JP7406102B2 - Pile foundation structure and construction method of structure foundation - Google Patents

Description

The present invention relates to a pile foundation structure and a construction method for a structure foundation.

Conventionally, as the foundation structure of a building built on ground that is expected to liquefy and where a large overturning moment is generated during an earthquake, we have used indentation-resistant piles driven into the ground and installations installed at the pile heads of these indentation-resistant piles. Pile foundation structures with reinforced footings and footings are common. In such a pile foundation structure, the footing and the indentation-resistant pile are structured to transmit the vertical load of the superstructure, the horizontal load caused by inertia during an earthquake, and the rotational bending moment through reinforcing bars.

On the other hand, as an indentation-resistant pile structure in which the pile is expected to support vertical force, the structure shown in Patent Document 1, for example, is known. Patent Document 1 discloses that the soil improvement body is used as the main load-bearing member, and piles are used to withstand the pull-out force that occurs when there is a risk of falling, etc., and the clearance between the footing and the anchoring part of the pile that occurs when the soil improvement body sinks is reduced. A configuration is described in which the height of the attachment part is adjusted by inserting a spacer into the attachment part.

Japanese Patent Application Publication No. 2003-74070

However, conventional pile foundation structures have the following problems.
In other words, the expansion foot protection method, which mainly has a high bearing capacity, has relatively low uprooting resistance compared to the vertical bearing capacity, so there are issues such as an increase in the number of piles for structures where uprooting occurs. . Examples of structures where pull-out occurs include steel towers, chimneys, and structures with large tower ratios, such as condominiums, and there are many cases where pull-out resistance must be taken into account, especially when a major earthquake is assumed. In this case, there is a structure that uses the bladed rotating steel pipe pile construction method, which has excellent pull-out resistance. However, as the bending moment and vertical force are shared with the piles that are expected to be pulled out, the plate thickness and pile diameter increase, resulting in an increase in the materials used and the length of construction.

Furthermore, as in the above-mentioned Patent Document 1, there is also a structure in which a foundation frame that bears a vertical load such as ground improvement and piles are arranged to provide a clearance therebetween to prevent pulling out. In this case, depending on the amount of rotation of the foundation framework, there is a risk that bending loads may be transmitted due to contact between the pile body and the foundation framework, and a method for transmitting the pulling force more reliably is required. There was room for improvement.

The present invention was made in view of the above-mentioned problems, and by efficiently sharing the pull-out force of the indentation-resistant pile with a simple structure, it is possible to prevent footings from falling over, and to reduce the cost of constructing a pile foundation structure. The purpose of the present invention is to provide a pile foundation structure and a construction method for a structure foundation that can reduce the construction period.

In order to achieve the above object, the pile foundation structure according to the present invention includes an indentation-resistant pile driven into the ground, a footing integrally provided on the pile head of the indentation-resistant pile, and a footing of the indentation-resistant pile. a pull-out resistance pile driven into the ground nearby; and an anchoring member that is in contact with the upper surface of the footing in a non-bonded state and transmits upward movement of the footing to the pull-out resistance pile as a tensile force. , a connecting member that connects the pull-out resistance pile and the fixing member to which only the tensile force of the footing is transmitted; and a height adjusting member that is provided to adjust the height of the fixing member in contact with the footing. It is characterized by having the following.

A method for constructing a structure foundation according to the present invention is a method for constructing a structure foundation using the above-described pile foundation structure, comprising the steps of constructing the pile foundation structure and constructing a structure above the footing. and a step of adjusting the height of the fixing member using the height adjusting member so that it contacts the upper surface of the footing in a non-bonded state .

