JP6667277B2 - Construction method of foundation pile reinforced with pile head - Google Patents

Description

  The present invention relates to a method for constructing a foundation pile in which a pile head of a foundation pile serving as a foundation of an upper structure is reinforced.

  In the Great Hanshin-Awaji Earthquake and the Great East Japan Earthquake, large seismic forces caused damage to foundation piles of buildings and the like, causing buildings to collapse or tilt. Investigations by various agencies have shown that most of these accidents were caused by damage to the pile head. It is considered that the strength of the pile head (including the top of the pile and the joint between the pile head and the footing) is insufficient, or that the pile has been subjected to a seismic force greater than expected in the design.

  On the other hand, in recent years, various pile construction methods have been developed, and a large number of pile construction methods having a greater vertical bearing capacity than before have been developed. However, since the horizontal load increases almost in proportion to the vertical load acting on the pile, it may not be possible to cope with a large bending moment of the pile head by design. As a result, the large vertical bearing capacity of the foundation pile may not be used effectively. This tendency has been found to be particularly strong when the ground near the pile head is soft.

  In order to solve the above-mentioned problems, various proposals have been made on a technique for reinforcing a pile head. As a typical example thereof, a steel pipe pile having a projection on the outer surface is penetrated to a predetermined depth, and is then covered with an outer pipe having a lower end provided with a flange or a cutting blade, and is rotated and penetrated to a predetermined position. Reference 1). The protrusion disturbs and softens the ground around the steel pipe pile, and facilitates penetration of the outer pipe into the ground. Further, in the type in which the flange is mounted, it is disclosed that the flange prevents intrusion of earth and sand and injects mortar or the like into the resulting space. Further, there is known a method in which a steel pipe pile is driven into the ground, an outer pipe is inserted and driven, and grout is injected between the two (see Patent Document 2). FIG. 1 of Patent Document 2 shows a method of bending the lower end of the outer pipe to reduce the diameter to the outer diameter of the steel pipe pile to prevent intrusion of earth and sand.

  In both cases, an outer pipe is arranged on the head of a steel pipe pile to make the pile head a double pipe structure, and mortar or grout is filled between them.

JP 2009-30372 A JP 2010-248811 A

  The former and the latter have two problems to be solved. The first issue is the hiring stake (known as “Yattoko”). Normally, the height of the foundation pile head is set below the construction ground surface (for example, 2 m below), so that a hiring pile is required for both penetration of the steel pipe pile and penetration of the outer pipe. Normally, the outer diameter of the hire pile for the steel pipe pile is the same as that of the steel pipe pile due to the convenience of the pile driver, but in order to connect with the steel pipe pile head, for example, as shown in FIG. A cylindrical portion having a diameter larger than the diameter of the steel pipe pile is fixed to the cylindrical portion. A rotating metal fitting fixed near the head of the outer surface of the steel pipe pile fits into the groove machined on the inner surface of the cylindrical part, and the two are connected to each other, and a rotational force and a pushing force are transmitted from the hiring pile to the steel pipe pile.

  By the way, if the hiring pile is removed immediately after the steel pipe pile penetrates, the flange or the reduced diameter portion at the lower end of the outer pipe cannot be inserted into the steel pipe pile head. For this reason, the hiring piles for steel pipe piles must be kept connected until the outer pipe penetrates or is filled with mortar or grout. However, if there is a protrusion such as the above-mentioned tubular part on the outer surface of the hiring pile, the outer pipe cannot pass through this part because it is larger than the inner diameter of the flange or the reduced diameter part, and the outer pipe can penetrate. Absent. Regarding this point, in the former Japanese Patent Application Laid-Open No. 2009-30372, paragraph [0013] states that "when a pile head position is deeper than the surface of the ground, a hiring pile (so-called" yattoko ") is used to penetrate the pile. However, in order to sink the outer pipe to the same depth, this hired pile may be left in the ground and another hired pile may be used for the outer pipe. No specific configuration is disclosed for the hiring stakes used in this case. Regarding the latter JP-A-2010-248811, the paragraph No. 0010 also states, “The construction of the double-pipe pile head structure is as follows: first, the steel pipe pile 11 is driven into the ground, and then the steel pipe pile 11 is attached to the head. The outer pipe 12 is inserted and driven in, "but the specific configuration of the hiring pile similarly used for penetrating the steel pipe pile is not disclosed. In other words, in both the former and the latter, there is no specific reference to inserting the outer pipe into the steel pipe pile head through the hiring pile, and how the outer pipe is inserted into the steel pipe pile head and penetrated. It is unknown.

