JPH1082056A - Method of earthquake-resisting pile foundation construction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of piles and the diameters of the piles, and to resist even large seismic force while enabling an economic design by driving ground anchors into the piles without resisting against external force at the time of an earthquake as pile single bodies and working the piles as resistors to the pile drawing-out direction in a pile foundation. SOLUTION: In the method of earthquake-resisting pile foundation construction, ground anchors 11, 12 penetrated to a footing 5 on pile foundations 6, 7, 8, 9 and the insides of the piles 6, 9 are driven into the piles 6, 9 at both end sections of a plurality of the pile foundations 6, 7, 8, 9 buried into a ground and arranged and installed respectively, and each ground anchor 11, 12 is fixed to the fixing sections 13, 14 of a bearing layer 2 in the ground 1. Tensile force is given and the pile foundations are fastened by fasteners 15, 16 respectively on the footing 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earthquake-resistant pile foundation method in which a ground anchor is passed through a pile of a pile foundation.

[0002]

2. Description of the Related Art For example, a pile foundation applied to all structural foundations such as a pier foundation, a steel tower foundation, a building building foundation, an underground structural foundation, etc. Each stake resisted itself. In addition, a large number of pile foundations are required to resist large seismic forces with the bending and shear strength of individual piles. In addition, additional piles were cast as seismic reinforcement for existing pile foundations. In recent years, ground anchor design and
The reliability of the construction method is increasing, and the results as permanent anchors, for example, slope collapse protection works, building foundation works, etc. are increasing.

[0003]

By the way, an appropriate pile interval is necessary for a pile foundation structure to exhibit the maximum horizontal and vertical support force as a pile. In addition, a large number of piles or large-diameter piles are required in order to resist a large seismic force, which is particularly infrequent. Therefore, the plane dimensions of the foundation also become large, which is uneconomical. Also,
There are many design and construction problems, such as expansion of the footing or cutting of the existing reinforcing steel bar, for placing additional piles for seismic reinforcement of existing pile foundation structures.

Therefore, an object of the present invention is to provide a ground anchor in a pile and to function as a resistor in the pulling-out direction of the pile, instead of resisting an external force at the time of an earthquake as a single pile. It is an object of the present invention to provide an earthquake-resistant pile foundation method capable of reducing a pile diameter, enabling economic design, and resisting a large seismic force.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention according to claim 1 is, for example, an earthquake-resistant pile foundation method for a pier foundation or the like, wherein the pile foundation is a steel pipe pile or the like buried underground. A ground anchor made of, for example, a tensile material such as PC steel is penetrated through the inside of the pile, and the anchor body is fixed to a support layer in the ground.

Here, the present invention can be applied to all structural foundations related to pile foundations, such as pier foundations, steel tower foundations, building building foundations, underground structural foundations, and the like. Examples of the pile include a steel pipe pile and a cast-in-place concrete pile. The present invention is also applicable to an existing pile foundation.

As described above, since the ground anchor is cast inside the pile of the pile foundation and fixed to the support layer in the ground, the ground anchor penetrating the inside of the pile functions as a resistor in the pull-out direction. , Can resist large seismic force. In addition, the adoption of the inexpensive ground anchor increases the strength of the pile foundation in the pulling-out direction, so that the number of piles and the diameter of the piles can be reduced, and economic design can be performed.

[0008] Further, the invention according to claim 2 is based on claim 1.
The method according to the above-mentioned earthquake-resistant pile foundation method, wherein the ground anchor is constructed on a plurality of pile foundations, for example, the anchor head is fixed to a footing such as a bridge pier. The ground anchor may be fixed to the footing upper surface by penetrating the ground anchor through the footing, or the anchor head may be fixed inside the footing.

As described above, the anchor head of the ground anchor according to the first aspect is fixed to the footing on the pile foundation, so that the foot anchor and the ground anchor cast inside the pile are used to resist the footing together with the footing in the pile pull-out direction. Can be reasonably increased.

[0010] The invention according to claim 3 is based on claim 1.
Or the seismic pile foundation method according to 2, wherein the ground anchors are respectively driven into the piles at least at both ends of a plurality of pile foundations provided side by side.

As described above, the ground anchor according to claim 1 or 2 is installed at least in the inside of the pile at both ends, so that the ground anchor is installed inside the pile at both ends of the pile. It is possible to reasonably provide a resistance against the pile pull-out direction due to the external force.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an earthquake-resistant pile foundation method according to the present invention will be described below with reference to FIGS. First, FIG. 1 is a side view of an essential part showing a construction structure of an earthquake-resistant pile foundation as an example to which the present invention is applied, and FIG. 2 is a schematic plan view showing an arrangement of the pile foundation and a pile-through ground anchor. . 1 and 2, 1 is the ground, 2 is the support layer, 3 is the pier, 4 is the superstructure, 5 is the footing, 6, 7, 8, and 9 are pile foundations (steel pipe pile foundations), 1
Reference numerals 1 and 12 denote ground anchors, 13 and 14 denote ground anchor fixing portions, and 15 and 16 denote fastening fittings.