In the present invention, when an excessive rotational bending moment acts on the footing that is integrally provided on the push-in resistance pile, the pull-out resistance pile shares the resistance force on the tensile side of the rotational component of the bending moment. I can do it. In other words, the vertical load of the structure and the vertical downward load caused by the inertia force during an earthquake are mainly shared by the indentation resistance pile, and the pullout force generated in the indentation resistance pile is transmitted to the pullout resistance pile to function as pullout resistance. be able to.
At this time, since the connecting member that connects the pull-out resistance pile and the anchoring member is a member to which only the tensile force of the footing is transmitted, it is possible to transmit only the pull-out force of the push-in resistance pile to the pull-out resistance pile. can. Therefore, since the pull-out resistance pile immediately functions when pull-out occurs, it is possible to construct a resistance mechanism with a rational and simple structure in which the functions are shared between the push-in resistance pile and the pull-out resistance pile. This makes it possible to further improve the stability of the footing against overturning, reduce the overall number of piles and the thickness of the piles, reduce the amount of materials used, and shorten the construction length, so it takes longer to construct the foundation structure. It is possible to reduce costs and construction period.

In addition, in the present invention, since the pull-out resistance pile is provided with a height adjustment member via a connecting member, vertical loads are introduced to the entire foundation after the footing is constructed or the superstructure is constructed. With respect to subsidence, the clearance generated between the fixing member and the footing can be reduced by the height adjusting member, and the fixing member and the footing can be brought into reliable contact.

Furthermore, in the present invention, the pull-out resistance pile is connected to the anchoring member by a connecting member such as a chain member or wire rod that hardly transmits vertical downward force (compressive force), so that external forces other than the pull-out force are This creates a structure that is unlikely to occur. Therefore, in the ultimate state of open-ended piles as pile materials, the yield strength is determined by local buckling on the compression edge side, so by not transmitting compressive force, it is not possible to maximize the yield strength of the pile material of pull-out resistant piles. can.

Further, in the pile foundation structure according to the present invention, the ground has a support layer and an intermediate layer located above the support layer, and the push-in resistance pile is supported by the support layer, and the pull-out resistance pile is supported by the support layer. It may be characterized in that the lower end of the resistance pile is disposed to stop at the intermediate layer.

In this case, indentation-resistant piles should be supported on a solid support layer in order to exhibit high bearing capacity, and pull-out resistance piles should have their tips pinned to an intermediate layer shallower than the support layer in order to shorten the pile length as much as possible. This makes it possible to perform the rotary pile construction method with blades even if the heavy construction equipment is downsized or, for example, is a medium digging construction machine for performing the expanded foot protection method with small rotational torque. Therefore, the same machine can be used to perform the expanded foot protection method and the rotating bladed pile method, which improves work efficiency, reduces the amount of heavy machinery and the number of times it is brought to the site, and reduces construction costs and construction periods. I can do it.

Further, in the pile foundation structure according to the present invention, the footing may be arranged at an edge of the structure among footings that support the structure from below.

According to the present invention, for example, in a board-shaped condominium where pull-out force is often generated on the foundation located at the outermost edge, cost reduction can be achieved by using pile foundation structure only for the footing located at the edge of the structure. can demonstrate more.

Furthermore, the pile foundation structure according to the present invention may be characterized in that a friction reducing material is provided between the fixing member and the footing.

According to such a configuration, by installing the friction reducing material on the lower surface of the anchoring member, when the footing moves horizontally due to horizontal force, relative displacement occurs between the footing and the anchoring member, thereby increasing the pull-out resistance pile. It is possible to prevent bending deformation due to diagonal tensile force being applied to the material.

According to the pile foundation structure and structure foundation construction method of the present invention, by efficiently sharing the pull-out force of the indentation-resistant pile with a simple structure, it is possible to prevent the footing from falling over, and the construction method of the pile foundation structure is reduced. It is possible to reduce costs and construction period.

FIG. 1 is a longitudinal cross-sectional view showing a pile foundation structure according to an embodiment of the present invention. FIG. 1 is a cross-sectional view taken along line AA, which is a horizontal cross-sectional view of the pile foundation structure. FIG. 3 is a vertical cross-sectional view showing a state in which the height of the anchoring plate is adjusted in a structure foundation having a pile foundation structure. FIG. 2 is a vertical cross-sectional view showing a state in which a horizontal force is applied to the pile foundation structure shown in FIG. 1. FIG. FIG. 2 is a plan view showing an example of the arrangement of a pile foundation structure. It is a longitudinal cross-sectional view which shows the pile foundation structure by the 1st modification. It is a longitudinal cross-sectional view showing a pile foundation structure according to a second modification. It is a longitudinal cross-sectional view which shows a part of pile foundation structure by a 3rd modification. It is a horizontal sectional view of the pile foundation structure by the 4th modification, and is a figure corresponding to Drawing 2. It is a longitudinal cross-sectional view which shows a part of pile foundation structure by the 5th modification. It is a top view of the pile foundation structure according to the fifth modified example, in which (a) is a diagram in which the widening portion is not provided on the foundation beam, and (b) is a diagram in which the widening portion is provided in the foundation beam.

