JPH11323924A - Execution method for cast-in-place pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fill the void between a bag and the ground with a filler flowing out from the bag and to improve the bearing power, horizontal yield strength and deformation performance of a cast-in-place pile by inserting the bag having prescribed openings through which the filler can flow out in the cut ground, and filling the filler into the bag with a rod. SOLUTION: A vertical through hole 4 is bored on an existing foundation 1, the ground is cut, a bag 6 formed with prescribed openings 11 is inserted from the through hole 4 together with a rod, a filler 8 such as mortar is filled into the bag 6, and a columnar ground improving body covered with the bag 6 is constructed as a pile body 9. The filler 8 flows out to the outside from the openings 11 of the bag 6 and is filled in the void between the bag 6 and the cut ground, the bag 6 is pinched by the filler 8, and the integration between the bag 6 and the filler 8 is improved. Fibers in the vertical direction of the bag 6 function as main movement, and fibers in the peripheral direction function as tie hoops to exert the prescribed horizontal yield strength and deformation performance. The adhesiveness between the bag 6 spread into a cylindrical shape and the ground is increased, and the vertical yield strength and horizontal yield strength as a pile is improved.

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 The present invention relates to a method of constructing a cast-in-place pile for the purpose of improving the yield strength and deformation performance of a foundation when the deformation performance is insufficient.

[0002]

2. Description of the Related Art As reinforcement of an existing foundation, FIGS.
As shown in (1), there is a method of increasing the pile 23 on the outside of the existing footing 21 and the existing pile 22 and also increasing the footing 21 to improve the bearing capacity, the proof strength and the deformation performance at the time 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 the existing pile is not taken into account, the cost is high.

[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.

[0006] As shown in FIGS. 12, 13 and 14 to 18, 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 the cast-in-place pile constructed by the method shown in the above-mentioned item, when air or the like is trapped in the bag 6, the filling material 8 such as mortar is filled and the bag 6 and the filling material 8 spread in a cylindrical shape are integrated. It is difficult to ensure the property, and there is a possibility that a gap may be formed between the bag 6 that has spread in a columnar shape and the ground that has been cut, and in any case, a defect that is important in quality is caused.

It is an object of the present invention to provide a method for constructing a cast-in-place pile which solves the above-mentioned disadvantages of the conventional example and which can improve the bearing capacity, horizontal strength and deformation performance as a pile.

[0010]

In order to achieve the above object, the present invention firstly cuts the ground, inserts a bag having a predetermined opening through which a filler can flow out, and inserts the bag into the ground. The gist of the present invention is to fill a filler such as cement milk, mortar or concrete with a rod therein and expand the filler, and to fill the gap between the bag and the ground with the filler flowing out of the bag.

Second, the bag is made of polyvinyl alcohol fiber, polyester fiber, polyamide fiber, polyethylene fiber, aramid fiber, PBO (polyparaphenylene benzobisoxazole) fiber, glass fiber, carbon fiber, metal fiber. Etc.
Alternatively, the gist is that a belt made of these high-strength fibers is attached as a reinforcing material to improve the strength, or that the belt made of these high-strength fibers is knitted in a lattice shape.

According to the first aspect of the present invention, by using a bag having a predetermined opening through which the filler can flow out, mortar is provided not only inside the bag but also between the bag and the cut ground. It becomes possible to fill. When the mortar is filled inside and outside of the bag in this way, the bag is sandwiched between the mortar in a sandwich shape, so that the integrity of the bag and the mortar is improved. The fibers in the directions function reliably as band rebars, and can exhibit predetermined horizontal proof stress and deformation performance.

[0013] Further, since the gap between the bag and the ground spread in a columnar shape is reliably filled with mortar, the adhesion between the bag and the ground is enhanced, and the vertical strength and the horizontal strength as a pile are improved.

According to the second aspect of the present invention, in addition to the above-described functions, high strength fibers are used as the bag material, and the bag has the same function as the vertical and circumferential reinforcing bars, thereby providing a reinforcing bar. Thus, it is possible to improve the bending strength of the pile without using such a method.

According to the third aspect of the present invention, a second aspect is provided.
In addition to the effect of the above, the cost can be reduced while securing the required strength by using the reinforcing material portion instead of manufacturing the entire bag with high-strength fiber.