  The second problem is that mud adheres to the outer surface of the steel pipe pile even if the outer pipe can be inserted into the head of the steel pipe pile through the hiring pile (see FIG. 8). If the inner diameter of the outer pipe flange or reduced diameter portion is set slightly larger than the outer diameter of the steel pipe pile, most of the mud adhering to the outer surface of the steel pipe pile will be removed, and between the outer surface of the steel pipe pile and the inner surface of the outer pipe. There should be enough space to fill the mortar or grout. However, in practice, in the field tests conducted by the present inventors, even when the diameter difference between the inner diameter of the flange or the reduced diameter portion of the outer pipe and the outer diameter of the steel pipe pile was 1 mm, the mud was slightly reduced. It has been found that they penetrate through such gaps and adhere to the outer surface of the steel pipe pile. When the outer pipe rotates and penetrates without removing the soil, the volume of the space is compressed and the soil near the lower end of the outer pipe generates a very high pressure. As a result, the mud penetrates into the space even from a small gap and adheres to the outer surface of the steel pipe pile. According to the test of the present inventors, it has been found that mud having a thickness of about 2 mm to 5 mm adheres in a spiral shape. Even if the space is filled with mortar or grout while the mud is attached, the frictional force between the pile and the steel pipe pile is greatly reduced, so that the pile head reinforcing effect has to be reduced.

  The former method of constructing a double-pipe pile head structure has a problem that it cannot cope with the case where the support layer position is shallower than the planned depth. At the position corresponding to the outer pipe lower end depth of the steel pipe pile, a projection is provided in advance for the purpose of softening the ground or as a positioning material of the outer pipe lower end, but if the support layer position is shallower than the planned depth, the position of the protrusion And the outer tube cannot be installed to a predetermined depth, and the length of the double tube portion is shortened. This becomes a fatal defect as a pile.

  An object of the present invention is to provide a method of constructing a foundation pile that can reliably reinforce a pile head of a foundation pile by rotating a foundation pile and an outer pipe into the ground using a hiring pile.

The method for constructing a foundation pile according to claim 1 of the present invention is characterized in that an outer pipe having an annular plate fixed to an upper outer periphery of a steel pipe pile, which is shorter than the steel pipe pile and has a center hole at a lower end thereof, through which the steel pipe pile penetrates is provided. A foundation pile, which is installed, and then fills a space formed between an upper outer periphery of the steel pipe pile and an inner periphery of the outer pipe with a fluid solidifying material to form a reinforcing member to enhance horizontal resistance. The construction method according to the above, wherein the lower end of the first hiring pile for a steel pipe pile having the same outer diameter as the steel pipe pile and having no protrusion over the entire outer surface is attached to the head of the steel pipe pile via a connection fitting. The lower end and the head are connected to each other detachably and rotationally so as to prevent the protrusion from being formed on the outer surface of the connecting portion, and transmit the rotational force to the steel pipe pile via the first hiring pile. Rotating the steel pipe pile into the ground to a predetermined depth, and moving the outer pipe to the center of the annular plate. Through the first hiring stake through the first hiring stake, and moving the outer tube from the first hiring stake along the connection portion and the steel pipe stake to move the outer tube head to the first hiring stake. A step of rotating and penetrating into the ground until is located near the surface of the ground, connecting a second hiring pile for the outer pipe to the head of the outer pipe, and transmitting a rotational force to the outer pipe via the second hiring pile. Forming the space between the outer periphery of the steel pipe pile and the inner periphery of the outer tube by rotating the outer tube further into the ground to a predetermined depth; and forming the fluid solidifying material in the space. And forming the reinforcing body by filling the steel pipe pile with an outer diameter slightly smaller than the inner diameter of the head of the steel pipe pile, and provided on the outer surface of the steel pipe pile in the head. It is characterized in that a pair of grooves into which the rotating bracket is detachably fitted are formed .

