JP4707599B2 - Construction method of tip-reinforced cast-in-place piles - Google Patents

Description

  The present invention relates to a method for constructing a tip-reinforced cast-in-place pile in which an injection bag is provided at the tip and inflated at the bottom of the pile.

  The present applicant has already proposed a tip preload cast-in-place pile method in which an injection bag is provided at the tip and inflated at the bottom of the pile (Patent Document 1). This tip preload cast-in-place pile method is a method that improves the support ground properties and suppresses the settlement of the pile, and improves the pile tip design support force by compressing and strengthening the pile tip ground with high pressure. .

FIG. 11 is a view for explaining a conventional infusion bag.
The infusion bag 1 has a bag shape in which the periphery is wrapped with a protective sheet 3 made of a nonwoven fabric. Each of the injection bags is composed of a double base fabric, and includes a circular upper base fabric 2a and a lower base fabric 2b each having a circular opening at the center, and a cylindrical base fabric 2c facing the drain hole 7 respectively. The base fabric is composed of a fabric of high-density fibers so that the injection material does not leak. Reference numeral 4 denotes a fine mesh-like spacing retainer (grid material) which prevents the upper base fabric and the lower base fabric from sticking to each other without gaps, and injects cement milk or the like through the injection hose 15 through the injection port 6. Makes it easier to inject.

FIG. 12 is a view showing a state where the injection bag is attached to the steel frame.
The injection bag having the structure shown in FIG. 11 is attached to the tip of the reinforcing bar 10 disposed in the pile hole for constructing the cast-in-place pile with a fixing tool such as a wire, and surrounds the steel frame 11. Install. This reinforcing bar is built into the excavated pile hole, and the steel frame is crushed at the bottom of the pile to spread the injection bag over the entire pile bottom. The steel frame 11 has a braided structure with a ring-shaped side at the upper and lower ends, a plurality of vertical sides connecting the ring-shaped sides, and a cross-shaped side connected to the lower-end ring-shaped side. It is a bending point, and this part is bent so that the injection bag can be spread over the entire pile bottom. In addition, 15 is an injection hose for injecting an injection material into the injection bag, and 16 is a slime discharge hose for discharging slime at the bottom of the pile.

FIG. 13 is a diagram for explaining the cast-in-place pile construction sequence.
FIG. 13A shows a state in which excavation of the pile hole has been completed, and there is a lot of slime on the bottom of the pile and it is fragile. Insert a rebar rod with a steel frame at the tip and a tip preload unit consisting of an injection bag into this pile hole (Fig. 13 (b)), press the steel frame against the pile bottom and crush it, The pile main body concrete is laid out over the entire pile bottom (FIG. 13C). At this time, depending on the situation, the reinforcing bar is pulled up to a predetermined position, and after the concrete has hardened, cement milk, etc., is injected under pressure from the injection hose through the pile body to inflate the injection bag, and the pile tip ground is compressed under pressure. To strengthen it (FIG. 13D). At this time, the slime is press-fitted into the slime discharge hose disposed through the back surface of the injection bag and formed with a plurality of holes, and the slime is discharged through the hose due to pressurization of the tip of the pile.
JP 2003-171930 A

The conventional tip preload cast-in-place pile method has the following problems.
(1) Breaking of the infusion bag (a) Since the current infusion bag as shown in FIG. 11 uses a high-density base fabric without elasticity, it can follow the irregular shape when the pile bottom has irregularities. However, there is a case where the elongation is not sufficient and it breaks.
(B) If a large amount of slime is accumulated on the bottom of the pile, the current infusion bag may not be sufficiently stretched and may break.
(C) Due to the difference in the pile construction method, when the tip end of the pile is drilled at an acute angle by the excavation bit, the current injection bag shown in FIG.
(2) Displacement of injection bag The injection bag is temporarily fixed with a hook-and-loop fastener on a steel frame fixed with a wire at the tip of the reinforcing bar. When it reaches the bottom of the pile, the steel frame is crushed by its own weight, and the injection bag is unfolded. In actual construction, it is necessary to build the reinforcing bar while adding the reinforcing bar by the pile length, and to raise and lower the reinforcing bar to a predetermined position depending on the amount of surplus and slime. With the up-and-down operation of the reinforcing bar, the infusion bag deployed on the bottom of the pile becomes suspended, causing misalignment, which may lead to breakage of the infusion bag without being installed at a predetermined position.

