Bored pile structure and bored pile construction method

Abstract

To propose a new bored pile structure and a method for making the bored pile structure.SOLUTION: A bored pile structure of this invention comprises a foot protection material filled in a pile hole, and a steel pipe pile inserted into the foot protection material, the steel pipe pile comprising a first steel pipe section and a second steel pipe section, wherein a first flange section having a larger diameter than the first steel pipe section is provided at an end of the first steel pipe section, a second flange section having a larger diameter than the second steel pipe section is provided at an end of the second steel pipe section, and the first flange section and the second flange section are mechanically connected.SELECTED DRAWING: Figure 13

Description

[Technical Field]

[0001] The present invention relates to a bored pile structure and a bored pile construction method. [Background technology]

[0002] In urban areas, the bored pile method is often chosen due to its quietness and low vibration characteristics. In this buried pile method, pile holes are drilled in the ground using an auger or similar tool, and then filled with cement milk. A prefabricated pile made of concrete or steel pipe is then buried in the hole before the cement milk hardens. BACKGROUND ART Precast piles are known that have convex portions on their circumferential surfaces in order to improve the bonding strength between the precast pile and cement milk, which serves as a base protection material (see Patent Documents 1 and 2). See also Patent Document 3, which discloses technology related to the present invention. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-124991 [Patent Document 2] Japanese Patent Application Publication No. 09-031982 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-302940 Summary of the Invention [Problem to be solved by the invention]

[0004] When steel pipe piles are used as precast piles, the length of the pile body is limited to, for example, 6 to 8 m due to constraints on pile length imposed by the machine used to install the piles, constraints on storage space at the construction site, and constraints on length during transportation. For lengths exceeding this, the pile is extended as it is drilled. The lower end of the succeeding pile is connected to the upper end of the previously buried pile. This connection has traditionally been achieved by welding. Generally, the length of piles required in urban areas is short, and when preparing prefabricated piles of, for example, 8m, the excess length must be cut off, which is wasteful. When driving piles into inclined ground, precast piles of various lengths are required.

[0005] If several short steel pipe piles (1 to 5 m) are prepared in advance and then connected together, it is possible to prevent the piles from having to be cut off and to adjust the length according to the ground conditions. However, welding the end faces of steel pipe piles on-site is time-consuming and may unnecessarily extend the construction period. There is also a risk that the base protection material will harden and hinder the embedding of the steel pipe piles, which may increase construction costs and reduce quality. [Means for solving the problem]

[0006] The present invention solves the above problems, and its first aspect is defined as follows: A foot protection material filled in the pile hole; A steel pipe pile inserted into the foot protection material, comprising a first steel pipe portion and a second steel pipe portion, a first flange portion having a larger diameter than the first steel pipe portion provided at an end of the first steel pipe portion, and a second flange portion having a larger diameter than the second steel pipe portion provided at an end of the second steel pipe portion, A buried pile structure, wherein the first flange portion and the second flange portion are mechanically connected to each other.

[0007] In the bored pile structure of the first aspect defined as above, the first steel pipe section and the second steel pipe section are mechanically connected by the first flange section and the second flange section. Generally, bolting can be used as the mechanical connection. By using such a mechanical connection, the labor required for connection is significantly reduced compared to welding, and the bored pile structure itself can be constructed in a short time and at low cost. Furthermore, since the first flange portion and the second flange portion have a larger diameter than the first steel pipe portion and the second steel pipe portion, respectively, these flange portions bite into the base reinforcement material, improving the bonding strength between the prefabricated pile and the base reinforcement material, and therefore improving the supporting capacity of the building.

[0008] As the pile hole becomes deeper, it takes longer to fill it with cement milk or other foot protection material, which can cause some of the cement milk to become harder. Therefore, a blade is provided at the tip of the steel pipe pile, and the connecting part between the first and second steel pipe sections is required to have high mechanical strength. Here, the part where the flanges are connected has higher rigidity than each steel pipe part (the pipe part of the pile), and due to the difference in rigidity between the two, a large bending moment occurs at the boundary between the flange and the steel pipe part, similar to that which occurs at the fixed end.

