JPH08144255A - Loading device of pile - Google Patents

Abstract

PURPOSE: To make it possible to measure actual bearing force of a cast-in-place pile by fixing a plurality of fluid pressure operating jacks equipped with flow regulating devices between reinforced cages, and measuring vertical movement of the jacks with pressurization and thrust of the jacks. CONSTITUTION: Doughnut-shaped edge cutting plates 12 and 15 are mounted to the lower end of a cylinder 9 of each of jacks 3 through flanges 11 and 14, and they are tightly with tension rods 18 and 18 cutting off the flanges 11 and 14 at low pressurization. A plurality of jacks are fixed between reinforced cages, they are hung down into an excavated hole 2, and concrete is placed. After the solidification, pressure fluid is pumped to the jacks 3, and the cutting of the concrete in a part of the edge cutting plate 12 is confirmed by detecting the rapidly decrease of pressure and the slight movement of a ram 10. After that, the same amount of pressure fluid is supplied to the jacks through flow regulating devices to measure actual bearing force of a pile while measuring displacement of every part by a displacement detector. After the test, pressure fluid is changed to hardenable fluid, and the inside of each of the jacks 3 and a crack of part of the edge cutting plate 12 are filled with the hardenable fluid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a force applying device for confirming the supporting force of a pile or for increasing the supporting force.

[0002]

2. Description of the Related Art Embedded piles, cast-in-place piles, deep foundation piles, etc. are made by drilling the ground, and there are cases where the peripheral surface and tip of the pile loosen or slime remains on the bottom of the pile. I have no choice but to take a lower bearing capacity. In order to improve this problem, various methods of increasing the bearing capacity of the pile and measuring the bearing capacity of the pile have been proposed. As an example thereof, Japanese Patent Laid-Open No. 3-90706 discloses a force applying device in which a jack is provided at the tip of a pile and pressure is applied to the jack.

[0003]

Known jack structures include a cylinder having a diameter approximately equal to that of a pile and a ram fitted to the cylinder, or a bellows made of reinforced rubber. However, since jacks like these have a structure in which the center part is closed,
It is difficult for concrete to wrap around the underside of the jack, which makes it easy to create cavities. In addition, when the jack is installed in the middle of the pile, the structure is such that the center is closed, so it is difficult for the concrete to turn around.Therefore, after the concrete is first driven into the bottom of the jack, the rebar with the jack is attached. It is necessary to hang the basket and drive concrete. In this way, when concrete is poured in two times, there arises a problem that slime remains below the jack. Further, it is difficult to attach a reinforcing cage below the jack and integrate it with the jack. If the supporting force is not uniform in the circumferential direction due to looseness during drilling or inclination of the formation, the above-mentioned force applying device will be displaced by tilting the pile and the original supporting force of the pile cannot be measured. Become.

The present invention has been devised in order to eliminate such disadvantages of the prior art, and its main purpose is to:
It is an object of the present invention to provide a load applying device for a pile, which can be mounted at any position on the pile, does not hinder the placing of concrete, and can measure the original supporting force of the pile.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention is to measure the peripheral frictional force of a pile, the tip supporting force, or both supporting forces. Is a force applying device that is mounted at one location or at a plurality of depths to apply a thrust force, and a plurality of fluid pressure-operated jacks arranged at intervals are interlocked, and the upper and lower sides of the jacks are interlocked. It is a force device that measures the side movement and the thrust of the jack.
In addition, when the supporting force is not uniform in the circumferential direction of the pile, install a flow rate adjusting device for sending an equal flow rate to each jack and a force applying device for the pile provided with a pressure gauge to detect the thrust of each jack. Configure.

[0006]

According to the present invention, as described above, a plurality of jacks are interlocked with each other to apply a thrust force. The same flow rate of fluid is supplied to each jack to pressurize each ram to move uniformly. In addition, the jack is fixed to the rebar cage and hung in the excavation hole, and then concrete is placed using a tremie pipe to form cast-in-place piles. Further, when each jack is pressed, the concrete is cut at the position of the edging plate.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described in detail with reference to FIGS. FIG. 1 is a cross-sectional view schematically showing a case of applying to a cast-in-place pile, in which a pile 1 has a reinforced cage 4 with a jack 3 attached to an excavated hole 2 and a tremie pipe (not shown). ) Is dropped to the bottom of the hole and concrete 5 is poured into the hole to form the concrete.