  From these facts, there is a problem in that the reliability as the construction method is reduced and the cost is increased by adding cement milk to the maximum injection amount along with the breakage of the injection bag, and the construction period is prolonged due to the increase in cycle time.

The present invention is intended to solve the above-mentioned problems, and an object thereof is to prevent the injection bag from being broken or displaced in the tip preload cast-in-place pile method.
The present invention attaches a steel frame composed of a braided structure of a cross-shaped side connected to a ring-shaped side of the upper and lower ends, a plurality of vertical sides connecting these, and a lower-side ring-shaped side, to the tip of the reinforcing bar rod, The peripheral edges of the circular upper base fabric and lower base fabric, each having a central opening, are sewn together, and the cylindrical base fabric, the upper base fabric, and the central opening of the lower base fabric are sewn together to drain holes. An infusion bag surrounded by a protective sheet is attached so as to surround the steel frame, a reinforcing bar is built in the excavation hole, and the steel frame is crushed at the bottom of the pile so as to surround it. In the construction method of a cast-in-place concrete pile in which an injection bag attached to the pile is spread to the bottom of the pile, and an injection material is pressurized and injected into the injection bag to compress and compress the pile tip ground, the injection bag includes at least a lower base fabric Elastic material Characterized by using.
In addition, the present invention attaches a steel frame having a braided structure of cross-shaped sides connected to the ring-shaped sides of the upper and lower ends and a plurality of vertical sides connecting these, and the lower-end ring-shaped sides to the rebar bar tip, The peripheral edges of the circular upper base fabric and the lower base fabric, each having a circular central opening, are sewn together, and the central openings of the cylindrical base fabric, the upper base fabric, and the lower base fabric are sewn together to form water. It consists of a bag body with a punched hole, and an infusion bag surrounded by a protective sheet is attached so as to surround the steel frame, a reinforcing bar is built in the excavation hole, and the steel frame is crushed at the bottom of the pile. In the construction method of the cast-in-place concrete pile which expands the injection bag attached so as to surround the pile bottom, pressurizes and injects the injection material into the injection bag, and pressurizes and compresses the pile tip ground, the bag body is an outer bag body To surround the inner bag It consists of separate bag, characterized by pressure inject grout to the inner bag body.
In addition, the present invention attaches a steel frame having a braided structure of cross-shaped sides connected to the ring-shaped sides of the upper and lower ends and a plurality of vertical sides connecting these, and the lower-end ring-shaped sides to the rebar bar tip, The peripheral edges of the circular upper base fabric and the lower base fabric, each having a circular central opening, are sewn together, and the central openings of the cylindrical base fabric, the upper base fabric, and the lower base fabric are sewn together to form water. It consists of a bag body with a punched hole, and an infusion bag surrounded by a protective sheet is attached so as to surround the steel frame, a reinforcing bar is built in the excavation hole, and the steel frame is crushed at the bottom of the pile. In the construction method of cast-in-place concrete pile that spreads the injection bag attached so as to surround the pile bottom, pressurizes and injects the injection material into the injection bag and pressurizes and compresses the pile tip ground, and the upper base fabric of the injection bag Perimeter of lower base fabric Characterized in that a larger margin bulge is folded portions Awa are in the infusion bag center side.
In addition, the present invention attaches a steel frame having a braided structure of cross-shaped sides connected to the ring-shaped sides of the upper and lower ends and a plurality of vertical sides connecting these, and the lower-end ring-shaped sides to the rebar bar tip, The peripheral edges of the circular upper base fabric and the lower base fabric, each having a circular central opening, are sewn together, and the central openings of the cylindrical base fabric, the upper base fabric, and the lower base fabric are sewn together to form water. It consists of a bag body with a punched hole, and an infusion bag surrounded by a protective sheet is attached so as to surround the steel frame, a reinforcing bar is built in the excavation hole, and the steel frame is crushed at the bottom of the pile. In the construction method of a cast-in-place concrete pile in which an infusion bag attached so as to surround is spread to the bottom of the pile, and an injection material is injected into the injection bag under pressure to compress and compress the pile tip ground, the lower base fabric of the injection bag Drain the center And cut out a part in a fan shape and stitched the cut parts so that the center of the lower base fabric is below the stitching position of the peripheral edge of the upper and lower base fabrics It is characterized by three-dimensional sewing.
Moreover, the present invention is characterized in that a guide member for preventing misalignment passes through the drain hole formed in the injection bag from the steel frame.
The present invention also fixes the infusion bag and the protective sheet by fixing one end of the fixing member to the upper part of the injection bag in the protective sheet and fixing the other end of the fixing member to the steel frame through the protective sheet. It is characterized by that.
Further, the present invention is characterized in that the injection bag and the protective sheet are bonded and fixed at a plurality of locations with a double-sided adhesive.
In the present invention, the infusion bag is provided with a spacing member for separating the upper base fabric and the lower base fabric therein, and an injection port having a shape for separating the spacing material and the upper base fabric. And an injection material is injected under pressure through the injection port.

