JP6168336B2 - Steel pipe pile embedding method - Google Patents

Description

  The present invention relates to a method for embedding a steel pipe pile which is mainly applied when embedding a steel pipe pile having a small pile diameter in the ground.

  From the standpoint of the support mechanism, the pile foundation for supporting the structure consists of a support pile that secures the support force by penetrating the lower end into a good quality support layer, and the surrounding ground when there is no good quality support layer. Friction piles that secure supporting force by friction are broadly classified, but from the viewpoint of construction method, they are classified as driven piles, embedded piles, cast-in-place piles, etc., and from the viewpoint of pile diameter, φ300 mm or less A pile method called a micropile method using embedded piles or driven piles is known.

  Since the micropile method can be implemented with relatively small construction machines, it has proven itself as an effective method when it is not possible to secure sufficient construction space in confined areas, places with limited heads, mountains, slopes, etc. is there.

  In the case of using a steel pipe pile as an embedded pile in the micropile construction method, first, a drill hole is first formed in the ground, and then a steel pipe pile is built in the drill hole and then grouted below and around the steel pipe pile. Fill the material.

  In this case, the filled grout material is solidified below the steel pipe pile to solidify the steel pipe pile, and the axial force of the steel pipe pile is transmitted to the ground in a dispersed state, and around the steel pipe pile. It solidifies and plays the role which transmits the horizontal force and the frictional force along the surrounding surface of a steel pipe pile between this steel pipe pile and a surrounding ground, and, thereby, the support force of a steel pipe pile is fully ensured.

JP 2001-81770 A

  However, the built-up steel pipe pile may sink due to its own weight, or the steel pipe pile may sink due to the reaction when the casing for protecting the hole wall is pulled out from the drilling hole. A sufficient space for filling grout material is not secured on the lower end side of the steel plate, so that the load distribution effect due to root consolidation is not exerted, and much of the axial force from the steel pipe pile is transmitted directly to the ground without going through root consolidation. As a result, there was a problem that the supporting force in the vertical direction was insufficient.

  Further, when forming the excavation hole obliquely downward, the steel pipe pile built in the excavation hole comes into contact with the hole wall of the excavation hole, and the filling space of the grout material is not secured around it, As a result, not only the above-described vertical support force is insufficient, but also the horizontal support force and the frictional force along the circumferential surface are insufficient.

  In addition, when the steel pipe pile comes into contact with the ground at its lower end or peripheral surface, the steel pipe pile is corroded due to the influence of groundwater in the ground, so that there has been a problem that the cross-sectional design must be performed.

  The present invention has been made in consideration of the above-described circumstances, and provides a method for embedding a steel pipe pile that can reliably form a filling space for a grout material below or in addition to the steel pipe pile. With the goal.

In order to achieve the above object, a steel pipe pile embedding method according to the present invention includes a steel pipe pile built in an excavation hole formed in the ground or an improved body in the ground, as described in claim 1, and the steel pipe pile. In the method of embedding a steel pipe pile in which a grout material is filled between the pile and the bottom surface and hole wall of the excavation hole,
When building the steel pipe pile, by attaching a spacer in advance to the tip of the steel pipe pile, the spacer is interposed between the tip of the steel pipe pile and the bottom surface of the excavation hole, and from the spacer to the steel pipe pile, The penetration means which is the opposite side and extends in the material axis direction of the steel pipe pile is attached to the spacer or the tip of the steel pipe pile .

  Moreover, the embedding method of the steel pipe pile which concerns on this invention performs the filling of the said grout material after the construction of the said steel pipe pile.

  Moreover, the embedding method of the steel pipe pile which concerns on this invention forms the said excavation hole in the said ground facing diagonally downward.

  In order to embed a steel pipe pile using the method of embedding a steel pipe pile according to the present invention, the steel pipe pile is built in the excavation hole formed in the ground or an improved body in the ground, and the bottom face of the steel pipe pile and the excavation hole and The grout material is filled between the hole wall, and in the present invention, when the steel pipe pile is built, a spacer is interposed between the tip of the steel pipe pile and the bottom surface of the excavation hole.

  In this way, the built-in steel pipe pile is held in a state in which the weight or the component in the axial direction of the weight is supported on the bottom surface of the drilling hole via the spacer and the tip is separated from the bottom surface of the drilling hole. .