In this embodiment, a plurality of jacks 3 are mounted immediately above the enlarged bulb portion 6. Each jack 3,
2, ... are sandwiched from the top and bottom by horizontal ring-shaped upper and lower flange plates 7 and 8 which have a space around which a tremie pipe and concrete can go, as shown in FIGS. 2 and 3, and are concentric with the center of the pile 1. They are arranged on the circumference at substantially equal intervals.

As shown in FIG. 3, each of the jacks 3, 3, ... has a cylinder 9 fixed to the lower surface of an upper flange plate 7 and a ram 10 provided therein, and a flange is provided at the lower end of the cylinder 9. A donut-shaped edging plate 12 is provided via 11. On the other hand, a plurality of spherical seat protection tubes 13 are provided on the upper surface of the lower flange plate 8, and a donut-shaped edge cutting plate 15 is provided on the upper end of the lower flange plate 8 via a flange 14. The edge cutting plate 15 and the edge cutting plate 12 are connected to each other. A bellows 16 is provided between them.

Then, the spherical seat 17 is provided in the spherical seat protection tube 13.
Is provided and the flange 11 and the flange 14 are tightly connected by the tension rods 18 and 18 so that the lower reinforcing bar cage does not drop. This tension rod is provided with a notch at the center length position, and is structured so that it can be cut with a small amount of elongation with low force. Further, as an example of a method of attaching the jack and the upper and lower rebar cages, a steel pipe 20 having a flange plate 20a is fixed to the upper surface of the upper flange plate 7, the steel pipe 20 is fixed to the main bar 4a of the rebar cage 4, and the lower flange Board 8
The steel pipe 21 with the flange plate 21a fixed to the lower surface of is fixed to the main bar 4a of the reinforcing bar cage 4. Alternatively, the main bar 4a is fixed to the flange plates 20a and 21a by welding or screws,
The upper flange plate 7 and the flange plate 20a, the lower flange plate 8
Alternatively, the flange plate 21a may be fixed.

On the other hand, the pressurized fluid is supplied from the pressurizing pump 22 on the ground into the cylinder 9 through the supply pipe 23. As shown in FIG. 2, a flow rate adjusting device 24 and a pressure gauge (not shown) are attached to each of the jacks 3, 3, ..., Each flow rate adjusting device 24, 24 is connected by a connecting pipe 25, and is connected to the supply pipe 23. An exhaust pipe 26 for exhaust in the cylinder 9 is connected. The applied pressure is detected by attaching a pressure gauge (not shown) to the ground portion of the supply pipe 23 and a pressure gauge (not shown) to each jack to obtain the thrust.

Displacement detecting rods 27 and 28 are attached to the upper and lower flange plates 7 and 8, respectively, extend to the pile head 33 and are connected to displacement detectors 29 and 30 to detect displacement. The displacement detection rods 27 and 28 are protected by protection pipes 31 and 32 such as steel pipes so as not to come into contact with surrounding concrete. Therefore, the movements of the top and the bottom of the jack can be accurately detected. Reference numeral 34 in FIG. 1 is a displacement detector.

The first embodiment is constructed as described above, and at the time of installation, the main bars of the rebar cage 4 are attached to the steel pipes 20 and 21 fixed to the upper and lower flange plates 7 and 8 which sandwich the jacks 3, 3 ,. 4a is welded to rebar cage 4 and jacks 3,3
Assemble ... and are integrally connected in the axial direction on the ground. This rebar cage 4 is hung in the excavation hole 2, a tremie pipe (not shown) is inserted, and the concrete 5 is excavated in the excavation hole 2.
A cast-in-place concrete pile will be constructed by placing it in the.

In this way, the jacks 3, 3 are placed at arbitrary positions on the reinforcing bar cage 4 via the ring-shaped upper and lower flange plates 7, 8.
3, ... Can be attached, and the edging plates 12, 15
Also, since the upper and lower flange plates 7 and 8 are formed in a donut shape and a space is provided in the central portion, a cast-in-place pile can be formed by inserting a tremie pipe (not shown) without changing the conventional method.

The bellows 1 is formed between the pair of edge cutting plates 12 and 15.
Since they are connected by 6, the earth, sand and cement paste are prevented from entering the inside of the jack 3, the spherical seat 17 and the sphere portion 19, the protective tube 32 of the displacement detection rod and the like.