[0009] Therefore, simply butting the first flange and the second flange and tightening them with bolts may cause deformation of the steel pipe near the joint between the flange and the steel pipe. While this deformation can be prevented by making the steel pipe thicker, this is not desirable because it increases manufacturing costs.

[0010] The second aspect of the present invention has been made in view of the above problem, and its object is to provide a precast pile that is easy to adjust in length, is resistant to deformation, and has low manufacturing costs.

[0011] A bored pile structure according to a second aspect of the present invention is defined as follows: In the bored pile structure according to the first aspect, a blade is provided at the other end of the first steel pipe portion, and a reinforcing portion is further provided that connects the first steel pipe portion and the first flange portion.

[0012] The outer diameter of the first flange portion exceeds the outer diameter of the first steel pipe portion and is equal to or smaller than the outer diameter of the blade, the thickness of the reinforcing portion exceeds the thickness of the first steel pipe portion and is equal to or smaller than the thickness of the first flange, and the length of the reinforcing portion in the direction along which the steel pipe portion extends is equal to or larger than 20% of the outer diameter of the steel pipe portion and is equal to or smaller than 50% of the outer diameter of the first steel pipe portion. The second steel pipe section may also be provided with a reinforcing section connecting the second steel pipe section and the second flange section, wherein the outer diameter of the second flange section exceeds the outer diameter of the second steel pipe section and is equal to or smaller than the outer diameter of the blade, the thickness of the reinforcing section exceeds the thickness of the second steel pipe section and is equal to or smaller than the thickness of the second flange, and the length of the reinforcing section in the direction along which the second steel pipe section extends is equal to or larger than 20% of the outer diameter of the second steel pipe section and is equal to or smaller than 50% of the outer diameter of the second steel pipe section.

[0013] In this way, the outer diameter of each flange exceeds the outer diameter of each steel pipe section, making it easy to mechanically connect the flanges that protrude radially from the steel pipe sections all around. Also, by making the outer diameter of each flange equal to or smaller than the outer diameter of the blade, the flanges do not cause any problems when burying the precast pile.

[0014] The reinforced section near the flange, which is subjected to a large bending moment, is thicker than the steel pipe section, making it stronger. By making the length of the reinforced section at least 20% and no more than 50% of the outer diameter of the steel pipe section, the reinforced section does not become unnecessarily large or heavy. In other words, it is possible to effectively reinforce the area where loads are concentrated and which is prone to deformation, while suppressing excess material from being carried away.

[0015] According to a third aspect of the present invention, in the precast pile defined in the second aspect, a plate-like lid portion is interposed between the reinforcing portion and the other end of the second steel pipe portion. This makes it possible to easily manufacture concrete-filled piles or mortar-filled piles by injecting concrete or mortar into the hollow portion of the steel pipe section.

[0016] According to a fourth aspect of the present invention, in the precast pile defined in the second aspect, the flange portion is an annular plate member. This allows the flange portion to be made lighter in weight.

[0017] According to a fifth aspect of the present invention, in the precast pile of the fourth aspect, axial holes are formed in the first flange portion at equal intervals in the circumferential direction and at equal positions from the central axis of the first steel pipe portion. According to this, the first flange portion can be fastened evenly by passing bolts or the like through holes that are evenly provided in the circumferential direction.

[0018] According to a sixth aspect of the present invention, in the precast pile defined in the fifth aspect, the first and second flange portions are mechanically coupled to each other by passing a connector through a hole in the first flange portion and a hole in the second flange portion that face each other. According to this, the first and second flange portions are quickly and reliably joined together by passing a connector through the holes in the first flange portion and the holes in the second flange portion.

