JP2000080662A - Connecting structure of cast-in-place pile and foundation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connecting structure of a cast-in-place pile and a foundation capable of certainly fixing the pile on the foundation, securing transmission of horizontal force, vertical drawing force, vertical pushing and fitting force and a moment to the pile from the foundation and improving bearing force of the foundation and deformation performance. SOLUTION: A pile body 9 and a foundation are connected by a bar type steel material by inserting a lower part of the bar type steel material such as a steel bar 11, etc., into a pile head part 9a of the pile body 9 and inserting an upper part of the bar type steel material into the foundation above the pile body 9 in connecting structure of a cylindrical cast-in-place pile covered by a bag and the foundation, for example, an existing foundation 1 to make by cutting a ground, inserting the bag 6 in a cutting hole 3, filling a filler 8 such as cement milk, mortar or concrete, etc., in the bag 6 by a rod and inflating the bag 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to seismic reinforcement (including liquefaction countermeasures), or to an existing foundation with an increase in the load on a superstructure, the bearing capacity, the strength of the foundation itself (vertical and horizontal), and If the deformation performance is insufficient, cast-in-place piles constructed for the purpose of improving the yield strength and deformation performance of the foundation, or even new foundations are covered with bags formed by inserting them into cutting holes and inflating the bags with filler to create them. It relates to a connection structure between a cast-in-place column and a foundation.

[0002]

2. Description of the Related Art For example, as for reinforcement of an existing foundation, FIG.
20, existing footing 21 and existing pile as shown in Fig. 21
There is a method in which an additional pile 23 is provided outside of the base 22 and a footing 21 is additionally provided to improve the bearing capacity, the proof strength and the deformation performance in the event of an earthquake.

However, this method of increasing piles and the like is not sufficient in terms of area only within the plane of the existing foundation, and cannot be used in places where there are restrictions on land or restrictions on headspace just below the existing structure.

[0004] In both the case of a pile foundation and a direct foundation, the entire ground below and around the ground is improved by improving the ground,
Alternatively, there is a method of increasing the ground strength immediately below the existing piles.However, such reinforcement by the ground improvement method cannot satisfy the required performance unless the entire area immediately below the foundation or a wide area outside the foundation is improved. Since many piles do not consider the existing piles, the cost increases as a result.

[0005] Therefore, without increasing the area and without removing the existing foundation, it is possible to easily and surely improve the supporting force, the proof stress, and the horizontal deformation performance of the foundation. Japanese Patent Application No. 8-285200 proposes a cast-in-place pile construction method directly under the existing foundation that can be used.

As shown in FIGS. 13, 14 and 15 to 19, a vertical through hole 4 is formed in an existing foundation 1 having an existing pile 2 and a rod is formed by using the through hole 4. From 5, the ground is cut by a high-pressure injection displacement method or the like to form holes 3 filled in muddy water. In that case, muddy water such as bentonite may be replaced. The cut earth and sand is discharged upward from the gap of the double pipe or the triple pipe inserted into the through hole 4.

The bag 6 is inserted together with the rod 7, and the bag 6 is filled with a filler 8 such as cement milk, mortar, or concrete, and is spread. The columnar ground improvement body covered with the bag 6 is piled up 9. To build. In the figure, reference numeral 10 denotes a support layer.

[0008]

[Problems to be Solved by the Invention] Japanese Patent Application No. 8-285200
In addition to the case where a cylindrical pile body covered with a bag, which is a cast-in-place pile constructed by the method shown in the above item, is formed below the existing foundation such as footing, foundation beam, foundation slab, etc. Even when such a cast-in-place pile and a foundation are newly constructed, the connection between the pile and the foundation mainly depends on the frictional resistance between the filler filled in the bag and the lower part of the foundation.

For this reason, the load cannot be sufficiently transmitted from the foundation to the pile, the horizontal strength, the vertical pull-out strength, and the vertical push-in strength cannot be sufficiently obtained, and the strength and deformation performance of the foundation are not sufficient.