According to the present invention described in claim 4, according to claim 2,
In addition to the above-described operation, a bag having a predetermined opening can be easily formed by appropriately opening the stitches when knitting a belt made of high-strength fibers in a lattice shape.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a front view showing an embodiment of a method for constructing a cast-in-place pile according to the present invention, FIG. 2 is a sectional view taken along the line AA in FIG.
It is a line sectional view.

Also in the present invention, like the cast-in-place pile constructed by the method shown in the above-mentioned Japanese Patent Application No. 8-285200,
As shown in FIGS. 12 to 18, a vertical through-hole 4 of about 200 mm in diameter is drilled in an existing foundation (footing) 1 having an existing pile 2 and a high-pressure injection replacement method is performed from a rod 5 using the through-hole 4. The ground is cut into muddy water by the method described above. 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.

According to the present invention, the bag 6 has a cylindrical shape, and when the bag 6 is filled with the filler 8 such as cement milk, mortar or concrete, the filler 8 flows out of the bag 6 to the outside of the bag 6. It is assumed that a predetermined opening 11 is formed so as to be able to.

The ratio of the opening 11 to the bag 6 is preferably an opening ratio n = 10 to 30%. The opening ratio n is determined by the amount of filler 8 such as cement milk, mortar or concrete.
Is determined in consideration of the relationship between the outflow property of the fiber 6 outside the bag 6 and the strength of the fiber reinforcing pile. The material of the bag 6 will be described below. In a test for testing the effect of the present invention, a polyester bag measuring 250 mm in length and 300 mm in length was used in four cases with opening ratios of n6%, 13%, 25%, and 57%. When it is 13% or more, the outflow property of the mortar out of the bag is good, and it has been confirmed that the proof strength of the pile has a maximum proof strength not less than the value calculated by RC theory. Although it is judged that there is no problem in proof stress even when the opening ratio n is 40 to 50%, it is preferably 30% or less in consideration of the restraining effect as a bag, economy, and the like.

Examples of the material of the bag 6 include polyvinyl alcohol fiber, polyester fiber, polyamide fiber, polyethylene fiber, aramid fiber, PBO (polyparaphenylene benzobisoxazole) fiber, glass fiber, carbon fiber, and metal fiber. And the like were used as warp and weft to form a bag-like fabric.

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 200 mm in diameter.

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. Although not shown, it is also possible to transmit a horizontal force by inserting a reinforcing bar or a steel rod into the through hole 4 and fixing it to the existing footing and columnar pile.

FIG. 11 shows the state of filling of the filling material 8. The filling material 8 flows out of the opening 11 and fills the mortar not only inside the bag but also between the bag and the ground ground. It becomes possible.

FIGS. 5 and 6 show a second embodiment of the present invention, in which polyvinyl alcohol fiber, polyester fiber, polyamide fiber, polyethylene fiber, aramid fiber, PBO (polyparaphenylene benzobisoxazole) are used. A) A belt made of similar high-strength fibers in the longitudinal direction of a bag formed of high-strength fibers such as fibers, glass fibers, carbon fibers, and metal fibers or a woven fabric of ordinary fibers.
Was installed as reinforcement.

FIGS. 7 and 8 show a second embodiment of the present invention. The bag 6 is made of polyvinyl alcohol fiber, polyester fiber, polyamide fiber, polyethylene fiber, aramid fiber, PBO (polyethylene fiber). Paraphenylene benzobisoxazole) fiber, glass fiber, carbon fiber,
A horizontal belt 13a and a vertical belt 13b made of high-strength fibers such as metal fibers were knitted in a lattice shape to form a bag.

At this time, the horizontal belt 13a and the vertical belt
The opening 11 is secured by opening the stitch 13b.

In each of the first to third embodiments, the vertical support force is increased by enlarging the diameter of the pile tip and the pile head as shown in FIGS. 9 and 10. You can also.

In the above-described first to third embodiments, as in the case of the cast-in-place pile constructed by the construction method disclosed in Japanese Patent Application No. 8-285200, an existing foundation (footing) having the existing pile 2 is provided. The case where the ground is cut into a muddy state by cutting the ground from the rod using a high-pressure injection replacement method or the like using the through-hole has been described, but the present invention is not limited to such a case immediately below the existing foundation. It can also be used for cast-in-place piles.

Further, the cutting of the ground is not limited to the high-pressure injection displacement method, but may be the case of cutting with an earth auger or another cutting machine.

