement target ground, Side pressure etc. may have an adverse effect.

<Rail laying process>
The laying process of the rail 50 is a process of laying the pair of rails 50 on the girder 70 along the formation direction of the ground improvement body, while spanning the girder 70 between the upper portions of the paired support piles 60. is there. Specifically, as shown in FIGS. 1, 4, and 5, after driving a plurality of paired support piles 60 having a predetermined width into the ground to be improved, each pair of support piles 60 A girder 70 made of H-shaped steel is placed between the upper parts. Then, a pair of rails 50 are laid at equal intervals on the upper part of the girder 70 to construct a separation facility.

  The rail 50 is formed by welding an angle material on the upper part of a rail girder 51 made of H-shaped steel to form a mountain-shaped rail protrusion, and the interval between adjacent support columns 12 along the formation direction of the ground improvement body. It has a length according to. And a rail is comprised by making the several rail 50 continue in a length direction. In addition, a rail is not restricted to linear form, You may bend according to the shape of the ground for improvement.

  As shown in FIGS. 1, 4, and 5, a pile head cap 61 having a cylindrical shape and having a flange portion 62 at the top is placed on the upper end portion of each support pile 60. And the collar part 62 and the girder 70 are connected and fixed by the clamp member 63 which is a fixing tool. That is, as shown in FIG. 6, a pair of clamp members 63 sandwich a flange 62 of a pile head cap 61 that covers the head of the support pile 60 and a receiving plate 71 welded to both ends of the girder 70. The girder holder 70 is fixed to the upper end portion of the support pile 60 by screwing the fixing screw 64 into the clamp member 63 and pressing the tip end portion of the fixing screw 64 against the flange portion 62 and the receiving plate 71, respectively.

  Further, in order to fix the rail 50 on the girder holder 70, as shown in FIG. 4, the girder 70 and the rail girder 51 are sandwiched by a clamp member 72 as a fixing tool, and a fixing screw (see FIG. (Not shown), and the tip of the fixing screw may be pressed against the girder 70 and the rail girder 51, respectively. The clamp member 63 that fixes the girder 70 to the support pile 60 and the clamp member 72 that fixes the rail girder 51 to the girder 70 use, for example, a small C-shaped clamp. The fixture is not limited to the clamp members 63 and 72, and bolts or the like may be used.

<Soil retaining plate>
The earth retaining plate 100 is continuously installed in the formation direction of the ground improvement body along the ground part of the support pile 60, so that the earth and sand discharged to the ground part in the ground improvement process leaks outside the separation facility. To prevent it from coming out. Moreover, the earth and sand discharged to the ground part by installing the end part of the earth retaining plate so as to have an angle with respect to the formation direction of the ground improvement body (for example, the direction perpendicular to the formation direction of the ground improvement body). Can flow in one direction. As shown in FIGS. 1 and 5, the earth retaining plate 100 is made of a rectangular steel plate and has a length larger than the interval between the support piles 60 adjacent to each other in the formation direction of the ground improvement body. In addition, an opening 101 is provided at the upper center in the length direction for the operator to insert his / her hand when installing or removing the retaining plate 100.

  As shown in FIGS. 1 and 5, the earth retaining plate 100 is disposed between adjacent support piles 60 so that the lower edge of the earth retaining plate 100 is in contact with the ground surface portion. Then, as shown in FIG. 7, both end portions in the length direction are overlapped with the end portions of the adjacent earth retaining plate 100, U-shaped bolts 103 are inserted in series into the bolt insertion holes 102, and the end portions of the bolt 103 The retaining plate 100 adjacent to the support pile 60 is attached by tightening the nut 104 attached to. By repeating this operation, a series of earth retaining plates 100 can be installed.

<Installation of mechanical stirring device and ground improvement process>
When the earth retaining plate 100 is installed, the mechanical stirring device 10 is installed on the rail 50 as shown in FIG. The support column 12 of the mechanical stirring device 10 can be raised and lowered in the front-rear direction. When moving to the construction site, the support column 12 is kept laid down, and after the mechanical stirring device 10 is installed on the rail 50, the hoisting cylinder 15 is driven to raise the support column 12 into a vertical state. Further, the left / right adjustment cylinder 16 is driven to adjust the inclination in the left / right direction.

  And the mechanical stirring apparatus 10 is moved to a ground improvement position, the mechanical stirring apparatus 10 is fixed on the rail 50 with a brake device (not shown), and ground improvement is started. In the ground improvement process, as shown in FIG. 5A, the ground is rotated while the excavating blade 30 is rotated in an area (indicated by a virtual circle) surrounded by a pair of rails 50 and a girder 70 adjacent to the front and rear. The ground improvement body is formed by stirring with the stirring blade 40 while discharging the improvement material into the ground. And the mechanical stirring apparatus 10 is moved so that a part of adjacent ground improvement body may overlap, and the continuous ground improvement body is formed.