The present invention uses an elastic material for at least the lower side base fabric of the infusion bag, and also has a structure that can take a large allowance downward even if a high density base fabric is used. Etc.
In addition, passing the guide member from the steel frame through the central drain hole, joining between the protective sheet and the injection bag and fixing it to the steel frame can cause misalignment even when the rebar rod is operated up and down. In addition, by fixing the protective sheet and the injection bag with a double-sided adhesive member, it is possible to prevent the installation position of the injection bag from being shifted in the protective sheet.

Embodiments of the present invention will be described below.
FIG. 1 is a cross-sectional view for explaining an injection bag according to the present embodiment used in a method for constructing a tip-reinforced cast-in-place pile, showing only one side from the center, and FIG. 2 is an explanatory view for materials used for the injection bag. .
The point that the injection bag 20 of the present embodiment is also surrounded by the protective sheet 3 made of nonwoven fabric, and the mesh-type interval maintaining material (grid material) 4 with a fine mesh is arranged in the injection bag as in the conventional case. The infusion bag sews circular portions S1 of a circular upper base fabric 21 and a lower base fabric 22 made of a double base fabric, and a circular base fabric 23, a circle of the upper base fabric 21 and the lower base fabric 22. The upper base fabric 21 is made of a high-density base fabric as in the prior art, and the lower base fabric 22 and the cylindrical base fabric 23 are made of a stretchable material such as polyurethane ( Example shown), raw rubber, elastic rubber, polyester, polypropylene, etc. are used. Thus, by using an elastic material for the lower base fabric and the cylindrical base fabric, when an injection material such as cement milk is injected from the injection hose 15 through the injection port 6, Regardless of indeterminate factors such as the shape of drilling holes and the amount of slime deposited, it can be expanded and contracted to follow any ground shape at the tip of the pile, and a reliable preload can be obtained. 1 and 2, the elastic material is used for the lower base fabric and the cylindrical base fabric. However, the elastic material is used for the entire base fabric including only the lower base fabric or the upper base fabric. You may use it properly depending on the situation. When stretchable materials are used for all the base fabrics including the upper base fabric, S1, S2, and S3 are not stitched but bonded.

FIG. 3 is a view showing an example in which the injection bag body is a double bag. In addition, the point which surrounds the injection | pouring bag of this embodiment with the protective sheet 3 which consists of a nonwoven fabric, and the point which arrange | positions the mesh-like space | interval holding | maintenance material (grid material) 4 with a fine mesh in the injection bag are the same.
In the example of FIG. 1, each base fabric made of double base fabrics is stitched together at S1, S2, and S3 to form one bag body. However, in this embodiment, the upper base fabric 21, the lower base fabric 22, and the cylindrical base fabric are used. Double cloth each using a high-density base cloth, and the circumferential portion of each inner base fabric and the circumferential portion of each outer base fabric are sewn independently to form a double bag, An injection material such as cement milk is injected into the inner bag. By making a double bag in this way, the friction between the outer bag and the inner bag is reduced, so the inner bag can move freely, and even if a high-density base fabric is used, the tip of the pile It is possible to follow any ground shape of the part. Also in this example, an elastic material is used for the lower base cloth 22 of the inner and outer bags, an elastic material is used for the lower base cloth 22 and the cylindrical base cloth 23, or all the base cloths are used. On the other hand, an elastic material may be used.