[0031]

As described above, the method for constructing a cast-in-place pile according to the present invention uses a high-strength fibrous bag having a predetermined opening, so that not only the inside of the bag but also the gap between the bag and the ground can be obtained. Can also be filled with cement milk or mortar, etc., and since the integrity of the bag and the mortar and the adhesion between the bag and the ground are increased, the support capacity as a pile, horizontal strength, and deformation performance are improved. It can be realized.

[Brief description of the drawings]

FIG. 1 is a partially cut-away longitudinal side view showing a first embodiment of a method of constructing a cast-in-place pile according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is a sectional view taken along line CC of FIG. 1;

FIG. 5 is a vertical sectional side view showing a second embodiment of the method for constructing a cast-in-place pile according to the present invention.

FIG. 6 is a sectional view taken along line AA of FIG. 5;

FIG. 7 is a vertical sectional side view showing a third embodiment of the casting method for cast-in-place piles of the present invention.

FIG. 8 is a sectional view taken along line AA of FIG. 7;

FIG. 9 is a longitudinal sectional side view showing a modified example of the expansion.

FIG. 10 is a vertical sectional side view showing an example of head enlargement.

FIG. 11 is a vertical sectional side view showing a filling state of a filler.

FIG. 12 is a vertical sectional side view showing one example of a conventional cast-in-place pile construction method.

FIG. 13 is a plan view showing an example of a conventional cast-in-place pile construction method.

FIG. 14 is a side view of the first step of the conventional cast-in-place pile construction method.

FIG. 15 is a side view of a second step of the conventional cast-in-place pile construction method.

FIG. 16 is a side view of a third step of the conventional cast-in-place pile construction method.

FIG. 17 is a side view of a fourth step of the conventional cast-in-place pile construction method.

FIG. 18 is a side view of a fifth step of the conventional cast-in-place pile construction method.

FIG. 19 is a vertical sectional side view showing another conventional example.

FIG. 20 is a plan view showing another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Existing foundation 2 ... Existing pile 3 ... Hole 4 ... Through-hole 5 ... Rod 6 ... Bag 7 ... Rod 8 ... Filler 9 ... Pile body 10 ... Support layer 11 ... Opening 12 ... Belt 13a ... Horizontal belt 13b ... Vertical Directional belt 21 ... Existing footing 22 ... Existing pile 23 ... Additional pile

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Tadashi Yoshikawa, Inventor Kashima Construction Co., Ltd. 1-2-7 Moto-Akasaka, Minato-ku, Tokyo (72) Inventor Teruaki Akiyama 2-9-1-1, Tobita-Shibi, Chofu-shi, Tokyo Kashima Construction Co., Ltd.Technical Research Institute (72) Kazuo Hira 2-9-1-1, Tobita-Shi, Chofu-shi, Tokyo Kashima Construction Co., Ltd.Technology Research Center (72) Inventor Isaburo Yagi 10 (72) Inventor Taji Makimoto 2-7-14-7 Sakamoto, Otsu City, Shiga Prefecture (72) Inventor Akihiko Ikeda 1-6-4 Moto-Akasaka, Minato-ku, Tokyo Inside Chemica Lugrout Co., Ltd.

Claims (4)

[Claims] 1. A ground is cut, a bag having a predetermined opening through which a filler can flow out is inserted into the ground, and a filler such as cement milk, mortar or concrete is filled into the bag with a rod. A method for constructing a cast-in-place pile, characterized by inflating and filling a gap between the bag and the ground with a filler flowing out of the bag. 2. The bag is made of polyvinyl alcohol fiber, polyester fiber, polyamide fiber, polyethylene fiber, aramid fiber, PBO (polyparaphenylenebenzobisoxazole) fiber, glass fiber, carbon fiber,
The method for constructing a cast-in-place pile according to claim 1, wherein the pile is made of high-strength fiber such as metal fiber. 3. The bag is made of polyvinyl alcohol fiber, polyester fiber, polyamide fiber, polyethylene fiber, aramid fiber, PBO (polyparaphenylene benzobisoxazole) fiber, glass fiber, carbon fiber,
3. The method for constructing a cast-in-place pile according to claim 1, wherein a belt made of a high-strength fiber such as a metal fiber is attached as a reinforcing material to improve the strength. 4. The bag is made of polyvinyl alcohol fiber, polyester fiber, polyamide fiber, polyethylene fiber, aramid fiber, PBO (polyparaphenylene benzobisoxazole) fiber, glass fiber, carbon fiber,
3. The method for constructing a cast-in-place pile according to claim 1, wherein the belt is formed by knitting a belt made of high-strength fibers such as metal fibers in a lattice shape.