JP3122889U - Foundation pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently install a foundation pile built inside a steel pipe pile by pulling out a steel pipe pile used for excavation and to reuse the steel pipe pile, thereby reducing the construction cost. Providing foundation piles that can be reduced in price.
A steel pipe pile 6 is provided with a bayonet joint that is held in engagement with a head 4 by rotation in a fixed direction at a lower end thereof, and is a solid solid inserted from the upper opening end of the steel pipe pile 6 in a loosely fitted state. The molded body 2 and the head 4 having the solid molded body 13 mounted in the insertion hole 4a formed in the center, and the lower end portion of the solid molded body 2 is disposed in the head insertion hole 4a. When the foundation pile 1 is constructed by joining to the solid molded body 13, the steel pile pile 6 is reversely driven and separated from the head 4 by the bayonet joint and pulled out from the ground G. Is configured to be buried in the excavation ground G.
[Selection] Figure 1

Description

  The present invention relates to a foundation pile embedded in a ground excavated by a rotational drive in a certain direction and a straight movement of a steel pipe pile connected to a head having a drilling blade at the lower end.

  Conventionally, as this type of foundation pile, a spiral excavation blade is provided on the outer periphery of a pipe pile body composed of steel pipes, etc., and a plate-like bottom lid member is engaged with the locking means inside the bottom of the pipe pile body. A stopped rotary press-fit steel pipe pile is used (see Patent Document 1).

  This rotary press-fit steel pipe pile is propelled to the ground while rotating the excavating blades forward, and when the bottom of the rotary press-fit steel pipe pile reaches the support layer, the rotary press-fit steel pipe pile is slightly reversed to reverse the bottom cover. The member is opened, and the excavated soil is discharged through the inside of the rotary press-fit steel pipe pile while propelling it again by forward rotation, and is buried in the ground by being rooted at an appropriate depth in the support layer.

JP 2000-11178 A

  The above-mentioned rotary press-fit steel pipe pile is used as a foundation pile while being embedded in the excavated ground as it is, while being sequentially connected according to the excavation depth and extending until it hits the support layer. .

  By the way, since this rotary press-fit steel pipe pile is expensive, such as a general structural carbon steel pipe or a building structural carbon steel pipe as a material having strength, if it is used in large numbers, the construction cost increases, which is uneconomical. Therefore, the construction cost has been required to be reduced.

  The present invention has been made paying attention to such a demand, and by pulling out the steel pipe pile used for excavation, the foundation pile constructed inside the steel pipe pile is efficiently installed in the excavation hole. In addition, an object is to provide a foundation pile capable of realizing a reduction in construction cost by reusing the steel pipe pile.

In order to solve the above-mentioned object, a foundation pile 1 according to claim 1 of the present invention is excavated by rotating and driving in a fixed direction with a head 4 having a drilling blade connected to the lower end of a steel pipe pile 6. In the foundation pile 1 embedded in the ground G, the steel pipe pile 6 is provided with a locking means that is held in engagement with the head 4 by rotation in a fixed direction at the lower end thereof. A cylindrical molded body 13 having a cylindrical molded body 2 inserted in a loosely fitted state from the upper opening end and the head 4 having an insertion hole 4a formed at the center thereof, and mounted in the insertion hole 4a of the head 4. The lower end of the cylindrical molded body 2 is joined to form the foundation pile 1, and the steel pipe pile 6 is driven reversely to be detached from the head 4 by the locking means and pulled out from the ground G. The foundation pile 1 is buried in the excavation ground G. It is the foundation pile according to claim.
According to the foundation pile described above, the head 4 provided with the excavating blade 5 is connected to the lower end of the steel pipe pile 6 via the locking means, and the ground G is excavated by rotational driving and linear movement in a certain direction. When excavating the ground G, the lower end portion of the cylindrical molded body 2 inserted in a loosely fitted state from the upper opening end of the steel pipe pile 6 is joined to the cylindrical molded body 13 mounted in the insertion hole 4 a of the head 4. Thus, the foundation pile 1 integrated with the head 4 is constructed. After excavation, the foundation pile 6 is embedded in the excavation ground G when the steel pipe pile 6 is driven reversely and detached from the head 4 by the locking means and pulled out from the ground G.