FIG. 4 is a view showing an example in which the stitched portion of the upper base fabric and the lower base fabric is folded in the center direction of the infusion bag. The infusion bag of this embodiment is also surrounded by a protective sheet 3 made of nonwoven fabric, the infusion bag The point that the mesh-like spacing member (grid material) 4 with fine mesh is arranged inside is the same.
S1 in the figure is a sewing position of the upper high-density base fabric 21 and the circumferential portion of the lower high-density base fabric 22, and S2 is a sewing position of the upper high-density base fabric 21 and the cylindrical high-density base fabric 23. , S3 is a stitching position between the cylindrical high-density base fabric 23 and the lower high-density base fabric 22, and the stitching position S1 is folded downward toward the center of the injection bag, and the lower high-density base fabric 22 is also centered. Fold it in the direction. By adopting such a folding structure, it is possible to increase the downward bulge allowance when the injection material is injected even if a high-density base fabric is used. Also in this example, an elastic material is used for the lower base fabric 22, an elastic material is used for the lower base fabric 22 and the cylindrical base fabric 23, or an elastic material is used for the entire base fabric. It may be.

FIG. 5 is a cut image of the lower base fabric, and FIG. 6 is a cross-sectional view of the base fabric of FIG.
As shown in FIG. 5, the cut base fabric 22 is cut out at the center for a drain hole, and the C portion is cut into a fan shape. By sewing the cut C portions, as shown in FIG. 6, the lower base fabric 22 has a three-dimensional (conical) structure in which the center side is below the sewing position of the upper base fabric and the lower base fabric. Even if a base cloth is used, it is possible to increase the allowance for the downward swelling. Also in this example, an elastic material is used for the lower base fabric, an elastic material is used for the lower base fabric and the cylindrical base fabric, or an elastic material is used for the entire base fabric. Good. In addition, the point which surrounds the injection | pouring bag of this embodiment also with the protective sheet which consists of nonwoven fabrics, and the point which arrange | positions a mesh-like space | interval holding | maintenance material (grid material) with a fine mesh are the same.

FIGS. 7A and 7B are diagrams showing an example of preventing the displacement of the injection bag due to the up-and-down operation of the reinforcing bar, FIG. 7A is a side sectional view, and FIG. 7B is a plan view. In addition, the point which surrounds the injection | pouring bag of this embodiment also with the protective sheet which consists of nonwoven fabrics, and the point which arrange | positions a mesh-like space | interval holding | maintenance material (grid material) with a fine mesh are the same.
The injection bag 20 is attached so as to surround the steel frame 11 attached to the tip of the reinforcing bar. The infusion bag may be any of the infusion bags described in FIGS. Two guide rods 30 extend through the drain hole 7 from the steel frame and protrude 10 to 100 cm from the injection bag. The guide bag 30 regulates the injection bag, and no positional deviation (center misalignment) occurs even when the reinforcing bar rod is operated up and down. Of course, three or four guide bars may be provided. However, it is necessary to make the number and strength that do not hinder crushing the steel frame at the bottom of the pile.

8A and 8B are diagrams for explaining a method for preventing the displacement of the infusion bag installation position. FIG. 8A is a plan view and FIG. 8B is a front view. In addition, the point which surrounds the injection | pouring bag of this embodiment also with the protective sheet which consists of nonwoven fabrics, and the point which arrange | positions a mesh-like space | interval holding | maintenance material (grid material) with a fine mesh are the same.
In this embodiment, one end of the fixing member 30 made of an adhesive tape or a hook-and-loop fastener is fixed to the upper part of the injection bag 20 in the protective sheet 3, and the other end of the fixing member 30 is attached to the steel frame through the protective sheet 3. Fix it. The infusion bag may be any of the infusion bags described in FIGS. By setting it as such a structure, since the injection | pouring bag 20 and the protection sheet 3 are fixed to a steel frame, the shift | offset | difference of an installation position can be prevented.

