JP2020051063A - Ground improvement pile, construction method of ground improvement body and protrusion of ground improvement pile - Google Patents

Abstract

To provide a ground improvement pile, a construction method of a ground improvement body and a protrusion of the ground improvement pile in which a core material is sunk with almost no gap between an improved body formed by injecting a solidifying material into the ground and the horizontal strength of the core material is prevented from lowering with a simple configuration.SOLUTION: A ground improvement pile comprises a cylindrical core material to be sunk in an improved body formed by injecting a solidifying material into the ground, and a protrusion 12 attached to an outer periphery of the core material and protruding in the radial direction of the core material. The protrusion 12 includes a skeleton 16 that partitions a communication path 14 in the protrusion 12. The communication path 14 communicates on both sides of the protrusion 12 in the axial direction of the core material. The skeleton 16 has an outer wall portion 18 extending in the axial direction and the circumferential direction of the core material and partitioning the outside of the communication path 14 in the radial direction of the core material.SELECTED DRAWING: Figure 6

Description

  The present disclosure relates to a ground improvement pile, a construction method of a ground improvement body, and a protrusion of the ground improvement pile.

  2. Description of the Related Art Conventionally, ground improvement has been performed to increase the supporting force of soft ground and to suppress settlement. For example, the ground improvement disclosed in Patent Literature 1 is to construct a soil cement composite pile on soft ground. In constructing the soil cement composite pile, a cement material such as cement milk is poured into the ground while stirring and mixing to form a soil cement column (improved body) on the ground, and a core material is pressed into the soil cement column. I have. An annular ring is loosely fitted to the core, and the annular ring is engaged with an annular protrusion provided on the core. The annular ring has a larger diameter than the core material, and the annular ring enhances the adhesive force between the soil cement column and the core material.

On the other hand, Patent Literature 2 discloses a soil cement in which a prefabricated pile with blades using helical blades instead of an annular ring and a large-diameter cylindrical prefabricated pile connected to the prefabricated pile with blades are embedded in a soil cement column. A composite stake is disclosed. In the soil cement composite pile, the horizontal strength is also improved by providing a large-diameter cylindrical ready-made pile.
Patent Document 3 discloses a wooden support pile in which a penetration aid is attached to a wooden pile having a taper. The penetrating holder includes a fitting ring and a spiral blade. According to the wooden support pile, the wooden pile is tightened and restrained by the penetrating holder, thereby improving the buckling strength of the wooden pile.

JP 2013-256841 A JP 2003-96770 A JP 2007-32018 A

When an annular ring is used as disclosed in Patent Document 1, when the viscosity of the soil cement is high and the fluidity is low, the soil cement is pushed downward by the annular ring when the core material is pressed into the soil cement. In some cases, the soil cement around the annular ring may become independent. In such a case, there is a possibility that the gap is generated because the soil cement does not wrap around the annular ring, the adhesion between the core material and the soil cement is reduced, and the support force may be reduced. Further, if a gap is formed around the core material, the core material is easily deformed, and the horizontal proof stress of the core material is reduced.
A similar problem can occur even when a helical blade is used as disclosed in Patent Documents 2 and 3. That is, even if the blade is rotated, if the vertical press-fitting speed is high, the soil cement is pushed in by the blade, and a gap is formed around the blade.

On the other hand, as disclosed in Patent Document 2, it is considered effective to use a large-diameter cylindrical ready-made pile as a core material for improving horizontal strength, but it takes time and effort to connect the core materials, and There is a problem that the core material becomes large. In this regard, it is thought that if the annular ring has a certain thickness, the horizontal strength can be improved to some extent with a simple configuration, but if the ground into which the solidified material is injected has a high viscosity, There is a possibility that a gap is more likely to be formed in the upper portion, which may have an adverse effect.
In view of the circumstances described above, it is an object of at least one embodiment of the present invention to provide a core having a simple configuration in which a core material is sunk with substantially no gap between the ground and an improved body formed by injecting a solidifying material. It is an object of the present invention to provide a ground improvement pile capable of preventing a reduction in horizontal strength of a material, a method of constructing a ground improvement body, and a protrusion of the ground improvement pile.

(1) The ground improvement pile according to at least one embodiment of the present invention includes:
A cylindrical core material to be submerged in an improved body formed by injecting a solidifying material into the ground,
A projection attached to the outer periphery of the core material and protruding in a radial direction of the core material,
The protrusion includes a skeleton that defines a communication path within the protrusion,
The communication path communicates with both sides of the protrusion in the axial direction of the core material,
The skeleton has an outer wall portion extending in an axial direction and a circumferential direction of the core material and defining an outside of the communication path in a radial direction of the core material.

