JP2020002598A - Excavating and agitating apparatus - Google Patents

Abstract

To provide an excavating and agitating apparatus capable of forming a columnar improved body having a large supporting force with respect to a foundation pile around the foundation pile without being restricted by a timing at which the foundation pile is installed.SOLUTION: An excavating and agitating apparatus 10 that excavates the ground around a steel pipe pile 2 buried in the ground and mixes and agitates a cement-based solidifying material with the agitated soil to form the columnar improved body 3 around a foundation pile comprises a cylindrical casing 11 that covers a pile head of the steel pipe pile 2 and rotates around the axis of the foundation pile during excavation and agitation, excavating blades 14 and 15 extending from an outer peripheral surface of the casing 11 in the radial direction of the casing 11 and fixed to the casing 11, and supply channels 13 and 13 that are provided on the outer peripheral surface of the casing 11 and supply the cement-based solidifying material to sediment so that the cement-based solidifying material is introduced from the base end of the casing 11 and discharged from the base end of the excavating blade 14 or the vicinity thereof.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a drilling and stirring device for constructing a pile structure in which the ground around a foundation pile buried underground is improved.

  BACKGROUND ART Conventionally, a pile structure has been constructed in which the ground around a foundation pile buried underground is improved. When constructing this pile structure, a cement-based solidification material is mixed and stirred with the earth and sand excavated by using an excavating and stirring device to form a columnar improved body. Next, before the columnar improved body is solidified, a foundation pile is driven into the columnar improved body. For example, Patent Literature 1 proposes an excavating and stirring device having such an excavating and stirring device that includes an excavating rod and an excavating blade fixed to the excavating rod and having an excavating blade below.

JP 2012-127082 A

  However, when constructing a pile structure with the excavating and stirring device according to Patent Document 1, in order to form a columnar improvement body before driving a foundation pile into the ground, a columnar improvement body in which earth and sand and a cement solidifying material are mixed is used. Prior to solidification, the foundation pile must be driven, which limits the timing at which the foundation pile is driven. In addition to this, when trying to cast a foundation pile into the formed columnar improvement body, a gap may be formed between the foundation pile and the columnar improvement body. The support of the improved body may decrease.

  The present invention has been made in view of such a problem, and an object of the present invention is to support a foundation pile around a foundation pile without being restricted by the timing of placing the foundation pile. An object of the present invention is to provide a drilling and stirring device capable of forming a columnar improved body having a large force.

  In order to achieve the above object, a drilling and stirring device according to the present invention is to mix and stir a cement-based solidifying material into earth and sand excavated in the ground around a foundation pile buried in the ground, thereby forming a columnar shape around the foundation pile. An excavating and stirring device for forming an improved body, comprising: a cylindrical casing that covers a pile head of the foundation pile, and rotates around an axis of the foundation pile as a rotation axis during excavation and stirring, and an outer peripheral surface of the casing. A wing wing extending in the radial direction of the casing, fixed to the casing, and having a digging blade at least in a lower part, provided on an outer peripheral surface of the casing, and the cement-based solidified material from a base end of the casing. And a supply flow path for supplying the cement-based solidified material to the earth and sand so that the cement-based solidified material is discharged from or near the base end of the excavation wing.

  According to the present invention, the ground around the foundation pile is excavated with the excavation blade of the excavation wing in a state where the pile head of the foundation pile is covered with the casing, and sediment is generated from the ground excavated with the excavation wing. A cement-based solidifying material can be supplied to the earth and sand through a supply channel on the outer peripheral surface of the casing, and these can be mixed and stirred. Therefore, the columnar improvement body can be formed around the foundation pile without being restricted by the timing of placing the foundation pile. In particular, since the cement-based solidification material is discharged from the base end of the excavation wing or in the vicinity thereof, the cement-based solidification material can be efficiently supplied to the earth and sand stirred by the excavation wing. Furthermore, since the steel pipe pile is cast before or during the formation of the columnar improved body by this excavation and stirring device, a gap is hardly formed between the columnar improved body and the steel pipe pile. It can be supported with a larger supporting force.

  In addition, when the supply flow path is provided inside the casing, the supply flow path may be blocked by the pile head accommodated in the casing during excavation. Since the supply flow path is provided on the outer peripheral surface of the pile, the supply flow path is not blocked by the pile head.