[0010] An object of the present invention is to solve the above-mentioned disadvantages of the prior art, and when forming a bag pile into which a filler is to be filled as a cast-in-place pile, securely fix the pile to the foundation and remove the pile from the foundation. It is an object of the present invention to provide a connection structure between a cast-in-place pile and a foundation that ensures the transmission of horizontal force, vertical pulling force, vertical pushing force, and moment, and improves the strength and deformation performance of the foundation.

[0011]

According to the present invention, in order to achieve the above object, first, the ground is cut, a bag is inserted into the cut hole, and cement milk, mortar or mortar is inserted into the bag with a rod. In a joint structure between a cylindrical cast-in-place pile and a foundation covered with a bag filled with a filler such as concrete and inflated to form the lower part, the lower part of a bar-shaped steel material such as a steel rod is placed in the pile head of the pile. And the upper part of the bar-shaped steel material is inserted into the foundation above the pile, and the pile and the foundation are joined by the bar-shaped steel material.

Secondly, the foundation is an existing foundation, and a bar-shaped steel material is inserted into a pile head through a through hole formed in the existing foundation. Third, the inserted bar-shaped steel material and the through hole are inserted. And filling the gap between the existing foundation and the pile head with a filler such as mortar. Fourth, the pile head is expanded, and a plurality of bar-shaped steel materials are inserted into the expanded portion. Fifth, the bar-shaped steel material is fixed to the foundation with an anchor. Sixth, the bar-shaped steel material is formed by filling a filler such as mortar into a rod for filling the filler in the bag. It is an abstract.

According to the first aspect of the present invention, the steel rod inserted so as to straddle both the pile head of the cylindrical cast-in-place pile covered with the bag and the foundation above the pile head. And so on, the connection is secure, the horizontal force can be reliably transmitted from the foundation to the pile side, and the horizontal strength is improved.

According to the second aspect of the present invention, in addition to the above-mentioned functions, when the foundation is an existing one, a through-hole is formed in the existing foundation, so that the existing foundation is inserted through the through-hole. The bar-shaped steel material can be easily inserted from above into the pile head below.

According to the third aspect of the present invention, in addition to the above effects, the filling of the filler increases the adhesion between the foundation and the pile, and the transmission of vertical force, horizontal force, and the like from the foundation to the pile. It becomes reliable and the vertical indentation strength is improved.

According to the fourth aspect of the present invention, in addition to the above operation, by fixing with a plurality of bar-shaped steel materials,
The degree of fixation of the pile head is increased, not only horizontal force is generated, but also moment can be transmitted, and the strength of the foundation is further improved.

According to the fifth aspect of the present invention, in addition to the above-mentioned function, the pull-out resistance of the pile is improved by fixing the bar-shaped steel material to the foundation with the anchor.

According to the sixth aspect of the present invention, in addition to the above operation, the rod for filling the filler in the bag can be left as it is in the bag and used as a bar-shaped steel material. In such a case, it is possible to save members and construction steps.

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a longitudinal sectional front view showing a first embodiment of a connection structure between a cast-in-place pile and a foundation according to the present invention, and FIG.
Is a plan view of the same, and in the present invention, the aforementioned Japanese Patent Application No. 8-2852.
As in the case of the cast-in-place pile constructed by the method shown in No. 00, as shown in FIGS. 13 to 19, for example, a vertical through hole 4 of about φ200 mm is formed in an existing foundation (footing) 1 having an existing pile 2. The ground is cut from the rod 5 using the through-hole 4 by a high-pressure injection displacement method or the like, and is brought into a muddy state. In that case, muddy water such as bentonite may be replaced.

In the case of the high-pressure injection replacement method, the cut earth and sand is discharged upward from the gap of the double pipe or the triple pipe inserted into the through hole 4. The bag 6 is inserted together with the rod 7 with the bag 6 closed through the through-hole 4, and the bag 6 is filled with a filler 8 such as mortar and spread, and the columnar ground improvement body covered with the bag 6 is piled. Construct as body 9.