The foundation pile according to claim 2 of the present invention is a foundation pile in which the cylindrical molded body 2 is formed of foamed resin.
According to said foundation pile, the thing of the required fixed length is selected from what was shape | molded in the column shape with the commercially available foamed resin, or it cut | disconnects and uses it for required length.

The foundation pile according to claim 3 of the present invention is characterized in that the cylindrical molded body 2 is formed of waste plastic.
According to the foundation pile described above, a commercially available waste plastic formed into a cylindrical shape is selected to have a necessary fixed length, or is cut into a required length and used.

The foundation pile according to claim 4 of the present invention is a foundation pile in which the cylindrical formed body 2 is formed of rubber.
According to said foundation pile, the thing of the required fixed length is selected from what was shape | molded in the column shape with the commercially available rubber | gum, or it cut | disconnects and uses it for required length.

In the foundation pile according to claim 5 of the present invention, the locking means includes a locking piece 10 projecting from the upper outer periphery of the head 4, and an opening at the lower end of the steel pipe pile 6. A longitudinal groove 12a formed in a straight line with a width that allows the engagement piece 10 to be inserted in order to be guided in the axial direction, and the engagement piece 10 extending in the lateral direction from the bottom of the abutment of the longitudinal groove 12a. Is formed of a locking groove 12 formed in a key shape from a lateral groove 12b having a height that can be inserted and formed at least substantially the same depth as the width of the locking piece 10. It is a foundation pile.
According to the foundation pile, the steel pipe pile 6 at the time of excavation has a locking groove 12 formed in a key shape at the lower end of the steel pipe pile 6 and the head 4 when the head 4 rotates in the same direction as the excavation direction. The steel pipe pile 6 at the time of completion of excavation is pulled out on the ground G by releasing the locking piece 10 of the head 4 from the locking groove 12 by the reverse drive.

The foundation pile according to claim 6 of the present invention is a foundation pile in which a reinforcing member 14 is welded to the side wall at the lower end of the steel pipe pile 6 so as to straddle the longitudinal groove 12a.
According to said foundation pile, according to said foundation pile, at the time of excavation, opening of vertical groove 12a is carried out by reinforcement member 14 by the excavation load of the excavation direction and rotation direction which the lower end of said steel pipe pile 6 receives from ground G Is prevented.

  The present invention has the following effects.

  According to the invention described in claim 1, a cylindrical molded body in which a lower end portion of a cylindrical molded body inserted in a loosely fitted state from an upper opening end of a steel pipe pile used for excavation is mounted in an insertion hole of a head. It is possible to install the foundation pile in the excavation ground efficiently by providing the foundation pile that is joined and integrated to the ground, and pulling out the steel pipe pile from the ground. it can.

  According to the second aspect of the present invention, as the cylindrical molded body, a commercially available foamed resin molded into a solid cylindrical shape is used. Therefore, processing and construction work are facilitated, and the total cost is reduced. Can be planned.

  According to the third aspect of the present invention, as the cylindrical molded body, a commercially available waste plastic molded into a solid cylindrical shape is used, so that processing and construction work can be facilitated and the total cost can be reduced. Can be planned.

  According to the fourth aspect of the present invention, as the cylindrical molded body, a commercially available rubber molded into a solid cylindrical shape is used. Therefore, processing and construction work are facilitated, and the total cost is reduced. be able to.

  According to the invention described in claim 5, the locking groove formed in a key shape at the lower end of the steel pipe pile and the locking piece of the head are configured to engage in the same direction as the head excavation direction. Therefore, when the ground is excavated, the engagement state with the head is securely maintained, and when the excavation is completed, the engagement state with the head is released by driving the steel pipe pile in reverse, so only the steel pipe pile is removed from the ground. It can be pulled out and construction work becomes easy.