That is, this embodiment is a case where the present invention is applied to, for example, a pier foundation as shown in FIG.
As examples of pile foundations, many steel pipe pile foundations 6,7,
.. Are respectively driven up to the support layer 2, and the pier 3 is constructed on the footing 5 constructed thereon, and the upper structure 4 is supported by the pier 3.
As shown in FIG. 2, a total of 16 steel pipe pile foundations 6, 7, 8, 9,... , 7,8,9,
..., four steel pipe pile foundations 6,6,6,6,9,9,9,9 parallel to each other at the right and left ends of the figure are passed through the footing 5 and the inside of each pile. Ground anchor 1
1,11,11,11,12,12,12,12 are respectively cast.

Next, a concrete example of the construction of an earthquake-resistant pile foundation using such pile penetrating ground anchors 11 and 12 will be described. First, as shown in FIG. 1, steel pipe pile foundations 6, 7, 8, 9,... Are cast on the ground 1 and the lower end thereof is driven into the support layer 2, and then reinforcing bars of reinforcing steel are placed thereon. And footing 5 is constructed by formwork and concrete casting. Then, on the footing 5, the inside of each pile of four steel pipe pile foundations 6, 6, 6, 6, 9, 9, 9, 9 including the footing 5, which are parallel to each other at the left and right ends in the drawing, are drilled. . Although not shown, the drilling is performed by using a drill pipe with an appropriate boring machine (drilling machine) from the upper surface of the footing 5 to the steel pipe pile foundation 6, 6, 6, 6, 9, 9, 9,
9, the inside of each stake, and the support layer 2 thereunder
Drill vertically to

Then, ground anchors 11 and 1 made of PC steel (JIS) as a tensile material are inserted into the drilled holes.
2 is inserted up to the hole drilled in the support layer 2, and a grout material such as cement paste or cement mortar is injected into the hole drilled in the support layer 2 by an injection pipe (not shown). At this time, the grout material is injected under pressure while pulling out the drill pipe. When the grout thus injected reaches a predetermined compressive strength, the ground anchor 11,
The lower end portions (anchor bodies) of the ground anchor fixing portions 13 and 14 fixed in the solidified grout material. When the grout material reaches a predetermined compressive strength, the ground anchors 11 and 12 are fixed. To tension.

That is, the ground anchors 11 and 12 are mounted on the footing 5 using a tension jack (not shown).
With a predetermined tension applied to the fasteners,
6, the upper ends (anchor heads) of the ground anchors 11 and 12 are fixed to the upper surface of the footing 5. As described above, as shown in FIGS. 1 and 2, the steel pipe pile foundations 6, 6, 6, 6, 9, 9, 9,
Ground anchors 11 and 1 penetrating the insides of the piles 9 and 9
The installation of 1, 11, 11, 12, 12, 12, 12 is completed.

As described above, according to the earthquake-resistant pile foundation method using the pile-through ground anchor according to the embodiment of the present invention, the following effects can be exerted. When an earthquake occurs, as shown in FIG. 3, which shows the effect of the resistance force on the pile pull-out direction due to the external force during the earthquake exaggeratedly in the drawing, for example, with respect to the external force in the direction of arrow I from the left side of the drawing, , Steel pipe pile foundations 6, 6, 6, 6 at the left end of the figure and ground anchors 11, 11, 11, 11,
11 and the adjacent row of steel pipe pile foundations 7,7,7,7 resist forces acting in the pull-out direction. At this time, the steel pipe pile foundations 9, 9, 9, 9 at the right end in the figure and the steel pipe pile foundations 8, 8, 8, 8 in the row adjacent thereto receive compressive force and resist seismic force. Steel pipe pile foundation 9,9,
Ground anchors 12,1 penetrating the inside of each pile of 9,9
2, 12, 12 are loose and do not contribute as a resistor.