On the other hand, after hardening the concrete, the exhaust pipe 2
The pressure fluid is pressure-fed from the supply pipe 23 to the jacks 3, 3, ... While bleeding from 6, and when the exhaust is completed, the opening of the exhaust pipe 26 is closed. After that, when pressure is applied to the jacks 3, 3, ..., Tensile stress acts on the concrete on the inside and the outside of the edging plate 12, and when the tensile strength of the concrete is reached, the concrete is cut and the pressure drops sharply. Ram 10 of 3, ... Moves slightly.
It is possible to confirm the cutting of the concrete by the detection of the sudden drop of the pressure and the detection of the vertical displacement detectors 29 and 30 of the jack 3.

After this, the displacement detectors 29, 30,
When the jack 3 is pressed while measuring the displacement of each part at 34, the actual supporting force of the pile can be measured by making the peripheral frictional force on the jack and the supporting force under the jack a mutual reaction force. Even if the supporting force in the circumferential direction is not uniform, the piles can be displaced without tilting because the structure is such that the same flow rate is sent to the jacks 3, 3, ....

After the test, the pressure fluid is switched to a hardening fluid such as cement milk or mortar and the jacks 3, 3 ,.
Pump to. At the same time, a curable fluid also flows in from the protective tube 32 to fill the space between the edge cutting plates 12 and 15. This allows
The cracks formed by dividing the inside of each of the jacks 3, 3, ... And the edging plate 12 are filled with a curable fluid and can be used as a permanent pile.

In the case of reinforcing the edge cut plate portion with a reinforcing bar, a deformed steel bar is welded to the lower edge cut plate 15 in advance, the deformed steel bar is inserted through the upper edge cut plate 12 and extended upward, and the sheath tube is provided outside thereof. With the provision of, the curable fluid is filled between the sheath tube and the deformed steel bar after the curable fluid is injected. When the number of deformed steel bars for reinforcement is large, if several sheath pipe heads are connected to each other by pressure-feeding pipes and extended to the ground, they serve as an exhaust pipe when filling a hardening fluid. It can serve as a pipe for filling the curable fluid. It should be noted that the deformed steel bar may be fixed to the upper edging plate 12 and the above procedure may be reversed. Enlarged bulb portion 6 shown in FIG.
The present invention can be applied not only to those having the above, but also to a straight cast-in-place pile, and further to a pile having a rectangular cross section instead of the ring shape.

Next, a second embodiment will be described with reference to FIG. 4. A plurality of bellows 35, 35, ... Is installed between the ring-shaped upper and lower flange plates 7, 8, and each bellows 35, 35 ,.
The periphery of ... is surrounded by the steel pipe 36 fixed to the lower surface of the upper flange plate 7, and the ring-shaped edge cutting plate 12 is provided around the lower end of the steel pipe 36.
Is fixed to the upper surface of the lower flange plate 8, and a bellows 16 is attached to the ring-shaped edging plate 15 fixed to the upper surface of the lower flange plate 8. A plurality of tension rods 18, 18, ... Are attached to the upper and lower flange plates 7, 8.

In the figure, 37 is a grout tube, 37a is a communicating tube, 38 is a deformed steel bar, and 39 is a sheath tube. The flow of the hardening fluid through the grout pipe 37 or the protective pipe 32 can help discharge the water or air between the edging plates 12, 15 from the other protective pipe 32 to the ground. When there are many deformed steel bars 38, the above object can be achieved by providing several grout tubes 37. The other parts are the same as those in the first embodiment, so the same reference numerals are given and the description thereof is omitted.

Next, a third embodiment will be described with reference to FIG. In this embodiment, a through hole 40 is provided in the center of a rectangular upper flange plate 7 in a pile 1'having a rectangular cross section, and four jacks 3, 3 are provided between a lower flange plate (not shown) and the upper flange plate 7. ，
Steel plates 20b on the upper and lower flange plates 7 and 8 in which the ...
Is attached. In the figure, 37 is a grout pipe extended to the ground, 38 is a deformed steel bar, and 39 is a sheath pipe. Since all others are the same as those in the first embodiment, the same reference numerals are given and description thereof is omitted.

Next, a fourth embodiment will be described with reference to FIGS. 6 to 8 in which this embodiment is used for a hollow cast-in-place pile. A plurality of jacks 3, 3, ... Are installed on the hollow divided piles 41, 42, 43. For example, the division pile 4 which is located under
The cylinders 9 of the jacks 3, 3, ... Are provided on the upper surface of 1.
A spherical support portion 44 is provided on the upper surface of the ram 10 to support the lower surface of the upper divided pile 41 and the fixed ball seat 45.