  According to the above configuration (1), since the communication path is provided in the projection, even if the improved body formed by injecting the solidifying material into the ground has a high viscosity, the improvement is performed through the communication path when the projection is pushed in. The body passes through the protrusion. For this reason, a gap is not easily generated above the protrusion, and the core material and the improved body are in close contact with each other. As a result, when a horizontal force is applied, the deformation of the core material is suppressed, and a decrease in the horizontal proof stress of the core material is prevented.

(2) In some embodiments, in the above configuration (1),
The outer wall has at least one through hole penetrating the outer wall in a radial direction of the core.
According to the above configuration (2), by providing the through hole in the outer wall portion, the improved body is filled in the through hole, the shear strength with the improved body is increased, and the adhesion resistance of the protrusion in the improved body is improved. Can be increased.

(3) In some embodiments, in the above configuration (1) or (2),
The skeleton further has an end wall that partially covers the opening of the communication path.
According to the above configuration (3), by providing the end wall that partially covers the opening of the communication path, the bearing pressure resistance of the projection in the improved body can be increased.

(4) In some embodiments, in the above configuration (3),
The communication passage has an opening closer to the core than the outer wall in the radial direction of the core.
According to the above configuration (4), since the communication path has an opening closer to the core material than the outer wall in the radial direction of the core material, the flow of the improved body inside the communication path in the radial direction is ensured. be able to. Therefore, it is possible to reliably prevent a gap from being generated in the vicinity of the core above the protrusion.

(5) In some embodiments, in any one of the above configurations (1) to (4),
The core is made of concrete,
The protrusion is made of a material different from the core material.
According to the above configuration (5), when the core is made of concrete, it is difficult to form the projection integrally with the core. However, when the projection is made of a material other than concrete, the projection is easily manufactured. be able to.

(6) In some embodiments, in any one of the configurations (1) to (5),
The skeleton further has an inner wall portion that can be fitted to the core material.
According to the above configuration (6), since the skeleton has the inner wall portion that can be fitted to the core material and the skeleton has the projection, the projection can be easily attached to the core material.

(7) In some embodiments, in the above configuration (6),
The core has a small diameter portion and a large diameter portion having a larger diameter than the small diameter portion,
An inner wall portion of the projection can be fitted to the small diameter portion.
According to the above configuration (7), by providing a small-diameter portion to the core material and fitting the inner wall portion of the projection to the small-diameter portion, the position of the projection with respect to the core material can be determined with certainty. The acting vertical force can be reliably transmitted to the improved body through the projection.

(8) In some embodiments, in the above configuration (6),
The core material has a male tapered surface whose outer diameter gradually changes,
The inner wall of the projection has a female tapered surface whose inner diameter gradually changes,
The male tapered surface can be fitted to the female tapered surface.
According to the above configuration (8), by fitting the male taper surface of the core material and the female taper surface of the projection, the position of the projection with respect to the core material can be reliably determined and acts on the core material. The vertical force can be reliably transmitted to the improved body through the projection.

(9) In some embodiments, in the above configuration (8),
Further comprising an adapter ring interposed between the male tapered surface and the female tapered surface,
The male tapered surface can be fitted to the female tapered surface via the adapter ring.

According to the above configuration (9), by fitting the male taper surface of the core material and the female taper surface of the projection via the adapter ring, the position of the projection with respect to the core material can be reliably determined. The vertical force acting on the core material can be reliably transmitted to the improved body through the projection.
In addition, if a plurality of adapter rings having different sizes are prepared, a plurality of protrusions having the same inner diameter of the female tapered surface are attached to the core material while being spaced apart in the axial direction of the core material via the adapter rings. be able to. Therefore, the specifications of the projections can be reduced, and the cost can be reduced.

(10) The method for constructing a ground improvement body according to at least one embodiment of the present invention includes:
An improved body forming step of injecting a solidified material into the ground to form an improved body,
A pile setting step of setting the ground improvement pile according to the above configuration (8) or (9) in the improved body,
The pile laying step,
A projection preparing step of coaxially stacking the plurality of projections on the improved body,
A core material depositing step of depositing the core material in the improved body while inserting the core material into the plurality of stacked protrusions,
including.