[0019] According to a seventh aspect of the present invention, in the precast pile defined in the sixth aspect, an enlarged diameter portion is interposed between the first flange portion and the second flange portion, and the outer diameter of the enlarged diameter portion exceeds the outer diameters of the first flange portion and the second flange portion and is equal to or smaller than the outer diameter of the blade. This improves the penetration of the precast pile into the foot protection material, thereby improving the bearing capacity of the precast pile. In addition, the enlarged diameter portion can be attached quickly and easily as needed, simply by sandwiching it between the first flange portion and the second flange portion.

[0020] According to an eighth aspect of the present invention, in the precast pile defined in the second aspect, the second steel pipe portion is located above the first steel pipe portion, and the outer diameter of the second steel pipe portion exceeds the outer diameter of the first steel pipe portion. This allows the first steel pipe portion and the second steel pipe portion, which have different outer diameters, to be reliably and easily connected by the flange.

[0021] According to a ninth aspect of the present invention, in the precast pile defined in the third aspect, the steel pipe portion is filled with concrete or mortar. According to this, by filling the piles with concrete or mortar, the rigidity of the precast piles can be increased, thereby improving the bearing capacity of the bored pile structure.

[0022] According to a tenth aspect of the present invention, a third flange portion is further provided at an upper end of the precast pile as defined in the second aspect, and a reinforcing steel bar of a building is fixed to the third flange portion. According to this, by fixing the reinforcing steel bars of the building to the third flange portion, the foundation of the building can be firmly and quickly connected to the precast pile.

[0023] According to an eleventh aspect of the present invention, in the precast pile defined in the second aspect, the reinforcing portion connecting the first flange portion and the first steel pipe portion is a rib welded to the first flange portion and the peripheral surface of the first steel pipe portion. This allows the ribs welded to the first flange portion and the peripheral surface of the first steel pipe portion to simply and effectively reinforce the area where loads due to bending moments are concentrated and prone to plastic deformation.

[0024] The eleventh aspect is defined as follows: That is, a method for embedding a precast pile as defined in the first aspect into a pile hole filled with a foot protection material, comprising a step of preparing an attachment, the attachment comprising a receiving pipe section that is shorter than the first and second steel pipe sections and has a key attached to its circumferential surface, a receiving flange section that is disposed at one end of the receiving pipe section, and a receiving reinforcement section that connects the receiving flange section and one end of the receiving pipe section, the outer diameter of the receiving flange section being greater than the outer diameter of the receiving pipe section and being equal to or smaller than the outer diameter of the blade, a step of connecting the receiving flange portion of the attachment to the flange portion of the end of the precast pile protruding from the ground; A method for burying a precast pile, comprising the steps of attaching the receiving pipe portion to an auger and rotating and pressing it in. This allows the precast pile to be attached to the auger easily and quickly using the attachment. [Brief explanation of the drawings]

[0025] [Figure 1]1 is a front view showing a part of a cross section of a first embodiment of a precast pile of the present invention. [Figure 2] FIG. 4 is a schematic diagram of a first flange portion viewed from above. [Figure 3] FIG. 2 is a view showing a state in which the first steel pipe portion and the second steel pipe portion are opposed to each other. [Figure 4] FIG. 2 is a view showing the state in which the first steel pipe portion and the second steel pipe portion are connected. [Figure 5] FIG. 10 is a front view showing the second embodiment. [Figure 6] FIG. 10 is a front view showing a third embodiment. [Figure 7] FIG. 10 is a front view showing a fourth embodiment. [Figure 8] FIG. 13 is a diagram showing a state in which concrete is filled into the connected steel pipe sections of the fifth embodiment. [Figure 9] FIG. 13 is a diagram showing a structure for connecting to the foundation of a building in the sixth embodiment. [Figure 10] FIG. 13 is a front view of a seventh embodiment in which the reinforcing portion is a rib. [Figure 11] FIG. 13 is a plan view showing a lower steel pipe portion in the seventh embodiment. [Figure 12] FIG. 13 is a front view showing the connection state between the attachment and the steel pipe portion used in the eighth embodiment. [Figure 13] 1 is a schematic diagram showing an embedded pile structure according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0026] FIG. 13 shows a bored pile structure 1000 according to an embodiment of the present invention. This embedded pile structure 1000 comprises a pile hole 1001, a base protection material 1020, and a precast pile 1. The depth and diameter of the pile hole 1001 are determined appropriately using a general-purpose civil engineering machine (auger, etc.) depending on the characteristics of the ground and the structure and weight of the building to be supported by the pile. Cement milk is generally used for the foot protection material 1020. The foot protection material may be filled into the pile hole 1001 by injecting the highly fluid foot protection material while drilling the pile hole 1001, or by injecting the highly fluid foot protection material after the pile hole 1001 is completely formed. The precast pile 1 is embedded in the foot protection material 1020 along the central axis of the pile hole 1001 before the foot protection material 1020 hardens. 13, a flange portion is formed on the precast pile 1. This flange portion bites into the foot protection material 1020, improving the bearing capacity of the precast pile 1.