FIG. 3 shows the pile body 9 formed as described above. The shape of the bag 6 is cylindrical, and the material of the bag 6 is polyvinyl alcohol fiber, polyester fiber, polyamide fiber, polyethylene fiber. , Aramid fiber,
PBO (polyparaphenylene benzobisoxazole)
A bag-shaped woven fabric was formed using high-strength fibers such as fibers, glass fibers, carbon fibers, and metal fibers as warp and weft.

The bag 6 has a different bag diameter between the main body of the pile 9 and the footing penetrating portion, and the bag at the footing penetrating portion has a diameter of 150 mm.
It is composed of a small-diameter woven fabric of about φ200 mm.

As described above, since the bag 6 is made of high-strength fiber, the bag 6 can have the same function as the reinforcing bars in the vertical direction and the circumferential direction, and the bag 6 is used as a mold. In this case, the filling material 8 such as cement milk or mortar is replaced with muddy water, so that qu = 300 kgf
/ Cm ^{2 to} 500 kgf / cm ² can be strengthened.

For the pile body 9 thus formed,
In the present invention, as shown in FIGS. 1 and 2, a steel rod 11 is inserted as a bar-shaped steel material from the through hole 4 provided in the existing foundation 1 to the pile head 9 a of the pile body 9, and the existing foundation is 1 and the pile 9 were connected, and the gap between the steel rod 11 and the existing foundation 1 and the gap between the existing foundation 1 and the pile 9 were filled with a high-strength filler 12 such as mortar.

Next, a method of fixing the pile body 9 to the existing foundation 1 will be described. As shown in FIG. 3, the upper part of the through-hole 4 provided in the existing foundation 1 is enlarged to form an enlarged-diameter portion 4a, and as shown in FIG. It is inserted into the pile head 9a of the body 6. 11a in the figure is a steel bar
11 shows a nut provided on the head of No. 11 as a locking member to the enlarged diameter portion 4a.

Next, as shown in FIG.
The gap between the through hole 4 and the gap between the existing foundation 1 and the pile head 9a is filled with a high-strength filler 12 such as mortar, and finally formed on the existing foundation 1 as shown in FIG. The recess formed by the enlarged diameter portion 4a is filled with a filler 12 such as mortar to smooth the upper surface of the existing foundation 1.

By connecting the existing foundation 1 and the pile 9 with the steel rod 11 in this manner, the transmission of the horizontal force from the existing foundation 1 to the pile 9 is ensured, and the horizontal strength is improved. In addition, the steel rod 11 and the existing foundation 1, and the existing foundation 1 and the pile head 9
By injecting the filler 12 into the gap between the pile 1 and the existing foundation 1, the adhesion between the pile 1 and the pile 9 is increased, and the vertical force can be transmitted from the existing foundation 1 to the pile 9 to improve the vertical indentation resistance. I do.

In the first embodiment, the bar-shaped steel material is
In the second embodiment, a plurality of through-holes 4 are formed in the existing foundation 1 and a plurality of bar-shaped steel materials are formed in the pile 9 as shown in FIGS. insert. In the example shown in the figure, one steel rod 11 is inserted at the center, and six rebars or steel rods 13 are inserted radially from the existing foundation 1 to the pile head 9a through the through holes 4 so as to surround the circumference in a circular shape. did. In this case, even if a plurality of reinforcing bars or steel bars 13 are arranged around the
Since 13 has a smaller diameter than the steel rod 11, it can be arranged also on the pile head 9a having a limited diameter.

As a result, the degree of fixation of the pile head 9a to the existing foundation 1 is increased, and not only the horizontal strength and the vertical pull-out strength are improved, but also the transmission of moment becomes possible, and the pile body 9 is sufficiently reinforced.

