JP2008075255A - Ground improving device and soil improving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily realize optimum excavating/agitating conditions according to the hardness and properties of ground particularly for an excavating action and an agitating and mixing action. <P>SOLUTION: This ground improving device comprises a drive shaft 4 formed of double shafts, i.e., inner and outer shafts, a lifting means 3 for the drive shaft, an outer shaft side excavating/agitating means 20 attached to an outer shaft 6, an inner shaft side excavating/agitating means 10 attached to an inner shaft 5, a supply passage 15 for a stabilizer, and a discharge part 17. The ground is excavated by reversely rotating the outer shaft side excavating/agitating means 20 and the inner shaft side excavating/agitating means 10, and the stabilizer is discharged from the discharge part 17 into the soil to be excavated and the soil is agitated and mixed. The inner shaft side excavating/agitating means 10 has a small-diameter blade part 11 and an excavating bit 12 fixed to the inner shaft lower end. The outer shaft side excavating/agitating means 20 has an arm large-diameter blade part 20 and an excavating bit 23 fixed to the outer shaft lower end. The outer shaft side excavating/agitating means 20 and the inner shaft side excavating/agitating means 10 are so formed that the vertical distance therebetween can be adjusted by a height adjusting means 38 to separate the large-diameter blade part 21 and the small-diameter blade part 11 from each other and approach them each other. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a ground improvement device and method used when excavating the ground, injecting various kinds of stabilizers into the excavated soil, stirring and mixing, and improving the ground strength and the like.

  As illustrated in FIGS. 9 and 10, the ground improvement device is provided on the lower end side of the outer shaft, a drive shaft having a double shaft structure of an inner shaft and an outer shaft, lifting means for moving the drive shaft up and down, and The outer shaft side excavating and stirring means, the inner shaft side excavating and stirring means provided on the lower end side of the inner shaft, the stabilizer feed passage and the discharge section, and the outer shaft side excavating and stirring means and the inner shaft side drilling. It is known to excavate the ground while reversing the stirring means, and to discharge and stir the stabilizer from the discharge section into the excavated soil. this house,

  In the apparatus structure of FIG. 9 (Patent Document 1), reference numeral 10 is a drive shaft composed of an outer shaft 11 and an inner shaft 12 that are reversed to each other, reference numerals 14 and 15 are discharge parts for stabilizing material, reference numeral 16 is a drilling blade, reference numeral 17 is The inner shaft side excavating and stirring means (17a is a drilling and stirring blade body, 17b is a stirring blade body, and 17c is a drilling blade) provided on the lower end side of the inner shaft 12, and reference numeral 18 is provided on the lower end side of the outer shaft 11. The outer shaft side excavating and stirring means (18a is a drilling and stirring blade body, 18b is a stirring blade body, and 18c is a drilling blade).

  In the apparatus structure of FIG. 10 (Patent Document 2), reference numeral 1 is a drive shaft (excavation shaft) composed of an inner shaft 8 and an outer shaft 9 that are reversed with each other, and reference numeral 6 is an inner shaft side provided on the lower end side of the inner shaft 8. Excavation agitation means (15 is an excavation bit, 19 is a vertical blade, 25 is an agitation blade), 7 is an outer shaft side excavation agitation means provided on the lower end side of the outer shaft 9 (11 is a vertical blade, 12 is a ring, 16 Is a stirring blade, 15 is an excavation bit), 17 and 23 are discharge parts for stabilizing material, 10 is a joint, and 29 is a screw.

In each of the above device structures, as the excavation action, the lower inner shaft side excavation agitation means excavates first, and then the upper outer shaft side excavation agitation means performs final excavation, so excavation efficiency is excellent, Further, as the stirring and mixing action, the lower inner shaft side excavating and stirring means and the upper outer shaft side excavating and stirring means are inverted with each other, so that the rotation of the excavated soil is prevented and the stirring efficiency is improved.
Japanese Patent Laid-Open No. 11-81297 JP 2004-316287 A