  According to the above configuration (10), a plurality of projections are stacked coaxially, and the core material is inserted through the projections, whereby the projections can be easily attached to the core material. In addition, by accurately determining the position where the plurality of protrusions are stacked, positioning of the core material can be easily performed.

(11) The protrusion of the ground improvement pile according to at least one embodiment of the present invention includes:
In a projection configured to be able to be attached to a core material disposed in an improved body formed by injecting a solidifying material into the ground, and configured to project radially from the core material,
Including a skeleton that defines a communication path in the projection,
The communication path communicates with both sides of the protrusion in the axial direction of the core material,
The skeleton has an outer wall portion extending in an axial direction and a circumferential direction of the core material and defining an outside of the communication path in a radial direction of the core material.

  According to the above configuration (11), since the communication path is provided in the projection, even if the improved body formed by injecting the solidifying material into the ground has a high viscosity, the improvement is performed through the communication path when the projection is pushed in. The body passes through the protrusion. For this reason, a gap is not easily generated above the protrusion, and the core material and the improved body are in close contact with each other. As a result, when a horizontal force is applied, the deformation of the core material is suppressed, and a decrease in the horizontal proof stress of the core material is prevented.

  According to at least one embodiment of the present invention, the core material is sunk with substantially no gap between the improved body formed by injecting the solidified material into the ground, and the horizontal strength of the core material is reduced with a simple configuration. Provided are a ground improvement pile that can be prevented, a method of constructing a ground improvement body, and a protrusion of the ground improvement pile.

It is a sectional view showing roughly the ground improvement object using the ground improvement pile concerning one embodiment of the present invention. FIG. 3 is a diagram schematically illustrating a ground improvement pile in FIG. 1, a left half of FIG. 2 is a front view, and a right half of FIG. 2 is a cross-sectional view. FIG. 3 is an enlarged view of a region III in FIG. 2. FIG. 3 is a plan view schematically showing a protrusion of a ground improvement pile in FIG. 2. FIG. 5 is a schematic cross-sectional view of a protrusion taken along line VV in FIG. 4. It is a schematic perspective view of a projection. FIG. 3 is a schematic exploded perspective view of a skeleton of a projection. It is a figure which shows schematically the ground improvement pile which concerns on another embodiment of this invention, The left half of FIG. 8 is a front view, and the right half of FIG. 8 is sectional drawing. FIG. 9 is an enlarged view of a region IX in FIG. 8. It is a top view which shows the projection of the ground improvement pile in FIG. 8 schematically. FIG. 11 is a schematic cross-sectional view of a projection taken along line XI-XI in FIG. 10. FIG. 9 is a cross-sectional view schematically showing an adapter ring according to another embodiment of the present invention together with a protrusion. FIG. 13 is a perspective view schematically showing the adapter ring in FIG. 12. It is a flow chart for explaining an outline procedure of a construction method of a ground improvement object concerning one embodiment of the present invention. It is a schematic sectional drawing for demonstrating a protrusion preparation process. It is a schematic sectional drawing for demonstrating a core material setting process. FIG. 9 is a perspective view schematically showing a protrusion according to another embodiment of the present invention. FIG. 9 is a plan view schematically showing a protrusion according to another embodiment of the present invention. FIG. 19 is a schematic cross-sectional view of the protrusion taken along the line IXX-IXX in FIG. 18. FIG. 19 is a plan view schematically showing a bottom wall applied to the protrusion of FIG. 18. FIG. 9 is a cross-sectional view schematically illustrating a protrusion according to another embodiment of the present invention. It is sectional drawing which shows schematically the pile for ground improvement which concerns on another embodiment of this invention. FIG. 23 is a plan view schematically showing the protrusion in FIG. 22. FIG. 9 is a cross-sectional view schematically illustrating a protrusion according to another embodiment of the present invention. It is a figure which shows schematically the pile for ground improvement which concerns on another embodiment of this invention, The left half of FIG. 25 is a front view, and the right half of FIG. 25 is sectional drawing.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention thereto, but are merely illustrative examples. Absent.
For example, the expression representing a shape such as a square shape or a cylindrical shape not only represents a shape such as a square shape or a cylindrical shape in a strictly geometrical sense, but also an uneven portion or a chamfer as long as the same effect can be obtained. A shape including a part and the like is also represented.