  According to the invention described in claim 6, by providing a reinforcing member straddling the longitudinal groove, the longitudinal groove is opened by the excavation load in the advancing direction and the rotational direction received by the lower end of the steel pipe pile from the ground during excavation. The action can be prevented.

  An embodiment of the present invention will be described below.

  1 and 2 show an embodiment of the present invention. FIG. 1 is an external view showing a partial cross section of a steel pipe pile in which a foundation pile according to an embodiment is installed, FIG. 2 is a front view of the steel pipe pile viewed from the head side provided with a drilling blade, and FIG. It is sectional drawing of the steel pipe pile by which the foundation pile was equipped.

  1 to 3, 6 is a steel pipe pile having a required diameter determined in advance according to the depth of excavation and the quality of the ground composed of a carbon steel pipe for general structure or a carbon steel pipe for building structure. The steel pipe pile 6 has, for example, an outer diameter of about 100 mm to 500 mm, a thickness of 4.5 mm to 12.7 mm, and a unit length of 3 m to 12 m. A head 4 made of cast steel having a drilling blade 5 at the lower end is connected as a locking means via, for example, a bayonet joint. In addition, the one excavating blade 5 provided in the head 4 may be constituted by an excavating blade having a configuration in which two blades are crossed and a spiral blade attached to the outer periphery of the head. it can.

  The bayonet joint has a rectangular locking piece 10 (black portion in the figure) projecting on the upper outer periphery of the head 4 and an opening at the lower end of the steel pipe pile 6 to guide the locking piece 10 in the axial direction. A vertical groove 12a formed in a straight line with a width that allows the engagement piece 10 to be inserted, and a height extending from the bottom of the abutment of the vertical groove 12a in a horizontal direction so that the engagement piece 10 can be inserted. And a locking groove 12 formed in a key shape (inverted L-shape) from a lateral groove 12b formed at least substantially the same depth as the width of the locking piece 10. In addition, although the example which used the bayonet coupling as the detachable engaging means was demonstrated, joining by a screw is also possible besides this.

  A pressing ring 8 is joined to the outer periphery of the head 4 below the locking piece 10. When the pressing ring 8 is inserted into a steel pipe pile 6 to be described later from the upper end of the head 4, When the locking piece 10 on the outer periphery of the head 4 is inserted into the vertical groove 12a, the locking piece 10 is positioned so that the horizontal groove 12b corresponds.

  A reinforcing member 14 is welded to the side wall of the lower end of the steel pipe pile 6 so as to straddle the vertical groove 12a, thereby preventing the vertical groove 12a from being opened due to a load acting during ground excavation.

  According to the bayonet joint configured as described above, the state of engagement with the head 4 is reliably maintained at the time of ground excavation, and when the excavation is completed, the steel pipe pile 6 is driven in reverse to engage with the head 4. Since the state is released, only the steel pipe pile 6 can be pulled out from the ground G, and the construction work becomes easy.

  The steel pipe pile 6 which connected the head 4 provided with the digging blade 5 in the lower end is formed in the outer periphery of the socket (not shown) which mentions an upper and lower steel pipe pile 6 later, or the opposite end face of the steel pipe pile 6 according to a digging depth. The steel pipe pile 6 is constructed so that it can be stretched by fitting the concave-convex grooves and sequentially joining them in the axial direction. The steel pipe pile 6 has a foundation slightly smaller in diameter than the inner diameter of the steel pipe pile 6 according to the present invention. The pile 1 is inserted in a loosely fitted state from the upper opening end, and the foundation pile 1 is also a joining means to be described later using an adhesive or the like in the same manner as the steel pipe pile 6 according to the excavation depth. It is possible to extend by joining sequentially through the.