Hereinafter, a pile foundation structure and a construction method for a structure foundation according to an embodiment of the present invention will be described based on the drawings.

As shown in FIG. 1, a pile foundation structure 1 according to the present embodiment is provided as a foundation structure of a building where a large overturning moment is generated during an earthquake. That is, the superstructure is supported from below by the pile foundation structure 1.

The pile foundation structure 1 includes an indentation-resistant pile 2 driven into the ground G, a footing 3 integrally provided on the pile head 2A of the indentation-resistant pile 2, and a footing 3 driven into the ground G near the indentation-resistant pile 2. The provided pull-out resistance pile 4 and a fixing plate 5 (fixing member) that regulates the vertical movement of the footing 3 are connected, and the pull-out resistance pile 4 and the fixing plate 5 are connected so that only the tensile force of the footing 3 is transmitted. a low-rigidity chain member 6 (connection member) that does not transmit bending or shear; and a height adjustment screw 7 (height adjustment member) that is provided so as to be able to adjust the height of contact with the footing 3 of the fixing plate 5. It is equipped with

Here, the ground G on which the push-in resistance pile 2 and the pull-out resistance pile 4 are driven includes a support layer and an intermediate layer located above the support layer.

The push-resistance pile 2 is supported when its lower end reaches the support layer, and the pile head 2A is integrally embedded and joined to the concrete portion of the footing 3. As the push-in resistance pile 2, a pile constructed using a construction method that provides high performance in vertical bearing capacity at the same pile outer diameter, such as an expanded foot protection construction method, is suitable. For example, a foot hardening section (not shown) is formed at the lower end of the push-in resistance pile 2, and the foot hardening section is constructed within the support layer. As the indentation resistance pile 2, a concrete pile, a steel pipe pile, a concrete-filled steel pipe pile, etc. can be adopted. A pile head reinforcing bar 21 is provided on the pile head 2A so as to protrude upward, and the pile cap reinforcing bar 21 is embedded and fixed in the concrete of the footing 3.

Indentation resistance piles 2 include indentation resistance piles whose tips are sufficiently embedded in the support layer, friction piles that secure the necessary vertical support force mainly by circumferential friction, and many indentation resistance piles in one footing. A group pile format in which friction piles are arranged can be adopted.

The footing 3 is configured as a part of the basic frame of the superstructure. The footing 3 is located at the intersection of foundation beams extending in the vertical and horizontal directions, and the columns 12 of the upper structure 10 shown in FIG. 3 are joined. The footing 3 is formed into a rectangular shape when viewed from above, and is a concrete block cast to a predetermined thickness so as to be buried in the surface layer of the ground G. As described above, since the footing 3 is joined to the indentation-resistant pile 2, the vertical force of the footing 3 and the horizontal force F (see FIG. 4) during an earthquake are supported by the indentation-resistant pile 2.

As shown in FIGS. 1 and 2, the footing 3 is formed with a plurality of (four in FIG. 2) through holes 31 that penetrate in the thickness direction. A chain member 6 connected to the pull-out resistance pile 4 is inserted through the through hole 31 . The plurality of through holes 31 are arranged so that the distances from the pile axis C of the indentation resistance pile 2 are equal when viewed from above. Moreover, it is preferable that the pull-out resistance piles 4 are arranged symmetrically with the pile axis C in between. The hole diameter of the through hole 31 is set to a size such that the chain member 6 passing through when the footing 3 falls does not come into contact with the hole wall of the through hole 31.