FIG. 9 shows a third embodiment, in which a pile head 9a of a pile body 9 is enlarged, and a plurality of bar-shaped steel materials are inserted into the enlarged pile head 9a. In this case, the diameter of the pile head 9a is increased and the number of parts into which the bar-shaped steel material can be inserted is increased. Then, a plurality of, for example, six short steel bars 11 having a length were arranged so as to surround the periphery thereof in a circular shape.

This not only improves the horizontal strength and the vertical pull-out strength, but also increases the contact strength between the pile head 9a and the existing foundation 1, thereby improving the strength against the vertical pushing force.

FIG. 10 shows a fourth embodiment, in which a plate 14 is attached to the head of a steel bar 11 made of bar-shaped steel, and the plate 14 is fixed to the upper surface of the existing foundation 1 with an anchor 15. As a result, the steel bar 11 is fixed to the existing foundation 1 by the anchor 15 via the plate body 14, so that the pull-out strength is further improved.

A nut 11b is provided on the side of the lower portion of the steel rod 11.
By attaching a, the pull-out resistance is further improved.

FIG. 11 shows a fifth embodiment, in which the rod 7 used for injecting the filling material 8 into the bag 6 can be used as a bar-shaped steel material instead of the steel rod 11. In this case, all or a part of the rod 7 is buried in the bag 6 or the existing foundation 1, and the inside of the rod 7 is filled with a filler 16 of high strength mortar or the like to obtain a bar-shaped steel material. .

FIG. 12 shows a sixth embodiment. When the rod 7 is used as a bar-shaped steel material as in the fifth embodiment, a screw is cut inside the upper part of the rod 7 to form a screw portion 7a. On the other hand, the steel rod is also turned into a threaded steel rod 11c provided with a threaded portion 11d by cutting a screw on the peripheral surface, and the rod 7 is buried in the bag 6 and the existing foundation 1, and the threaded portion 7a at the lower portion of the rod 7 is formed. Is filled with a filler 16 of high-strength mortar or the like, a threaded steel bar 11c is inserted into the threaded portion 7a above, and a threaded portion 11d is screwed into the threaded portion 7a. 11c is fixed to the rod 7. Thus, a bar-shaped steel material is constituted by the rod 7 and the threaded steel bar 11c.

Although not shown, a threaded steel rod is used.
The length of the rod 7 to which the thread 11c is screwed is as short as the length of the threaded steel rod 11c, the filler 16 is not filled, and only the combination of the threaded steel rod 11c and the rod 7 is used. A shaped steel material can also be used.

The first to sixth embodiments can be combined with each other. Further, the bar-shaped steel material is not limited to the steel bar 11, the reinforcing bar or the steel bar 13, and the rod 7 as described above, and the existing foundation 1 and the pile head 9a are vertically connected to each other to form the existing foundation 1.
If the force can be reliably transmitted from the
For example, an H-beam, an I-beam, or the like can be used.

In the first to sixth embodiments, the bag 6 forming the pile 9 has the opening provided only at the upper part where the rod 7 is inserted. However, the structure of the bag 6 is as follows. However, as shown in FIG. 22, a predetermined opening 17 through which the filler 8 can flow out is provided at an appropriate position of the bag 6, and the filler 8 is inserted through the opening 17 into the bag 6 and the hole 3. The present invention can also be applied to a pile body 9 which flows out into the space between the piles 9 and is filled with the filler 8.

In this case, since the bag 6 is sandwiched between the fillers 8, the integrity of the bag 6 and the filler 8 is improved, and predetermined horizontal strength and deformation performance can be reliably exhibited. The shape of the hole provided in the bag 6 is not limited to a rectangular opening as shown in FIG. 22, and as shown in FIG. 23, the bag 6 may be formed of a polyvinyl alcohol fiber, a polyester fiber, a polyamide fiber, a polyethylene fiber, Aramid fiber, P
It consists of a horizontal belt 18a and a vertical belt 18b made of high-strength fiber such as BO (polyparaphenylene benzobisoxazole) fiber, glass fiber, carbon fiber, metal fiber, etc., which are woven in a grid and formed into a bag shape. At this time, the opening 17 is secured by opening the stitches of the horizontal belt 18a and the vertical belt 18b.