  Further, in a case where the supply flow path is provided inside the casing so that the supply flow path is not blocked, the casing may have a double pipe structure, and the cement-based solidifying material may flow between the double pipes. Although it is assumed, in this case, the weight of the excavating and stirring device increases. However, according to the present invention, since the supply flow path is provided on the outer peripheral surface of the casing, a simpler structure can be adopted, and the weight of the excavating and stirring device can be reduced.

  In the above aspect, the supply flow path for supplying the cement-based solidification material is not particularly limited, but as a more preferable aspect, a flow path forming member having a cross section orthogonal to the rotation axis direction of the casing is bent or curved. However, the supply passage is formed by being fixed to the outer peripheral surface of the casing along the rotation axis direction of the casing.

  According to this aspect, by fixing the flow path forming member to the outer peripheral surface of the casing, the supply flow path can be formed stably and compactly. Specifically, as a material whose cross section orthogonal to the rotation axis direction of the casing is bent, an angle material having an L-shaped cross section can be cited, and as a curved material, a half pipe material having a semi-cylindrical cross section can be used. Can be mentioned. By fixing these to the outer peripheral surface of the casing by welding or the like along the rotation axis direction of the casing, a supply flow path of the cement-based solidified material can be easily formed.

  Further, as a more preferable aspect, on the base end side of the casing relative to the excavation wing, it is rotatable with respect to a ring material fixed to the outer peripheral surface of the casing so as not to rotate together with the rotation of the casing. A co-rotation prevention wing attached to the ring member, and a groove is formed on the inner peripheral surface of the ring material along the rotation axis direction of the casing, and the supply flow path is formed in the groove. It is characterized by being formed.

  According to this aspect, since the supply flow path is formed in the groove formed along the rotation axis direction of the casing on the inner peripheral surface of the ring material, the casing and the casing and the co-rotation prevention blade are formed with a simpler structure. Can be prevented from being blocked by the co-rotation prevention blade during the relative rotation of. Therefore, the supply of the cement-based solidifying material can be stably performed. In addition, the excavation wing rotates with the rotation of the casing during excavation and stirring, but the co-rotation prevention wing rotatably attached to the outer peripheral surface of the casing remains in the excavated and stirred earth and sand. In addition, the stirring of the earth and sand is efficiently performed by the rotating excavating wing and the co-rotating anti-rotating wing.

  As still another preferred aspect, a discharge port from which the cement-based solidifying material is discharged from the supply channel is formed at a position protruding from an outer peripheral surface of the casing in a radial direction of the casing, and In the invention, a protection blade for protecting the discharge port is formed at a position along the rotation axis direction of the casing from the discharge port on a tip end side of the casing relative to the discharge port.

  According to this aspect, at the time of excavation, the discharge port rotates together with the casing, and a portion forming the discharge port easily comes into contact with the earth and sand, but the protection blade that protects the discharge port is formed on the tip side than the discharge port. Therefore, the portion forming the discharge port can be protected from earth and sand, and a stable supply of the cement-based solidifying material can be achieved.

  ADVANTAGE OF THE INVENTION According to the excavation stirring device of this invention, the columnar improvement body with a large supporting force with respect to a foundation pile can be formed around a foundation pile, without being restricted by the timing which drives a foundation pile.

It is a typical sectional view for explaining the pile structure constructed with the excavation stirring device concerning the present invention. (A) is a schematic front view of one embodiment of the excavating and stirring device for constructing the pile structure shown in FIG. 1, and (b) is a cross-sectional view along the line AA of (a). (A) is a sectional view for showing the dimensions of the excavating and stirring device along the line BB in FIG. 2 (b), and (b) is a sectional view of the pile head of the steel pipe pile. 3A is a sectional view taken along the line CC of FIG. 3A, FIG. 3B is a sectional view taken along the line DD of FIG. 3A, and FIG. It is sectional drawing which follows the E line. It is sectional drawing for demonstrating the process of forming a columnar improvement body using the excavation stirring device of this embodiment, and constructing a pile structure. FIG. 6 is a cross-sectional view showing a step subsequent to the step shown in FIG. 5. FIG. 7 shows a post-step of the step shown in FIG. 6 and is a cross-sectional view of a main part of a pile structure in which a columnar improvement body is formed. It is sectional drawing of the excavation stirring apparatus which shows the modification of the supply flow path which supplies a cement solidification material shown to Fig.4 (a). (A) is a front view of the excavation and stirring device corresponding to FIG. 2 (a) showing a modification of the protective blade, and (b) is a cross-sectional view along the line FF of (a). It is sectional drawing of the excavation stirring device which shows the modification of the casing shown to Fig.3 (a). It is sectional drawing for demonstrating the other process implemented using the digging stirring apparatus shown in FIG.