  However, in each apparatus structure described above, since the vertical interval between the lower inner shaft side excavation stirring means and the upper outer shaft side excavation stirring means is fixed in the construction work, both of them are set according to the ground conditions. It is impossible to satisfy the optimum excavation and stirring conditions by changing the interval of the excavating and stirring means. This is because, for example, it is preferable to bring the two excavation stirring means closer together in order to prevent co-rotation of the soil in the stirring and mixing. Further, in each device structure, since the interval between the two excavation stirring means is fixed, the upper outer shaft side excavation stirring means penetrates until reaching the design depth in the penetration process, that is, the height of the lower inner shaft side excavation stirring means increases. Excavation must be made deeper than the design depth by an amount corresponding to the length. In addition, as the stirring and mixing action, it is preferable to attach the stabilizing material discharge portion to the outer shaft side excavation stirring means together with the inner shaft side excavation stirring means in order to achieve uniform mixing of the stabilizing material. In this way, if the stabilizer is derived from the inner shaft side, the shape of the stirring blades constituting the outer shaft side excavating and stirring means is restricted to the shape shown in the figure, or the distance between the inner shaft side excavating and stirring means Cannot be set arbitrarily.

  The object of the present invention is to eliminate all the problems as described above, and in particular, a ground improvement device capable of easily realizing more optimal excavation and stirring conditions according to the hardness and properties of the ground, in particular as excavation and stirring and mixing. It is to provide a method.

  In order to achieve the above object, the present invention of claim 1 is directed to a drive shaft having a double shaft structure of an inner shaft and an outer shaft that are reversed to each other, lifting means for moving the drive shaft up and down, and a lower end side of the outer shaft. An outer shaft side excavation and stirring means provided; an inner shaft side excavation and stirring means provided on the lower end side of the inner shaft; a supply path for a stabilizer provided along the drive shaft; and A discharge unit connected to discharge the stabilizing material, excavating the ground while inverting the outer shaft side excavation stirring means and the inner shaft side excavation stirring means, and discharging the stabilizing material into the excavated soil In the ground improvement device for discharging and stirring and mixing, the inner shaft side excavating and stirring means has a small wing portion fixed to the lower end side of the inner shaft and a drill bit protruding from the small wing portion. The outer shaft side excavating and stirring means is an arm-shaped large wing portion fixed to the lower end side of the outer shaft. And the outer shaft side excavation stirring means and the inner shaft side excavation stirring means are adjusted in height with respect to each other by a height adjusting means so that the larger diameter blade portion is provided. And the small wings can be separated from each other. Here, the arm-shaped large wing portion means a ring or a cylindrical large wing portion as shown in FIG. The large wing portion and the small wing portion mean that the large wing portion is relatively longer than the small wing portion.

In the present invention described above, it is preferable to be embodied as follows.
(A) The small wing portion of the inner shaft side excavating and stirring means is substantially spiral, and the large wing portion of the outer shaft side excavating and stirring means can accommodate at least the upper part of the small wing portion inside. The height adjusting means has a piston-type cylinder interposed between the upper end side of the inner shaft and the upper end side of the outer shaft. (Claim 2).
(A) The supply passage is provided corresponding to a first supply passage for sending a stabilizer to the discharge portion provided corresponding to the inner shaft side excavation stirring means and the outer shaft side excavation stirring means. The second supply passage includes at least a second supply passage for sending a stabilizer to the discharge portion, and the inner supply portion includes an inner shaft radial passage portion communicating with an outer periphery of the inner shaft, the inner shaft, and the outer shaft. A peripheral lead-out reservoir portion provided between the shaft and partitioned by upper and lower seal members sandwiching the inner-shaft radial passage portion, and an outer shaft communicating from the peripheral lead-out reservoir portion to the outer periphery of the outer shaft A radial passage portion and a connection portion that connects the outer shaft radial passage portion and the corresponding discharge portion (claim 3).

  The present invention of claim 4 captures the above invention from the method, and includes a drive shaft having a double shaft structure of an inner shaft and an outer shaft that are reversed to each other, lifting means for moving the driving shaft up and down, and the outer shaft. An outer shaft side excavation and stirring means provided on the lower end side of the shaft; an inner shaft side excavation and stirring means provided on the lower end side of the inner shaft; and a stabilizer supply passage provided along the drive shaft; A discharge portion that is connected to the supply passage and discharges a stabilizing material, excavating the ground while inverting the outer shaft side excavation stirring means and the inner shaft side excavation stirring means, and In the ground improvement method in which the material is discharged from the discharge unit and stirred and mixed, the ground improvement method includes a height adjusting unit that adjusts a vertical interval between the outer shaft side excavation stirring unit and the inner shaft side drilling stirring unit, and the drive An intrusion process for lowering the shaft into the ground via the elevating means and an ascending pull In the can process, the upper and lower gap between the inner shaft side drilling stirring means and the outer axial side drilling stirring means is characterized by varying by the height adjusting means. In this configuration, for example, the outer shaft-side excavation stirring means and the inner shaft-side excavation stirring means are separated from each other through the height adjusting means in the penetration step, and the outer shaft-side excavation stirring means and the inner shaft in the drawing step. The side excavating and stirring means is brought into an approaching state via the height adjusting means.