Further, in the first to sixth embodiments, the foundation to which the pile body 9 is connected is the existing foundation 1, but the present invention is not limited to this. In this case, the bag-shaped pile body 9 is formed as described above, and the lower portion of the bar-shaped steel material is piled up so that the upper portion protrudes upward. Body 9
In this state, if a formwork is assembled on the pile 9 and concrete is poured into the formwork, a foundation in which bar-shaped steel materials are disposed can be formed. Then, in this state, the pile body 9 is connected to the newly installed foundation via the bar-shaped steel material.

In addition, in the case of a new installation, other than the above, FIGS.
26 and FIG. 26 to FIG. 28.

FIGS. 23 to 25 show a reinforcing bar 24 in the form of a reinforcing bar in which a reinforcing bar 24a is wound around the head of a bag 6 filled with the filling material 8 so that the upper half thereof protrudes. , Footing, slabs and the like 25 are installed so as to bury the upper half thereof.

FIGS. 26 to 28 show a case where the head itself of the bag 6 filled with the filler 8 is formed so as to protrude above the ground, and a footing, a slab, or the like 25 is formed so that the head of the protruding bag 6 is fitted. Is constructed by embedding the upper half.

[0044]

As described above, the joint structure between the cast-in-place pile and the foundation according to the present invention can be applied to a case in which a bag pile filled with a filler is formed as a cast-in-place pile. To secure the transmission of horizontal force, vertical pull-out force, vertical push-in force and moment from the foundation to the pile, thereby improving the yield strength and deformation performance of the foundation.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view showing a first embodiment of a connection structure between a cast-in-place pile and a foundation according to the present invention.

FIG. 2 is a cross-sectional plan view showing a first embodiment of the connection structure between the cast-in-place pile and the foundation according to the present invention.

FIG. 3 is a vertical sectional front view showing a first step of construction of a cast-in-place pile in which the present invention is implemented.

FIG. 4 is a longitudinal sectional front view showing a second step of the construction of the cast-in-place pile in which the present invention is implemented.

FIG. 5 is a vertical sectional front view showing a third step of the construction of the cast-in-place pile in which the present invention is implemented.

FIG. 6 is a longitudinal sectional front view showing a fourth step of the construction of the cast-in-place pile in which the present invention is implemented.

FIG. 7 is a longitudinal sectional front view showing a second embodiment of the connection structure between the cast-in-place pile and the foundation according to the present invention.

FIG. 8 is a cross-sectional plan view showing a second embodiment of the connection structure between the cast-in-place pile and the foundation according to the present invention.

FIG. 9 is a longitudinal sectional front view showing a third embodiment of the connection structure between the cast-in-place pile and the foundation according to the present invention.

FIG. 10 shows a fourth example of the connection structure between the cast-in-place pile and the foundation according to the present invention.
It is a vertical front view showing an embodiment.

FIG. 11 shows a fifth example of the connection structure between the cast-in-place pile and the foundation according to the present invention.
It is a vertical front view showing an embodiment.

FIG. 12 shows a sixth example of the connection structure between the cast-in-place pile and the foundation according to the present invention.
It is a vertical front view showing an embodiment.

FIG. 13 is a longitudinal sectional front view showing an example of a conventional connection structure between a cast-in-place pile and a foundation.

FIG. 14 is a plan view showing an example of a conventional connection structure between a cast-in-place pile and a foundation.

FIG. 15 is the first construction of the cast-in-place pile below the existing foundation.
It is a front view showing a process.

FIG. 16 is the second example of the construction of the cast-in-place pile below the existing foundation.
It is the front view which carried out the process and was notched partially.

