JP2001254349A - Pile loading test method and its loading test device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pile loading test method and its loading test device capable of being tested by using a testing pile in a state to make it possible to actually use, simplifying the constitution, extending the flexibility of the test and contributing to shortening of the testing process and reduction of costs. SOLUTION: Load transferring members of steel frames, etc., are integrally provided to the testing pile and a reaction pile in the vertical direction, a pushing and pulling jack alternately operating pushing force and pulling force is provided between the upper end of the load transferring member on the testing pile side and the lower end of the load transferring member on the reaction pile side, a large hollow section necessary for pulling out the testing pile is provided to the upper part of the testing pile, and the pushing force and pulling force is transferred to the testing pile by the pushing and pulling jack to execute a vertical alternating loading test.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pile load test method for conducting a vertical orthogonal load test on a test pile constructed underground using a reaction force pile provided vertically above the test pile. And the technical field of load test equipment.

[0002]

2. Description of the Related Art In recent years, the importance of evaluating the bearing capacity of a foundation during a large earthquake has increased. In a building with a large tower ratio, a large pushing force and a strong pulling force are applied to the foundation pile during an earthquake, and the building may rise or even fall. In the basic design of such a building,
In order to measure the supporting force of the pile against the pushing force and the pulling force, the following pile loading tests are performed.

[0003] At the tip of the pile and the middle part where the pile is cut,
A method of measuring the supporting force against the pushing force of the pile by installing and loading a jack that acts only on the pushing force (Japanese Patent No. 2551800, Japanese Patent Publication No. 6-48224)
Japanese Patent Publication No. 6-63879).

As shown in FIG. 5, a plurality of portions of a test pile 1 are divided so as to be vertically expandable and contractable, and a jack a which can apply only a pushing force to expansion and contraction (division) portions of vertically adjacent piles. , B, and c are set, and the peripheral frictional force of the divided pile 1A is set as a reaction force to load the jack a and simultaneously unload the jack b and apply a pushing force to the divided pile 1B. At the same time as loading the jack a, unloading the jack a and applying a pulling force to the split pile 1B alternately to perform a vertical orthogonal loading test to measure the supporting force (described in Japanese Patent No. 2694510). .

The pile heads of two reaction force piles arranged side by side at a distance are connected by a reaction beam, and the test pile pile head and the reaction force beam constructed at an intermediate portion between the two reaction force piles are connected. And a jack that acts only on the pushing force, and a jack is also provided at the tip of the test pile. Loading and unloading by the two jacks can be used properly depending on the contents of the loading test, and the loading direction is fixed or the perpendicular orthogonal loading. A method of measuring a bearing force by performing a test (described in JP-A-7-19973).

[0006]

In the above-mentioned prior art, since the jack which acts only on the pushing force is installed at only one place, only the supporting force for the pushing force of the test pile can be measured.

In the prior art, a lead orthogonal loading test can be performed. However, since the jack acts only on the pushing force, it is necessary to install the jack at at least two places.
The test pile 1 must be divided, and a load test cannot be performed using a pile in an actually used state. In addition, the middle divided pile 1B can perform the lead orthogonal loading test, but the upper divided pile 1A and the lower divided pile 1C
Only a test with a fixed loading direction can be performed. In addition, it is necessary to provide jacks at each of the expansion and contraction points of the split pile, which complicates the operation and increases the cost. In addition, in order to perform the lead orthogonal loading test, it is necessary to control the jack a and the jack b in conjunction with each other, and the degree of freedom of the test is reduced.

In the prior art, a vertical orthogonal loading test can be performed using a test pile in an actually used state. However, other than that, there is the same problem as the prior art. In addition, it is necessary to construct a reaction force pile and a reaction force beam, and the load test device becomes large, the test process becomes long, and the cost increases.

Accordingly, an object of the present invention is to enable a test using a test pile in an actually used state, to have a simple configuration, to increase the degree of freedom of a test, and to shorten a test process. Another object of the present invention is to provide a pile load test method and a load test device that contribute to cost reduction.

[0010]

According to a first aspect of the present invention, there is provided a pile loading test method according to the first aspect of the present invention, wherein a test pile constructed underground is provided vertically above the pile. In a load test method for a pile for performing a load test using the peripheral frictional force of a reaction force pile, a load transmission member such as a steel frame is integrally provided in a vertical direction on the test pile and the reaction force pile, respectively, A push / pull jack is provided between the upper end of the load transmitting member on the test pile side and the lower end of the load transmitting member on the reaction force pile side to alternately apply a pushing force and a pulling force. A hollow portion having a size necessary for pulling out the test pile is provided in the portion, and a pushing force and a pulling force of the push / pull jack are transmitted to the test pile to perform a vertical orthogonal loading test.