  In the first aspect of the invention, since the outer shaft side excavating and stirring means and the inner shaft side excavating and stirring means can adjust the vertical distance by the height adjusting means as compared with the conventional structure of FIG. 9 and FIG. To achieve more optimal excavation and agitation according to the hardness and ground properties. This is because, for example, the vertical distance between the outer shaft side excavation stirring means and the inner shaft side excavation stirring means is changed according to the hardness of the ground to properly distribute the drilling force, or the outer shaft side excavation stirring means and the inner shaft side It is also clear from the fact that more uniform stirring and mixing can be realized by reducing the vertical spacing with the excavation stirring means in the drawing process compared to the penetration process so that the soil co-rotation preventing action can be obtained more reliably. .

  In the invention of claim 2, for example, since the small wing portion is spiral, the excavability is excellent, and it is easy to reduce the driving force required for excavation of the inner shaft side excavation stirring means. Since the outer shaft side excavating and stirring means and the inner shaft side excavating and stirring means are approached to reduce the vertical interval by the height adjusting means, the two excavating and stirring means are integrated. Since the height adjusting means is a known piston type cylinder, the cost can be reduced.

  According to the third aspect of the present invention, the supply passage for the stabilizer corresponds to the first supply passage for sending the stabilizer to the discharge portion provided corresponding to the inner shaft side excavation stirring means, and the outer shaft side excavation stirring means. 10 is the same as the apparatus structure of FIG. 10 in that the second supply passage is provided with a second supply passage for feeding a stabilizing material to the discharge portion provided in the above-described manner, but the second supply passage has a peripheral lead-out reservoir portion and an outer shaft radial passage portion. Therefore, it is not restricted by the shape of the large wing part of the outer shaft side excavation stirring means and the installation height and position of the discharge part, and a degree of design freedom is obtained.

  In the fourth aspect of the invention, by changing the vertical distance between the outer shaft side excavation stirring means and the inner shaft side excavation stirring means through the height adjusting means in the penetration step and the drawing step, problems associated with excavation (for example, , How to reduce the load applied to the drive motors of the outer shaft and inner shaft, how to reduce fluctuations, how to maintain vertical excavation), and problems associated with stirring and mixing (for example, preventing soil co-rotation (How to achieve a uniform degree of agitation between the slab and the stabilizer), so that more optimal excavation and agitation mixing can be realized according to the hardness and properties of the ground.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 shows the entire ground improvement device, FIGS. 2 and 3 show the lower side of the drive shaft, FIG. 4 shows the upper side of the drive shaft, and FIG. 5 shows other diameter and small wing parts. Modified example 1 showing an example, FIGS. 6 and 7 show a modified example 2 showing a supply passage for a stabilizer connected to the discharge portion of the outer shaft side excavating and stirring means, and FIG. 8 shows the procedure of the ground improvement method. In the following description, the structure of the apparatus, Modifications 1 and 2 in FIG. 5, Modification 3 in FIGS. 6 and 7, and the ground improvement method in FIG.