FIG. 9 is a view for explaining a method for preventing displacement of the injection bag in the protective sheet.
If there is an up / down operation of the reinforcing bar rod, the injection bag will be displaced in the protective sheet and may not be deployed on the bottom of the pile. Therefore, as shown in the drawing, the double-sided adhesive 40 is used to bond and fix the injection bag 20 and the protective sheet 3 at a plurality of locations. The infusion bag may be any of the infusion bags described in FIGS. By setting it as such a structure, an injection | pouring bag does not raise | generate a position shift within a protection sheet, but expansion | deployment in a pile bottom is performed smoothly.

FIG. 10 is a view for explaining a method for preventing the spacing member and the upper base fabric of the injection bag from sticking to each other. In addition, the point which surrounds the injection bag of this embodiment also with the protective sheet which consists of a nonwoven fabric is the same.
Since the spacing material 4 is a mesh made of fine fibers, especially when it sticks to the upper base fabric, it interferes with the pressure injection of the injection material such as cement milk, and the injection bag cannot be inflated well. End up. Therefore, in the present embodiment, the shape of the injection port 6 is devised so that the spacing member and the upper base fabric are separated from each other. The infusion bag may be any of the infusion bags described with reference to FIGS.

As the inlet, for example, a sprinkler type inlet 50 as shown in 10 (b) is used. The injection port 50 is open at the lower side and has a cylindrical shape having a hole 51 to which an injection hose is attached on the upper side. The peripheral surface has a plurality of holes 52 for discharging the injection material. Therefore, it is possible to prevent the spacing member and the upper base fabric from sticking to each other.
Also, what is shown in FIG. 10 (c) is a C-type injection port 60, which has a lower side and one side surface open, a hole 61 to which an injection hose is attached on the upper side, and the other side surface It has a height necessary for separating the spacing member and the upper base fabric, and can prevent the spacing member and the upper base fabric from sticking to each other.

  According to the present invention, it is possible to deal with the uneven shape of the pile bottom and the like, and since there is no position shift even if the reinforcing bar is operated up and down, the industrial utility value is great.

It is sectional drawing explaining the injection bag of this embodiment. It is explanatory drawing about the material used for an injection bag. It is a figure which shows the example which made the injection bag main body the double bag. It is a figure which shows the example which folded the sewing part in the injection bag center direction. It is a cutting image figure of a lower side base fabric. It is sectional drawing which solid-sewn the base fabric of FIG. It is a figure which shows the example which prevented the position shift of the injection | pouring bag. It is a figure explaining the method of preventing the position shift of an injection bag. It is a figure explaining the method of preventing the position shift of the injection | pouring bag within a protection sheet. It is a figure explaining the method of preventing sticking of a space | interval holding material and an injection bag. It is a figure explaining the conventional injection | pouring bag. It is a figure which shows the state which attached the injection bag to steel frames. It is a figure explaining a cast-in-place pile construction order.

Explanation of symbols

20 ... Injection bag, 21 ... Upper base fabric, 22 ... Lower base fabric, 23 ... Cylindrical base fabric.

Claims (8)