As shown in FIGS. 7 and 8, each jack 3, 3, ... Is provided with a flow rate adjusting device 24 and is connected by a connecting pipe 25. The connecting pipe 25 is connected with a supply pipe 23 and an exhaust pipe 26. . In FIG. 6, 46 is a displacement detection rod and 47 is a displacement detector. Since all others are the same as those in the first embodiment, the same reference numerals are given and description thereof is omitted.

This embodiment is constructed as described above,
The divided piles 41, 42, 43 are made of concrete by placing a space in the center in advance. The pile is divided into appropriate lengths according to the magnitude of the peripheral friction force and the purpose of the test, and the peripheral friction force and tip support force of the divided divided piles are measured. That is, each jack 3, 3, ...
The test is conducted by using the frictional forces of the peripheral surfaces 1 and 42 as mutual reaction forces.

[0026]

Since a plurality of jacks annularly arranged on the outer peripheral portion of the pile are used as the force applying device for the pile,
A space can be provided in the center of the pile, and since a small-diameter jack can be used, a large pressing force can be applied to the jack. Therefore, the desired thrust can be reliably obtained. Moreover, since a flow rate adjusting device is provided so that an equal flow rate is sent to each jack, even if the supporting force is not uniform over the circumferential direction of the pile, the pile can be uniformly displaced without tilting. Therefore, the original bearing capacity can be measured. In the pile where concrete is placed by fixing it to the rebar cage and hanging the jack in the excavation hole, the concrete wraps around from the space between the jacks, so there is no concern of creating a cavity in the jack installation part. There is no fear of adversely affecting the supportive power of. Further, when the jack is extended, the position where the pile is separated is specified by the edging plate, so after the test, it can be used as a permanent pile by injecting a curable fluid. In addition to this, the jack can be attached to any position of the rebar cage via a flange plate that has a space through which a tremie pipe for concrete placement can pass in the center of the pile, and the conventional construction method can be changed. You can build piles without.

[0027]

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a first embodiment of a pile force applying device according to the present invention.

FIG. 2 is a cross-sectional plan view thereof.

FIG. 3 is a partially enlarged cross-sectional view.

FIG. 4 is a sectional view of the second embodiment.

FIG. 5 is a cross-sectional plan view of the third embodiment.

FIG. 6 is a sectional view of a fourth embodiment.

FIG. 7 is a plan view thereof.

FIG. 8 is an enlarged cross-sectional view thereof.

[Explanation of symbols]

 1 Pile 1'Pile of rectangular cross section 2 Drilling hole 3 Jack 4 Reinforcing bar basket 4a Main bar 5 Concrete 6 Expanded bulb part 7 Upper flange plate 8 Lower flange plate 9 Cylinder 10 Ram 11 Flange 12 Edge cut plate 13 Spherical seat protection pipe 14 Flange 15 Edge cut plate 16 Bellows 17 Spherical seat 18 Tension rod 19 Ball portion 20 Steel pipe 20a Flange plate 20b Steel plate 21 Steel pipe 21a Flange plate 22 Pressurizing pump 23 Supply pipe 24 Flow rate adjusting device 25 Connecting pipe 26 Exhaust pipe 27 Displacement detecting rod 28 Displacement detecting rod 29 Displacement detector 30 Displacement detector 31 Protective pipe 32 Protective pipe 33 Pile head 34 Displacement detector 35 Bellows 36 Steel pipe 37 Grout pipe 37a Communication pipe 38 Deformed bar steel 39 Sheath pipe 40 Through hole 41 Split pile 42 Split pile 43 Split pile 44 Spherical support part 45 Spherical support Seat 46 Displacement detection rod 47 Displacement detector

Claims (2)

[Claims] 1. A force applying device for measuring thrust of a pile, which is mounted at one or a plurality of depths in the middle or at the tip of the pile so as to apply a thrust to each other, and the spaces are spaced from each other. And a means for operating a plurality of fluid-pressure-operated jacks arranged in interlock with each other to measure the upward and downward movements of the jacks and the thrust of the jacks. 2. A force applying device for a pile, comprising a flow rate adjusting device for sending an equal flow rate to each jack according to claim 1.