(Device Structure) In FIG. 1 and FIG. 2, the ground improvement device includes a traveling base machine 1, a support leader 2 erected so as to be movable by the base machine 1, and a vertical movement along one side of the support leader 2. The lifting / lowering device 3, the inner shaft 5 and the outer shaft 6 that are reversed to each other, the drive shaft 4 that is lifted / lowered by the lifting / lowering device 3, and the outer shaft provided on the lower end side of the outer shaft 6 Side excavation and stirring means 20, inner shaft side excavation and stirring means 10 protruding from the lower end of the outer shaft 6 and provided on the lower end side of the inner shaft 5, and for the stabilizer provided along the inner shaft 5 of the drive shaft 4 Supply passage 15 and a discharge portion 17 that is connected to the lower end of the supply passage 15 via a connecting pipe 16 and discharges a stabilizing material. The drive shaft 4 is lowered by the lifting device 3 to penetrate into the ground or ascend. In the process of drawing out, the outer shaft side excavation stirring means 20 and the inner shaft side excavation stirring means 1 Drilled ground while reversing the door is for stirring and mixing from the ejection portion 17 stable material during the excavating soil. Reference numeral 8 denotes a suspension member such as a rope that supplements the lifting and lowering of the lifting device 3, and reference numeral 9 denotes a steadying portion that is provided below the support reader 2 and prevents the drive shaft 4 from shaking.

  Here, the support leader 2 is held upright by a plurality of backstays 7 on the base machine 1 side. As shown in FIG. 4, the elevating device 3 is provided so as to be movable along the support reader 2 described above, and is provided on the upper side of the movable substrate 30 to rotate the inner shaft 5 forward and backward. Between the upper drive unit 31, the lower drive unit 35 disposed below the upper drive unit 31 and holding the upper end side of the outer shaft 6 and rotating forward and backward, and between the upper drive unit 31 and the lower drive unit 35 The piston type hydraulic cylinder 38 interposed between the upper drive device 31 and the swivel device 39 installed on the upper drive device 31.

  Among these, the movable base 30 is moved up and down along rack-like rails disposed on one side of the support leader 4. The upper drive device 31 has a casing 32 connected to the moving base 30, a motor 33 held on the casing 32, an output shaft side of the motor 33 provided in the casing 32, and an upper end of the inner shaft 5. And a gear mechanism (not shown) that is operatively connected to the side. The lower drive device 35 has a relationship in which the casing 36 is slidably guided with respect to the moving base 30, and a motor 37 held on the casing 36 and a motor 37 provided in the casing 36. A gear mechanism (not shown) that operatively connects the output shaft side and the upper end side of the outer shaft 6 is provided. A plurality of hydraulic cylinders 38 are used, and each main body is locked to the corresponding portion of the casing 32 on the upper drive device side, and the tip of each rod 38a is locked to the corresponding portion of the casing 36 on the lower drive device side. . The swivel device 39 is a supply passage 15 (in the vertical direction inside the inner shaft 5 that holds and rotates a stabilizer fed by a pump from a material reservoir prepared on the ground side with the upper drive device 31). It can be supplied to the upper inlet of FIG.

  That is, in this structure, the position in the height direction with respect to the inner shaft 5 can be adjusted by extending and contracting the rod 38a of the hydraulic cylinder 38 in a state where the outer shaft 6 is suspended and supported by the lower drive device 35. Yes. In this example, as shown in FIG. 3, the vertical distance L between the excavation stirring means 20 of the outer shaft 6 and the excavation stirring means 10 of the inner shaft 5 corresponds to the amount of rod expansion and contraction of the hydraulic cylinder 38. It is set to be adjusted within a range of 100 cm. The height adjusting means of the present invention is not limited to this structure. For example, the inner shaft 5 may be moved up and down with a hydraulic cylinder or the like relative to the outer shaft 6 or the casing 36 on the lower drive device side.

  On the other hand, as shown in FIG. 2 and FIG. 3, the inner shaft side excavating and stirring means 10 protrudes from the small diameter blade portion 11 fixed to the lower end side of the inner shaft 5 and the lower end side of the small diameter blade portion 11. It has a plurality of excavation bits 12 provided, a discharge portion 17 provided on the lower surface side of the small-diameter blade portion 11, and the like. In addition, the state which looked up at the small wing | blade part from the bottom is typically shown in the lower circle of FIG. Here, the inner shaft 5 has a cylindrical shape, and the supply passage 15 is arranged in a necessary number in the inner vertical direction, and the lower end is closed. The small-diameter wing part 11 is composed of a substantially spiral wing body, and is joined to the lower periphery of the inner shaft 5. Each excavation bit 12 is joined to the lower edge portion of the spiral wing body in a state of being juxtaposed outward from the inner shaft center side, and the tip projects downward from the small wing portion 11. . The discharge portion 17 is attached to the lower surface of the small wing portion 11 and is connected to the supply passage 15 via the connection pipe 16. After the stabilizer is introduced from the supply passage 15 via the connection pipe 16, It is possible to inject into excavated soil at a predetermined angle. In this example, a mixture ejector (see Japanese Patent No. 3416774, Japanese Patent No. 3622903, or the like) is assumed as the discharge unit 17 so that the stabilizer can be jetted with the compressed gas. For this reason, a plurality of supply passages 15 are also provided for the stabilizer and the compressed gas. However, the type and supply and discharge structure of the stabilizer can be changed as appropriate depending on the ground improvement conditions.