As shown in FIG. 1, the pull-out resistance piles 4 are arranged at intervals around the push-in resistance piles 2, and are provided in the ground G with their lower ends stopping at the middle layer G2 of the ground G. As the pull-out resistance pile 4, a pile constructed by a method that provides high pull-out resistance at the same pile outer diameter, such as a pile constructed by the vaned rotary steel pipe pile construction method or a steel pipe soil cement pile, is suitable. For example, the pull-out resistance pile 4 is made of a steel pipe, and a blade member 41 is provided at the tip (lower end 4a), and is penetrated into the ground by rotating the blade member 41 together with the steel pipe during driving. The pull-out resistance pile 4 is located on the same axis as the through hole 31 of the footing 3. The upper end 4b of the pull-out resistance pile 4 is located below the lower surface 3b of the footing 3. One end of the chain member 6 is connected to the upper end 4b of the pull-out resistance pile 4.

The chain member 6 is a steel chain material, and the lower end 6a of the chain is rigidly fixed to the upper end 4b of the pull-out resistance pile 4 by a fixing means such as welding or bolt connection, and the upper end 6b of the chain is connected to the height adjusting screw 7. It is rigidly fixed to the lower end 7a of the screw by the same fixing means as described above.
As described above, the chain member 6 has the characteristic that only the tensile force of the footing 3 is transmitted, and the compressive force is not transmitted. That is, the chain member 6 is a member that requires tensile rigidity but does not require compressive rigidity, and is also a member to which bending and shear forces are difficult to be transmitted. In other words, by using the chain member 6, loosening occurs between the chains of the chain member 6 during compression, thereby providing the above-mentioned characteristic of having only tensile rigidity.

The height adjustment screw 7 is fixed to the chain upper end 6b of the chain member 6 with the screw shaft oriented in the direction of the axis of the pull-out resistance pile 4. The fixing plate 5 is screwed into the height adjustment screw 7. The height adjustment screw 7 is positioned in the height direction so that the fixing plate 5 screwed onto the height adjustment screw 7 can come into contact with the upper surface 3a of the footing 3.

The fixing plate 5 has a flat plate shape and is provided so as to be screwable with the height adjusting screw 7. The planar area of the fixing plate 5 is set larger than the hole area of the through hole 31 of the footing 3. The fixing plate 5 screwed onto the height adjustment screw 7 is in contact with the upper surface 3a of the footing 3 from above in a non-bonded state. Note that, since it is preferable that the fixing plate 5 has high rigidity, it may be stiffened with, for example, vertical ribs.

Next, a method of constructing a structure foundation including the pile foundation structure 1 described above will be explained.
As shown in FIG. 3, first, a pile foundation structure 1 is constructed. Specifically, the push-in resistance pile 2 is driven into the ground G by, for example, a rotary press-in method. At this time, at the lower end of the indentation resistance pile 2, a pile cap reinforcing bar 21 is provided on the pile head 2A of the indentation resistance pile 2 that has been driven. Then, the pull-out resistance pile 4 is driven into the ground G at the same time as the driving of the push-in resistance pile 2, or after the driving of the push-in resistance pile 2. Thereafter, the upper structure 10 is constructed above the footing 3.

Here, the superstructure 10 shown in FIG. 3 includes a foundation body 11 that is integrally constructed on the footing 3 of the pile foundation structure 1, and a column 12 that is joined to the foundation body 11. A communication hole 11b coaxial with the through hole 31 is formed in the base body 11. The diameter of the communicating hole 11b is larger than that of the through hole 31 of the footing 3. A height adjusting screw 7 and a fixing plate 5, which are connected to the pull-out resistance pile 4 via a chain member 6, are housed in the communicating hole 11b. The upper opening of the communicating hole 11b is closed from above by a removable lid member 13.

Next, when adjusting the height of the fixing plate 5 so that it is in contact with the footing 3 using the height adjustment screw 7, the cover member 13 is removed and the screw operation jig 14 is inserted into the communication hole 11b. do. The screw operation jig 14 is formed from a support rod 14A and a female threaded cylindrical portion 14B in which a female thread is formed at the tip of the support rod 14A.
By rotating the threaded portion of the height adjustment screw 7 above the fixing plate 5 using the screw operation jig 14, the height of the fixing plate 5 is adjusted to a position where it contacts the upper surface 3a of the footing 3.

