JPH0434649B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method and apparatus for carrying out a pile loading test.

[Background technology]

The bearing capacity performance of foundation piles that support above-ground structures is investigated by driving test piles into the actual ground before constructing the structure, and conducting loading tests using the actual loading method, reaction pile method, etc. However, each method has the problem of requiring a large amount of cost and time. FIG. 12 shows a conventional loading test method using the reaction pile method. 12th
In the figure, 50 is a test pile, 51 is a reaction pile, 52 is a reaction device consisting of a reaction beam and a reaction girder, and 53 is a force applying device such as a hydraulic jack.
The loading test was performed by activating the test pile 50 to push it downward and measuring the amount of sinking of the test pile 50 using a sinking amount measuring device 54 such as a dial gauge attached to the immovable beam 55. However, in this conventional loading test method using reaction piles, the pile bearing capacity becomes large, especially when the test pile is a large diameter pile or long pile, or when the ground at the tip of the pile is hard ground. Therefore, the test load loaded on the piles becomes large, and as a result, a large number of reaction piles corresponding to the test load are required.

Driving reaction piles requires a considerable amount of time and cost.

Reaction devices such as loading beams constructed between test piles and reaction piles are large-scale and expensive.

It will take a considerable number of days to obtain the bearing capacity performance (loading test results) of the piles, which will affect the start of actual construction.

In the above-mentioned application test method in which force is applied from the pile head,
It is not possible to accurately know the division of the pile's supporting capacity between the pile's peripheral surface bearing capacity and the pile's tip bearing capacity (if the load test results show that the pile's bearing capacity is insufficient, it will be difficult to take countermeasures).

There were various drawbacks such as:

[Purpose of the invention]

The present invention was invented in view of the above points, and its purpose is to shorten the test period without requiring a large-scale reaction force device or large actual load, and to improve the pile bearing capacity. The bearing capacity at the pile tip and the bearing capacity at the pile circumferential surface can be known separately, allowing for economical design of piles, making it easier to deal with insufficient bearing capacity based on test results, and further facilitating load testing of cast-in-place piles. An object of the present invention is to provide a pile loading test method and an apparatus therefor.

[Disclosure of the invention]

In the pile loading test method and apparatus of the present invention, a loading pipe 3 is inserted into the ground 4, and the inner pipe 2 is movable inside the outer pipe 1 so that the lower part thereof protrudes downward from the outer pipe 1. Then, at the same time that the loading device 5 applies an upward pushing force to the outer tube 1, a reaction force of the pushing up force is applied to the inner tube 2 as a pushing force, thereby increasing the amount of upward movement of the outer tube 1 and the amount of the inner tube 2. The first invention is a pile loading test method characterized by examining the amount of push-in movement into the ground 4, and also includes a method for testing piles, which is characterized by examining the amount of displacement of piles into the ground 4. The inner tube 2 is movable so as to protrude downward, and the loading tube 3, which has a large diameter section 6 at the bottom of the outer tube 1, is inserted. 1. Concrete 7 is poured into the cavity in the borehole 9 on the outer periphery of the concrete 7, and after the concrete 7 hardens, the loading device 5
At the same time, the reaction force of the upward force is applied to the inner tube 2 as a downward force, thereby increasing the amount of upward movement of the outer tube 1 and the amount of movement of the inner tube 2 into the ground 4. The second invention is a pile loading test method characterized by examining the amount of pushing movement.In addition, an inner tube 2 is movably inserted into the outer tube 1, and the lower part of the inner tube 2 is inserted into the outer tube 1. The large-diameter lower part 8 is configured to have the same diameter as the outer pipe 1, and the large-diameter lower part 8 is made to protrude downward from the lower end of the outer tube 1 to apply an upward pushing force to the outer tube 1 and at the same time to apply a reaction force to the pushing force. Loading device 5 for applying a downward force to the inner tube 2
A third invention provides a loading test device characterized by comprising: an inner tube 2 movably inserted into the outer tube 1; a lower portion of the outer tube 1 having a large diameter portion 6;
The lower part of the inner tube 2 has approximately the same diameter as the lower large diameter part 6 of the outer tube 1 to form a large diameter lower part 8, and the large diameter lower part 8 is made to protrude downward from the lower end of the outer tube 1. A fourth invention provides a pile loading test device characterized in that it is provided with a loading device 5 for applying an upward pushing force to the inner pipe 2 and at the same time applying a reaction force of the pushing force to the inner pipe 2 as a pushing down force. That is. That is, in the first to fourth inventions of the present invention, the lower part of the outer tube 1 is located inside the outer tube 1.
Using a loading tube 3 configured by movably inserting an inner tube 2 so as to protrude downward from the inner tube, a loading device 5 applies an upward pushing force to the outer tube 1, and at the same time, a reaction force of the pushing force is applied to the inner tube. 2 as a pushing force, the device configuration is simplified, the test period can be shortened, and the amount of push-up movement of the inner tube 2 and the amount of push-up movement of the outer tube 1 can be reduced. By examining this, it is now possible to separately determine the pile tip bearing capacity and the pile circumferential bearing capacity. In addition to this, in the second invention, concrete 7 is poured into the cavity in the borehole 9 on the outer periphery of the outer tube 1 above the large diameter portion 6 of the outer tube 1, and after the concrete 7 hardens. Since the loading device 5 applies an upward pushing force to the outer tube 1 and at the same time applies the reaction force of the pushing force to the inner tube 2 as a pushing force, it is now possible to carry out loading tests on cast-in-place piles. Furthermore, in the third invention, the lower part of the inner tube 2 has the same diameter as the outer tube 1 to form a large diameter lower part 8, and the large diameter lower part 8 projects downward from the lower end of the outer tube 1. Therefore, it has been possible to provide a device with a simple configuration capable of carrying out loading tests on ready-made piles.Furthermore, in the fourth invention, the lower part of the outer pipe 1 is the large diameter part 6, and the inner pipe A large-diameter lower part 8 is formed by making the lower part of the outer pipe 2 approximately the same diameter as the large-diameter part 6 at the lower part of the outer pipe 1, and this large-diameter lower part 8 is made to protrude downward from the lower end of the outer pipe 1, so that the cast-in-place pile We were able to provide a device with a simple configuration that can perform loading tests.