  Here, the coupling of the steel pipe piles 6 by the socket is a coupling method in which the thick part is fastened in the direction perpendicular to the axial direction from the outer periphery of the socket into which the upper and lower steel pipe piles 6 are inserted, The axial fitting between the concave and convex grooves means that axial concave and convex grooves formed at regular intervals on the outer peripheral surfaces of the opposing end faces of the upper and lower steel pipe piles 6 are inserted into each other so that the axial pressing force and rotational force are increased. It is a coupling method for communicatively coupling. In addition, although the said steel pipe pile 6 and the foundation pile 1 change with the quality of the ground G excavated, and the excavation capability of an excavator, the thing of a single required length can also be used.

  The foundation pile 1 includes a solid molded body 2 formed as a cylindrical molded body of a petrochemical material (for example, a foamed resin system, a rubber system, and a plastic system), and a lower end portion of the solid molded body 2 is the head 4. The solid molded body 13 mounted in the insertion hole 4a via an adhesive and the solid molded body 13 and the adhesive B are integrally joined to form a rigid body.

  In this embodiment, the solid molded body 2 is made of a commercially available foamed resin that is molded as a solid molded body. The thing of length can be used selectively.

  Here, the joining means J for joining and extending the solid molded bodies 2 constituting the foundation pile 1 in sequence will be described. As this joining means J, in this embodiment, the end portions where the adhesive B is applied to the flat surface perpendicular to the axis of the solid molded body 2 facing each other are inserted into the socket SC where the adhesive is applied to the inner periphery. A means for fitting and joining the both ends abutting and joining together is employed. Similarly, in the head 4, the lower end of the solid molded body 2 is formed by a foamed resin cylindrical molded body 13 that is mounted in advance in the head 4 via the adhesive B by the bonding means J. The foundation pile is constructed as a rigid body by being integrally joined via the adhesive B.

  Next, a modification of the joining means J will be described. FIG. 4 is a cross-sectional view showing a state in which the foundation piles are joined together by fitting the concave grooves formed on the joining end faces facing each other as a modification of the joining means and the protrusions, and FIG. It is explanatory drawing which shows the state joined via a socket by fitting of a protrusion part.

As shown in FIG. 4 and FIG. 5, the joining means J according to this modified example is formed with concave grooves 15 a and ridges 15 b crossing the axis perpendicular to both end surfaces of the solid molded body 2 constituting the foundation pile 1, respectively. Then, an adhesive is applied to the concave grooves 15a and the ridges 15b facing each other, and the ends of the solid molded body 2 to be joined to the socket SC coated with the adhesive on the inner periphery are inserted, Means is adopted in which the concave grooves 15a and the protrusions 15b are fitted together to integrally join the solid molded bodies 2 together.
Similarly, in the head 4, the lower end of the solid molded body 2 is recessed with a cylindrical molded body 13 made of foamed resin that is mounted in the head 4 through the adhesive B in advance by the bonding means J. The groove 15a and the ridge portion 15b are fitted, and are integrally joined via the adhesive B to construct the foundation pile 1 as a rigid body.

  Next, other modified examples of the joining means J are shown in FIGS. 6 to 9, and FIG. 6 shows a partial cross-section of a steel pipe pile having a foundation pile joined by the joining means of the other modified examples. FIG. 7 is a cross-sectional view of a steel pipe pile including a foundation pile joined by a joining means of another modification, and FIG. 8 shows a state in which the foundation piles are joined by the joining means of another modification. FIG. 9 is an explanatory view, and FIG. 9 is an external view of a steel pipe pile including a foundation pile in which the foundation piles are joined by joining means of another modification.

  In FIG. 6, reference numeral 20 denotes a cylindrical solid molded body that becomes the foundation pile 18 used in the present modification, and this solid molded body 20 is integrated with, for example, a reinforcing resin S inside a foamed resin. In general, a molded product having a fixed length or a product cut to a required length is used.