  As shown in FIG. 2 and FIG. 3, the outer shaft side excavating and stirring means 20 protrudes from the lower large wing portion 21 fixed to the lower end side of the outer shaft 6 and the lower end side of the large wing portion 21. A plurality of excavation bits 23 provided, an upper large wing portion 22 having a length substantially the same as that of the large wing portion 21, and the like. A co-rotation prevention plate 25 is provided between them. 3 schematically shows a state in which the large-diameter wing portion 21 is viewed from the side surface (the lower end side of the inner shaft 5 is omitted). Further, as the outer shaft side excavation and stirring means of the present invention, the upper large-diameter blade portion 22 and the co-rotation prevention plate 25 may be omitted as in the example of FIG.

  Here, the outer shaft 6 has a cylindrical shape that is rotatably inserted through the inner shaft 5 and is relatively slidable in the axial direction while being inserted through the inner shaft 5, and a lower end between the inner shaft 5 and the inner shaft 5. It is processed so that dirt etc. do not enter carelessly. The lower large-diameter wing portion 21 includes a horizontal plate portion 21a and a vertical plate portion 21b extending obliquely downward. The large-diameter wing portion 21 of the large-diameter wing portion 21 corresponding to a location displaced approximately 180 degrees with respect to the periphery of the outer shaft 6 The horizontal plate portions 21a are joined to each other, and have a generally U shape as a whole. Each excavation bit 23 is joined to the lower edge of the vertical plate portion 21b, and the tip protrudes downward from the vertical plate portion 21b. Further, the upper large-diameter wing portion 22 has a rectangular plate shape, and corresponding ends are joined to locations displaced by about 180 degrees with respect to the periphery of the outer shaft 6. In addition, the large-diameter wing parts 21 and 21 and the large-diameter wing parts 22 and 22 are arranged in different orientations with respect to the outer shaft 6 and in the relationship of X when the horizontal plate parts are brought close to each other. Further, as can be inferred from the lower diagram of FIG. 3, the lower large-diameter wings 21 and 21 have a vertical plate portion 21 b that keeps a predetermined distance from the outer shaft 6 from the protruding end of the horizontal plate portion 21 a and is obliquely downward. Is protruding. This shape improves the penetration and excavation of the excavation bit 23 (and the lower end of the vertical plate portion) with respect to the ground according to the downward inclination angle of the vertical plate portion 21b, and makes the excavated soil obliquely upward of the vertical plate portion 21b. It should be raked along the surface so that a good excavation effect can be obtained. In addition, the excavation performance can be improved and the excavation resistance can be reduced by the resistance of only the excavation (cutting) portion.

  On the other hand, the co-rotation prevention plate 25 is rotatably fitted on the outer periphery of the outer shaft 6 and protrudes from the cylindrical body 24 whose vertical movement is restricted by the vertical stoppers 26a and 26b. The co-rotation prevention plate 25 is slightly longer than the maximum diameter of the large-diameter wings 21 and 22, and after being penetrated into the soil, it receives resistance from soil and the like, so that it can be stopped by the rotation of the outer shaft 6. Thus, the movement of the soil with the rotation of the large-diameter wings 21 and 22 is restrained.

(Modification 1) FIG. 5A shows a modification of the large-diameter wing portion 21 constituting the outer shaft side excavation stirring means 20. The large-diameter wing portion 21 includes ribs 27a, 27b, and 27c that protrude from the horizontal plate portion 21a, and ribs 27d that protrude from the vertical plate portion 21b. Each rib 27a-27b is provided in the surface side of the horizontal board part 21a or the vertical board part 21b. Of these, the ribs 27a and the ribs 27b are substantially U-shaped, and a plurality of the ribs 27a and the ribs 27b are joined in a state of sandwiching the upper and lower edges of the horizontal plate portion 21a. The ribs 27c are joined in a vertical arrangement to the upper and lower intermediate portions of the horizontal plate portion 21a. The ribs 27d are joined to the vertical plate portion 21b in the vertical direction. The ribs 27a to 27b as described above are used when, for example, soil or the like is sent obliquely upward along the inclination of the vertical plate portion 21b and the horizontal plate portion 21a in the rotating state of the large-diameter wing portion 21. It is possible to break up the lump of soil that has been sent and to promote the stirring and mixing action.