  Hereinafter, an embodiment of a digging and stirring device according to the present invention will be described in detail with reference to the drawings. First, with reference to FIG. 1, a description will be given of a pile structure 1 that is constructed by improving the ground around a foundation pile buried in the ground with the excavating and stirring device 10 of the present embodiment. FIG. 1 is a schematic cross-sectional view for explaining a pile structure 1 constructed with the excavating and stirring device 10 according to the present invention.

[Pile structure]
In FIG. 1, a pile structure 1 includes a steel pipe pile 2 as a foundation pile buried in the ground, and a columnar improved body 3 formed around the steel pipe pile 2 and solidifying earth and sand with a cement-based solidifying material. The steel pipe pile 2 is formed of a steel pipe having a diameter d1 of about 100 to 300 mm and has a length reaching the support layer 4 from the ground surface. In the case of the deep support layer 4, a steel pipe of about 6 to 10 m is welded. To the required length. The depth L1 of the support layer 4 is generally about 10 to 30 m.

  A tip wing 2A as a drilling wing is fixed to the lower part of the steel pipe pile 2 as a foundation pile by welding or the like. The tip wing 2A is formed in a spiral shape with a steel plate inclined as viewed from the side, and its diameter d2 is set to about 300 to 800 mm. The tip wing 2A excavates the ground when the steel pipe pile 2 penetrates into the ground, and supports the steel pipe pile 2 with respect to the ground. The steel pipe pile 2 is installed perpendicularly to the surface of the ground by a pile driver (not shown), and its tip reaches the support layer 4. At the time of installation, the steel pipe pile 2 is rotated, and the steel pipe pile 2 is penetrated into the ground while excavating earth and sand with the tip wing 2A. If necessary, the steel pipe pile 2 is added by welding or the like. The tip including the tip wing 2A is reached.

  The steel pipe pile 2 allows the pile structure 1 to obtain a vertical supporting force. The periphery of the steel pipe pile 2 reaching the support layer 4 is covered with earth and sand 5 excavated by the tip wing 2A, and the excavated earth and sand 5 has the diameter of the tip wing 2A and is separated from the ground by the support layer 4A. Exist in the range up to. A part of the earth and sand 5 existing at a depth L2 from the surface of the ground constitutes a part of the columnar improvement body 3 hardened with cement milk (specifically, cement hardening material). In addition, the cement milk is obtained by mixing a cement solidifying material with water.

  The columnar improvement body 3 is formed in a cylindrical shape around the steel pipe pile 2, and has a diameter D of about 0.4 to 1.5 m and a depth L2 of about 4 m. The columnar improvement body 3 excavates the ground in a portion larger than the diameter d2 of the tip wing 2A in a portion near the surface of the earth and sand 5 (a portion from the surface to the depth L2), and cement milk is added to the earth and sand generated by the excavation. Are mixed and solidified. Therefore, the columnar improvement body 3 is formed from the surface to a depth L2 shorter than the length L1 of the steel pipe pile 2. The diameter D of the columnar improvement body 3 is set larger than the diameter of the steel pipe pile 2 and the diameter d2 of the tip wing 2A. For example, the diameter D / diameter d2 is preferably in the range of 1.2 to 2.0.

  In the pile structure 1 configured as described above, since the steel pipe pile 2 as the foundation pile reaches the support layer 4, the support force in the vertical direction can be received by the support layer 4 via the steel pipe pile 2. And has sufficient strength in the vertical direction. On the other hand, in the pile structure 1, a columnar improvement body 3 solidified with cement milk is formed on the surface portion above the steel pipe pile 2, and is reinforced with a larger outer diameter than the excavated earth and sand 5 portion, so that the rigidity is reduced. Even if a large horizontal force acts on the steel pipe pile 2, the columnar improvement body 3 can sufficiently oppose it. In addition, since the length L2 of the columnar improvement body 3 is shorter than the length L1 of the steel pipe pile 2, the configuration is simplified, and the amount of cement milk used is reduced as compared with the past when constructing the pile structure 1 described below. Therefore, the columnar improvement body 3 can be formed in a short time, and the cost can be reduced. Further, as will be described later, since the steel pipe pile 2 is cast before or together with the formation of the columnar improved body 3, it is difficult to form a gap between the columnar improved body 3 and the steel pipe pile 2. Thus, the steel pipe pile 2 can be supported with a larger supporting force.