[0027] The length of the steel pipe between the flanges can be designed as desired. In other words, by connecting short steel pipes, the number of flanges can be increased, and the bearing capacity of the precast pile 1 can be further strengthened. Furthermore, by connecting the flanges with mechanical means such as bolts, the steel pipe sections can be easily connected. In other words, even if the steel pipe sections are shortened, the time required to connect the steel pipe sections to form a precast pile of the desired length does not become a significant burden in the total work time required to carry out the borehole pile construction method.

[0028] The precast pile applied to the bored pile structure shown in FIG. 13 will be described below. (First embodiment) A first embodiment of a precast pile according to the present invention will be described below with reference to FIGS. When there is a structure, an imaginary center line is considered for the structure, and the side closer to the center line is called the "inside" and the side farther from the center line is called the "outside."

[0029] The precast pile 1 in this embodiment is driven into the foot protection material by applying a rotational force to a steel pipe pile having a blade 2 at its tip.

[0030] The blades 2 at the tip not only generate propulsive force through rotation during construction, but also act as base expansion members, providing a larger support area than steel pipe piles. The precast pile 1 of the first embodiment includes a lower first pile body 1a and an upper second pile body 1b, as shown in Fig. 1. The first pile body 1a and the second pile body 1b have the same structure at the connecting portion, so the first pile body 1a will be described below as a representative.

[0031] (First pile body) The first pile body 1a includes a first steel pipe portion 3, a reinforcing portion 4, and a first flange portion 5a. (Steel pipe section) The first steel pipe portion 3 is made of, for example, iron and formed into a cylindrical shape. In this embodiment, the first steel pipe portion 3 has an outer diameter D3 of, for example, 600 mm. The first steel pipe portion 3 has a thickness t3 of, for example, 20 mm. A reinforcing portion 4 is provided at the upper end of the first steel pipe portion 3 .

[0032] (reinforcement part) The reinforcing portion 4 is made of iron and formed into a cylindrical shape, and has a thickness t4 of 50 mm and a length h4 of 70 mm, for example. The reinforcing portion 4 is pre-connected to the steel pipe portion 3 by welding at the factory. The reinforcing portion 4 has an upper end provided with a first flange portion 5a.

[0033] (First flange part) The first flange portion 5a is formed of, for example, an annular iron plate member, as shown in Fig. 2. The first flange portion 5a has an outer diameter D5 of, for example, 900 mm and a thickness t5 of, for example, 60 mm.

[0034] The first flange portion 5a has a plurality of (for example, 14 in this embodiment) axial mounting holes 51 formed evenly in the circumferential direction and at equal positions from the central axis CL of the first pile main body 1a, as shown in Figures 2 and 3. The first flange portion 5a is pre-connected to the reinforcing portion 4 by welding at the factory.

[0035] An excavation blade 2 is provided at the lower end of the first steel pipe portion 3, i.e., the end opposite the first flange portion 5a. The outer diameter D2 of the blade 2 is, for example, 1200 mm. The blade 2 is a known technique, so a description thereof will be omitted. The first pile body 1a is connected to the second pile body 1b.