(Modification 2) FIG. 5 (b) shows a modification of the small-diameter wing part 11 constituting the inner shaft side excavation stirring means 10. FIG. In the small wing portion 11, a plurality of ribs 14a and 14b are joined to each spiral wing body for the same purpose as described above, and an opening 13 is added in the middle of the inclination at the same time. Among these, a plurality of ribs 14a are joined to the upper edge portion of each spiral wing body. For example, when the soil is transported upward along the spiral shape, the rib 14a is divided and easily dropped. The rib 14b is joined to the upper side of the opening 13, and for example, the soil is transferred along a spiral and is divided immediately before passing through the opening 13, or the opening 13 is easily dropped. The opening 13 makes it easy to fall from this opening, for example, when soil has been transferred along a spiral. It has been confirmed that Modifications 1 and 2 can greatly promote the stirring and mixing action with a relatively simple configuration.

(Modification 3) FIGS. 6 and 7 show a case where a dedicated discharge portion 17a is provided on the outer shaft side excavating and stirring means 20 side, and the stabilizer cannot be supplied from the inner shaft 5 side protruding from the outer shaft 6. This is an effective structure example. That is, in the structure of FIGS. 6 and 7, the discharge portion 17a is also provided in the upper large-diameter blade portion 22 constituting the outer shaft side excavation stirring means 20 with respect to FIGS. The difference is that the supply passage 15 disposed inside the shaft 15 is connected to the discharge portion 17a. That is, a total of four supply passages 15 (15a to 15c) are provided inside the inner shaft 5, and the supply passages 15a and 15b are provided corresponding to the inner shaft side excavating and stirring means 10 described above. 2 is connected to the discharge section (a discharge section similar to the discharge section 17 in FIG. 2 or a general discharge section) via a connecting pipe 16 or the like, and a supply passage 15c is connected to the discharge section 17a in a configuration to be described later. . The supply passage 15d is set as a spare. That is, in this modification, the supply passages 15a and 15b correspond to the first supply passage of claim 3, and the supply passage 15c corresponds to the second supply passage of claim 3. In the drawing, the inner shaft 5 has a columnar shape, but in reality, only the lower side corresponding portion is formed in a columnar shape to form supply passages 15a to 15c therewith, or tubes for the supply passages 15a to 15c in the cylindrical shape. Will be mounted via a holding material.

  Further, as shown in FIG. 7A, the second supply passage 15c includes an inner shaft radial passage portion 5a, a surrounding lead storage portion 18, an outer shaft radial passage portion 6a, and a discharge portion 17a. The connecting pipe 16a is connected. Among these, the inner-shaft radial passage portion 5 a is penetrated from the lower end side of the second supply passage 15 c to the outer periphery of the inner shaft 5. The peripheral lead-out reservoir portion 18 is provided between the inner shaft 5 and the outer shaft 6 and is partitioned by upper and lower seal members 19 and 19 sandwiching the inner shaft radial direction passage portion 5a. The total size M of the peripheral lead-out reservoir 18 is adjusted to adjust the vertical distance L between the excavation stirring means 20 of the outer shaft 6 and the excavation stirring means 10 of the inner shaft 5. On the other hand, when the outer shaft 6 is moved up or down to the maximum, the inner shaft radial passage portion 5a is set so as not to be disengaged from the peripheral lead-out reservoir portion 18. The outer shaft radial passage portion 6a is penetrated from the peripheral lead-out reservoir portion 18 to the outer periphery of the outer shaft. The connecting pipe 16a connects the outer axial radial direction passage portion 6a and the corresponding discharge portion 17a.