A method for constructing a foundation pile according to claim 2 of the present invention is the method for constructing a foundation pile according to claim 1, wherein the outer pipe is connected to the first hiring pile near a lower end portion in the outer pipe. In the process of rotating and penetrating the ground to a predetermined depth along the portion and the steel pipe pile, a mud removing device including a removing member that presses against an outer surface of the steel pipe pile to remove mud attached to the outer surface is disposed, The method is characterized in that the mud removing device is removed from the outer pipe before filling the space with the fluid solidifying material.

  According to the first aspect of the present invention, the lower end of the first hiring pile for the steel pipe pile having the same outer diameter as the steel pipe pile is attached to the head of the steel pipe pile at the connecting portion between the lower end and the head. The outer pipe is removably connected so that no protrusion is formed on the outer surface, and the outer pipe is made to rotate and penetrate into the ground from the first hiring pile to a predetermined depth along the connecting portion and the steel pipe pile. A space for filling the fluid solidifying material with the outer tube can be secured. As a result, the three members of the steel pipe pile, the reinforcing body, and the outer pipe are integrated, and exhibit extremely high rigidity and strength. In addition, since the outer pipe penetrates the surrounding earth and sand in a lateral direction without discharging the soil, the density of the surrounding earth and sand increases, and the horizontal resistance of the ground increases. Furthermore, even when the depth of the support layer of the ground is shallower than expected, the steel pipe pile has no members that limit the penetration of the outer pipe, and the outer pipe can be penetrated to a predetermined depth without any hindrance. The double pipe pile composed of the outer pipe and the outer pipe can secure a predetermined axial length.

  According to the present invention as set forth in claim 2, a space for filling the fluid solidifying material between the steel pipe pile and the outer pipe can be ensured, and mud adhering to the steel pipe pile can be easily removed. And it can be removed at low cost, and as a result, the frictional force between the reinforcing member formed by filling the flowable solidifying material and the steel pipe pile can be reliably maintained.

1 shows an embodiment of a method for constructing a foundation pile according to the present invention, in which (a) describes a process of rotating and penetrating a steel pipe pile into a ground to a predetermined depth using a hiring pile (first hiring pile) for a steel pipe pile. Fig. (B) is an explanatory view of a step of passing the center hole of a circular plate provided at the lower end of the outer pipe through the head of the first hired pile, and (c) is a rotary driving penetrating the outer pipe into the ground by a pile driver. (D) is an explanatory view of a step of removing the first hiring pile and connecting the hiring pile for the outer pipe (second hiring pile) to the head of the outer pipe protruding from the ground surface; ) Is an explanatory view of a process of rotating and penetrating the outer pipe to a predetermined depth to the ground using the second hiring pile, and (f) is a drawing showing a space between the inner surface of the outer pipe and the outer surface of the steel pipe pile via a tremy pipe. FIG. 7 (g) is an explanatory view of a step of filling a fluid solidifying material, and FIG. 7 (g) is an explanatory view of a step of removing a second hiring pile from the head of the outer tube. 1A and 1B show an example of a steel pipe pile used in the construction method of FIG. 1, wherein FIG. 1A is a plan view of a pile head of the steel pipe pile, and FIG. 1A and 1B show an example of a first hiring stake used in the construction method of FIG. 1, wherein FIG. 1A is a longitudinal sectional view of a lower end portion (connection part) of the first hiring stake, FIG. It is a front view of the T-shaped groove provided in the lower end part (connection part) of the 1st hiring pile. FIG. 2 is a partial vertical cross-sectional view showing an example of an outer tube used in the construction method of FIG. 1. 1A and 1B show an example of attachment of a mud removing device used in the construction method of FIG. 1, wherein FIG. 1A is a cross-sectional view when the mud removing device is attached to a lower end portion of an outer pipe, and FIG. is there. FIG. 2 is a partially omitted longitudinal sectional view of a foundation pile whose pile head is reinforced by the construction method shown in FIG. 1. 1 is a view showing a conventional technique, and is a partial longitudinal sectional view of a connecting portion between a hiring pile and a steel pipe pile. FIG. 4 is a partial vertical cross-sectional view for explaining intrusion of mud and adhesion of mud generated when the outer pipe is rotationally penetrated into the ground.