According to a second aspect of the present invention, in the pile loading test apparatus according to the first aspect of the present invention, a lower end of a displacement rod is fixed to a pile head and a lower end portion of the test pile, respectively. A displacement meter is provided at the upper end of the rod, and the displacement of the test pile in the vertical direction by the vertical orthogonal loading test is measured by the displacement meter.

According to a third aspect of the present invention, there is provided a load test apparatus for piles, which performs a load test on a test pile constructed underground by utilizing a peripheral frictional force of a reaction force pile provided vertically above the test pile. In the pile loading test device, a load transmitting member such as a steel frame is integrally provided in the test pile and the reaction force pile in a vertical direction, respectively, and an upper end portion of the load transmission member on the test pile side and the reaction force pile side. A connecting plate is provided at the lower end of the load transmitting member in the horizontal direction, and one side of the push / pull jack that alternately applies the pushing force and the pulling force is one connecting plate, and the other side is the other connecting plate. A cavity having a size necessary for pulling out the test pile is provided above the connecting plate of the load transmitting member of the test pile, and the pushing force and the pulling force by the push / pull jack are provided. Transfer to a test pile and conduct a vertical orthogonal loading test And performing.

According to a fourth aspect of the present invention, in the pile loading test apparatus according to the third aspect, the lower end of the displacement rod having the double pipe structure is fixed to the pile head and the lower end of the test pile. A displacement gauge is provided on the upper end of the displacement rod that is attached and raised vertically upward to the ground, and the displacement of the test pile in the vertical orthogonal loading test is measured by the displacement gauge.

According to a fifth aspect of the present invention, in the pile loading test device according to the third or fourth aspect, the push / pull jack is a jack capable of telescopic movement such as a hydraulic double-acting cylinder. , Characterized in that the piston is installed while maintaining a substantially neutral state.

The invention described in claim 6 is the invention according to claims 3 to 5
In the pile loading test device according to the invention described in any one of the above, the reaction force pile, the pile diameter is large so as to ensure the peripheral frictional force required for the test, or a number of resistance grooves on the periphery of the pile It is characterized by being provided.

[0016] The invention described in claim 7 is the third to sixth aspects of the present invention.
In the load testing device for a pile according to any one of the above aspects, a liquid for preventing collapse of the hole wall, such as a stabilizing liquid, is injected into the cavity.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG.
1 schematically shows an embodiment of a pile load test device according to the invention described in (1). This loading test apparatus performs a vertical orthogonal loading test on a test pile 1 constructed underground by utilizing a peripheral frictional force of a reaction force pile 5 provided in a series of arrangements vertically above the test pile 1, This is suitably performed when measuring the supporting force of the test pile 1 against the pushing force and the pulling force.

As described in detail in FIG. 2, the load test apparatus described above has the test piles 1 and the reaction force piles 5 in which the steel frames 2 and 6 as load transmitting members are concentrically arranged in series in the vertical direction. It is buried and fixed in concrete and provided integrally. The upper and lower ends of the steel frame 2 of the test pile 1 and the lower end of the steel frame 6 of the reaction pile 5 are spaced apart from each other by two.
The connecting plates 3, 3 and 7, 7 are provided in a substantially horizontal direction. One connecting plate 7 on the reaction force pile 5 side also serves as a concrete partition plate at the lower end of the reaction force pile 5. Therefore, an upper concrete stopper packer 14 is provided in the gap between the pile hole and the pile wall surface so that concrete does not flow into the cavity 8.

A push / pull jack 4 which alternately applies a pushing force and a pulling force between the upper and lower connecting plates 3 and 7.
Is installed. In the illustrated example, the cylinder 4a of the push-pull jack 4 and its rod 4f are connected to the connecting plate 7 of the reaction force pile 5. On the other hand, the piston rod 4e is connected to the connecting plate 3 of the test pile 1 by a nut 13.

A double-acting cylinder type hydraulic jack is used for the push / pull jack 4, and its piston 4b
Are installed while maintaining a neutral state (the invention according to claim 5). A hollow portion 8 having a distance (stroke) required for pushing and pulling the test pile 1 is formed between the lower end of the cylinder 4a of the push / pull jack 4 and the nut 13 at the upper portion on the test pile 1 side. Is provided.

With the above construction, the pushing force and the pulling force of the push / pull jack 4 are reduced by the upper and lower connecting plates 3 and 7.
And transmitted from the steel frames 2 and 6 to the test pile 1 and the reaction force pile 5.