[0036] (connected structure) The structure for connecting the first pile body 1a to a similar second pile body 1b will be described below. When the length of the first pile body 1a alone does not reach the bottom of the pile hole at the excavation site, the pile is extended.

[0037] As shown in Figure 4, the connecting structure is such that the first and second flange portions 5a, 5b are mechanically connected to the mounting holes 51 of the first flange portion 5a of the first pile body 1a and the second flange portion 5b of the second pile body 1b, which face each other, through connectors (bolts B and nuts N).

[0038] (Connection work) In the connecting work, the second flange portion 5b of the second pile main body 1b, which has been erected in the vertical direction by, for example, a crawler crane, is brought to face the first flange portion 5a of the buried first pile main body 1a. Next, the mounting holes 51 of the first flange portion 5a and the mounting holes 51 of the second flange portion 5b are aligned so as to communicate with each other. Next, a bolt B is inserted into the communicating mounting hole 51 from below, and the tip end is fastened with a nut N. In this way, the connection can be performed more easily and quickly than by welding at the excavation site. The first pile body 1a and the second pile body 1b connected together are attached to, for example, a full-circle rotating machine and are rotationally pressed into the ground.

[0039] As is clear from the above description, the precast pile 1 of the first embodiment of the present invention is a steel pipe pile including a first pile body 1a and a blade 2 provided at the tip of the first pile body 1a. The first pile body 1a comprises a first steel pipe portion 3, a first flange portion 5a arranged at at least one end of the first steel pipe portion 3, and a reinforcing portion 4 connecting the first flange portion 5a and one end of the first steel pipe portion 3.

[0040] The outer diameter D5 of the first flange portion 5a exceeds the outer diameter D3 of the first steel pipe portion 3 and is not greater than the outer diameter D2 of the blade 2, the thickness t4 of the reinforcing portion 4 exceeds the thickness t3 of the first steel pipe portion 3 and is not greater than the thickness t5 of the first flange portion 5a, and the length h4 of the reinforcing portion 4 in the direction along which the first steel pipe portion 3 extends is not less than 20% of the outer diameter D3 of the first steel pipe portion 3 and not greater than 50% of the outer diameter D3 of the first steel pipe portion 3.

[0041] According to this, the outer diameter D5 of the first flange portion 5a exceeds the outer diameter D3 of the first steel pipe portion 3, and therefore connection can be made extremely easily by the first flange portion 5a which protrudes radially over the entire circumference from the first steel pipe portion 3. Furthermore, by making the outer diameter D5 of the first flange portion 5a equal to or smaller than the outer diameter D2 of the blade 2, the first flange portion 5a does not interfere with excavation work.

[0042] The thickness t4 of the reinforcing portion 4 exceeds the thickness t3 of the first steel pipe portion 3, which effectively improves the strength of the vicinity of the first flange portion 5a, which is subjected to a large bending moment. In addition, it is possible to prevent excess material from being removed, which would result in excessive reinforcement.

[0043] By setting the length h4 of the reinforcing section 4 to be at least 20% of the outer diameter D3 of the first steel pipe section 3 and at most 50% of the outer diameter D3 of the first steel pipe section 3, it is possible to prevent excess material from being removed and effectively reinforce the areas where loads are concentrated and which are prone to plastic deformation.

[0044] In the first pile body 1a, the first flange portion 5a is an annular plate member. This allows the weight of the first flange portion 5a to be reduced.

[0045] Furthermore, the first flange portion 5a has axial holes (mounting holes 51) formed at equal intervals in the circumferential direction and at equal positions from the central axis CL of the first pile main body 1a.

[0046] According to this, the first flange portion 5a can be fastened evenly by passing connecting tools such as bolts B through the mounting holes 51 provided evenly in the circumferential direction.