  As shown in FIG. 6, a foundation pile constructed by the method for constructing a foundation pile of the present embodiment shown in FIGS. 1A to 1G includes a steel pipe pile 10, an outer shell steel pipe 20 as an outer pipe, and a steel pipe pile. A reinforcing member 40 made of concrete, mortar, or the like as a fluid solidifying material is provided in a space 30 between the shell 10 and the outer shell steel tube 20.

  The steel pipe pile 10 has a pair of rotation fittings 13 (see FIGS. 2A and 2B) fixed to an inner surface of a pile head 11 which is an upper part thereof. Further, the steel pipe pile 10 is provided with a spiral wing 12 having a screwing action near a tip end thereof, and when a rotational force is applied to the pile head 11, the steel pipe pile 10 rotationally penetrates into the ground. The outer shell steel pipe 20 has an axial length shorter than the steel pipe pile 10 and an inner diameter larger than the outer diameter of the steel pipe pile 10. The space 30 can be secured between itself and the peripheral surface. The inner diameter of the outer shell steel pipe 20 is desirably about 1.5 to 2.5 times the outer diameter of the steel pipe pile in terms of design and economy. An annular plate 21 is fixed to the lower end of the outer shell steel pipe 20 by welding or the like as shown in FIG. The steel pipe pile 10 and a first hiring pile 70 which is a hiring pile for the steel pipe pile are inserted into the center hole 22 of the annular plate 21. The inner diameter of the center hole 22 is set slightly larger than the outer diameter of the steel pipe pile 10 or the first hiring pile 70 (see FIGS. 3A to 3C). Specifically, it is desirable that the diameter difference between the inner diameter of the center hole 22 and the outer diameter of the steel pipe pile 10 or the first hiring pile 70 be as small as possible. However, in consideration of the production dimensional accuracy of both, it is preferably about 1 mm to 3 mm. Is set. This makes it possible to prevent intrusion of earth and sand as much as possible. The first hiring pile 70 is a steel pipe having the same diameter as the steel pipe pile 10 and has no protrusion over the entire outer surface, and can be passed through the center hole 22 of the annular plate 21 of the outer shell steel pipe 20 without any trouble. Further, on the bottom surface (lower end surface) of the first hiring pile 70, a connection metal fitting 71 for connecting to the pile head 11 of the steel pipe pile 10 is provided. The connecting bracket 71 is an annular body having an axial length shorter than the first hiring stake 70 by a fraction and being slightly smaller than the inner diameter of the pile head 11. A pair of T-shaped grooves 72 into which the rotation metal fittings 13 in the portion 11 are detachably fitted are formed. The lower end of the first hiring pile 70 and the pile head 11 of the steel pipe pile 10 are attached and detached by fitting the connecting metal fitting 71 into the pile head 11 and fitting the rotating metal fitting 13 into the T-shaped groove 72. It is connected so as to be able to transmit torque. As described above, since the connecting metal fitting 71 is fitted into the pile head 11 and the rotating metal fitting 13 is fitted into the T-shaped groove 72, the steel pipe pile 10 and the first hiring pile 70 are connected. No protrusions larger than the outer diameters of the steel pipe pile 10 and the first hiring pile 70 are generated on the outer surface of the connecting portion of the present invention unlike the prior art shown in FIG. The pile head 11 of the steel pipe pile 10 is integrated with the steel pipe pile 10, the outer shell steel pipe 20, and the concrete (reinforcement 40) by the concrete poured into the space 30, and has high rigidity and bending strength. Reinforced.