  FIG. 1 is a sectional view schematically showing a ground improvement body 3 using a ground improvement pile (hereinafter, also referred to as a pile) 1 according to an embodiment of the present invention. FIG. 2 is a diagram schematically showing the stake 1, the left half of FIG. 2 is a front view, and the right half of FIG. 2 is a cross-sectional view. FIG. 3 is an enlarged view of a region III in FIG. FIG. 4 is a plan view schematically showing the protrusion 12 of the pile 1. FIG. 5 is a schematic cross-sectional view of the protrusion 12 taken along line VV in FIG. FIG. 6 is a schematic perspective view of the protrusion 12. FIG. 7 is a schematic exploded perspective view of the skeleton 16 of the projection 12.

  As shown in FIG. 1, the ground improvement body 3 is formed by injecting a solidifying material such as cement milk into the ground 5 and stirring and mixing the soil improvement body 7 and the improvement body 7. And a stake 1. The area and depth of the improved body 7 are not particularly limited, and the number of the piles 1 disposed in the improved body 7 is not particularly limited. Further, when the pile 1 is laid, the pile 1 may be press-fitted while rotating or may be press-fitted without rotating.

  However, since the ground improvement body 3 mainly supports the upper structure by the vertical support force generated according to the bottom area of the improvement body 7 and the frictional force of the side surface of the improvement body 7, the bottom area of the improvement body 7 is generally Is sufficiently larger than the area of the pile 1. Further, since the supporting force required for the ground improvement body 3 is relatively small, it is not necessary that the ground improvement body 3 always reaches the supporting ground, and the depth of the improvement body 7 is generally determined by a pre-boring method or the like. It is shallower than the pile foundation formed by the cement milk method.

  Further, generally, excavated soil is hardly discharged when the improved body 7 is formed, and the excavated earth and sand is stirred and mixed with the solidified material to form soil cement. For this reason, the improved body 7 contains more earth and sand than the soil cement constituting the pile periphery of the pile foundation formed by the cement milk method. For this reason, the viscosity of the improved body 7 tends to increase depending on the soil quality of the ground 5. That is, in general, the properties of the improved body 7 are significantly different from those of the soil cement at the periphery of the pile formed by the cement milk method.

As shown in FIGS. 2 and 3, the pile 1 includes a core material 10 and a protrusion 12 attached to the core material 10.
The core material 10 has, for example, a cylindrical shape such as a cylindrical shape or a rectangular tube shape, and may be hollow or solid. In the case of a rectangular tube shape, the plan view shape may be a square shape or another polygonal shape. The core 10 is made of, for example, steel pipe or concrete. When the core 10 is made of concrete, the core 10 may further include a reinforcing reinforcing bar.

The protrusion 12 is attached to the outer periphery of the core 10 and protrudes in the radial direction of the core 10. As shown in FIGS. 4 to 7, the protrusion 12 includes a skeleton 16 that defines a communication path 14 in the protrusion 12. The communication passage 14 communicates on both sides of the protrusion 12 in the axial direction of the core material 10, that is, on the upper side and the lower side.
The skeleton 16 has an outer wall portion 18 extending in the axial direction and the circumferential direction of the core member 10 and defining the outside of the communication passage 14 in the radial direction of the core member 10.

According to the above configuration, since the communication path 14 is provided in the projection 12, even if the improved body 7 formed by injecting the solidifying material into the ground 5 has a high viscosity, the communication path is formed when the projection 12 is pushed in. The improved body 7 passes through the projection 12 through 14. For this reason, a gap is not easily generated above the protrusion 12, and the core material 10 and the improved body 7 are in close contact with each other. As a result, deformation of the core 10 when a horizontal force is applied is suppressed, and a decrease in the horizontal proof stress of the core 10 is prevented.
On the other hand, the skeleton 16 of the projection 12 has an outer wall portion 18. The outer wall portion 18 extends in the axial direction and the circumferential direction of the core material 10 and partitions the outside of the communication passage 14 in the radial direction of the core material 10. Adhesion can be improved and horizontal force can be received. For this reason, by embedding the core 10 and the protrusions 12 in the improved body 7, the horizontal strength of the core 10 constituting the pile 1 can be improved with a simple configuration.

  In some embodiments, the length (height) L of the outer wall portion 18 in the axial direction of the core material 10 is 50 mm or more and 300 mm or less. When the length L of the outer wall portion 18 is 50 mm or more, the protrusion 12 can reliably receive the horizontal force. On the other hand, even when the length of the outer wall portion 18 is 50 mm or more, since the communication path 14 is defined inside the projection 12, the improved body 7 can pass through the inside of the projection 12.