A steel frame consisting of a braided structure of upper and lower ring-shaped sides, a plurality of vertical sides connecting them, and a cross-shaped side connected to the lower ring-shaped side is attached to the end of the reinforcing bar rod, and a circular center opening A bag having a drain hole formed by sewing the peripheral edges of the circular upper base fabric and the lower base fabric, respectively, and sewing the cylindrical base fabric, the center base portion of the upper base fabric, and the lower base fabric, respectively. made from the body, attachment to the infusion bag was surrounded with a protective sheet so as to surround the steel frame, like an anchor a reinforcing bar cage in the borehole, fitted with the steel frame in the pile bottom to surround this with ulcer Succoth In the construction method of cast-in-place concrete piles that expand the injection bag to the bottom of the pile, pressurize and inject the injection material into the injection bag and pressurize and compress the pile tip ground.
A construction method for a tip-reinforced cast-in-place pile, wherein the injection bag uses an elastic material for at least the lower base fabric. A steel frame consisting of a braided structure of upper and lower ring-shaped sides, a plurality of vertical sides connecting them, and a cross-shaped side connected to the lower ring-shaped side is attached to the end of the reinforcing bar rod, and a circular center opening A bag having a drain hole formed by sewing the peripheral edges of the circular upper base fabric and the lower base fabric, respectively, and sewing the cylindrical base fabric, the center base portion of the upper base fabric, and the lower base fabric, respectively. made from the body, attachment to the infusion bag was surrounded with a protective sheet so as to surround the steel frame, like an anchor a reinforcing bar cage in the borehole, fitted with the steel frame in the pile bottom to surround this with ulcer Succoth In the construction method of cast-in-place concrete piles that expand the injection bag to the bottom of the pile, pressurize and inject the injection material into the injection bag and pressurize and compress the pile tip ground.
The bag body is composed of a double independent bag body in which the outer bag body surrounds the inner bag body, and the injection material is pressurized and injected into the inner bag body. . A steel frame consisting of a braided structure of upper and lower ring-shaped sides, a plurality of vertical sides connecting them, and a cross-shaped side connected to the lower ring-shaped side is attached to the end of the reinforcing bar rod, and a circular center opening A bag having a drain hole formed by sewing the peripheral edges of the circular upper base fabric and the lower base fabric, respectively, and sewing the cylindrical base fabric, the center base portion of the upper base fabric, and the lower base fabric, respectively. made from the body, attachment to the infusion bag was surrounded with a protective sheet so as to surround the steel frame, like an anchor a reinforcing bar cage in the borehole, fitted with the steel frame in the pile bottom to surround this with ulcer Succoth In the construction method of cast-in-place concrete piles that expand the injection bag to the bottom of the pile, pressurize and inject the injection material into the injection bag and pressurize and compress the pile tip ground.
A construction method for a tip-reinforced cast-in-place pile characterized in that a peripheral seam portion of the upper base fabric and the lower base fabric of the infusion bag is folded toward the center side of the infusion bag to increase a bulge margin. A steel frame consisting of a braided structure of upper and lower ring-shaped sides, a plurality of vertical sides connecting them, and a cross-shaped side connected to the lower ring-shaped side is attached to the end of the reinforcing bar rod, and a circular center opening A bag having a drain hole formed by sewing the peripheral edges of the circular upper base fabric and the lower base fabric, respectively, and sewing the cylindrical base fabric, the center base portion of the upper base fabric, and the lower base fabric, respectively. made from the body, attachment to the infusion bag was surrounded with a protective sheet so as to surround the steel frame, like an anchor a reinforcing bar cage in the borehole, fitted with the steel frame in the pile bottom to surround this with ulcer Succoth In the construction method of cast-in-place concrete piles that expand the injection bag to the bottom of the pile, pressurize and inject the injection material into the injection bag and pressurize and compress the pile tip ground.
The lower base fabric of the injection bag is formed by cutting out the central portion for a drain hole, cutting a part in a fan shape, and stitching the cut portions, and the central portion of the lower base fabric is the upper base fabric. A method for constructing a tip-reinforced cast-in-place pile, characterized in that it is three-dimensionally sewn so as to be below the peripheral sewing position with the lower base fabric. The construction method according to any one of claims 1 to 4 , wherein a guide member for preventing misalignment passes through the drain hole formed in the injection bag from the steel frame. One end of the fixing member is fixed to the upper part of the injection bag in the protective sheet, and the other end of the fixing member is fixed to the steel frame through the protective sheet, thereby fixing the injection bag and the protective sheet. The construction method according to claim 1.   The construction method according to any one of claims 1 to 4, wherein the injection bag and the protective sheet are bonded and fixed at a plurality of locations with a double-sided adhesive. The infusion bag, along with the interval holding member to separate the upper base fabric within the lower base cloth is arranged, the inlet shape of separating and the upper base fabric the interval holding member is provided, the infusion inlet 5. The construction method according to claim 1, wherein the injection material is injected under pressure.

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