[0047] In addition, the precast pile 1 has a connecting structure with a second pile body 1b configured in the same manner as the first pile body 1a, and the first and second flange portions 5a and 5b are mechanically connected to each other through connecting devices such as bolts B and nuts N through mounting holes 51 in the first flange portion 5a of the first pile body 1a and mounting holes 51 in the second flange portion 5b of the second pile body 1b, which face each other.

[0048] According to this, the first and second flange portions 5a and 5b can be easily and quickly joined by passing connecting devices such as bolts B and nuts N through the mounting holes 51 of the first flange portion 5a of the first pile body 1a and the mounting holes 51 of the second flange portion 5b of the second pile body 1b.

[0049] (Second embodiment) Next, a second embodiment of the pile body 101 of the present invention will be described below with reference to FIG. As shown in FIG. 5, in the pile main body 1 of this embodiment, a plate-shaped lid portion 106 is interposed between the reinforcing portion 4 and the second steel pipe portion 3 in the upper second pile main body 1b. The plate-shaped lid portion 106 is made of, for example, iron and formed into a disk-shaped plate material. The plate-shaped lid portion 106 is formed to have the same outer diameter as the steel pipe portion 3 and is joined to the steel pipe portion 3 and the reinforcing portion 4 by factory welding. The other configurations are the same as those of the first embodiment, so explanations will be omitted.

[0050] This makes it possible to easily manufacture a concrete-filled pile or a mortar-filled pile by pouring concrete or mortar into the hollow portion of the steel pipe portion 3 of the upper second pile main body 1b.

[0051] (Third embodiment) Next, a third embodiment of the pile body 201 of the present invention will be described below with reference to FIG. As shown in FIG. 6, in the pile body of the third embodiment, an enlarged diameter portion 202 is sandwiched and connected between a first flange portion 5a and a second flange portion 5b.

[0052] The expanded diameter portion 202 is formed, for example, from a disk-shaped iron plate, and has a plurality of through holes 2021 formed therein that correspond to the mounting holes 51 of the first flange portion 5a and the second flange portion 5b. The outer diameter D20 of the expanded diameter portion 202 is formed to be, for example, 1000 mm, which is greater than the outer diameter D5 of the first flange portion 5a and the second flange portion 5b, which is 900 mm, and is equal to or smaller than the outer diameter D2 of the blade 2, which is 1200 mm.

[0053] This allows the enlarged diameter portion 202 to penetrate deeper into the base protection material than the flange portion, further improving the bonding strength between the precast pile and the base protection material. In addition, the enlarged diameter portion 202 can be attached quickly and easily as needed by simply sandwiching it between the first flange portion 5a and the second flange portion 5b.

[0054] (Fourth embodiment) Next, a fourth embodiment of the pile body 301 of the present invention will be described below with reference to FIG. As shown in Fig. 7, the fourth embodiment shows a connecting structure of two pile bodies, one above the other, whose steel pipe portions have different outer diameters. The outer diameter D33b of the steel pipe portion 303b of the second pile body 301b, which is located on the upper side, is larger than the outer diameter D33a of the steel pipe portion 303a of the first pile body 301a, which is located on the lower side. The outer diameter D35b of the second flange portion 305b of the second pile body 301b is formed to be the same size as the outer diameter D35a of the first flange portion 305a of the first pile body 301a.

[0055] Furthermore, the number and arrangement of mounting holes 51 formed in both flange portions 305a, 305b are the same. Therefore, first flange portion 305a and second flange portion 305b can be fastened together with bolts B and nuts N.

[0056] Even if the outer diameter D33b of the steel pipe portion 303b of the second pile body 301b located above is larger than the outer diameter of the steel pipe portion 333a of the first pile body 301a, the pile bodies 301a and 301b can be easily and reliably connected as long as the flange portions 305a and 305b can be connected to each other.

[0057] Fifth Embodiment Next, a fifth embodiment of the pile body of the present invention will be described below with reference to FIG. The pile body 401 of the fifth embodiment is a steel pipe pile, and as shown in FIG. 8, a plate-like lid portion 106 is fitted between the reinforcing portion 4 and the steel pipe portion 3 and fixed by welding at the factory.