In some embodiments, the core 10 is made of concrete, and the protrusions 12 are made of a different material from the core 10, for example, metal.
According to the above configuration, when the core 10 is made of concrete, it is difficult to form the projection 12 integrally with the core 10, but if the projection 12 is made of a material other than concrete, the projection 12 can be easily formed. Can be manufactured.
In addition, the protrusion 12 may be attached to the core material 10 at the site, or a product obtained by attaching the protrusion 12 to the core material 10 at the factory may be transported to the site.

In some embodiments, as shown in FIGS. 3 to 6, the skeleton 16 of the projection 12 further includes an inner wall 20 that can be fitted to the core 10.
According to the above configuration, since the protrusion 12 has the inner wall portion 20 that can be fitted to the core member 10, the protrusion 12 can be easily attached to the core member 10.

In some embodiments, as shown in FIG. 3, the core material 10 has a small diameter portion 10a and a large diameter portion 10b having a larger diameter than the small diameter portion 10a, and the inner wall portion 20 of the protrusion 12 is attached to the small diameter portion 10a. Can be fitted.
According to the above configuration, the position of the projection 12 with respect to the core material 10 can be reliably determined by providing the small diameter portion 10a on the core material 10 and fitting the inner wall portion 20 of the projection 12 to the small diameter portion 10a. Thus, the vertical force acting on the core 10 can be reliably transmitted to the improved body 7 through the projections 12.

In some embodiments, as shown in FIGS. 4 to 6, the skeleton 16 of the projection 12 includes a cylindrical outer wall 18, a cylindrical inner wall 20 having a smaller diameter than the outer wall 18, and an outer wall And a plurality of plate-shaped rims 22 connecting the inner wall 18 and the inner wall 20. The outer wall portion 18 and the inner wall portion 20 are arranged concentrically with an interval therebetween, and the plurality of rim portions 22 are radially arranged between the outer wall portion 18 and the inner wall portion 20. Therefore, a plurality of communication paths 14 are defined in the projection 12. Each communication path 14 is open at the upper surface and the lower surface of the projection 12 and has a fan shape in plan view.
For example, the outer wall portion 18, the inner wall portion 20, and the rim portion 22 are formed of a metal plate and are mutually welded. The shape of the outer wall portion 18 and the inner wall portion 20 may be a cylindrical shape or a rectangular tube shape. Further, although the rim portion 22 is arranged along the radial direction of the outer wall portion 18 and the inner wall portion 20, it may be arranged to be inclined with respect to the radial direction. Further, although the rim portion 22 is arranged along the axial direction of the outer wall portion 18 and the inner wall portion 20, it may be arranged to be inclined with respect to the axial direction.

  In some embodiments, as shown in FIG. 7, the skeleton 16 of the projection 12 is formed by half bodies 16a and 16b, and the half bodies 16a and 16b are mutually connected by fastening means such as bolts 24, rivets or welding. Can be connected to

Hereinafter, other embodiments of the present invention will be described. However, the same or similar configurations as those of the above-described embodiments will be denoted by the same names or reference numerals, and description thereof will be omitted or simplified.
FIG. 8 is a diagram schematically showing a ground improvement pile 28 according to another embodiment of the present invention. The left half of FIG. 8 is a front view, and the right half of FIG. 8 is a cross-sectional view. FIG. 9 is an enlarged view of a region IX in FIG. FIG. 10 is a plan view schematically showing the protrusion 32 of the pile 28. FIG. 11 is a schematic cross-sectional view of the protrusion 32 along the line XI-XI in FIG.

The core 30 of the pile 28 has a tapered shape. The projection 32 attached to the core member 30 has a skeleton 36 that defines a communication path 34, and the skeleton 36 has an outer wall 38, an inner wall 40, and a rim 41.
The core material 30 has a male taper surface 30a whose outer diameter gradually changes, the inner wall portion 40 of the projection 32 has a female taper surface 40a whose inner diameter gradually changes, and the male taper surface 30a becomes a female taper surface 40a. Can be fitted. The outer diameter of the male tapered surface 30a increases as approaching upward, and the inner diameter of the female taper surface 40a decreases as approaching downward. The projection 32 is fitted and fixed to the core member 30 at a position where the outer diameter of the male tapered surface 30a and the inner diameter of the female tapered surface 40a match.

  According to the above configuration, by fitting the male tapered surface 30a of the core material 30 and the female tapered surface 40a of the projection 32, the position of the projection 32 with respect to the core material 30 can be determined with certainty. The vertical force acting on 30 can be reliably transmitted to the improved body 7 through the projection 32.