Hereinafter, the first invention and the third invention will be referred to as the first invention.
The explanation will be given based on the drawings shown in FIGS. 5 to 5. Outer tube 1
A loading tube 3 is constructed by inserting an inner tube 2 therein.
Here, the inner tube 2 is held by a removable inner tube temporary holding device 10, and in the embodiment shown in the drawings, the outer tube 1 is provided with a holding portion 11, and the inner tube 2 is provided with a held portion 12.
The inner tube holding device 10 is constructed by providing a holding part 11 and a held part 12, which are detachably attached by bolts 13 or the like. This is to temporarily hold the inner tube 2 to the outer tube 1 in order to prevent the tip of the inner tube 2 from slipping off when the loading tube 3 is staked.
When carrying out a loading test after inserting the loading pipe 3 into the ground 4, the bolts 13 and the like are removed to make the inner pipe 2 movable relative to the outer pipe 1. In the embodiment shown in the drawings, the inner tube 2 has an upper body 2a and a lower body 2b.
The lower end of the upper body 2a and the upper end of the lower body 2b are connected to a shear pin 15 via a joint 14.
It is connected by A plurality of reinforcing ribs 16 are provided on the lower inner circumferential surface of the outer tube 1 so as to protrude in the circumferential direction, and an annular body 17 is further provided on the lower part of the reinforcing ribs 16. A large diameter lower part 8 is attached to the lower part of the lower body 2b via a connecting reinforcing rib part 18 and a connecting annular part 19.
is fixed. This large-diameter lower portion 8 has the same diameter as the outer tube 1. A guide ring 20 for sliding is provided at the upper end of the large diameter lower part 8 or at the lower end of the outer tube 1.
The end of the large diameter lower part 8 or outer tube 1 is fixed.
Among them, the end portion to which the sliding guide ring 20 is not fixed is adapted to move so as to overlap with the sliding guide ring 20. A loading device 5 is attached to the upper end of the outer tube 1 using attachment means such as welding or bolts. This loading device 5 is provided with a hydraulic jack 21 which applies an upward pushing force to the outer tube 1 and at the same time applies a reaction force of the pushing force to the inner tube 2. When the inner tube 2 is held on the outer tube 1 by the inner tube temporary holding device 10, the lower end surface portion 22 of the outer tube 1
comes into contact with the upper end surface portion 23 of the large diameter lower portion 8 of the inner tube 2,
Further, the annular body 17 is in contact with the stepped portion 24 of the inner tube 2, and the loading tube 3 is constructed by inserting the inner tube 2 into the outer tube 1.
When press-fitting into the ground 4 by impact force, the impact force is transmitted from the outer tube 1 to the large diameter lower part 8. A cavity 25 is provided between the connecting annular portion 19 of the inner tube 2 and the annular body 17 of the outer tube 1, and an injection pipe 26 is installed so as to open into the cavity 25. The injection pipe 26 may be arranged in the gap between the outer tube 1 and the inner tube 2 or inside the inner tube 2. In the present invention, the outer tube 1
A device for checking the amount of upward movement of the inner pipe 2 and a device for checking the amount of movement of the inner pipe 2 by pushing it into the ground 4 are attached. As this device, for example, a fixed beam 27 is formed on the ground, and a displacement meter 28 such as a dial cage for measuring the amount of pushing up of the outer tube 1 is connected to the fixed beam 27.
7, and the measuring tip 29 of the dial gauge is applied to a contact portion 30 protruding from the outer tube 1 to measure the amount by which the outer tube 1 is pushed up. Further, in the embodiment shown in the drawings, the inner tube 2 is provided with a tip depression measuring rod 31, and the lower end of the tip depression measuring rod 31 is fixed to the lower part of the inner tube 2. Further, the tip settlement measuring rod 31 is placed inside a cover 60 to prevent the tip settlement measuring rod 31 from being affected by earth and sand. A protruding body 32 protrudes from the side of the tip settlement measuring rod 31, and this protruding body 32 is inserted into a vertically elongated hole 33 provided in the outer tube 1. A probe 35 of a displacement meter 34 such as a dial cage for measuring the pushing amount of the inner tube 2 is applied to the protruding portion, and the amount of subsidence of the tip of the inner tube 2 is measured. In the accompanying drawings, reference numeral 49 indicates a hydraulic hose.