Therefore, a space for filling the grout material is formed between the tip of the steel pipe pile and the bottom surface of the excavation hole, and the steel pipe pile may sink before the grout material is solidified due to its own weight or pulling out of the casing. Thus, the load dispersing action due to the consolidation is surely exhibited, and accordingly, the supporting force in the vertical direction is sufficiently secured.
Moreover, in the embedding method of the steel pipe pile according to the present invention, the penetration means extending from the spacer to the opposite side of the steel pipe pile and extending in the axial direction of the steel pipe pile is attached to the spacer or the tip of the steel pipe pile. .
In such a configuration, when the steel pipe pile is built in the excavation hole, the penetration means penetrates into the above-mentioned ground or the improved body at the bottom surface of the excavation hole. Positioning is performed, and movement in the direction perpendicular to the material axis is constrained.
Therefore, by separately positioning the steel pipe pile on the base end side, it becomes possible to hold the steel pipe pile in such a way that its peripheral surface does not contact the hole wall of the drilling hole, and there is no concern about strength reduction due to corrosion. It becomes possible to determine the cross section of the steel pipe pile more rationally.
Whether to fill the grout material or build the steel pipe pile is optional. After the grout material is prefilled in the drilling hole, the steel pipe pile is built in the drilling hole before the grout material solidifies. However, in the case where the grout material is filled after the steel pipe pile is built, the grout material filling space is sufficiently secured around the steel pipe pile by the penetration means. A situation in which the supporting force and the frictional force along the circumferential surface are insufficient can be avoided in advance.

  The excavation holes include those formed in the ground, as well as those formed in the ground, for example, soil cement columns. In addition, the construction method for forming the excavation hole is arbitrary. While appropriately selecting an excavation machine such as a boring machine and protecting the hole wall with a casing as necessary, the excavation hole can be appropriately excavated using a known excavation method. That's fine.

  By interposing the spacer between the tip of the steel pipe pile and the bottom surface of the excavation hole, the weight of the steel pipe pile or its axial component can be transmitted to the ground at the bottom surface of the excavation hole. As long as the grout material filling space is reliably formed on the tip side, the configuration and the intervening time are arbitrary, and it is possible to place the steel pipe pile in advance in the excavation hole, but in the present invention Shall be attached to the tip of the steel pipe pile before building the steel pipe pile.

  If it does in this way, since positioning of the spacer with respect to a steel pipe pile becomes easy, it becomes possible to exhibit the effect | action of the spacer of the self-weight support of a steel pipe pile, and ensuring the filling space of a grout material reliably.

  Steel pipe piles are mainly the ones of 300mm or less that are adopted in the micropile method, but the grout material filled on the tip side is solidified and solidified, and the axial force is grounded through the grout material. A steel pipe pile having an outer diameter of more than 300 mm, as long as the horizontal support force and the frictional force along the peripheral surface are ensured by the grout material filled around the outer periphery, It doesn't matter.

  The construction of the steel pipe pile may be performed after forming the excavation hole in advance, or may be performed while forming the excavation hole. Steel pipe piles can be built directly into the excavation hole, or when a casing is installed to protect the hole wall during excavation, Construction is also included.

  Steel pipe piles are included not only in the case of being built in a drilling hole formed vertically downward, but also in the case of being built in a drilling hole formed obliquely downward. Even if there is, since the posture of the steel pipe pile is maintained by the penetration means described above, the peripheral surface of the steel pipe pile is in contact with the hole wall of the excavation hole, or the filling space of the grout material is not secured around the steel pipe pile. There is no risk.

The flowchart which showed the implementation procedure of the embedding method of the steel pipe pile which concerns on this embodiment. It is an arrangement plan of steel pipe pile 1 in the embedding method of the steel pipe pile concerning this embodiment, (a) is a side view and (b) is an arrow line view seen from the AA line direction. Explanatory drawing which showed the procedure which implements the embedding method of the steel pipe pile which concerns on this embodiment. The side surface layout figure which showed the mode after embedding in the embedding method of the steel pipe pile which concerns on a modification. It is the layout of the steel pipe pile 1 in the embedding method of the steel pipe pile which concerns on another modification, (a) is a side view, (b) is the arrow view seen from the BB line direction. The layout of the steel pipe pile 1 in the embedding method of the steel pipe pile which concerns on another modification.

  Hereinafter, an embodiment of a method for embedding a steel pipe pile according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a flowchart showing an implementation procedure of a steel pipe pile embedding method according to the present embodiment. In the steel pipe pile embedding method according to this embodiment, first, as shown in FIG. 2, a spacer 5 is attached to the tip of the steel pipe pile 1 (step 101).

  The steel pipe pile 1 is built in the excavation hole 3 provided in the ground 2 and is not illustrated by being solidified by a grout material filled between the tip and the bottom surface 6 of the excavation hole 3. Axial force, which is a vertical load from the superstructure, can be dispersed and transmitted to the ground 2, and the horizontal support force can be increased by the grout material filled between the hole wall 7 of the excavation hole 3. It is configured to ensure a frictional force along the peripheral surface. For example, it can be configured by a steel pipe pile of approximately 300 mm or less employed in the micropile method.