  A mud removing device 50 is disposed near the lower end of the outer shell steel pipe 20. As shown in FIGS. 5A and 5B, the mud removing device 50 includes a pair of fixing pieces 23 fixed to an inner peripheral portion near a lower end portion of the outer shell steel pipe 20 via bolts and nuts 24. It can be attached detachably. The mud removing device 50 is configured based on a short steel pipe 51 whose axial dimension is about a fraction of the outer shell steel pipe 20. On the outer peripheral surface of the short steel pipe 51, a pair of fixing pieces 52 that are detachably attached to the fixing pieces 23 via bolts and nuts 24 are provided. On the inner peripheral surface of the short steel pipe 51, a pair of removing members 53 each having a brush at a tip portion pressed against the outer peripheral surface of the steel pipe pile 10 are arranged. The mud removing device 50 is rotated together with the outer shell steel pipe 20 at the time of rotation penetration and descends while rotating around the steel pipe pile 10 (pile head 11), and the brush of the removing member 53 slides on the outer peripheral surface of the steel pipe pile 10. Removes mud adhering in contact. According to the field test of the present inventors, it was confirmed that the adhering mud can be removed neatly by adjusting the hardness and pressing force of the brush of the removing member 53. The tip of the removing member 53 is not limited to a brush, but may be a plate-like rubber or resin. The short steel pipe 51 is provided with a wire 54. After removing the bolts and nuts 24, the mud removing device 50 can be removed from the outer shell steel pipe 20 by pulling the wire 54 with a pile driver.

  Next, a method of constructing a foundation pile according to the present embodiment will be described with reference to FIGS.

  With reference to FIG. 1A, a description will be given of a rotation penetration process of the steel pipe pile 10. The steel pipe pile 10 is rotated by a motor (not shown) mounted on the pile driver, and penetrates the ground by the screwing action of the spiral blade 12. At the stage where the steel pipe pile 10 penetrates into the support ground and the pile head 11 penetrates deeper than the construction ground surface, the first hiring pile 70 is connected to the pile head 11.

  That is, the connection metal fitting 71 is fitted into the pile head 11, the rotation metal fitting 13 is fitted into the T-shaped groove 72, and the first hired pile 70 is connected to the pile head 11. Next, the steel pipe pile 10 is further rotated by the first hiring pile 70 so that the steel pipe pile 10 penetrates until the tip portion thereof reaches the supporting ground, and the pile head 11 penetrates to a predetermined depth of the ground. In the rotation penetration process of the steel pipe pile 10, the pile head 11 of the steel pipe pile 10 is penetrated to a predetermined depth of the ground, but the head of the first hired pile 70 is left protruding above the ground.

  Next, a process of inserting the first hired pile 70 into the outer steel pipe 20 will be described with reference to FIG. After previously installing the mud removing device 50 slightly above the lower end of the outer shell steel pipe 20 on the ground, the head of the first hiring pile 70 protruding above the ground is attached to the annular plate 21 of the outer shell steel pipe 20. The first hiring pile 70 is inserted through the center hole 22 into the outer shell steel pipe 20 (see FIG. 4). The outer surface of the first hiring stake 70 has no protrusion over its entire length, and the diameter difference between the first hiring stake 70 and the center hole 22 of the annular plate 21 is about 1 mm to 3 mm. The first hiring stake 70 can be inserted without any trouble.

  Next, a process of making the outer shell steel pipe 20 penetrate into the ground will be described with reference to FIG. When a pushing force is applied while rotating the outer shell steel pipe 20 using a pile driving machine, the outer shell steel pipe 20 moves along the steel pipe pile 10 from the first hired pile 70 and rotates and penetrates into the ground. The connecting portion between the steel pipe pile 10 and the first hiring pile 70 has a configuration in which the connecting metal fitting 71 is fitted into the pile head 11 and the rotating metal fitting 13 is fitted into the T-shaped groove 72. No protrusions larger than the outer diameter of the first or first hiring stake 70 are generated. For this reason, the outer shell steel pipe 20 moves along the steel pipe pile 10 from the first hired pile 70 through the connecting portion without any trouble. Here, the outer shell steel pipe 20 is rotationally penetrated into the ground until the head of the outer shell steel pipe 20 is located near the surface of the ground. Since the ground to which the construction method of the present invention is applied is often soft ground, the outer steel pipe 20 can be penetrated without a wing by slightly applying a pushing force with a pile driver. If penetration is difficult, a digging blade or wing may be attached to the outer surface of the lower end of the outer shell steel pipe 20. When the outer shell steel pipe 20 penetrates, the earth and sand are not discharged to the ground, and the volume of the earth and sand sandwiched between the steel pipe pile 10 and the outer shell steel pipe 20 is compressed, and therefore, around the annular plate 21 at the lower end of the outer shell steel pipe 20. High pressure is generated in the earth and sand. Since the inner diameter of the center hole 22 of the annular plate 21 is set slightly larger than the outer diameters of the first hiring pile 70 and the steel pipe pile 10, the annular plate 21 is penetrated into the ground by the outer shell steel pipe 20. There is a possibility that mud may enter through a narrow gap between the first hiring pile 70 and the steel pipe pile 10 (see FIG. 8), but the brush of the removing member 53 provided in the mud removing device 50 causes the rotation of the outer steel pipe 20 to rotate. As a result, the first hiring pile 70 and the outer peripheral surface of the steel pipe pile 10 are slid in contact with each other to remove the adhering mud.