Therefore, when carrying out a pile loading test using the above-mentioned device, first insert the inner tube 2 into the outer tube 1 without attaching the loading device 5 to the outer tube 1. The constructed loading pipe 3 is inserted into the ground 4 (in this case, the loading device 5 is not attached to the outer pipe 1). In order to insert the loading pipe 3 into the ground 4, it is possible to press it into the ground 4 by applying a striking force, or insert a screw auger into the inner pipe 2 and excavate the ground 4 at the tip of the loading pipe 3. A method of inserting the loading pipe 3 into the ground 4 without vibration can be adopted. After inserting the loading pipe 3 to a predetermined depth in the ground 4, the holding of the inner pipe 2 to the outer pipe 1 by the inner pipe holding device 10 is released, and the loading device 5 is further welded, bolted, etc. to the top of the outer pipe 1. The loading device 5 applies an upward force to the outer tube 1 and at the same time applies a reaction force to the upward force to the inner tube 2 as a downward force. Then, the outer tube 1 is pushed upward, the inner tube 2 is pushed downward, and the tip of the inner tube 2 sinks. And displacement meter 28,3
5, the amount of upward movement of the outer tube 1 and the amount of downward movement of the tip of the inner tube 2 are measured separately. Here, by measuring the amount of upward movement of the outer pipe 1, the support force on the pile peripheral surface can be determined, while the inner pipe 2
By measuring the amount of downward movement of the tip of the pile (that is, the amount of subsidence of the lower part of the inner pipe 2), the supporting force of the pile tip can be determined.