Conversely, when an external force is applied in the direction of arrow II from the right side in the figure, the steel pipe pile foundations 9, 9, 9, 9
9 and a ground anchor 12 penetrating the inside of each pile,
12, 12, 12 and the adjacent row of steel pipe pile foundations 8, 8,
8, 8 resists forces acting in the pull-out direction. At this time, the steel pipe pile foundation 6, 6, 6,
6 and the adjacent row of steel pipe pile foundations 7, 7, 7, 7 receive the compressive force and resist the seismic force, but the inside of each pile of the steel pipe pile foundations 6, 6, 6, 6 at the left end shown in the figure. The penetrating ground anchors 11, 11, 11, 11 are loosened and do not contribute as resistors. As described above, a structure having strength capable of resisting a large seismic force is provided.

Incidentally, the number of pile foundations is determined so as to be able to withstand the external force at the time of an earthquake. Especially,
In order for a pile to resist the horizontal force of an earthquake, it is necessary to resist the bending shear strength of the pile and the shear strength of the surrounding ground, but a large number of piles is required. However, as in the embodiment, from the footing 5 on the pile foundations 6, 7, 8, 9, ... to the inside of the pile foundations 6, 6, 6, 6, 9, 9, 9, 9, 9 at both ends. Ground anchor 11, 11, 11, 11, 12, 1
By placing 2,12,12, its footing 5 and pile foundations 6,6,6,6,9,9,9,9
9, ground anchors 11, 11, 11,
Since 11, 12, 12, 12, 12 function as a resistive element in the pile pull-out direction, the number of piles can be reduced,
Alternatively, the diameter of the pile can be reduced, and this can be realized with the use of a low-cost ground anchor method and the low construction cost through rational and economical design. In addition, it is effective as seismic reinforcement of the existing pile foundation structure, and can be easily performed.

In the above embodiment, the present invention is applied to a pier foundation. However, the present invention is not limited to this, and other examples include a steel tower foundation, a building building foundation, an underground structure foundation and the like. The present invention can be applied to all structural foundations related to foundations, and can also be applied to existing pile foundations. Further, in the embodiment, the steel pipe pile is used as the pile, but the present invention is not limited to this, and is applicable to a cast-in-place concrete pile or the like.

In the embodiment, the ground anchors penetrating the inside of the pile are installed at the two parallel end portions of the pile foundation. However, similar ground anchors are installed along each end in four directions. Alternatively, a ground anchor penetrating the inside of all the piles may be cast. In the embodiment, the anchor head of the ground anchor penetrating the footing is fixed on the upper surface of the footing, but the anchor head may be fixed inside the footing. Further, it goes without saying that other specific detailed structures can be appropriately changed.

[0022]

As described above, according to the earthquake-resistant pile foundation method according to the first aspect of the present invention, since the ground anchor is cast inside the pile, the ground anchor penetrating the inside of the pile has a resistance in the pull-out direction. It can function as a body and resist large seismic forces. In addition, the adoption of the inexpensive ground anchor increases the strength of the pile foundation in the pull-out direction, so that the number of piles and the diameter of the piles can be reduced, and economic design can be achieved.

Further, according to the seismic pile foundation method according to the second aspect of the present invention, the anchor head of the ground anchor to be cast into the pile is fixed to the footing on the pile foundation. In addition to the effect obtained by
The footing and the ground anchor cast inside the pile provide an advantage that the resistance in the pile pullout direction can be reasonably increased with the footing.

According to the seismic pile foundation method according to the third aspect of the present invention, the ground anchors are cast at least inside the piles at both ends.
In addition to the effects obtained by the described invention, the advantage that the ground anchor can be rationally provided with resistance to the pulling-out direction due to an external force at the time of an earthquake from both sides on both ends where the ground anchor is driven into the inside of the pile. Is obtained.

[Brief description of the drawings]

FIG. 1 is a side view of an essential part showing a construction structure of an earthquake-resistant pile foundation as an example to which the present invention is applied.

FIG. 2 is a schematic plan view showing an arrangement of a pile foundation and a pile-through ground anchor of FIG. 1;

FIG. 3 is a side view of a breakage of a main part, in which the effect of a resistance force in a pile pull-out direction due to an external force at the time of an earthquake from the side according to the example of the foundation of the earthquake-resistant pile shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ground 2 Support layer 3 Bridge pier 4 Upper structure 5 Footing 6,7,8,9 Pile foundation 11,12 Ground anchor 13,14 Ground anchor anchoring part 15,16 Fastening metal

Claims (3)

[Claims] 1. A seismic resistance, wherein a ground anchor which penetrates through the inside of a pile and is anchored to a support layer in the ground is cast inside a pile of a pile foundation buried underground. Pile foundation method. 2. The seismic pile foundation method according to claim 1, wherein said ground anchor has an anchor head fixed to a footing constructed on a plurality of pile foundations. 3. The seismic pile foundation method according to claim 1, wherein said ground anchors are respectively installed at least inside the piles at both ends of a pile foundation provided side by side.