  The excavation stirring diameter by the mechanical stirring device 10 is preferably in the range of about 0.5 m to 1.5 m. If the excavation agitation diameter is too small, effective liquefaction measures cannot be taken, and if the excavation agitation diameter is too large, there is a risk of adversely affecting an existing structure constructed adjacent to the ground to be improved. Even when the maximum diameter of the excavating blade 30 and the stirring blade 40 is larger than the width of the rail 50 and the girder 70, the ground surface and the base 11 are separated from each other. Width) can be secured.

  In order to improve the ground, first, as shown in FIG. 8A, the rod support device 13 is driven to lower the excavation blade 30 and the stirring blade 40 and bring the excavation blade 30 into contact with the ground surface. Subsequently, as shown in FIG. 8B, while the rod rotating device 14 is driven to rotate the rod 20, the rod supporting device 13 is driven to lower the rod 20, and the rod 20 is lowered to a predetermined depth (for example, from the ground surface). Excavate the ground to about 50cm). Subsequently, as shown in FIG. 8C, excavation is continued while the improving material (cement slurry) is discharged from the improving material discharge port 22. By performing such a process, as shown in FIGS. 9 and 10, the excavated soil layer 200 is formed up to a predetermined depth (for example, about 50 cm from the ground surface), and the improved material is agitated in the excavated soil at a deeper position. The mixed layer 210 is mixed.

  Further, when the single rod 20 does not reach the excavation depth, excavating and stirring is performed by adding a plurality of rods 20. That is, as shown in FIG. 9A, in a state where excavation and stirring is performed with one rod 20, the connection between the rod 20 and the rod support device 13 is released, and the rod support device 13 is raised. Then, as shown in FIG. 9B, a new rod 20 is hung on the upper part of the rod 20 which has already been excavated and stirred using a winch, and the pair of rods 20 are connected vertically.

  Subsequently, as shown in FIG. 9 (c), the rod rotating device 14 is driven to rotate the rod 20, while the rod supporting device 13 is driven to lower the rod 20, as shown in FIG. 9 (d). Then, the ground is excavated to a predetermined depth (for example, about 100 cm from the ground surface). By repeating such an operation, excavation and agitation is performed while adding the rod 20 until the design depth is reached.

  After excavating and stirring to the design depth, as shown in FIG. 10 (a), the rod rotating device 14 is driven to rotate the rod 20, and the improving material (cement slurry) is discharged from the improving material discharge port 22. The rod 20 is pulled up by the rod support device 13. Thereby, in the mixed layer 210, since the improvement material (cement slurry) is further added and stirred, the improvement material (cement slurry) is sufficiently mixed with the soil to improve the quality of the ground improvement body. it can.

  Subsequently, when the pulling and stirring corresponding to the length of one rod 20 is completed, the rod 20 is separated and the rod support device 13 is raised as shown in FIG. Then, after moving the rod 20 using the winch, as shown in FIG. 10C, the rod support device 13 is lowered again, and the rod support device 13 is connected to the upper part of the remaining rod 20, and the rod While driving the rotating device 14 to rotate the rod 20, the improving material (cement slurry) is discharged from the improving material discharge port 22, and the rod 20 is pulled up by the rod support device 13. By repeating such an operation, as shown in FIG. 10 (d), the rod 20 and the excavating blade 30 and the stirring blade 40 connected to the tip of the rod 20 are pulled upward from the rail 50. Then, excavation of the ground to be improved by the excavation blade 30 and mixing and stirring of the in-situ soil and the ground improvement material by the stirring blade 40 are performed in a reciprocating process of inserting and removing the excavation blade 30 and the stirring blade 40 from the ground to be improved. And the ground improvement of one place is complete | finished.

  Thereafter, the mechanical stirrer 10 and the rail 50 are unfixed, and the driving stirrer 17 is driven to move the mechanical stirrer 10 to the next ground improvement position. Do. At this time, a continuous wall-like improvement body can be constructed by overlapping a part of the adjacent ground improvement bodies.

<Mechanical stirring device removal process / separation equipment removal process>
When the ground improvement is completed over the entire ground to be improved, the mechanical stirring device 10 is removed from the rail 50. And the rail 50, the girder 70, and the earth retaining plate 100 are removed, and the mechanical stirrer 10 and the separation equipment are removed by pulling out the support pile 60 from the ground using the crawler traveling type mini-earth auger 80. Thereafter, the ground to be improved is leveled, and all the ground improvement processes are completed.