In the pile loading test as described above, the lower end surface 22 of the outer pipe 1 and the upper end surface 2 of the large diameter lower part 8 of the inner pipe 2
3, but if a solidified material such as mortar is injected into this gap portion from the injection pipe 26 after construction, the loading pipe 3 after the loading test can be used as the main pile. Instead of filling with solidified material such as mortar as described above, the outer tube 1 is press-fitted downward so that the lower end surface 22 of the outer tube 1 is in contact with the upper end surface 23 of the large diameter lower part 8. You can also use it as At this time, the annular body 17 also comes into contact with the stepped portion 24 of the inner tube 2. In this case, the injection pipe 26 is not necessarily required. In the embodiment shown in the drawing of FIG. 1, the lower end of the large diameter lower part 8 is open, but the lower end of the large diameter lower part 8 may be closed with a lid. After the loading test is completed, the loading device 5 is removed from the outer tube 1 and reused. Furthermore, after the loading test is completed, when the upper body 2a of the inner tube 2 is pulled upward, the shear pin 15 connecting the upper body 2a and the lower body 2b is cut, and only the upper body 2a can be recovered. . Here, in the above embodiment, an example was shown in which the upper body 2a and the lower body 2b were connected by the shear pin 15, but as shown in FIG. Fitting part 3
6 is provided, and a fitted portion 37 is provided on the other side,
A connecting pin 38 is provided in the fitting portion 36 and an L-shaped connecting groove 39 is provided in the fitted portion 37 to connect the connecting pin 3.
8 may be connected to the connecting groove 39 so as to be attached and detached by rotation, and by rotating the upper body 2a, only the upper body 2a may be pulled up.
Further, the upper body 2a and the lower body 2b may be detachably connected by a connecting means other than those described above. Note that if the inner tube 2 is not to be pulled up and recovered, there is no need to divide the inner tube 2 into the upper body 2a and the lower body 2b.

Next, the second invention and the fourth invention will be explained based on FIGS. 6 to 10. A large diameter portion 6 is provided at the bottom of the outer tube 1. On the other hand, inner pipe 2
A large-diameter lower part 8 is constructed with a lower part thereof having approximately the same diameter as the large-diameter part 6 of the lower part of the outer tube 1, and this large-diameter lower part 8 is made to protrude downward from the lower end of the outer tube 1. The lower end of the large-diameter lower portion 8 is closed by a tip loading plate 40 . The slide portion 41 of the large-diameter portion 6 and the slide portion 42 of the large-diameter lower portion 8 are slidably fitted together, and a gasket 43 is interposed at the fitting portion between the slide portion 41 and the slide portion 42. , to prevent dirt, cement liquid, etc. from entering the sliding part. Packing materials 45 are provided on the outer peripheries of the ring plate 44 at the upper part of the large diameter portion 6 and the tip loading plate 40, respectively. Inner pipe 2 has pipe 4
6 is disposed, and the lower end of the pipe 46 is open to the lower surface of the tip loading plate 40. Also cover 60
The lower end of the tip subsidence measuring rod 31 inserted therein is fixed to the tip loading plate 40. Therefore, the loading pipe 3 shown in FIG. 6 is first made by drilling a hole 9 into which the loading pipe 3 is inserted into a predetermined position using a drilling machine 47 such as an earth drill or a hammer grab, as shown in FIG. 10a. dig a hole Then, as shown in Fig. 10b, the loading pipe 3
is sunk to the bottom of borehole 9. Next, concrete 7 is poured using a tremie tube or the like into the cavity in the borehole 9 on the outer periphery of the outer tube 1 above the large diameter portion 6 of the outer tube 1.
In this case, concrete 7,
This prevents earth and sand from entering the large diameter lower part 8 side. Next, after the concrete 7 has hardened, a loading device 5 is attached to the upper end of the outer tube 1, and at the same time, the loading device 5 applies an upward pushing force to the outer tube 1, and at the same time, the reaction force of the pushing up force is applied as a downward force to the inner tube 2. Kake,
A displacement meter 2 measures the amount of upward movement of the outer pipe 1 and the amount of movement of the tip of the inner pipe 2 into the ground 4.
8 and 35. However, according to this lever method, by measuring the amount of upward movement of the outer pipe 1, the supporting force of the pile circumferential surface of the cast-in-place concrete pile can be determined, and on the other hand, the amount of downward movement of the inner pipe 2 (i.e., the amount of downward movement of the inner pipe 2) can be determined. By measuring the amount of settlement at the bottom of the pile, the bearing capacity of the tip of the cast-in-place concrete pile can be determined.
Here, the concrete 7 is formed in the gap above the large diameter part 6 at the bottom of the outer tube 1, so the concrete 7
An upward force is applied to the concrete 7 through the adhesion force between the concrete 7 and the outer pipe 1 and the large diameter portion 6, and as a result, the peripheral surface resistance of the concrete 7 that becomes the cast-in-place pile can be measured.