In some embodiments, protrusions 32 are configured as a single item that does not need to be assembled on site. That is, since the projection 32 can be fixed to the core material 30 by inserting the core material 30 into the inner wall portion 40 of the projection 32, it is not necessary to configure the projection 32 by two half bodies. However, it goes without saying that the projection 32 may be constituted by two half-pieces that can be connected to each other.
As shown in FIG. 8, when the plurality of protrusions 32 are attached to the core material 30 while being spaced apart in the axial direction of the core material 30, the female tapered surfaces 34 a of the plurality of protrusions 32 have mutually different inner diameters.

FIG. 12 is a cross-sectional view schematically showing an adapter ring 42 according to another embodiment of the present invention, together with the protrusion 32. FIG. 13 is a perspective view schematically showing the adapter ring 42.
In some embodiments, as shown in FIGS. 12 and 13, the stake 28 further includes an adapter ring 42 interposed between the male tapered surface 30a and the female tapered surface 40a. The male tapered surface 30a of the core member 30 can be fitted to the female tapered surface 40a of the projection 32 via the adapter ring 42. That is, the adapter ring 42 has a female tapered surface 42a that can be fitted to the male tapered surface 30a of the core member 30, and a male tapered surface 42b that can be fitted to the female tapered surface 40a of the projection 32.

According to the above configuration, the position of the projection 32 with respect to the core material 30 is reliably determined by fitting the male tapered surface 30a of the core material 30 and the female tapered surface 40a of the projection 32 via the adapter ring 42. And the vertical force acting on the core member 30 can be reliably transmitted to the improved body 7 through the projection 32.
If a plurality of adapter rings 42 having different sizes, that is, a plurality of adapter rings 42 having the same outer diameter of the male tapered surface 42b and different inner diameters of the female tapered surface 42a are prepared, the inner diameter of the female tapered surface 40a is reduced. The same plurality of protrusions 32 can be attached to the core member 30 via the adapter ring 42 while being separated from each other in the axial direction of the core member 30. For this reason, the projections 32 can be shared, the specifications can be reduced, and the cost can be reduced.

FIG. 14 is a flowchart illustrating a schematic procedure of a method for constructing a ground improvement body according to an embodiment of the present invention. FIG. 15 is a schematic cross-sectional view for explaining the projection preparing step S20. FIG. 16 is a schematic cross-sectional view for explaining the core material setting step S22.
As shown in FIG. 14, the construction method of the ground improvement body according to one embodiment of the present invention includes an improvement body formation step S1 of injecting a solidification material into the ground 5 to form the improvement body 7, and improving the pile 28. And a pile laying step S2 for laying in the body 7. The pile setting step S2 includes a projection preparing step S20 and a core material setting step S22.

  As shown in FIG. 15, in the projection preparing step S20, a plurality of projections 32 are coaxially stacked on the vertical axis on the improved body 7. Although the inner diameter of the female tapered surface 40a is different between the plurality of protrusions 32 to be stacked, if they are the same, a plurality of adapter rings 42 having different inner diameters of the female tapered surface 42a may be fitted to the protrusions 32. . The order in which the protrusions 32 are stacked is such that the smaller the inner diameter of the female tapered surfaces 40a and 42a, the lower the position. At this time, as shown in FIG. 15, a holding tool 46 for holding the plurality of stacked projections 32 movably in the vertical direction may be used. The holding tool 46 has, for example, a tubular portion 46a surrounding the plurality of projections 32 and a leg 46b supporting the tubular portion 46a.

  As shown in FIG. 16, in the core material depositing step S <b> 22, the core material 30 is deposited on the improved body 7 while inserting the core material 30 into the plurality of stacked protrusions 32. At this time, as the core material 30 sinks, the plurality of protrusions 32 are sequentially fitted to the core material 30 and are arranged at intervals in the vertical direction.

  According to the above configuration, the plurality of protrusions 32 are stacked coaxially, and the core material 30 is inserted through the protrusions 32, so that the protrusions 32 can be easily attached to the core material 30. In addition, by accurately determining the position where the plurality of protrusions 32 are stacked, the positioning of the core member 30 can be easily performed.