[0058] Concrete CC is poured into the hollow portion of the steel pipe portion 403b of the second pile main body 401b to form a concrete-filled pile. The other configurations are the same as those of the pile main body 1 in the first embodiment. By using concrete-filled piles, it is possible to obtain piles with high earthquake resistance. In the present embodiment, concrete is filled, but this is not limiting. For example, mortar may be filled.

[0059] (Sixth embodiment) Next, a sixth embodiment of the pile body of the present invention will be described below with reference to FIG. As shown in FIG. 9, the pile body 501 in the sixth embodiment can be connected to the foundation BS of a building.

[0060] According to this, the steel pipe pile (pile body 501) and the foundation BS of the building on it can be easily and reliably connected by fixing the flange portion 505 with reinforcing steel bars (for example, long bolts LB). The other configurations are the same as those of the first embodiment, so explanations will be omitted.

[0061] Seventh Embodiment Next, a seventh embodiment of the pile body of the present invention will be described below with reference to FIGS.

[0062] The pile body 601 of the seventh embodiment is a steel pipe pile body 601 comprising a pile body 601 and a blade 2 provided at the tip of the pile body 601, and comprising a steel pipe portion 603, a flange portion 605 arranged at at least one end of the steel pipe portion 603, and a reinforcing portion 604 connecting the flange portion 605 and one end of the steel pipe portion 603, and the reinforcing portion 604 is a rib welded to the flange portion 605 and the peripheral surface of the steel pipe portion 603.

[0063] By forming the reinforcing portion 604 as a rib welded to the flange portion 605 and the circumferential surface of the steel pipe portion 603, the reinforcing portion 604 can be easily formed by welding in a factory.

[0064] Eighth Embodiment Next, an eighth embodiment of the pile body of the present invention will be described below with reference to FIG. As shown in FIG. 12, the pile body 701 of the eighth embodiment includes an attachment 721.

[0065] The attachment 721 comprises a receiving pipe portion 723 which is shorter than the steel pipe portion 3 of the pile main body 701 and has a key 722 attached to its circumferential surface, a receiving flange portion 725 which is positioned at one end of the receiving pipe portion 723, and a receiving reinforcement portion 724 which connects the receiving flange portion 725 to one end of the receiving pipe portion 723.

[0066] The outer diameter d5 of the receiving flange portion 725 exceeds the outer diameter d3 of the receiving pipe portion 723 and is equal to or smaller than the outer diameter D2 of the blade 2. The receiving flange portion 725 of the attachment 721 is joined to the flange portion 705 at the end of the pile body 701 that protrudes from the ground, and the receiving pipe portion 723 is quickly attached to the auger and rotated and pressed into the ground.

[0067] This allows the pile body 701 provided with the flange portion 5 to be attached quickly and reliably using the attachment 721. In addition, the receiving flange portion 725 does not interfere with the excavation by the blades 2.

[0068] The present invention is not limited to the above-described embodiments shown in the drawings, but can be modified appropriately within the scope of the present invention. [Explanation of symbols]

[0069] 1: pile body, 1a: first pile body, 1b: second pile body, 2: blade, 3: steel pipe section, 4: reinforcement section, 5: flange section, 5a: first flange section, 5b: second flange section, 51: mounting hole (hole), 101: pile body, 106: plate-shaped cover section, 201: pile body, 202: expansion section, 301: pile body, 301a: first pile body, 301b: second pile body, 303a: first steel pipe section, 303b: second steel pipe section, 401: pile body, 501: pile body, 601: pile body, 603: steel pipe section, 604: rib (reinforcement section), 605: flange section, 701: pile body, 721: attachment, 722: key, 723: receiving pipe section, 724: receiving support Strengthened part, 725: Receiving flange part, 705: Flange part, 1000: Buried pile structure, 1001: Pile hole, 1020: Foot protection material, D2: Outer diameter (wing), D3: Outer diameter (steel pipe part), D4: Outer diameter (reinforced part), D5: Outer diameter (flange part), D20: Outer diameter (expanded part), D33a: Outer diameter (first steel pipe part), D33b: ​​Outer diameter (second steel pipe part), D35a: Outer diameter (first flange part), D35b: Outer diameter (second flange part), d3: Outer diameter (receiving pipe part), d5: Outer diameter (receiving flange part), h4: Length (reinforced part), LB: Long bolt (reinforced steel bar), t3: Thickness (steel pipe part), t4: Thickness (reinforced part), t5: Thickness (flange part).