[Drilling stirrer]
Next, the excavating and stirring device 10 of the present embodiment will be described in detail with reference to FIGS. FIG. 4A is a cross-sectional view of the excavating and stirring device 10 along the line CC of FIG. 3A, in which the co-rotation prevention blade 16 is rotated 45 ° clockwise with respect to the casing 11. FIG.

  The excavating and stirring device 10 according to the present embodiment is a device for forming the columnar improved body 3 after the steel pipe pile 2 has penetrated (poured) into the ground. Specifically, in order to construct the above-mentioned pile structure 1, the excavation and stirring device 10 excavates the ground around the steel pipe pile 2, mixes and mixes the cement-based solidifying material with the generated soil and mixes the steel pipe pile 2, This is a device suitable for forming the columnar improvement body 3 around the periphery of the body.

  The excavating and stirring device 10 includes a cylindrical casing 11, and the casing 11 rotates around the axis of the steel pipe pile 2 as a rotation axis during excavation and stirring. The casing 11 has a shape in which an upper end opening of a pipe such as a steel pipe is closed by a connecting portion 12 also serving as an upper lid, and is opened downward. The connecting portion 12 is formed in a hexagonal column shape, and is rotated in conjunction with a pile driver (not shown). In the center of the connecting portion 12, as shown in FIG. 2B, an injection hole 12a for injecting cement milk (cement-based solidified material) is formed from above, and a lower end of the injection hole 12a extends in a horizontal direction. It communicates with the horizontal hole 12b.

  As described above, the casing 11 is opened downward, and the inner diameter is set in this opened portion so that the steel pipe pile 2 can be inserted. That is, as shown in FIGS. 3A and 3B, the inner diameter d4 of the casing 11 is larger than the diameter d3 of the steel pipe pile 2. Thus, the casing 11 having the cylindrical lower opening has a shape capable of covering the pile head of the steel pipe pile 2.

  As shown in FIGS. 2A and 2B, cement milk is introduced from the base end of the casing 11 to the outer peripheral surface of the casing 11 of the excavating and stirring device 10, and from the vicinity of a first excavating wing 14 described later. Supply channels 13, 13 for supplying cement milk to the earth and sand are formed so as to protrude. Specifically, the two supply passages 13 are formed on the outer peripheral surface of the casing 11 in parallel from the base end (upper end) of the casing 11 toward the distal end (lower end).

  In the present embodiment, the supply flow path 13 is formed by fixing a flow path forming member having a bent cross section orthogonal to the rotation axis direction of the casing 11 to the outer peripheral surface of the casing 11. Specifically, as shown in FIGS. 4A and 4B, the flow path forming member is an angle member 13a having an L-shaped cross section. By fixing the two end portions of the angle member 13 a to the outer peripheral surface of the casing 11 by welding or the like, the supply flow channel 13 having a triangular prism shape in cross section is formed along the outer peripheral surface of the casing 11.

  As shown in FIGS. 3 (a) and 4 (a) to 4 (c), near the lower end of the casing 11, a first digging wing 14 and a second digging wing 15 are provided on the outer peripheral surface thereof in the rotation axis direction. They are fixed at a distance and extend in the radial direction of the casing 11. Between the first digging wing 14 and the second digging wing 15, an anti-corotating wing 16 is rotatably attached to the casing 11. The first excavation wing 14 is the “excavation wing” in the present invention.

  As shown in FIG. 3A, the first excavation wing 14 has two fixed arms 14a, 14a extending in opposite directions with the casing 11 interposed therebetween. Similarly, the second excavation wing 15 has two fixed arms 15a, 15a extending in opposite directions with the casing 11 interposed therebetween.

  A plurality of blades 14b, 15b are fixed to the fixed arms 14a, 15a so as to project vertically. In addition, the blade part attached to the lower part of the 1st excavation wing 14 among the blade parts 14b is the "digging blade" in the present invention. The blade portions 14b and 15b excavate the ground around the steel pipe pile 2 and agitate the sediment generated by the excavation. The blade portions 14b and 15b are tapered with a metal having high hardness. The plurality of blades 14b, 15b protrude vertically, but may protrude only downward. Further, the blade portion of the first digging wing 14 and the blade portion of the second digging wing 15 are formed as one blade along the direction in which the first digging wing 14 and the second digging wing 15 extend. You may.