FIG. 17 is a perspective view schematically showing a protrusion 50 according to another embodiment of the present invention. As shown in FIG. 17, the protrusion 50 differs from the protrusion 12 in having one or more through holes 52 in the outer wall portion 18. The through hole 52 penetrates the outer wall 18 in the radial direction of the core material 10.
According to the above configuration, by providing the through-hole 52 in the outer wall portion 18, the improved body 7 is filled in the through-hole 52 and the shear strength between the improved body 7 and the improved body 7 is increased, and the adhesion resistance of the projection 50 is reduced. Can be bigger.
Although not shown, one or more through holes may be formed in the rim 22 as well. Also in this case, the shear strength with the improved body 7 is increased, and the adhesion resistance of the protrusion 50 in the improved body 7 can be increased.

FIG. 18 is a perspective view schematically showing a protrusion 60 according to another embodiment of the present invention. FIG. 19 is a schematic cross-sectional view of the protrusion 60 along the line IXX-IXX in FIG. FIG. 20 is a plan view schematically showing the bottom wall 62 applied to the protrusion 60.
As shown in FIGS. 18 to 20, the protrusion 60 differs from the protrusion 12 in that the skeleton 16 of the protrusion 60 further has a bottom wall (end wall) 62. The bottom wall 62 is attached to the lower side of the rim 22 and has an annular shape. The bottom wall 62 extends in the radial direction and the circumferential direction of the core material 10 and partially covers the opening of the communication passage 14. Specifically, the bottom wall 62 covers a radial outside of the communication path 14.

According to the above configuration, by providing the bottom wall 62 that partially covers the opening of the communication path 14, the bearing resistance can be increased. On the other hand, even though the bottom wall 62 is provided, the communication passage 14 has an opening closer to the core 10 than the outer wall portion 18 in the radial direction of the core 10, so that the communication passage 14 on the radial inside of the communication passage 14 is formed. The flow of the improved body 7 can be secured. For this reason, it is possible to reliably prevent a gap from being generated near the core material 10 above the projection 60.
In addition, as shown in FIG. 20, the bottom wall 62 may also be constituted by the half bodies 62a and 62b. Further, the bottom wall 62 may be provided with one or more through holes. Further, instead of the bottom wall 62, a ceiling wall (end wall) having the same shape as the bottom wall 62 may be provided above the projection 60.

FIG. 21 is a cross-sectional view schematically illustrating a protrusion 70 according to another embodiment of the present invention. The projection 70 is different from the projection 60 in that the bottom wall 62 closes an intermediate portion of the opening of the communication passage 14 in the radial direction of the core material 10. Therefore, on the lower side of the projection 70, the radial inside and the radial outside of the communication path 14 are open.
According to the above-described configuration, the bottom wall 62 that closes the radial center of the opening of the communication path 14 is provided below the protrusion 70, in other words, the communication path 14 extends in the radial direction of the core 10. Therefore, by having an opening closer to the core material 10 than the outer wall portion 18 and also having an opening near the outer wall portion 18, the flow of the improved body 7 inside and outside the communication passage 14 in the radial direction and the radial direction is ensured. Meanwhile, the bearing pressure resistance can be increased.
Although the bottom wall 62 is provided over the entire area in the circumferential direction of the core material 10, the bottom wall 62 may be provided partially in the circumferential direction of the core material 10.
Further, the bottom wall 62 may be a mesh having a plurality of holes. In this case, the bottom wall 62 may cover the entire opening of the communication path 14.

FIG. 22 is a cross-sectional view schematically showing a ground improvement pile 72 according to another embodiment of the present invention. FIG. 23 is a plan view schematically showing the protrusion 74 of the pile 72.
The projection 74 is different from the projection 12 in that the skeleton 16 is constituted only by the half body 16 a and the half body 16 a is attached to the core 10 by the bracket 76. As illustrated in FIG. 22, the plurality of protrusions 74 are formed on the core 10 so that the half bodies 16 a of the protrusions 74 adjacent in the axial direction of the core 10 are shifted by 180 degrees in the circumferential direction of the core 10. Installed. In the projection 74, the outer wall portion 18 has a semi-cylindrical shape.
According to the above configuration, by forming the skeleton 16 only by the half body 16a, the adhesion resistance of the projection 74 can be appropriately adjusted.
Note that the outer wall portion 18 is not limited to a cylindrical shape or a semi-cylindrical shape, and may have a four-half cylindrical shape or the like.

FIG. 24 is a sectional view schematically showing a protrusion 78 according to another embodiment of the present invention. The projection 78 differs from the projection 32 in that the outer peripheral surface of the outer wall portion 38 is constituted by a male tapered surface 80.
According to the above configuration, since the outer peripheral surface of the outer wall portion 30 is configured by the male tapered surface 80, the projected area of the outer peripheral surface of the outer wall portion 30 in the vertical direction can be increased, and the protrusion 78 in the improved body 7 can be increased. Can increase the adhesion resistance.