The push / pull jack 4 has a hose 10a serving as a forward path or a return path of a hydraulic unit including a hydraulic pump 9 and a hydraulic control circuit installed on the ground, and a hose 10b serving as a return path or a forward path. The lower and upper oil chambers 4c, 4d are connected to each other, and the push / pull jack 4 is driven by the operation of the hydraulic unit including the pump 9 and the hydraulic control circuit, and the peripheral friction force of the reaction force pile 5 is changed to a reaction force. The pushing force and the pulling force are transmitted to the test pile 1 to perform a vertical orthogonal loading test.

The pile head and lower end of the test pile 1 are respectively provided with displacement rods 12a, 12a having a double pipe structure.
b is fixed to the lower end of the displacement rods 12a and 12b, and the displacement gauge 11,
11 is provided, and the vertical displacement of the test pile 1 in the vertical orthogonal loading test can be measured by the displacement meters 11, 11 (the invention according to claim 4).

The pile loading test method according to the inventions according to the first and second aspects is performed by using the pile loading test apparatus according to the third aspect configured as described above.

In the load test method described above, a pushing force and a pulling force by the push / pull jack 4 are transmitted to the test pile 1 to perform a vertical orthogonal load test.

More specifically, when transmitting a pushing force to the test pile 1, the hydraulic unit including the pump 9 and the hydraulic control circuit is operated to inject hydraulic oil into the upper oil chamber 4c. The test device transmits the pulling force to the reaction force pile 5 and the pushing force to the test pile 1 at the same time. Since the reaction force pile 5 is shaped to exhibit a support force larger than the test force force of the test pile 1, the pulling force transmitted to the reaction force pile 5 is such that the peripheral friction force of the reaction force pile 5 is less than that of the reaction force pile 5. The reaction force is offset, and the pushing force is transmitted to the test pile 1. Along with this, the piston 4b is lowered and the test pile 1 is pushed into the ground, and the hydraulic oil in the lower oil chamber 4d is pushed out by the amount of displacement to the return hose 10b connected to the lower oil chamber 4d and discharged. I do.

On the other hand, when transmitting the pulling force to the test pile 1, the hydraulic unit including the pump 9 and the hydraulic control circuit is operated to inject hydraulic oil into the lower oil chamber 4 d. The device transmits the pushing force to the reaction pile 5 and the pull-out force to the test pile 1 at the same time. The pushing force transmitted to the reaction force pile 5 is offset by the peripheral frictional force of the reaction force pile 5 acting as a reaction force, and a pull-out force acts on the test pile 1. Along with this, the piston 4b rises and the test pile 1 is pulled out from the ground, and the hydraulic oil in the upper oil chamber 4c is pushed out by the displacement amount to the return hose 10a connected to the upper oil chamber 4c and discharged.

The above-mentioned pushing force and pulling force are applied to the test pile 1
The means for transmitting to the vertical crossing test is alternately repeated.

The displacement amount of the test pile 1 by the above-mentioned vertical orthogonal loading test is determined by the displacement rods 12a and 12b fixed to the pile head and the lower end of the test pile 1, and the displacement amount is displaced. It is measured by a total of 11, 11 (the invention according to claim 2).

As described above, by operating the hydraulic unit including the pump 9 and the hydraulic control circuit, the push / pull jack 4 alternately applies the pushing force and the pulling force to the test pile 1.
Therefore, the vertical orthogonal loading test can be performed only by providing the push / pull jack 4 at one position.

The load test device described above transmits the pushing force and the pull-out force to the test pile 1 by utilizing the reaction force of the reaction force pile 5, so that the load test device does not have a large structure.

In the above embodiment, the reaction force pile 5 is a cylindrical reaction force pile as shown in FIGS. 1 and 2, but a large load is transmitted to the test pile 1. In this case, as shown in FIGS. 3 and 4, the pile diameter of the reaction force pile 5 may be increased, or a large number of resistance grooves may be provided on the outer periphery of the pile (the invention described in claim 6).

Further, in the above embodiment, nothing is put in the hollow portion 8, but the present invention is not limited to this, and a liquid for preventing collapse of the pore wall such as a stabilizing liquid may be injected. Invention described in Item 7).

Further, in the above embodiment, the lower connecting plate 7 on the reaction force pile 5 side and the concrete partition plate at the tip of the reaction force pile 5 are common members, but the present invention is not limited to this. It may be a separate member.

In addition, in the above embodiment, the steel frames 2 and 6
Is embedded and fixed in the concrete of the test pile 1 and the reaction pile 5, but may be fixed to the concrete partition plate by welding or the like. The rods 4e and 4f are fixed to the upper and lower connecting plates 3 and 7 with the nut 13, but are not limited thereto, and may be fixed by means such as welding.