The height of the fixing plate 5 may be adjusted by rotating the fixing plate 5 instead of rotating the height adjusting screw 7 as described above. In this case, a screw operating jig 14 is used in which the tip of the screw operating jig 14 has a recess that matches the cross-sectional shape of the fixing plate 5 (for example, rectangular or hexagonal). The height can be adjusted by rotating the fixing plate 5 using the screw operating jig 14.
After adjusting the height of the fixing plate 5, the communication hole 11b is closed with the cover member 13, and the work is completed.

Next, the effects of the above-described pile foundation structure and structure foundation construction method will be explained in detail based on the drawings.
In the pile foundation structure 1 according to this embodiment, as shown in FIG. 4, a horizontal force F acts due to an earthquake, and an excessive bending moment that rotates is applied to the footing 3 that is integrally provided to the indentation resistance pile 2. At this time, the pull-out resistance pile 4 can share the resistance force on the tensile side of the rotational component of the bending moment. That is, the vertical load of the superstructure and the load caused by the inertia force during an earthquake are mainly shared by the indentation resistance pile 2, and the pullout force generated in the indentation resistance pile 2 is transmitted to the pullout resistance pile 4 to function as a pullout resistance. be able to.

At this time, since the chain member 6 that connects the pull-out resistance pile 4 and the fixing plate 5 is a low-rigidity member that does not transmit bending or shear, the pull-out resistance pile 4 mainly only receives the pull-out force of the push-in resistance pile 2. can be transmitted. Therefore, since the pull-out resistance pile 4 immediately functions when pull-out occurs, it is possible to construct a resistance mechanism with a rational and simple structure in which the functions are shared between the push-in resistance pile 2 and the pull-out resistance pile 4. This makes it possible to further improve the stability of the footing 3 against overturning, reduce the overall number of piles and the thickness of the piles, reduce the amount of materials used, and shorten the construction length, making it easier to construct foundation structures. This cost and construction period can be reduced.

In addition, in this embodiment, since the pull-out resistance pile 4 is provided with the height adjustment screw 7 via the chain member 6, a vertical load is introduced to the entire foundation after the construction of the footing 3 or the superstructure. The height adjustment screw 7 can reduce the clearance generated between the fixing plate 5 and the footing 3 due to the sinking caused by the fixing plate 5 and the footing 3, and it is possible to ensure that the fixing plate 5 and the footing 3 are in contact with each other. .
In particular, in this embodiment, by appropriately tightening the height adjustment screw 7 to the extent that some tensile force is generated in the chain member 6, it is possible to achieve stability even against smaller rotational displacements of the footing. .

Furthermore, in this embodiment, the pull-out resistance pile 4 is connected to the fixing plate 5 by the chain member 6 that hardly transmits the vertical downward force (compressive force) caused by the footing 3, so that the structure is such that external forces other than the pull-out force are difficult to generate. becomes. Therefore, in the ultimate state of an open-ended pile, the proof strength is determined by local buckling on the compression edge side, so by not transmitting compressive force, the pull-out resistance pile 4 can maximize its proof strength.

In addition, in this embodiment, the push-in resistance pile 2 is supported on a solid support layer in order to exhibit high bearing capacity, and the pull-out resistance pile 4 is supported on an intermediate layer shallower than the support layer in order to shorten the pile length as much as possible. By stopping the tip, it is possible to downsize heavy construction equipment, or to perform rotary pile construction with blades, even if it is a medium digging construction machine for performing the expanded foot protection method, which requires small rotational torque. Therefore, the same machine can be used to perform the expanded foot protection method and the rotating bladed pile method, which improves work efficiency, reduces the amount of heavy machinery and the number of times it is brought to the site, and reduces construction costs and construction periods. I can do it.

Further, as shown in FIG. 5, in the pile foundation structure 1 according to the present embodiment, the footing 3 may be disposed at the edge 10a of the upper structure 10 of the footing 3 that supports the upper structure 10 from below. can. For example, in a board-shaped condominium where pull-out force is often generated on the foundation located at the outermost edge, cost reduction can be achieved by using the pile foundation structure 1 only for the footing 3 located at the edge 10a of the upper structure 10. can demonstrate more.

