KR930003502B1 - Load test method of file using self reaction - Google Patents

Abstract

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Description

Load test method of file using self reaction

1 shows a conventional loading test apparatus for applying a load directly to a pile.

2 shows a conventional loading test apparatus for applying a load box to a pile by means of a hydraulic jack.

3 shows a conventional loading test apparatus for applying a load acting on a fixed resistance beam to a pile on a pile by a hydraulic jack.

Figure 4 is a front sectional view showing a loading test apparatus for performing the loading test method according to the present invention.

* Explanation of symbols for main parts of the drawings

1: Pile test pile 2: Tip support

3: peripheral friction part 7: hydraulic jack

8: inner steel pipe 9: steel bar

10: reaction force support plate 12a: first dial gauge

12b: second dial gauge

The present invention relates to a load test apparatus for a pile using its own reaction force, and more particularly, to a load test method for confirming the bearing capacity of the ground for a pile installed in the ground during construction of a building.

In general, the well-known load settlement test method, the load is applied directly to the pile, the method of applying the load box or load table to the pile by the hydraulic jack and the load applied to the set resistance beam to the pile by the hydraulic jack Methods of making are known.

That is, the method of directly applying the load to the pile, as shown in Figure 1, by installing the load box 12 on the upper end of the test pile 11, the soil, sand, cement, iron wire in the load box 12 Alternatively, put other suitable materials, and lay down the beams 13 and I beams 14 sequentially, and load test by load.

In addition, as a method of applying the load box or the load table 22 to the pile by the hydraulic jack, as shown in FIG. 2, the load box or the load table 22 supported by the furniture 23a 23b is tested. ), The I-beams 24 are stacked between the beams 23a and 23b, and then the load box 22 is loaded with a suitable weight of material such as sand, cement or gravel. Fill to exceed load. Then, the hydraulic jack 25 equipped with the pressure gauge is inserted between the upper end of the test pile 21 and the load box 22, and the hydraulic jack 25 is operated to apply a load to the test pile 21 to test the load. Do it.

Third, as a method of applying the pressure of the hydraulic jack acting on the fixed resistance beam 34 to the pile, two or more fixing piles 33a and 33b are separated from the test pile 31 at regular intervals ( After embedding in 36, a resistance beam 34 having sufficient strength is attached to the upper ends of the fixing piles 33a and 33b by welding or the like. Thereafter, the hydraulic jack 35 equipped with the pressure gauge is inserted between the upper end of the test pile 31 and the lower portion of the resistance beam 34, and the hydraulic jack 35 is operated to test the test load by the test pile 31. The load test is to be applied to.

However, in the conventional load test method as described above, the load test member must be manufactured separately, and when the load test file of the load is made of concrete piles, the curing period of the load-loaded concrete takes a long time. However, in terms of time, a lot of loss follows.

Accordingly, an object of the present invention is to provide a test method for loading a file which is simple in installation and test method, which saves test cost and time.

The above object is a step of placing a predetermined depth in the ground pile consisting of the front end support and the peripheral friction portion manufactured separately from each other; Inserting a steel rod into the inner steel pipe of the tip support portion through the upper opening of the peripheral friction portion; Installing a hydraulic jack having a piston member on an upper end of the steel rod and connected to an external hydraulic pump; Fixing a plurality of tie bars on the upper circumference of the peripheral friction part, and fixing the reaction force supporting plate to the piston member of the hydraulic jack on the top of the tie bars; Installing and setting a first dial gauge on the side of the hydraulic jack and a second dial gauge on the side of the peripheral friction portion; Supplying hydraulic oil to the hydraulic jack by driving an external hydraulic pump to apply a load to the pile; It can be achieved by the pile loading test method using the self reaction force of the present invention, characterized in that the step of measuring the settlement amount of the tip support or the amount of missing the peripheral friction portion, and the pressure applied to the hydraulic jack.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is a cross-sectional view showing a loading test apparatus according to the present invention, the load supporting pile (2), the peripheral friction portion (3), the hydraulic jack (7) and dial gauges (12a, 12b) are assembled 1) The state of being buried in the ground is shown.

The tip support portion 2 and the peripheral friction portion 3 of the pile 1 have an outer diameter of about 355 mm and are made of steel pipe having a thickness of 10 to 15 mm. The tip support portion 2 has a conical lower end portion 6, an upper end portion 5 formed of a donut-shaped disk, a cylindrical portion 4 having an outer diameter of about 315 mm and a lower portion extending upwardly from the upper end portion 5 and a lower portion thereof. Is composed of an inner steel pipe (8) which is welded horizontally inside the lower end (6) and penetrates the center of the upper end (5) and extends vertically into the peripheral friction part (3).

As described above, the lower part of the inner steel pipe 8 welded inside the lower end 6 of the tip support part 2 is sealed with a disc of a predetermined thickness, and the upper part of the inner steel plate 8 is opened, A steel bar 9 for transmitting the load of the hydraulic jack 7 to the tip support 2 is inserted into the inner steel pipe 8. The inner diameter of the inner steel pipe (8) is 110mm, the outer diameter of the steel bar (9) is about 100mm to sufficiently transfer the load by the hydraulic jack (7). The steel bar 9 is prevented from bending by the inner steel pipe 8 when a load is applied.