  The spacer 5 is formed of a cylindrical member whose outer diameter is smaller than the inner diameter of the steel pipe pile 1 and the upper edge thereof is welded to the lower surface of the cross-shaped attachment member 8 spanned over the tip opening of the steel pipe pile 1. The steel pipe pile 1 is fixed with bolts, and when the steel pipe pile 1 is built into the excavation hole 3, the tip of the steel pipe pile can be separated from the bottom surface 6 of the excavation hole 3.

  The spacer 5 can be composed of, for example, a steel pipe pipe, but unlike the steel pipe pile 1 which requires a cross-sectional area and strength sufficient to transmit a vertical load from an unillustrated superstructure to the ground 2, it is filled with a grout material. It is sufficient if the weight of the steel pipe pile 1 can be supported before and after. The spacer 5 may be attached in a state where the steel pipe pile 1 is placed horizontally, for example.

  Next, as shown in FIG. 3 (a), the steel pipe pile 1 with the spacer 5 attached to the tip is built into the excavation hole 3 in which the casing 21 is built (step 102).

  The casing 21 is a casing built in the excavation hole for protecting the hole wall when the ground 2 is excavated with a boring machine by a double pipe to form the excavation hole 3 in the ground. The rod is pulled out and removed beforehand.

  Next, by driving a grout injection device (not shown) connected to the proximal end side of the steel pipe pile 1, a grout material is injected into the hollow space of the steel pipe pile 1 (step 103).

  In this way, as shown in FIG. 3 (b), the steel pipe pile 1 is supported by the bottom surface 6 of the excavation hole 3 through the spacer 5, and the tip is separated from the bottom surface by Δh. Since it is held, the grout material 22 injected into the hollow space of the steel pipe pile 1 passes through the cross-shaped attachment member 8 provided at the front end opening of the steel pipe pile as shown in FIG. 3 (c). The casing 21 is filled in between the tip of the steel pipe pile 1 and the bottom surface 6 of the excavation hole 3 while being partially filled in the cylindrical member constituting the spacer 5, and the casing 21 is pulled out simultaneously. Accordingly, the space between the outer peripheral surface of the steel pipe pile 1 and the hole wall 7 of the excavation hole 3 is filled.

  FIG. 3 (d) shows that the grout material 22 is filled between the tip of the steel pipe pile 1 and the bottom surface 6 of the excavation hole 3 and between the outer peripheral surface of the steel pipe pile and the hole wall 7 of the excavation hole 3. Is shown.

  As described above, according to the method for embedding a steel pipe pile according to the present embodiment, the steel pipe pile 1 built in the excavation hole 3 has its own weight through the spacer 5 and the bottom surface 6 of the excavation hole 3. And the tip is held in a state of being separated from the bottom surface 6 of the excavation hole 3.

  Therefore, a filling space for the grout material 22 is reliably formed between the tip of the steel pipe pile 1 and the bottom surface 6 of the excavation hole 3, and the steel pipe pile before the grout material 22 is solidified due to its own weight or the pulling out of the casing. Therefore, the grout material 22 solidified between the tip of the steel pipe pile 1 and the bottom surface 6 of the excavation hole 3 solidifies the steel pipe pile 1 in such a way that a load dispersing action is exerted. Sufficient support force in the vertical direction is ensured.

  Moreover, according to the embedding method of the steel pipe pile concerning this embodiment, since the spacer 5 was attached to the front-end | tip of this steel pipe pile before building the steel pipe pile 1, positioning of the spacer 5 with respect to the steel pipe pile 1 is easy. Thus, it is possible to reliably exert the action of the spacer 5 for supporting the weight of the steel pipe pile 1 and securing the filling space for the grout material 22.

  In this embodiment, after the steel pipe pile 1 is built, the grout material 22 is injected through the hollow space of the steel pipe pile. Instead, the grout material 22 is injected into the excavation hole 3 first. Then, the steel pipe pile 1 may be built in the excavation hole 3 before the grout material 22 is solidified.

  Further, in this embodiment, the excavation hole 3 is directly formed in the ground 2, but instead, as shown in FIG. 4, a soil cement column 41 as an improved body is formed on the ground 2. The steel pipe pile 1 may be embedded in the ground 2 by forming the excavation hole 3 in the soil cement pillar and then performing the same steps as described above.

  Although not specifically mentioned in the present embodiment, the spacer 5 is configured when the spacer 5 is recessed into the bottom surface 6 of the excavation hole 3 and the tip of the steel pipe pile 1 may not be sufficiently separated from the bottom surface 6. What is necessary is just to take measures appropriately to relieve stress concentration on the bottom surface 6, such as increasing the thickness of the cylindrical member or providing a flange on the lower edge of the cylindrical member.