  Therefore, the joining means J in the present modified example is formed with a concave groove 15a and a ridge 15b crossing the central axis on both end faces of the solid molded body 20 in the same manner as in the modified example. An insertion hole 21 having substantially the same depth as the bottom surface of the groove 15a of the solid molded body 20 is formed at one end of the solid molded body 20, and substantially the same height as the protrusion 15b protruding from the other end surface of the solid molded body 20. The protrusion 22 is formed in the center, and an adhesive is applied to the concave groove 15a and the protrusion 15b of the solid molded body 20 facing each other, and the insertion hole 21 and the columnar protrusion 22 to fit each other. Thus, means for integrally joining the solid molded bodies 2 is employed. In addition, the said insertion hole 21 and the protrusion part 22 may be not only a circular cross section but a polygonal cross section, for example, can also be comprised in a hexagonal cross section.

  Similarly, the head 4 protrudes from the upper surface of the solid molded body 13 ′ of the head 4 facing the insertion hole 21 at the lower end of the solid molded body 2 by the joining means J as shown in FIG. While the part 22 fits in, the concave groove 15a and the ridge part 15b also fit in each other, and are joined together via the adhesive B to construct the foundation pile 1 as a rigid body. Note that both ends of the solid molded body 20 to be joined to each other can be joined via the socket SC as described above.

  Note that the reinforcing bar S that is integrally mounted in the solid molded body 20 and the reinforcing bar S ′ in the solid molded body 13 ′ made of foamed resin that is mounted in the insertion hole 4 a of the head 4. Each member is joined by a general connection method such as annealing, iron wire, or welding.

  As described above, the step of forming the insertion hole 21, the protrusion 22, the groove 15 a and the protrusion 15 b at both ends of the solid molded body 20, and the solid molded body 13 ′ inside the head 4 are formed. The mounting step or the step of joining a plurality of solid molded bodies 20 with an adhesive is performed in the factory, and the solid molded body 20 integrated with the head 4 is connected to the steel pipe pile 6. The excavation proceeds in the ground G while stopping and rotating in a certain direction together with the steel pipe pile 6.

  The solid molded bodies 2 and 20 constituting the foundation piles 1 and 18 described so far have been described with respect to an example of molding using a commercially available foamed resin, but not limited to this, waste plastic may be used, Of course, it is possible to mold with hard vinyl chloride or rubber.

  Next, the operation of the bayonet joint serving as the engagement means will be described with reference to FIGS. 10 (a) to 10 (c). FIG. 10A is an explanatory view showing a state in which the steel pipe pile and the head are engaged during ground excavation, and FIG. 10B is an explanatory view showing a state in which the engagement between the steel pipe pile and the head is released at the end of ground excavation. These are explanatory drawings which show the state in which the steel pipe pile is detached from the head and pulled out by disengagement at the end of ground excavation.

  10A, when excavating the ground, the lower end of the steel pipe pile 6 is inserted into the upper end of the head 4 provided with the excavating blade 5 by moving in the excavating direction, and the vertical groove 12a at the lower end of the steel pipe pile 6 is inserted into the vertical groove 12a. The locking piece 10 on the outer periphery of the head 4 is inserted and engaged.

  Further, when the lower end of the steel pipe pile 6 is moved in the axial direction and brought into contact with the pressing ring 8 on the outer periphery of the head 4, the locking piece 10 reaches the abutting bottom at the upper end of the vertical groove 12a, and the steel pipe pile 6 is excavated. The locking piece 10 is engaged with the lateral groove 12b by rotating clockwise in the direction.

  When the locking piece 10 is engaged with the lateral groove 12b, the excavator is driven to rotate the excavating blade 5 of the head 4 clockwise through the steel pipe pile 6 and the excavation of the ground is started by the straight movement. The The process at the time of ground excavation will be described later. After the ground excavation work is completed, the steel pipe pile 6 and the head 4 are stopped from rotating clockwise, and then the steel pipe pile 6 is rotated counterclockwise as shown in FIG. As shown in b), the locking piece 10 is detached from the lateral groove 12b.