In addition, in FIG. 5, the pull-out resistance piles 4 are arranged only on both sides of the upper structure 10 in a plan view from above. In other words, the pile foundation structures 1 are arranged on two sides (edges 10b and 10c) that are vertically opposite long sides in the paper of the edge 10a of the superstructure 10, and on one side (on the top of the paper). The pull-out resistance piles 4 of the pile foundation structure 1 arranged at the edge 10b are arranged only above the push-in resistance piles 2, and the pull-out resistance piles 4 of the pile foundation structure 1 arranged at the other (lower side in the paper) edge 10c are arranged only above the push-in resistance piles 2. The resistance piles 4 are arranged only below the push-in resistance piles 2, and the pull-out resistance piles 4 are arranged on both the upper and lower sides of the paper with the outermost edge of the upper structure 10 interposed therebetween. In this case, the pull-out resistance pile 4 effectively acts against the horizontal force in the direction along the shorter side of the upper structure 10.

In the pile foundation structure and structure foundation construction method according to the present embodiment described above, by efficiently sharing the pulling force of the push-in resistance pile 2 with a simple structure, it is possible to prevent the footing 3 from overturning, and the pile foundation structure 1 It is possible to reduce the construction cost and construction period.

Next, modified examples of the pile foundation structure and the construction method of the structure foundation of the present invention will be explained based on the attached drawings, and the same reference numerals will be used for the same or similar members and parts as in the above-described embodiment. The explanation will be omitted, and the configuration different from the embodiment will be explained.

(First modification)
A pile foundation structure 1A according to a first modification example shown in FIG. 6 has a configuration in which the connecting members are changed from those in the above-described embodiment. That is, in the embodiment described above, the chain member 6 is used as a connecting member that connects the pull-out resistance pile 4 and the height adjustment screw 7 (height adjustment member), but the chain member 6 is used as a connection member that connects the pull-out resistance pile 4 and the fixing plate 5. However, the member is not limited to this as long as it is a member to which only the tensile force of the footing 3 is transmitted.
A pile foundation structure 1A according to a first modification shown in FIG. 6 employs a steel wire 6A as a connecting member. In this case, the steel wire 6A is fixed at its lower end 6a to the pull-out resistance pile 4 and at its upper end 6b to the height adjustment screw 7 using fixing means such as welding.

In the first modification, the pull-out resistance pile 4 is connected to the fixing plate 5 by a steel wire 6A such as a wire that transmits almost no vertical force, so that external forces other than the pull-out force are unlikely to occur. That is, the steel wire 6A can be buckled when the footing 3 is compressed, and has only tensile rigidity. Therefore, in the ultimate state of an open-ended pile, the proof strength is determined by local buckling on the compression edge side, so by not transmitting compressive force, the pull-out resistance pile 4 can maximize its proof strength.

(Second modification)
Next, as shown in FIG. 7, in the pile foundation structure 1B according to the second modification, a friction reducing material 8 may be provided directly between the fixing plate 5 and the upper surface 3a of the footing 3. As the friction reducing material 8, for example, a Teflon (registered trademark) material applied to the lower surface 5a of the fixing plate 5, a fluororesin-treated plate or tape installed, and a sliding material such as a bearing can be used. By inserting such a friction reducing material 8 between the fixing plate 5 and the footing 3, it is possible to prevent horizontal force of a certain magnitude or more from being transmitted to the pull-out resistance pile 4 between the fixing plate 5 and the footing 3. Can be suppressed.

In the second modification, even when a horizontal force acts on the footing 3, the friction reducing material 8 causes slippage, so the horizontal movement of the fixing plate 5 can be suppressed, and the chain member 6 is applied to the pull-out resistance pile 4. The structure is such that no horizontal force acts on it.

In this way, in the second modification, by installing the friction reducing material 8 on the lower surface 5a of the fixing plate 5, when the footing 3 receives horizontal force and moves horizontally, the relative displacement between the footing 3 and the fixing plate 5 is reduced. By generating this, it is possible to prevent bending deformation caused by diagonal tensile force being generated in the pull-out resistance pile 4.