  In the present embodiment, the ground 2 is excavated by a double pipe with a boring machine to form the excavation hole 3 in the ground. However, if there is no need for hole wall protection, double pipe excavation is performed. Alternatively, single pipe drilling may be used. In that case, since it is not necessary to use the casing 21, it is not necessary to pull out the casing 21.

  Moreover, in this embodiment, when the steel pipe pile 1 is built in the excavation hole 3, the steel pipe pile 1 is installed so that it may become substantially coaxial with the hole axis of the excavation hole 3 by using the casing 21 as a construction guide. Although the description has been made on the assumption that the coaxial arrangement of the steel pipe pile 1 is maintained by the casing 21 when the grout material 22 is injected, the steel pipe pile 1 of the steel pipe pile 1 is injected when the grout material is injected, for example, because the casing 21 is not provided. When there is a possibility that the coaxial arrangement may not be maintained, as shown in FIG. 5, a positioning rod 51 serving as a penetrating means extending from the spacer 5 to the side opposite to the steel pipe pile 1 and in the material axis direction of the steel pipe pile is used. It should just be made to attach to the tip of steel pipe pile 1 in the form which penetrates.

  The positioning rod 51 can be composed of, for example, a reinforcing bar whose proximal end is welded to the intersection of the attachment member 8 having a cross shape.

  In such a configuration, when the steel pipe pile 1 is built into the excavation hole 3 while using a guide or a leader (not shown) as necessary, the positioning rod 51 penetrates into the ground 2 at the bottom surface 6 of the excavation hole 3. The steel pipe pile 1 is positioned on the ground 2 in the vicinity of its tip, and the movement in the direction perpendicular to the material axis is constrained.

  Therefore, by separately positioning the steel pipe pile 1 also on its proximal end side, it becomes possible to maintain the posture of the steel pipe pile 1 so that the peripheral surface thereof does not come into contact with the hole wall 7 of the excavation hole 3 when the grout material is injected. Thus, a sufficient space for filling the grout material 22 around the steel pipe pile 1 can be secured, and as a result, a situation in which the horizontal supporting force and the frictional force along the circumferential surface are insufficient is avoided. be able to.

  In addition, since the periphery of the steel pipe pile 1 is reliably covered with the grout material 22, it is possible to prevent the corrosion of the steel pipe pile or to suppress the progress thereof, and thus when the cross-section design of the steel pipe pile 1 is performed. In addition, it is not necessary to anticipate the corrosion caused by the groundwater of the ground 2 and the thickness of the steel pipe pile can be reduced.

  Moreover, in this embodiment, although the case where the steel pipe pile 1 was embedded in the ground 2 facing perpendicularly downward was demonstrated, it replaces with this and, as shown in FIG. It may be embedded.

  In this case, the steel pipe pile 1 may be embedded in the ground 2 in substantially the same procedure as in the embodiment described above. However, as in the modification according to FIG. A positioning rod 51 extending in the material axis direction of the steel pipe pile is attached to the tip of the steel pipe pile 1 so as to penetrate the spacer.

  In such a configuration, when the steel pipe pile 1 is built in the excavation hole 3 using a guide or a leader (not shown), the positioning rod 51 is penetrated into the ground 2 at the bottom surface 6 of the excavation hole 3. In the vicinity of the tip, the material is positioned on the ground 2, and the movement in the direction perpendicular to the material axis is restricted.

  Therefore, even if it is a case where the steel pipe pile 1 is built in the diagonally downward direction by positioning the steel pipe pile 1 also in the base end side similarly to the modification shown in FIG. In addition, it is possible to secure a sufficient space for filling the grout material 22, thereby ensuring a horizontal support force and a frictional force along the circumferential surface, and eliminating the need to anticipate corrosion of the steel pipe pile 1. It is also possible to rationally determine the cross section of the pile.

DESCRIPTION OF SYMBOLS 1 Steel pipe pile 2 Ground 3 Excavation hole 5 Spacer 6 Bottom surface 7 Hole wall 22 Grout material 41 Improved body 51 Positioning rod (penetration means)

Claims (3)

In the method of embedding a steel pipe pile, the steel pipe pile is built in the excavation hole formed in the ground or an improved body in the ground, and the grout material is filled between the steel pipe pile and the bottom surface and the hole wall of the excavation hole.
When building the steel pipe pile, by attaching a spacer in advance to the tip of the steel pipe pile, the spacer is interposed between the tip of the steel pipe pile and the bottom surface of the excavation hole, and from the spacer to the steel pipe pile, A method for embedding a steel pipe pile, characterized in that a penetration means extending on the opposite side and extending in the axial direction of the steel pipe pile is attached to the spacer or the tip of the steel pipe pile. The steel pipe pile embedding method according to claim 1, wherein the grout material is filled after the steel pipe pile is installed. The method for embedding a steel pipe pile according to claim 1 or 2, wherein the excavation hole is formed in the ground with an oblique downward direction.

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