  In the structure as described above, the dedicated discharge portion 17a can be provided at an arbitrary position of the outer shaft side excavating and stirring means 20, and in particular, the second supply passage 15c is provided with the peripheral outlet reservoir 18 and the outer shaft radial passage portion. 6a is excellent in that it is not restricted by the installation height or position of the discharge portion 17a and is not restricted by the height or shape of the large-diameter wing portion 22. For example, when this structure is applied to the structure shown in FIG. 9, a discharge portion is also provided on the outer shaft side excavating and stirring means 18 side, and a stabilizer can be injected from there into the stirring and mixing trajectory of the excavating and stirring means 18 shown in FIG. Therefore, more uniform stirring and mixing can be realized.

(Ground Improvement Method) FIG. 8 schematically shows an example when the ground is improved using the above ground improvement device. The ground improvement device shown in FIG. 8 is based on the device shown in FIGS. 1 to 4, but the outer shaft side excavation and stirring means 20 is simplified by omitting the upper large-diameter blade portion 22 and the co-rotation prevention plate 25. It has become. In this kind of ground improvement method, the procedure is roughly divided into an intrusion process for lowering the drive shaft 4 and an extraction process for ascending. Moreover, various patterns are adopted for the discharge timing of the stabilizer, such as an intrusion process or a drawing process, an intrusion process, and a drawing process, depending on the ground properties and the like. In this example, the stabilizing material is discharged only by the drawing process. In FIG. 8, the location of the two lines indicates that the stabilizer was discharged and mixed with the in situ soil.

 First, in the penetration step, the outer shaft side excavation and stirring means 20 and the inner shaft side excavation and stirring means 10 are adjusted to a state where they are separated to the design value via the hydraulic cylinder 38 described above. From this state, the outer shaft 6 and the inner shaft 5 are reversely driven by the corresponding vertical driving devices 31 and 35 and are penetrated to a predetermined depth. In this penetration step, the pre-excavation is performed with the small wing portion 11 and the excavation bit 12 of the inner shaft side excavation stirring means 10, and then the large wing portion 20 and the excavation bit 23 of the outer shaft side excavation stirring means 20 are excavated. Will be excavated outside the area. In this excavation mode, for example, even when the ground is harder than usual, an optimum excavation state is achieved by separating the vertical distance between the outer shaft side excavation stirring means 20 and the inner shaft side excavation stirring means 10 via the hydraulic cylinder 38. For example, the entire excavation force and the load applied to the motors 33 and 37 can be properly distributed.

  In the drawing process, the outer shaft side excavating and stirring means 20 and the inner shaft side excavating and stirring means 10 are adjusted to be close to the design value via the hydraulic cylinder 38. In this example, the small-diameter wing part 11 of the inner-shaft side excavation stirring means 10 is approached inside the large-diameter wing part 21 of the outer-shaft side excavation stirring means 20. Further, the outer shaft 6 and the inner shaft 5 are driven to be reversed in the direction opposite to the penetration. At the same time, the stabilizing material is discharged from the discharge portion 17 and the like as described above. Then, the stabilizer is efficiently agitated and mixed with the in-situ excavated soil by the reversing action of the small-diameter wing part 11 and the large-diameter wing part 20, the co-rotation preventing action and the like. For this reason, in this ground improvement method, efficient excavation and efficient stirring and mixing are realized.

  In addition, this invention is not restricted to the above form, A various deformation | transformation and expansion | deployment are possible except the requirements specified by Claims 1 and 4. For example, the small wing portion can be shaped as shown in FIG. 10 or FIG. 10, or a screw as shown in FIG. 10 can be attached to the outer periphery of the outer shaft and the inner shaft as required.

It is a schematic diagram which shows the whole structure of the ground improvement apparatus of this invention form. It is a principal part schematic diagram which shows the structure of a drive shaft lower side as an apparatus of FIG. It is the schematic diagram which made small the vertical space | interval of the outer and inner-shaft side excavation stirring means of FIG. (A) And (b) is a schematic diagram which shows the height adjustment means etc. of the drive shaft upper side of FIG. (A) And (b) is a schematic diagram which shows the modification of a large wing part and a small wing part of FIG. It is a schematic diagram which shows the structural example which added the discharge part for stabilizers to the large wing part side. (A) is a model expanded sectional view along the AA line of FIG. 6, (b) is a model expanded sectional view along the BB line of (a). It is a figure which shows the example of a procedure which performs ground improvement in the state which simplified the said ground improvement apparatus. It is explanatory drawing which shows the ground improvement apparatus disclosed by patent document 1. FIG. It is explanatory drawing which shows the ground improvement apparatus disclosed by patent document 2. FIG.