(Third modification)
Further, in this embodiment, the pull-out resistance pile 4 is driven with the pile axis direction facing the vertical direction, but the arrangement is not limited to this. For example, in the pile foundation structure 1C according to the third modification shown in FIG. 8, the pull-out resistance pile 4A may be driven into the ground G with the pile axis direction obliquely. The pull-out resistance pile 4A is a diagonal pile that radially separates from the push-in resistance pile 2 toward the bottom. Also in this case, a diagonal through hole 32 is formed in the footing 3 from the upper surface 3a to the lower surface 3b, and the chain member 6 diagonally connects the pull-out resistance pile 4A and the fixing plate 5 through this through hole 32. There is.

(Fourth modification)
Further, the arrangement of the pull-out resistance piles 4 in the footing 3 can be appropriately set according to conditions such as the shape of the footing 3 and the arrangement of structures. For example, as in a fourth modification shown in FIG. 9, the pull-out resistance stakes 4 may be arranged at four corners of the footing 3, which is square in plan view when viewed from above.

(Fifth modification)
Moreover, the pile foundation structure 1C according to the fifth modification shown in FIGS. 10 and 11(a) and (b) has a configuration in which the anchoring member 5 is connected to the underground beam 8. As shown in FIGS. 10 and 11(a), the underground beam 8 is connected to the footing 3 and is provided with a penetrating hole that vertically penetrates the underground beam 8 at a position near the footing 3. A hole 81 is formed. The chain member 6 connects the anchor plate 5 to the pull-out resistance pile 4 driven into the ground G in a substantially vertical direction through the through hole 81 .

As shown in FIG. 11(b), the underground beam 8 is provided with a widened portion 82 at the position where the through hole 81 is provided, that is, at the position where the anchoring member 5 is connected to the pull-out resistance pile 4. You can.

Although the embodiments of the pile foundation structure and the construction method of the structure foundation according to the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be modified as appropriate without departing from the spirit thereof. be.

For example, in the present embodiment, a flat fixing plate 5 is used as a fixing member fixed to the pull-out resistance pile 4 via a chain member 6 (connection member), but such a fixing plate 5 may be used. is not limited to. For example, it may be a nut that can be screwed onto the height adjustment screw 7.

Furthermore, the height adjusting member is not limited to the height adjusting screw 7 as in this embodiment.

In addition, it is possible to appropriately replace the components in the embodiments described above with well-known components without departing from the spirit of the present invention.

1, 1A, 1B, 1C Pile foundation structure 2 Push-in resistance pile 2A Pile head 3 Footing 3a Top surface 4 Pull-out resistance pile 5 Anchor plate (anchor member)
6 Chain member (connecting member)
6A steel wire (connecting member)
7 Height adjustment screw (height adjustment member)
8 Friction reducing material G Ground

Claims (5)

An indentation resistance pile driven into the ground;
a footing integrally provided on the pile head of the indentation-resistant pile;
a pull-out resistance pile driven into the ground near the push-in resistance pile;
a fixing member that contacts the upper surface of the footing in a non-bonded state and transmits upward movement of the footing to the pull-out resistance pile as a tensile force;
a connecting member that connects the pull-out resistance pile and the fixing member, and only the tensile force of the footing is transmitted;
a height adjusting member that is provided so as to be able to adjust the height of the fixing member that contacts the footing;
A pile foundation structure characterized by comprising: The ground has a support layer and an intermediate layer located above the support layer,
The indentation resistance pile is supported by the support layer,
The pile foundation structure according to claim 1, wherein the lower end of the pull-out resistance pile is installed so as to stop at the intermediate layer. The pile foundation structure according to claim 1 or 2, wherein the footing is disposed at an edge of the structure among footings that support the structure from below. The pile foundation structure according to any one of claims 1 to 3, wherein a friction reducing material is provided between the fixing member and the footing. A method for constructing a structure foundation using the pile foundation structure according to any one of claims 1 to 4, comprising:
a step of constructing the pile foundation structure;
constructing a structure above the footing;
adjusting the height of the fixing member using the height adjusting member so that it contacts the upper surface of the footing in a non-bonded state ;
A construction method for a structure foundation, characterized by having the following.

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