<Advantageous effects compared to the prior art>
According to the ground improvement method of the present invention, the mechanical agitation placed on the rail 50 is present even in a narrow area where the improvement target ground exists between adjacent sites or existing buildings and the width is less than 2 m. Since the ground improvement can be performed while moving the device 10, there is no possibility that the mechanical stirring device 10 and the existing building come into contact with each other. In addition, since the mechanical agitating device 10 is supported by the separation equipment composed of the support pile 60, the girder 70, the rail 50, etc., a large excavation reaction force can be secured, so that the ground improvement body can be reliably and appropriately used. Can be formed. At this time, a larger excavation reaction force can be secured by fixing the base 11 on the rail 50 by the brake device. Furthermore, since the base 11 and the ground surface are separated, a ground improvement body having a sufficient width can be formed even in a narrow area.

  In addition, by forming the ground improvement body partly overlapping, it is possible to form a wall-like ground improvement body integrated into a series, and to exhibit a sufficient anti-liquefaction effect. In particular, by forming a wall-shaped ground improvement body that surrounds a site or an existing building, an even more sufficient liquefaction prevention effect can be exhibited.

  Moreover, since the separation equipment comprising the support pile 60, the girder 70, the rail 50, etc. has a simple structure, it can be easily installed and disassembled, and the construction can be facilitated and the construction time can be shortened. In addition, construction costs can be reduced.

DESCRIPTION OF SYMBOLS 10 Mechanical stirring apparatus 11 Base 12 Support pillar 13 Rod support apparatus 14 Rod rotation apparatus 15 Hoisting cylinder 16 Left-right adjustment cylinder 17 Travel drive apparatus 18 Hydraulic unit 19a Wheel 19b Traveling wheel 20 Rod 21 Improvement material delivery pipe 22 Improvement material discharge port 30 Excavation blade 40 Mixing blade 50 Rail 51 Rail girder 60 Support pile 61 Pile head cap 62 Butt 63 Clamp member (fixing tool)
64 Fixing screw 70 Girder receiver 71 Receiver plate 72 Clamp member (fixing tool)
80 Crawler traveling type mini earth auger 81 Crawler 82 Bending / extending arm 83 Rotating device 84 Holding part 90 Fixing tool 100 Earth retaining plate 101 Opening part 102 Bolt insertion hole 103 Bolt 104 Nut 200 Excavation soil layer 210 Mixed layer

Claims (7)

An excavation blade and an agitation blade are provided at the tip of the rod, the ground to be improved is excavated by the excavation blade, and the in-situ soil and the ground improvement material are mixed and agitated by the agitation blade inserted into the improvement target ground. A ground improvement method using a mechanical stirrer for creating a ground improvement body inside,
Driving a plurality of pairs of support piles having a predetermined width into the improvement target ground such that the upper part protrudes from the improvement target ground;
A step of laying a pair of rails on the girder along the formation direction of the ground improvement body, while spanning a girder between the upper parts of the paired support piles;
Placing the mechanical agitation device on the rail and performing ground improvement at the ground improvement positions set at predetermined intervals;
When the ground improvement is completed over the entire area of the improvement target ground, the step of removing the mechanical stirring device from the rail,
Dismantling and removing the rail, the girder, and the support pile;
The ground improvement construction method characterized by including. While making the opposing space | interval in the pile center reference | standard of the said support pile used as said pair, and the excavation stirring diameter by the said mechanical stirring apparatus in the range of 0.5-1.5m,
Constructing a continuous wall-like improvement body by overlapping a part of the adjacent ground improvement bodies,
The ground improvement construction method according to claim 1, wherein: Along with the ground part of the support pile, it is continuous with the formation direction of the ground improvement body, and the earth retaining plate having an angle with respect to the formation direction of the ground improvement body is installed.
The ground improvement construction method according to claim 1 or 2, characterized in that. Excavation of the ground to be improved by the excavating blade and mixed stirring of the in-situ soil and ground improvement material by the stirring blade are performed in a reciprocating process of inserting and removing the excavating blade and the stirring blade from the ground to be improved. To
The ground improvement construction method of any one of Claims 1-3 characterized by the above-mentioned. Cover the upper end of each support pile with a pile head cap that is tubular and has a heel at the top,
It is connected and fixed by the collar, the girder and the fixture,
The girder and the rail are connected and fixed by a fixture.
The ground improvement construction method according to any one of claims 1 to 4, characterized in that: The rod of the mechanical stirring device is detachably attached to a rod rotating device supported by a rod support device that moves up and down along a support column,
The excavation blade and the stirring blade are detachably attached to a lower end portion of the rod,
An improvement material discharge port is provided at the lower end of the rod,
The ground improvement construction method according to any one of claims 1 to 5, wherein: The mechanical stirring device includes a travel drive device for traveling along the rail.
The ground improvement construction method according to any one of claims 1 to 6, characterized in that.

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