Claims

1. A foot protection material filled in the pile hole; A steel pipe pile inserted into the foot protection material, comprising a first steel pipe portion and a second steel pipe portion, a first flange portion having a larger diameter than the first steel pipe portion provided at an end of the first steel pipe portion, and a second flange portion having a larger diameter than the second steel pipe portion provided at an end of the second steel pipe portion, A buried pile structure, wherein the first flange portion and the second flange portion are mechanically connected to each other.

2. a blade is provided at the other end of the first steel pipe portion, and a reinforcing portion is provided that connects the first steel pipe portion and the first flange portion; the thickness of the reinforcing portion is greater than the thickness of the first steel pipe portion and is equal to or less than the thickness of the first flange portion; 2. The embedded pile structure according to claim 1, wherein the length of the reinforcing portion in the direction along which the first steel pipe portion extends is 20% or more of the outer diameter of the first steel pipe portion and 50% or less of the outer diameter of the first steel pipe portion.

3. The structure according to claim 2, wherein a reinforcing portion is also provided between the second steel pipe portion and the second flange portion, and a plate-shaped lid portion is interposed between this reinforcing portion and the second steel pipe portion.

4. 3. The structure according to claim 2, wherein the first and second flange portions are annular plate members.

5. 5. The structure according to claim 4, wherein axial holes are formed in the first and second flange portions at equal intervals in the circumferential direction and at equal positions from the central axes of the first and second steel pipe portions.

6. 6. The structure of claim 5, wherein the first and second flange portions are mechanically coupled by passing connectors through holes in the first flange portion and holes in the second flange portion that face each other.

7. 4. The structure according to claim 3, wherein the second steel pipe section is filled with concrete or mortar.

8. The structure according to claim 2, further comprising a third flange portion at the upper end of the precast pile, and a reinforcing steel bar of a building is fixed to the third flange portion.

9. 3. The structure according to claim 2, wherein the reinforcing portion connecting the first flange portion and the first steel pipe portion is a rib welded to the first flange portion and the peripheral surface of the first steel pipe portion.

10. A method for embedding a precast pile into a foot protection material filled in a pile hole, comprising: preparing an attachment; the attachment comprises a receiving pipe portion that is shorter than the first and second steel pipe portions and has a key attached to its circumferential surface, a receiving flange portion that is disposed at one end of the receiving pipe portion, and a receiving reinforcement portion that connects the receiving flange portion and one end of the receiving pipe portion, the outer diameter of the receiving flange portion being greater than the outer diameter of the receiving pipe portion and being equal to or smaller than the outer diameter of the blade, a step of connecting the receiving flange portion of the attachment to the flange portion of the end of the precast pile protruding from the ground; A method for embedding a precast pile into a foot protection material filled in a pile hole, comprising the steps of attaching the receiving pipe portion to an auger and rotating and pressing it in.

11. providing pile holes in the ground; A step of filling the pile hole with a foot protection material; A buried pile construction method including a step of burying a prefabricated pile in the foot protection material, The precast pile comprises a first steel pipe portion and a second steel pipe portion, a first flange portion having a larger diameter than the first steel pipe portion is provided at an end of the first steel pipe portion, and a second flange portion having a larger diameter than the second steel pipe portion is provided at an end of the second steel pipe portion, A buried pile construction method including a step of burying a portion of the first steel pipe section in the foot protection material with the first flange section facing up, and mechanically connecting the second flange section of the second steel pipe section to the first flange section.

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