  Further, as shown in FIGS. 3A and 4A to 4C, the first digging wing 14 and the second digging wing 15 extend in the same direction with respect to the rotation axis of the casing 11. I have. However, these extending directions may be orthogonal to the rotation axis, and the angle at which these directions intersect may form a predetermined angle.

  The second digging wing 15 located above the first digging wing 14 is fixed by welding or the like to a position where the angle members 13a, 13a of the casing 11 do not contact. The first digging wing 14 located below the second digging wing 15 is fixed to the outer peripheral surface of the ring-shaped member 17 fixed to the lower end of the casing 11 by welding or the like. Angle members 13a, 13a are abutted against the ring-shaped member 17.

  As shown in FIGS. 2 (b) and 4 (c), the ring-shaped member 17 is provided with a supply hole 17a opened on the upper surface, and the supply hole 17a is bent to the side, and the discharge hole opened to the side. An outlet 17b is formed. Therefore, the supply hole 17a communicates with the internal space of the supply flow path 13, and the discharge port 17b is open. The side opening of the discharge port 17b is formed above the first excavation wing 14. In the present embodiment, the cement milk is discharged from the vicinity of the first excavation wing 14 by providing the discharge port 17 b in the ring-shaped member 17. May be formed.

  The discharge port 17 b formed in the ring-shaped member 17 is formed at a position protruding from the outer peripheral surface of the casing 11 in the radial direction of the casing 11. More specifically, the discharge port 17 b is formed so as to protrude from the outer peripheral surface of the ring-shaped member 17 fitted to the casing 11. In the casing 11, on the tip side of the casing 11 from the discharge port 17b, a protection blade 18 projecting from each of the discharge ports 17b along the rotation axis direction of the casing 11 so as to protect the discharge port 17b. Is formed. The protection blade 18 is made of a hard metal such as super steel and is tapered. The tip of the protective blade 18 further projects in the radial direction of the casing 11 than the discharge port 17b.

  As shown in FIGS. 3A, 4A and 4B, the co-rotation prevention blade 16 rotates the casing 11 closer to the base end of the casing 11 than the first excavation blade 14 located below. So that it does not rotate together with the ring member 19 fixed to the outer peripheral surface of the casing 11. In the present embodiment, since the excavating blades 14 and 15 are provided above and below the tip side of the casing 11, the co-rotation preventing blade 16 is attached between the excavating blades 14 and 15.

  Specifically, as shown in FIG. 4B, an annular ring member 19 for loosely fitting the co-rotation prevention wing 16 is fixed to an outer peripheral surface of a steel pipe constituting the casing 11. 19 is provided with upper and lower brim portions. On the outer periphery of the ring member 19, two semicircular rotating members 16 a, 16 a constituting a part of the co-rotation prevention wing 16 are connected by a bolt and a nut so as to fit into the upper and lower brim portions. It is mounted so that the outer circumference can be rotated. Shafts 16b, 16b are fixed from the rotating members 16a, 16a so as to extend in the radial direction of the casing 11, and stirring blades 16c are fixed vertically from the shafts 16b, 16b.

  Thus, the co-rotation prevention blade 16 is rotatable around the rotation axis with respect to the casing 11. The first excavation wing 14 and the second excavation wing 15 are set to have a length such that they rotate on the circumference of the diameter d5 in accordance with the rotation of the casing 11, and the co-rotation prevention wing 16 extends on the circumference of the diameter d6. The length is set so that it turns freely.

  As shown in FIG. 4B, a groove 19 a is formed on the inner peripheral surface of the ring member 19 that rotatably supports the co-rotation prevention blade 16 along the rotation axis direction of the casing 11. The angle member 13 a is accommodated in the concave groove 19 a, and the supply channel 13 passes through the ring member 19 and is fixed to the outer peripheral surface of the casing 11. As a result, the supply flow path 13 is formed in the concave groove 19a, so that the supply flow path 13 is not blocked by the co-rotation prevention blade 16. As shown in FIG. 2B, the upper end of the angle member 13 a is closed by a lid member, and the through hole 11 a formed in the upper part of the casing 11 in accordance with the horizontal hole 12 b of the connecting portion 12 forms a horizontal hole. The supply passage 13 communicates with the supply channel 12b.

  The operation of the digging and stirring device 10 of the present embodiment configured as described above, that is, a construction method of constructing the pile structure 1 using the digging and stirring device 10 will be described below with reference to FIGS. In this construction method, after the steel pipe pile 2 is buried in the ground with the pile head exposed, the columnar improved body 3 is formed.