[0036]

According to the present invention, there is provided a pile load test method and a pile test apparatus according to the present invention, wherein a push / pull jack capable of alternately applying a pushing force and a pulling force is used. By simply providing the test pile in one place, a test using a test pile in a state where it is actually used can be performed very easily, and the degree of freedom of the test can be widened. Furthermore, since the pushing force and the pulling force are transmitted to the test pile by using the reaction force due to the frictional force of the peripheral surface of the reaction force pile, the load testing device does not have a large-scale structure, and has a simple configuration. Can contribute to shortening of the test process and reduction of cost.

[Brief description of the drawings]

FIG. 1 is an elevation view showing an embodiment of the present invention.

FIG. 2 is an elevational view showing details of a push-pull jack used in the embodiment of the present invention.

FIG. 3 is an elevation view showing another embodiment of the present invention.

FIG. 4 is an elevation view showing another embodiment of the present invention.

FIG. 5 is an elevation view showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Test pile 2, 6 Steel frame 3, 7 Connecting plate 4 Pushing / pulling jack 5 Reaction pile 8 Cavity part 9 Pump 10a Hose to go forward or backward 10b Hose to go backward or forward 11 Displacement gauge 12a, 12b Displacement rod 13 Nut 14 Upper concrete stop packer

Continuation of the front page (72) Inventor Hidenori Kitaori 1-5-1, Otsuka, Inzai City, Chiba Prefecture Inside the Research Institute of Takenaka Corporation (72) Inventor Masao Maruoka 1-5-1, Otsuka 1, Inzai City, Chiba Prefecture Stock Company Inside Takenaka Corporation Technical Research Institute (72) Inventor Toshiaki Tsuchiya 8-21-1, Ginza, Chuo-ku, Tokyo Inside Co., Ltd. Takenaka Corporation Tokyo Main Store (72) Inventor Yoshihisa Yasutomi 8--21 Ginza, Chuo-ku, Tokyo No. 1 Inside the Takenaka Corporation Tokyo head office F-term (reference) 2D043 AA03 AB03 AC01 2D050 AA01 CA07 CB22 DB02 FF02 FF07 2F051 AA06 AB01 AB02 AC01 BA00

Claims (7)

[Claims] 1. A pile load test method for performing a load test using a circumferential friction force of a reaction force pile provided vertically above a test pile constructed underground, wherein the test pile and the reaction force A load transmitting member such as a steel frame is integrally provided in the pile in the vertical direction, and a pushing force and a pull-out force are provided between an upper end portion of the load transmitting member on the test pile side and a lower end portion of the load transmitting member on the reaction force pile side. A push / pull jack that alternately acts on force is provided, and a cavity having a size necessary for pulling out the test pile is provided above the test pile, and the pushing force and the pulling force of the push / pull jack are reduced by the force. A load test method for piles, characterized in that a vertical orthogonal load test is conducted by transmitting to a test pile. 2. A lower end of a displacement rod is fixed to a pile head and a lower end of a test pile, respectively, and a displacement meter is provided at an upper end of the displacement rod to measure a vertical displacement of the test pile by a vertical orthogonal loading test. The pile load test method according to claim 1, wherein the measurement is performed by the displacement meter. 3. A pile load test apparatus for performing a load test using a peripheral frictional force of a reaction pile provided vertically above a test pile constructed underground, wherein the test pile and the reaction force are provided. A load transmitting member such as a steel frame is integrally provided in the pile in the vertical direction, and a connecting plate is provided at the upper end of the load transmitting member on the test pile side and the lower end of the load transmitting member on the reaction force pile side in the horizontal direction. The push / pull jack, which alternately applies a pushing force and a pulling force, is formed by connecting one side of a push / pull jack to one connecting plate and the other side to the other connecting plate, and connecting the load transmitting member of the test pile. A cavity having a size necessary for pulling out the test pile is provided at the upper part of the plate, and the pushing force and the pulling force by the push / pull jack are transmitted to the test pile to perform a vertical orthogonal loading test. Characteristic, pile loading test equipment. 4. A lower end of a displacement rod having a double pipe structure is fixed to a pile head and a lower end of a test pile, respectively, and a displacement meter is provided at an upper end of the displacement rod which rises vertically to the ground. 4. The pile load test apparatus according to claim 3, wherein the vertical displacement of the test pile by the lead orthogonal load test is measured by the displacement meter. 5. The push / pull jack is a jack capable of expanding and contracting, such as a hydraulic double-acting cylinder, and its piston is installed while maintaining a substantially neutral state. 4. The pile load test device described in 4. 6. The pile according to claim 1, wherein the pile has a large diameter so as to secure a peripheral frictional force required for the test, or a plurality of resistance grooves are provided on an outer periphery of the pile. The pile load testing device according to any one of 3 to 5. 7. The pile loading test according to claim 3, wherein a liquid such as a stabilizing liquid for preventing collapse of the pore wall is injected into the hollow portion. apparatus.