FIG. 25 is a diagram schematically showing a ground improvement pile 82 according to another embodiment of the present invention. The left half of FIG. 25 is a front view, and the right half of FIG. 25 is a cross-sectional view.
As shown in FIG. 25, the ground improvement pile 82 differs from the ground improvement pile 28 in that a plurality of protrusions 78 are attached to the core material 30. Furthermore, the ground improvement pile 82 is also configured such that the male tapered surfaces 80 of the plurality of projections 78 are located on one tapered surface indicated by a two-dot chain line 84. Is different. That is, the outer diameter of the upper protrusion 78 is larger than the outer diameter of the lower protrusion 78.
According to the above configuration, the outer diameter of the upper projection 78 is increased, and the adhesion resistance of the projection 78 in the improved body 3 can be increased.

  Lastly, the present invention is not limited to the above-described embodiment, and includes a modification of the above-described embodiment and a combination thereof.

1,28,72,82 Pile for ground improvement body 3 Ground improvement body 5 Ground 7 Improvement body (Soil cement)
10 Core material 10a Small diameter part 10b Large diameter part 12, 32, 50, 60, 70, 74, 78 Projection 14, 34 Communication passage 16, 36 Frame 16a, 16b Half body 18, 38 Outer wall part 20, 40 Inner wall part 22 , 41 Rim portion 24 Bolt 30 Core material 30a Male taper surface 40a Female taper surface 42 Adapter ring 42a Female taper surface 42b Male taper surface 46 Holder 46a Tube portion 46b Leg portion 52 Through hole 62 Bottom wall (end wall)
62a, 62b Half body 76 Bracket 80 Male tapered surface S1 Improved body forming step S2 Pile setting step S20 Projection preparing step S22 Core material setting step

Claims (11)

A cylindrical core material to be submerged in an improved body formed by injecting a solidifying material into the ground,
A projection attached to the outer periphery of the core material and protruding in a radial direction of the core material,
The protrusion includes a skeleton that defines a communication path within the protrusion,
The communication path communicates with both sides of the protrusion in the axial direction of the core material,
The ground improvement pile according to claim 1, wherein the skeleton has an outer wall portion extending in an axial direction and a circumferential direction of the core material and defining an outer side of the communication passage in a radial direction of the core material.   The ground improvement pile according to claim 1, wherein the outer wall portion has at least one through hole penetrating the outer wall portion in a radial direction of the core material.   3. The ground improvement pile according to claim 1, wherein the skeleton further includes an end wall partially covering an opening of the communication passage. 4.   The ground improvement pile according to claim 3, wherein the communication passage has an opening closer to the core material than the outer wall portion in a radial direction of the core material. The core is made of concrete,
5. The ground improvement pile according to claim 1, wherein the protrusion is made of a material different from the core material. 6. The ground improvement pile according to any one of claims 1 to 5, wherein the skeleton further includes an inner wall portion that can be fitted to the core material. The core has a small diameter portion and a large diameter portion having a larger diameter than the small diameter portion,
The ground improvement pile according to claim 6, wherein an inner wall portion of the projection is fittable to the small diameter portion. The core material has a male tapered surface whose outer diameter gradually changes,
The inner wall of the projection has a female tapered surface whose inner diameter gradually changes,
The ground improvement pile according to claim 6, wherein the male tapered surface is fittable with the female tapered surface. Further comprising an adapter ring interposed between the male tapered surface and the female tapered surface,
The ground improvement pile according to claim 8, wherein the male tapered surface can be fitted to the female tapered surface via the adapter ring. An improved body forming step of injecting a solidified material into the ground to form an improved body,
A pile setting step of setting the ground improvement pile according to claim 8 or 9 in the improved body,
The pile laying step,
A projection preparing step of coaxially stacking the plurality of projections on the improved body,
A core material depositing step of depositing the core material in the improved body while inserting the core material into the plurality of stacked protrusions,
A method for constructing a ground improvement body, comprising: In a projection configured to be able to be attached to a core material disposed in an improved body formed by injecting a solidifying material into the ground, and configured to project radially from the core material,
Including a skeleton that defines a communication path in the projection,
The communication path communicates with both sides of the protrusion in the axial direction of the core material,
The protrusion of a ground improvement pile, wherein the skeleton has an outer wall portion extending in an axial direction and a circumferential direction of the core material and defining an outer side of the communication passage in a radial direction of the core material.

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