  Next, a step of further rotating and penetrating the outer shell steel pipe 20 into the ground will be described with reference to FIGS. First, as shown in FIG. 1 (d), on the head of the outer shell steel pipe 20 remaining (exposed) on the ground surface, the same diameter as the outer shell steel pipe 20 and the axial length are shorter than the outer shell steel pipe 20. A second hiring pile 80 which is a hiring pile for the outer shell steel pipe 20 made of steel pipe is connected. At this stage, since the role of the first hiring pile 70 has already been completed, the first hiring pile 70 is removed from the pile head 11 of the steel pipe pile 10 before the second hiring pile 80 is connected. You may leave. Next, as shown in FIG. 1 (e), the rotational force is transmitted to the outer shell steel pipe 20 via the second hiring pile 80, and the outer shell steel pipe 20 is further rotationally penetrated to a predetermined depth of the ground, so that the outer shell steel pipe 20 penetrates. To end. Also at the time of penetration using the second hiring pile 80, the brush of the removing member 52 provided in the mud removing device 50 slides on the outer peripheral surface of the steel pipe pile 10 to remove the adhered mud. After the penetration, the head of the second hiring stake 80 is in a state of protruding above the ground. After the penetration of the outer shell steel pipe 20, the mud removing device 50 is removed from the outer shell steel pipe 20. As a result, a space 30 to which mud is not adhered is formed (partitioned) between the outer peripheral surface of the pile head 11 and the inner peripheral surface of the outer shell steel tube 20.

  Next, with reference to FIGS. 1F and 1G, a process of placing concrete in the space 30 and removing the second hiring pile 80 will be described. As shown in FIG. 1 (f), concrete is cast into the space 30 using a tremy tube 90. The reason for using the tremy tube 90 is to prevent material separation of concrete. At the time of this driving, the second hiring stake 80 protrudes above the ground, and thus plays a role of retaining the earth, and prevents the surrounding earth and sand from falling into the space 30. The casting of the concrete is continued until the entire pile head 11 is buried in the concrete, and the reinforcing body 40 is formed in the space 30. Thereafter, as shown in FIG. 1 (g), the second hired pile 80 is removed and the pile construction is completed.

  After the completion of the pile work, a concrete footing 60 is built on the pile head 11 as shown in FIG.

  According to the method for constructing the foundation pile of the present embodiment, the connecting metal fitting 71 is fitted into the pile head 11 and the rotating metal fitting 13 is fitted into the T-shaped groove 72, so that the steel pipe pile 10 and the first With the configuration in which the employment stake 70 and the hiring stake 70 are connected so as to be able to transmit the rotational force, a projection larger than the outer diameter of the steel pipe stake 10 or the first employment stake 70 does not occur on the outer surface of the connecting portion. For this reason, the first hiring pile 70 and the steel pipe pile 10 can be passed through the center hole 22 of the annular plate 21 of the outer shell steel pipe 20, and the space 30 for placing concrete is secured without any trouble (compartment). You can do it.

  Further, when the outer shell steel pipe 20 is rotationally penetrated into the ground, mud enters through a narrow gap between the annular plate 21 and the first hiring pile 70 and the steel pipe pile 10 as the outer shell steel pipe 20 penetrates into the ground. However, since the brush of the removing member 53 provided in the mud removing device 50 slides on the outer peripheral surfaces of the first hire pile 70 and the steel pipe pile 10 as the outer shell steel pipe 20 penetrates and removes the adhering mud, the steel pipe Mud soil does not adhere to and remain on the outer peripheral surface of the pile 10, and the frictional force between the concrete poured into the space 30 and the steel pipe pile 10 can be ensured. For this reason, the three members of the steel pipe pile 10, the concrete (the reinforcing body 40), and the outer shell steel pipe 20 can be integrated to exhibit extremely large rigidity and strength.