FIG. 17 is a third example of the construction of the cast-in-place pile below the existing foundation.
It is the front view which carried out the process and was notched partially.

FIG. 18 is a third example of the construction of the cast-in-place pile below the existing base 4;
It is the front view which carried out the process and was notched partially.

FIG. 19: The fifth of the construction of the cast-in-place pile below the existing foundation
It is the front view which carried out the process and was notched partially.

FIG. 20 is a vertical sectional front view showing another example of a conventional connection structure between a cast-in-place pile and a foundation.

FIG. 21 is a plan view showing another example of a conventional connection structure between a cast-in-place pile and a foundation.

FIG. 22 is a partially cutaway front view showing another example of a pile body in which the present invention is implemented.

FIG. 23 is a partially cutaway front view showing still another example of a pile body in which the present invention is implemented.

FIG. 24 is a vertical sectional front view during construction showing an example of construction in the case of a new foundation.

25 is a sectional view taken along line AA of FIG. 24.

FIG. 26 is a longitudinal sectional front view after completion of construction, showing an example of construction in the case of a new foundation.

FIG. 27 is a vertical sectional front view during construction showing another example of construction in the case of a new foundation.

FIG. 28 is a sectional view taken along line BB of FIG. 27;

FIG. 29 is a longitudinal sectional front view after completion of construction showing another example of construction in the case of a new foundation.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Existing foundation 2 ... Existing pile 3 ... Hole 4 ... Through-hole 4a ... Expanded part 5 ... Rod 6 ... Bag 7 ... Rod 8 ... Filler 7a ... Screw part 9 ... Pile body 9a ... Pile head 10 ... Support layer 11 ... Steel rod 11a ... Nut 11b ... Nut 11c ... Steel rod with screw 11d ... Screw part 12 ... Filling material 13 ... Reinforcing bar or steel rod 14 ... Plate 15 ... Anchor 16 ... Filling material 17 ... Opening 18a ... Transverse belt 18b Vertical belt 21 Existing footing 22 Existing pile 23 Additional pile 24 Reinforcing bar 24a Band steel bar 25 Footing, slab, etc.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akiyama Akira 2-9-1 Tobita-Ki, Chofu-shi, Tokyo Kashima Construction Co., Ltd. (72) Inventor Kazuo Taira 2-9-1-1, Tobita-Kiita, Chofu-shi, Tokyo Kashima Construction Co., Ltd. Technical Research Institute F-term (reference) 2D046 CA03

Claims (6)

[Claims] 1. The ground is cut, a bag is inserted into the cut hole, and the bag is filled with a filler such as cement milk, mortar, concrete or the like with a rod and expanded to form a bag. In the joint structure between the cast-in-place cylindrical pile and the foundation, the lower part of a bar-like steel material such as a steel rod is inserted into the pile head of the pile, and the upper part of the bar-like steel material is placed in the foundation above the pile. A joint structure between a cast-in-place pile and a foundation, wherein the pile is connected to the foundation with the bar-shaped steel material. 2. The connection structure between a cast-in-place pile and a foundation according to claim 1, wherein the foundation is an existing foundation, and a bar-shaped steel material is inserted into a pile head through a through hole formed in the existing foundation. 3. The cast-in-place pile and the foundation according to claim 1 or 2, wherein a gap between the inserted bar-shaped steel material and the through hole and a gap between the existing foundation and the pile head are filled with a filler such as mortar. Connection structure. 4. The connection structure between a cast-in-place pile and a foundation according to claim 1, wherein the pile head is expanded in diameter, and a plurality of bar-shaped steel materials are inserted into the expanded diameter portion. 5. The joint structure between a cast-in-place pile and a foundation according to claim 1, wherein the bar-shaped steel material is fixed to the foundation with an anchor. 6. The joint structure between a cast-in-place pile and a foundation according to claim 1, wherein the bar-shaped steel material is a rod for filling a filler in a bag.