  Next, when the steel pipe pile 6 is pulled up from the top surface of the ground by pulling the steel pipe pile 6 upward, a plurality of pieces (two in the embodiment) are formed together with the head 4 in the steel pipe pile 6. ) And the foundation solid pile 1 (or the foundation pile 18) integrated with the lower and upper solid molded bodies 2a and 2b are embedded in the ground.

  Thus, according to the foundation pile which concerns on an Example, the column-shaped solid molded object 2 and 20 comprised with the foamed resin etc. which are marketed are inserted in the loose fitting state from the upper opening end of a steel pipe pile. It is constructed as a foundation pile 1 and 18 which is integrated by joining its lower end to a cylindrical solid molded body 13 and 13 'mounted in the head 4, and the steel pipe pile 6 is driven in reverse after ground excavation. Thus, the foundation piles 1 and 18 can be efficiently installed in the excavated ground by being separated from the head 4 and pulled out from the ground G by the locking means, and can be provided as an inexpensive foundation pile.

  Next, it attaches to the process of building a foundation pile in the ground, and demonstrates with reference to Fig.11 (a)-(e). FIGS. 11A to 11E are explanatory views of a process for constructing a foundation pile in the ground.

  Here, it demonstrates as an example which builds the foundation pile 1 which consists of the solid molded object 2 comprised with the foaming resin mentioned above. The foundation pile 1 has a different embedding depth depending on the quality of the ground, and is determined as a length from a soft ground G layer to a rock bed that becomes a stable support layer R. FIG. 11 shows an example in which two constant length steel pipe piles 6a and 6b are connected and excavated until the excavating blade 5 of the head 4 reaches the support layer R.

  First, in FIG. 11A, the excavation blade 5 provided in the head 4 locked to the lower end of the first lower steel pipe pile 6a is dug into the soft ground G by clockwise rotation and straight movement, and the upper end of the ground G is When moved to the vicinity of the upper surface, as shown in FIG. 11 (b), the lower solid molded body 2a made of foamed resin is inserted in a loosely fitted state from the upper end opening of the lower steel pipe pile 6a, and the lower end thereof is the head. 4 is joined to a cylindrical molded body 13 of the same kind of material, which is mounted in advance in the insertion hole 4a, with an adhesive B or the like, and is configured integrally with the head 4.

  In FIG. 11 (c), when the lower end of the upper steel pipe pile 6b is joined to the upper end of the first lower steel pipe pile 6a via a socket or an uneven portion (not shown), the excavating blade 5 is rotated clockwise and moved straight. The inside of the soft ground G is further dug, and the excavation blade 5 reaches a stable support layer R as shown in FIG.

  In this state, the upper end of the upper steel pipe pile 6b is in a state slightly protruding from the upper surface of the ground, and the upper solid molded body 2b is inserted in a loose fit state from the upper end opening of the upper steel pipe pile 6b, and the lower end thereof The upper part of the lower solid molded body 2a is integrally joined to the upper end of the lower solid molded body 2a via a socket or an uneven part, and the upper end part is located in the vicinity of the upper opening of the upper steel pipe pile 6b.

  Next, as shown in FIG. 11 (e), the lower steel pipe pile 6a and the upper steel pipe pile 6b that are integrally joined to each other are rotated counterclockwise so that the lower end of the lower steel pipe pile 6a is headed by the bayonet joint. 4 and the bottom steel pipe pile 6a and the upper steel pipe pile 6b are pulled out from the ground G, so that the foundation is composed of the upper solid molded body 2b, the lower solid molded body 2a and the head 4 inserted therein. The pile 1 will be buried in the excavated ground G. Then, the excess protrusion part of the upper solid molded object 2b used as the foundation pile 1 protruded from the ground upper surface is cut off at a position lower than at least the ground upper surface.