  First, in this embodiment, the steel pipe pile 2 as a foundation pile is installed vertically on the ground using a pile driver (not shown) and rotated, and excavates the ground with the tip wing 2A to penetrate into the ground. Is done. The steel pipe pile 2 is penetrated until it reaches the support layer 4. Thereby, the vertical supporting force of the pile structure 1 is sufficiently obtained.

  As shown in FIG. 5, the casing 11 of the digging and stirring device 10 is put on the pile head of the steel pipe pile 2 in this state, and the digging and stirring device 10 is installed vertically to the ground surface. That is, the pile head of the steel pipe pile 2 is inserted into the lower opening of the casing 11 and installed. Then, by rotating and lowering the excavating and stirring device 10, as shown in FIG. 6, the first excavating wing 14 and the second excavating wing 15 excavate the ground around the steel pipe pile 2 and generate the ground by excavating the ground. The mixed soil and cement milk are mixed and stirred.

  At this time, the first excavation wing 14 and the second excavation wing 15 that rotate together with the casing 11 draw surrounding earth and sand. However, the shaft portions 16b, 16b of the co-rotation prevention wing 16 located in the middle are longer than the fixed arm 14a of the first digging wing 14 and the fixed arm 15a of the second digging wing 15, so that they do not bite into the outer soil and rotate. . For this reason, the earth and sand near the first excavation wing 14 and the second excavation wing 15 turns, and the earth and sand near the anti-corotation wing 16 does not turn. And the cement milk can be surely mixed and stirred. Further, when the excavating and stirring device 10 is lowered while rotating, the stirring range of the earth and sand increases downward, and the pile head approaches the connecting portion 12 of the casing 11.

  At the time of this excavation and stirring, as shown in FIG. 6, cement milk is supplied from the injection hole 12a of the connecting portion 12 as shown by an arrow Y1. As a result, the cement milk passes through the lateral hole 12b of the connecting portion 12, passes through the through hole 11a of the casing 11, passes through the supply channel 13 formed on the outer periphery, and flows downward to discharge the outlet of the ring-shaped member 17. From 17b, it is discharged to the outside of the supply flow path 13 as indicated by an arrow Y2.

  The discharged cement milk is mixed with the earth and sand 5 stirred by the first excavation wing 14, the second excavation wing 15, and the co-rotation prevention wing 16. In this manner, since the cement milk is discharged from the vicinity of the first excavator blade 14, the cement milk can be efficiently supplied to the earth and sand 5 stirred by the first excavator blade 14.

  Thereafter, when the drilling and stirring device 10 is removed from the pile head of the steel pipe pile 2 while rotating the first drilling wing 14 and the second drilling wing 15, as shown in FIG. 7, the steel pipe pile 2 buried in the ground is removed. A mixture of the earth and sand and the cement milk which is to be the columnar improved body 3 is formed around the periphery. The mixture to be the columnar improved body 3 is formed from the surface to a depth shorter than the length of the steel pipe pile 2.

  After that, the excavating and stirring device 10 is pulled out from the ground, and the earth and sand mixed with the cement milk is gradually hardened (solidified) to form the columnar improved body 3 having improved ground. According to this embodiment, since the steel pipe pile 2 is previously cast before the columnar improved body 3 is formed, there is no restriction on the timing at which the steel pipe pile 2 is cast. The columnar improvement body 3 can be formed.

  The solidified columnar improved body 3 has good bite with the ground and reinforces the upper part of the agitated earth and sand 5 with the columnar improved body 3, so that the vertical supporting force and the horizontal supporting force are greatly improved. be able to. And the upper part of the steel pipe pile 2 is reinforced by the columnar improvement body 3, and the pile structure 1 has a strength enough to sufficiently resist even if a horizontal force is applied to the steel pipe pile 2.

  Here, for example, when the supply flow path is provided inside the casing 11, at the time of excavation, there is a possibility that the supply flow path is interrupted by the pile head accommodated in the casing 11. However, in this embodiment, since the supply channel 13 is provided on the outer peripheral surface of the casing 11, the supply channel 13 is not blocked by the pile head.

  The discharge port 17 b from which the cement milk is discharged is formed at a position protruding from the outer peripheral surface of the casing 11 in the radial direction of the casing 11. In accordance with this, since the protection blade 18 is formed on the tip side of the casing 11 of the discharge port 17b, the discharge port 17b can be protected from the agitated earth and sand. Specifically, it is possible to prevent deformation of the discharge port 17b due to rock or the like mixed in the stirred earth and sand, and to prevent the supply of cement milk from being stopped due to clogging of the discharge port 17b with earth and sand.