  Furthermore, the rotation of the outer shell steel pipe 20 into the ground is performed without earth removal, and the soil around the outer shell steel pipe 20 is compressed in the horizontal and downward directions, the density increases, and the horizontal resistance of the ground increases.

  Furthermore, even when the depth of the support layer of the ground is shallower than expected, the steel pipe pile 10 has no member that restricts the penetration of the outer shell steel pipe 20, and the outer shell steel pipe 20 is not hindered along the steel pipe pile 10 at all. It can penetrate to a predetermined depth of the ground. The portion of the steel pipe pile 10 (pile head 11) protruding from the head of the outer shell steel pipe 20 may be cut at the construction site.

  In the present embodiment, the steel pipe pile 10 and the first hiring stake 70 are connected to each other so as to be able to transmit a rotational force so that no protrusion is formed on the outer surface of the connecting portion. A connecting member 71 made of an annular body having an axial length that is several times shorter than the first hiring stake 70 and having an outer diameter slightly smaller than the inner diameter of the pile head 11 is provided. Although the case where the T-shaped groove 72 in which the rotation metal fitting 13 is detachably fitted is provided is shown, the present invention is not limited to this.

  Further, in the present embodiment, the mud removing device 50 is configured by arranging a pair of removing members 53 each having a brush at a tip portion pressed against the outer peripheral surface of the steel pipe pile 10. Is not limited to this.

  INDUSTRIAL APPLICABILITY The present invention is applied to a case where a foundation pile is constructed at a place where the ground near a pile head is soft.

10 steel pipe pile 11 pile head 20 outer shell steel pipe (outer pipe)
DESCRIPTION OF SYMBOLS 30 Space part 40 Reinforcement body 50 Mud removing device 60 Concrete footing 70 First hiring pile 71 Connecting bracket 72 T-shaped groove 80 Second hiring pile

Claims (2)

An outer pipe having an annular plate which is shorter than the steel pipe pile and has a center hole through which the steel pipe pile penetrates and which is fixed to a lower end thereof is installed on the upper outer circumference of the steel pipe pile. A method for constructing a foundation pile, in which a space formed between the circumference and a fluid solidifying material is filled to form a reinforcing body to enhance horizontal resistance,
The lower end of the first hiring pile for a steel pipe pile, which has the same outer diameter as the steel pipe pile and has no protrusion over the entire outer surface, is attached to the head of the steel pipe pile via a connection fitting. The connecting portion is detachably connected so that no protrusion is generated on the outer surface of the connecting portion with the connecting portion so as to transmit the rotational force, and transmits the rotating force to the steel pipe pile via the first hiring pile to thereby fix the steel pipe pile to a predetermined position. A process of rotating and penetrating the ground to the depth,
Causing the outer tube to pass through the center hole of the annular plate, through the head of the first hiring stake, and into the first hiring stake;
Moving the outer pipe from the first hire pile along the connecting portion and the steel pipe pile to rotate and penetrate the ground until the head of the outer pipe is located near the ground;
A second hiring pile for the outer pipe is connected to the head of the outer pipe, and a rotational force is transmitted to the outer pipe via the second hiring pile to further rotate the outer pipe into the ground to a predetermined depth. Forming the space between the upper outer periphery of the steel pipe pile and the inner periphery of the outer tube;
A step of filling the space portion with the fluid solidifying material to form the reinforcing body,
With
The connecting fitting has an outer diameter slightly smaller than the inner diameter of the head of the steel pipe pile, and has a pair of grooves formed on its outer surface to which a rotating fitting provided in the head is detachably fitted. A method for constructing a foundation pile, characterized in that it has been carried out . In the method for constructing a foundation pile according to claim 1,
Near the lower end of the outer pipe, the outer pipe is pressed against the outer surface of the steel pipe pile in a process of rotatingly penetrating the ground from the first hiring pile to a predetermined depth along the connection portion and the steel pipe pile to a predetermined depth. A mud removing device having a removing member for removing mud attached to the outer surface is arranged,
A method for constructing a foundation pile, comprising removing the mud removing device from the outer pipe before filling the space portion with the fluidized solidifying material.