Explanation of symbols

3 ... Support leader 3 ... Elevating device (30 is a moving base, 31 is an upper drive device, 35 is a lower drive device)
DESCRIPTION OF SYMBOLS 4 ... Drive shaft 5 ... Inner shaft 6 ... Outer shaft 10 ... Inner shaft side excavation stirring means (11 is a small wing part, 12 is a drill bit)
15, 15a-15b ... supply passage 16, 16a ... connection pipe (connection part)
17, 17a ... discharge part 20 ... outer shaft side excavation stirring means (21 is a large diameter blade part, 23 is a excavation bit)
22 ... Upper large blade section 25 ... Co-rotation prevention plate 38 ... Hydraulic cylinder (height adjustment means)

Claims (4)

A drive shaft having a double shaft structure of an inner shaft and an outer shaft that are reversed to each other, lifting and lowering means for raising and lowering the drive shaft, outer shaft-side excavation and stirring means provided on the lower end side of the outer shaft, and the inner shaft An inner shaft side excavation and agitation means provided on the lower end side, a supply passage for a stabilizer provided along the drive shaft, and a discharge unit connected to the supply passage to discharge the stabilizer. In the ground improvement device for excavating the ground while reversing the outer shaft side excavation stirring means and the inner shaft side excavation stirring means, the stabilizer is discharged from the discharge unit into the excavated soil, and stirred and mixed.
The inner shaft side excavating and agitating means has a small diameter wing portion fixed to the lower end side of the inner shaft and a drill bit protruding from the small diameter wing portion,
The outer shaft side excavating and stirring means has an arm-shaped large wing portion fixed to the lower end side of the outer shaft and a drilling bit protruding from the large wing portion,
The outer shaft side excavating and stirring means and the inner shaft side excavating and stirring means can adjust the vertical distance from each other by a height adjusting means so that the large blade portion and the small blade can be separated from each other. Ground improvement device.   The small-diameter wing portion of the inner shaft side excavating and agitating means is substantially spiral, and the large-diameter wing portion of the outer shaft side excavating and agitating means has a space that can accommodate at least the upper part of the small-diameter wing portion inside. 2. The ground improvement device according to claim 1, wherein the height adjusting means has a piston-type cylinder interposed between the inner shaft upper end side and the outer shaft upper end side. The supply passage includes a first supply passage for sending a stabilizer to the discharge portion provided corresponding to the inner shaft side excavation stirring means, and the discharge portion provided corresponding to the outer shaft side excavation stirring means. And at least a second supply passage for feeding the stabilizer to
The second supply passage is provided between an inner shaft radial passage portion communicating with an outer periphery of the inner shaft and an upper and lower portions sandwiched between the inner shaft radial passage portion and the inner shaft and the outer shaft. A peripheral lead-out reservoir section defined by a seal member; an outer shaft radial passage portion communicating from the peripheral lead-out reservoir portion to the outer periphery of the outer shaft; and the discharge portion corresponding to the outer shaft radial passage portion; The ground improvement apparatus of Claim 1 or 2 which has a connection part which has connected. A drive shaft having a double shaft structure of an inner shaft and an outer shaft that are reversed to each other, lifting and lowering means for raising and lowering the drive shaft, outer shaft-side excavation and stirring means provided on the lower end side of the outer shaft, and the inner shaft An inner shaft side excavating and agitating means provided on the lower end side, a stabilizing material supply passage provided along the drive shaft, and a discharge portion connected to the supply passage for discharging the stabilizing material, In the ground improvement method of excavating the ground while reversing the outer shaft side excavation stirring means and the inner shaft side excavation stirring means, the stabilizer is discharged from the discharge portion into the excavated soil, and stirred and mixed.
A penetration step of having a height adjusting means for adjusting a vertical distance between the outer shaft side excavation stirring means and the inner shaft side excavation stirring means, and lowering the drive shaft into the ground via the lifting means; A ground improvement method, wherein the vertical adjustment interval between the outer shaft side excavation stirring means and the inner shaft side excavation stirring means is changed by the height adjusting means in the ascending drawing step.

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