The steel bar 9 has a length that can protrude beyond the upper end of the peripheral friction portion 3 from the lower portion of the inner steel pipe 8, the upper member 13 is installed on the upper end of the steel bar (9). The upper member 13 is a steel plate having a thickness of about 50 mm, and the hydraulic jack 7 is installed in the upper member 13. In addition, the steel bar 9 may be replaced with a hollow bar so that the weight and strength can be improved.

On the upper circumference of the peripheral friction part 3 a number of, preferably 12, tie bars 14, which are formed as threaded rods, are fixed by bolts 16, and the upper part of the tie bars 14 is fixed. Reaction force supporting plate 10 is fitted, it is fixed to the tie bar by the nuts 15 to contact the piston member 11 of the hydraulic jack (7). The outer diameter of the tie bar 14 is about 20 mm to withstand the load by the piston member, and is the same as the upper member 13 of the reaction force supporting plate 10.

The hydraulic jack 7 is connected to a hydraulic pump (not shown) through a hydraulic hose (not shown), and can apply a load of up to about 150 tons to the pile 1 by driving the hydraulic pump.

The loading test method of the present invention using the loading test file 1 configured as described above is as follows.

Assembling the front end support portion 2 and the peripheral friction portion (3) manufactured separately from each other, and placed in the ground to a certain depth, the upper end of the poured peripheral friction portion (3) to protrude out of the ground. Thereafter, a steel bar 9 for transmitting a load to the tip support 2 is inserted into the inner steel pipe 8 of the tip support 2 through the protruded top opening of the peripheral friction portion 3. .

After installing the upper member 13 on the upper end of the steel bar (9) protruding above the upper end of the peripheral friction portion (3), the hydraulic jack (7) is installed on the upper member (13). Thereafter, the plurality of tie bars 14 are fixedly installed on the upper circumference of the peripheral friction portion 3 using bolts 16, and the reaction force supporting plate 10 is mounted on the top of the tie bars 14 by the hydraulic jack 7 In contact with the piston member 11 of the tie (15) is fixed to the tie bar (14).

After that, the first dial gauge 12a for measuring the amount of settlement of the tip support portion 2 is provided on the side of the hydraulic jack 7, and the amount of the peripheral friction portion released by the reaction force is provided on the side of the peripheral friction portion 3. Install a second dial gauge (12b) to measure the.

In the state of assembling the load test pile 1 as shown in FIG. 4, after setting the guidelines of the first and second dial gauges 12a and 12b to a constant scale position, the external hydraulic pump is Drive and supply hydraulic oil to the hydraulic jack (7) to apply a load to the pile (1).

With the operation of the hydraulic jack 7, the tip support 2 begins to sink, and the peripheral friction portion 3 is about to fall up. At this time, the extreme value (destructive value) of the tip support force acting on the tip support 2 is indicated in the displacement amount and the pressure gauge of the hydraulic pump when the settlement of the tip support 2 is settled by about 10% (about 40 mm) of the outer diameter. It can be obtained by measuring the pressure. The limit value (destruction value) of the peripheral frictional force acting around the peripheral friction part 3 is determined by the amount of displacement when the displacement of the peripheral friction part 3 falls by about 1% of the outer diameter (about 4 mm). This can be obtained by measuring the pressure in the pressure gauge of the hydraulic pump.

Although there are some differences depending on the area under test, since the tip support is usually larger than the peripheral friction, the breakage of peripheral friction is faster than the break of the tip support, and the extreme value of the tip support is usually twice as large as the ultimate value of the peripheral friction. to be.

According to the loading test apparatus of the pile using the self reaction of the present invention as described above, after placing the test pile in the ground, the load test member that is required separately to perform the test can be omitted, and the test method is simple Loading tests can be performed and the costs used for the tests can be significantly reduced.

Claims (1)

Placing a pile (1) composed of the tip support portion (2) and the peripheral friction portion (3) which are separated from each other in the ground; Inserting a steel rod (9) into the inner steel pipe (8) of the tip support (2) through the upper opening of the peripheral friction portion (3); Installing a hydraulic jack (7) having a piston member (11) at an upper end of the steel bar (9) and connected to a hydraulic pump; A plurality of tie bars 14 are fixedly installed on the upper circumference of the peripheral friction part 3, and a reaction force supporting plate 10 is mounted on the tie bars 14 with the piston member 11 of the hydraulic jack 7. Fixing to contact; Installing and setting a first dial gauge (12a) on the side of the hydraulic jack (7) and a second dial gauge (12b) on the side of the peripheral friction portion (3); Supplying hydraulic oil to the hydraulic jack (7) by driving the external hydraulic pump to apply a load to the pile (1); The load test method of the pile using its own reaction force, characterized in that it comprises the step of measuring the amount of settlement of the tip support (2) or the amount of missing of the peripheral friction portion 3 and the pressure applied to the hydraulic jack (7) .

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