  A modified example of the flow path forming member forming the supply flow path 13 for supplying the cement milk will be described with reference to FIG. The flow path forming member shown in this example has a shape in which a cross section orthogonal to the longitudinal direction of the casing 11 is curved, and more specifically, a half-split pipe material 13b obtained by half-split the pipe material in the longitudinal direction. 13b. The split pipe members 13b are fixed to the outer peripheral surface of the casing 11 along the rotation axis direction of the casing 11 to form a supply flow path 13 for supplying cement milk to earth and sand. The supply passage 13 can also be formed easily by fixing the half-split pipe members 13b, 13b to the outer peripheral surface of the casing 11 by welding or the like.

  A modification of the protection blade for protecting the discharge port 17b will be described with reference to FIGS. The protection blade 18A shown in this example is disposed at a position along the rotation axis direction of the casing 11 from each of the discharge ports 17b on the tip side of the casing 11 with respect to the discharge port 17b so as to protect the discharge port 17b. I have. Specifically, the protection blade 18A protrudes downward from the tip of the casing 11 along the rotation axis direction so as to protect the discharge port 17b. Thus, the earth and sand from the front end of the casing 11 toward the discharge port 17b can be crushed by the protective blade 18A, and the discharge port 17b can be protected.

  A modified example of the casing 11 will be described with reference to FIG. In this modification, the excavating and stirring device 10A is a device that forms the columnar improved body 3 while penetrating the steel pipe pile 2 into the ground. In this modification, a chuck 29 for fixing the steel pipe pile 2 is attached to the inner peripheral surface of the casing 11. On the other hand, a projection (not shown) that engages with the chuck 29 is formed on the outer peripheral surface of the pile head of the steel pipe pile 2.

  The chuck 29 is formed with a T-shaped engagement groove 29a formed by a vertical groove 29b and a horizontal groove 29c, which engages with the projection of the steel pipe pile 2. When connecting the steel pipe pile 2 and the casing 11, first, the above-described protrusions of the steel pipe pile 2 are inserted from below the T-shaped engagement groove 29a into a vertical groove 29b formed along the vertical direction. . Next, by rotating the steel pipe pile 2 and the casing 11 relatively, the protrusion is brought into contact with the end of the lateral groove 29c formed in the circumferential direction. Thereby, the steel pipe pile 2 and the casing 11 can be integrally rotated. In this embodiment, the engagement groove 29a is provided in the chuck 29. However, if the steel pipe pile 2 and the casing 11 can be integrally rotated, a chuck having a shape fitted to the pile head is used. The shape of the chuck is not particularly limited.

  A method of forming the columnar improved body 3 by improving the ground around the steel pipe pile 2 with the excavating and stirring device 10A shown in FIG. 10 will be described. As shown in FIG. 11, the steel pipe pile 2 is in a state where it does not reach a predetermined depth, for example, the support layer 4, and it is necessary to further penetrate the steel pipe pile 2 while excavating the ground further with the tip wing 2A. It is in a state.

  Next, the steel pipe pile 2 including the pile head is covered with the casing 11 of the excavating and stirring device 10A, and the steel pipe pile 2 is engaged with the chuck 29 as described above. In this state, the excavating and stirring device 10A has not reached the surface of the ground.

  Next, while rotating the casing 11 of the digging and stirring device 10A, the rotating force of the pile driver is transmitted to the casing 11 of the digging and stirring device 10A via the connecting portion 12 by the chuck 29 provided on the casing 11, 11 is rotated and transmitted to the steel pipe pile 2 via the chuck 29. Accordingly, when the steel pipe pile 2 is lowered while rotating so that the tip wing 2A excavates the ground, the steel pipe pile 2 is further penetrated into the ground.

  In this state, the steel pipe pile 2 and the drilling and stirring device 10A continue to descend, and when the first drilling wing 14 of the drilling and stirring device 10A reaches the surface, the drilling and stirring device 10A gradually excavates the ground around the steel pipe pile 2. At the same time, the penetration of the steel pipe pile 2 into the ground, excavation of the ground for forming the columnar improved body 3, and agitation of the generated earth and sand are simultaneously performed. The drilling and stirring device 10A continues to penetrate and excavate to a position corresponding to the depth of the columnar improvement body 3, and the penetration of the steel pipe pile 2 and the excavation of the ground for forming the columnar improvement body 3 to a predetermined depth are completed.