It is an external view which shows the partial cross section of the steel pipe pile by which the foundation pile which concerns on the Example of this invention was equipped internally. It is a front view of the steel pipe pile seen from the head side provided with the excavation blade. It is sectional drawing of the steel pipe pile by which the foundation pile which concerns on the Example of this invention was equipped. It is sectional drawing which shows the state by which the foundation pile was joined by the fitting of the ditch | groove formed in the joining end surface which faces as a modification of a joining means, and a protrusion part. It is explanatory drawing which shows the state by which a foundation pile is joined via a socket by the fitting of a ditch | groove and a protrusion part. It is an external view which shows the partial cross section of the steel pipe pile which equipped the foundation pile joined by the joining means of the other modification. It is sectional drawing of the steel pipe pile which equipped the foundation pile joined by the joining means of the other modification. It is explanatory drawing which shows the state in which foundation piles are joined by the joining means of another modification. It is an external view of the steel pipe pile which equipped the foundation pile by which the foundation pile was joined by the joining means of the other modification. (A) is explanatory drawing which shows the state which the steel pipe pile and the head engaged at the time of ground excavation, (b) is explanatory drawing which shows the state which the engagement of the steel pipe pile and the head was cancelled | released at the end of ground excavation, (c) is the ground It is explanatory drawing which shows the state which a steel pipe pile detaches | leaves from a head and is pulled out by the cancellation | release of engagement at the time of completion | finish of excavation. (A)-(e) is explanatory drawing of the process of constructing a foundation pile in the ground.

Explanation of symbols

1,18 Foundation pile 2 Solid compact (cylindrical compact)
2a Lower solid molded body 2b Upper solid molded body 4 Head 4a Insertion hole 5 Drilling blade 6 Steel pipe pile 6a Lower steel pipe pile 6b Upper steel pipe pile 8 Pushing ring 10 Locking piece 12 Locking groove 12a Vertical groove 12b Horizontal groove 13 , 13 'Solid molded body (cylindrical molded body)
14 Reinforcing member 15a Concave groove 15b Projection portion 20 Solid molded body (cylindrical molded body)
21 Insertion hole 22 Protruding part B Adhesive G Ground J Joining means R Support layer S, S 'Rebar SC Socket

Claims (6)

In the foundation pile 1 which is embedded in the ground G excavated by rotating in a certain direction and moving straight, by connecting a head 4 having a drilling blade to the lower end of the steel pipe pile 6,
The steel pipe pile 6 is provided with a locking means that is held in engagement with the head 4 by rotation in a fixed direction at the lower end thereof, and the cylindrical molded body 2 inserted in a loosely fitted state from the upper opening end of the steel pipe pile 6. And the head 4 having the insertion hole 4a formed at the center, and the lower end portion of the columnar molded body 2 is joined to the columnar molded body 13 mounted in the insertion hole 4a of the head 4. Made up of pile 1,
The foundation pile 1 is embedded in the excavation ground G when the steel pipe pile 6 is driven reversely and separated from the head 4 by the locking means and pulled out from the ground G. A foundation pile characterized by The foundation pile according to claim 1, wherein the cylindrical molded body 2 is formed of a foamed resin. The foundation pile according to claim 1, wherein the cylindrical molded body 2 is formed of waste plastic. The foundation pile according to claim 1, wherein the cylindrical formed body 2 is formed of rubber. The locking means includes a locking piece 10 projecting from the upper outer periphery of the head 4 and an opening at the lower end of the steel pipe pile 6 to insert the locking piece 10 to guide the locking piece 10 in the axial direction. A vertical groove 12a formed in a straight line with a possible width, and a height extending from the abutting bottom of the vertical groove 12a in a lateral direction so that the locking piece 10 can be inserted. The foundation pile according to claim 1, comprising a locking groove 12 formed in a key shape from a lateral groove 12 b formed with a width of 10 and at least substantially the same depth. The foundation pile according to claim 5, wherein a reinforcing member 14 is welded to the side wall of the lower end of the steel pipe pile 6 so as to straddle the longitudinal groove 12a.

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