  When the cement milk is supplied from the connection portion 12 side during such stirring, the cement milk passes through the injection hole 12a and the horizontal hole 12b of the connection portion 12, and is provided on the outer peripheral surface of the casing 11 through the through hole 11a. After reaching the ring-shaped member 17 on the distal end side through 13, 13, it is discharged from the casing 11 through the discharge port 17 b. The discharged cement milk is mixed with the earth and sand 5 being stirred by the first excavation wing 14, the second excavation wing 15, and the co-rotation prevention wing 16. After mixing for a predetermined time and the cement milk and the earth and sand are uniformly mixed, the engagement by the chuck 29 is released, the drilling and stirring device 10A is detached from the steel pipe pile 2, and the drilling and stirring device 10A is pulled up from the ground to improve the columnar shape. The body 3 is formed.

  In the method of constructing the pile structure 1, in addition to the effects shown in the operation description of the above-described embodiment, the penetration of the steel pipe pile 2 having the tip wing 2A, the excavation of the ground of the columnar improvement body 3, the supply of cement milk, and Mixing and stirring of earth and sand and cement milk can be performed in a series of steps, and a pile structure can be efficiently constructed in a short time.

  As described above, the embodiments of the present invention have been described in detail. However, the present invention is not limited to the above embodiments, and various designs may be made without departing from the spirit of the present invention described in the appended claims. Changes can be made. For example, as an example of the foundation pile, a steel pipe pile having a tip wing has been described, but another concrete pile such as a PHC pile without a tip wing may be used. Although the foundation pile has a length reaching the support layer, the foundation pile may be used as a friction pile without reaching the support layer.

  Further, in the above-described embodiment, the excavation wing is a two-stage excavation wing by using two types of first and second excavation wings. However, the number of excavation wings may be one or three or more. When three or more are provided above and below, an anti-corotating wing may be further provided between them.

  In addition, when excavating the ground and stirring the earth and sand, cement milk may be supplied thereto, and the earth and sand may be mixed with the cement milk. After excavating the ground, the first and second excavating wings and the second excavating wing are not lowered and fixed. While turning, the earth and sand around the steel pipe pile may be agitated, and cement milk may be supplied to the agitated earth and sand.

1: pile structure, 2: steel pipe pile (foundation pile), 2A: tip wing (drilling blade), 3: columnar improved body, 4: support layer, 5: excavated earth and sand, 10: excavation stirring device, 11: casing , 12: connecting portion, 13: supply flow path, 13a; angle material (flow path forming member), 13b: half-pipe material (flow path forming member), 14: first digging wing (digging wing), 15: No. 2 excavation wing, 16: co-rotation prevention wing, 17: ring-shaped member, 17a: supply hole, 17b: discharge port, 18: protective blade, 19: ring material, 19a: concave groove

Claims (4)

A drilling and stirring device that mixes and stirs cement-based solidifying material into earth and sand excavated around the foundation pile buried in the ground to form a columnar improved body around the foundation pile,
A cylindrical casing that covers the pile head of the foundation pile, and during excavation and stirring, rotates around the axis of the foundation pile as a rotation axis,
From the outer peripheral surface of the casing, extending in the radial direction of the casing, fixed to the casing, a digging wing having a digging blade at least in the lower portion,
The cement-based solidifying material is provided on the outer peripheral surface of the casing, and the cement-based solidifying material is supplied to the earth and sand such that the cement-based solidifying material is introduced from the base end of the casing and discharged from or near the base end of the excavation wing. A drilling and stirring device, comprising:   The supply flow path is formed by fixing a flow path forming member whose cross section orthogonal to the rotation axis direction of the casing is bent or curved to the outer peripheral surface of the casing along the rotation axis direction of the casing. The excavating and stirring device according to claim 1, wherein At the base end side of the casing relative to the excavation wing, a co-rotation prevention wing rotatably attached to a ring member fixed to the outer peripheral surface of the casing so as not to rotate together with the rotation of the casing. With
On the inner peripheral surface of the ring material, a concave groove is formed along the rotation axis direction of the casing,
The excavation and stirring device according to claim 1, wherein the supply flow path is formed in the concave groove. A discharge port from which the cement-based solidifying material is discharged from the supply channel is formed at a position protruding in a radial direction of the casing from an outer peripheral surface of the casing,
In the casing, a protection blade that protects the discharge port is formed at a position along the rotation axis direction of the casing from the discharge port on a tip side of the casing relative to the discharge port. The excavating and stirring device according to claim 1.

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