By the way, when inserting the loading pipe 3 shown in FIG. The loading pipe 5 is inserted while draining the muddy water from the drilling to the outside from the opening at the bottom, and after insertion, the mortar is pumped using the pipe 46 and the tip loading plate 40 is You may also try hardening the roots below.

In addition, in the above-mentioned method of the present invention, when performing a loading test on a cast-in-place expanded bottom pile, the bottom of the dug hole 9 is expanded in advance and concrete 7 is poured to form the expanded bottom portion 48, and then the bottom of the dug hole 9 is expanded. The loading pipe 3 is inserted into the outer pipe 1, and concrete 7 is poured into the cavity in the borehole 9 on the outer periphery of the outer pipe 1 above the large diameter part 6 of the outer pipe 1 using a tremie pipe or the like. After the concrete 7 has hardened, the outer pipe 1 is
A loading device 5 is attached to the upper end, and at the same time the loading device 5 applies an upward pushing force to the outer tube 1, a reaction force of the pushing up force is applied to the inner tube 2 as a pushing force, and the outer tube 1 is pushed upward. The displacement meter 2 measures the amount of upward movement and the amount of movement of the inner pipe 2 into the ground 4.
8 and 35 (see Figure 11).

In addition, in the case of each of the cast-in-place piles mentioned above, only the upper body 2a of the inner pipe 2 is pulled up and recovered after the test is completed, and when the loading pipe 3 is used as the main pile after the test is completed, the large diameter part 6 is The lower end of the slide part 41 and the lower tip loading plate 40 of the large diameter lower part 8 are separated, creating a gap, but the injection pipe 26 is inserted into this gap.
This is used to fill the pile with solidified material such as mortar to form the actual pile.

In addition, when testing the driven piles in each of the above cases, a reinforcing bar cage is placed in the cavity in the hole 9 on the outer periphery of the outer tube 1 above the large diameter portion 6 of the outer tube 1, and concrete is poured into the gap using a tremie pipe or the like. 7, and after the concrete 7 hardens, the loading device 5 applies an upward pushing force to the outer pipe 1, and at the same time, the reaction force of the pushing up force is applied as a downward force to the inner pipe 2. It is also possible to measure the amount of movement of the lower end. In this case, it will be possible to perform a loading test on cast-in-place piles containing reinforcing bar cages.
Furthermore, after the test is completed, the piles can be made into actual piles with reinforcing bar cages. If the inner tube 2 is divided into the upper body 2a and the lower body 2b as in each of the above embodiments, various types of the lower body 2b can be selected depending on the conditions of the ground 4 and the like.

〔Effect of the invention〕

In the present invention, as described above, the first aspect of the present invention is
In each of the inventions 1 to 4, a loading tube is constructed by movably inserting an inner tube into the outer tube so that the lower part thereof projects downward from the outer tube, and a loading device is used to load the outer tube. This is because it applies an upward force to the inner tube and at the same time applies the reaction force of the upward force to the inner tube as a downward force.
It does not require reaction piles, large-scale reaction devices, or reaction beams as in conventional reaction pile systems, nor does it require large actual loads compared to conventional actual loading systems. The structure has become simpler, and the test construction period can be shortened.The period from the time the test pile is driven until the load test results are obtained can be greatly shortened, and the construction of the superstructure can be completed quickly and construction costs can be reduced. This will result in savings. Moreover, by examining the amount of push-in movement of the inner pipe and the amount of push-up movement of the outer pipe, the tip bearing capacity of the pile and the bearing capacity of the pile's peripheral surface can be determined separately, allowing economical design of piles and testing. This makes it easy to deal with cases where the supporting capacity is insufficient depending on the result. In addition to this, in the second invention, concrete is poured into the cavity in the hole on the outer periphery of the outer pipe above the large diameter part of the outer pipe, and after the concrete hardens, it is placed in the outer pipe by a loading device. At the same time as an upward pushing force is applied, the reaction force of the pushing force is applied as a downward force to the inner pipe, making it possible to perform loading tests on cast-in-place piles.
Furthermore, in the third invention, the lower part of the inner tube has the same diameter as the outer tube to form a large diameter lower part, and the large diameter lower part projects downward from the lower end of the outer tube, so that
It has been possible to provide a device with a simple configuration capable of carrying out loading tests on ready-made piles.Furthermore, in the fourth invention, the lower part of the outer pipe is the large diameter part, and the lower part of the inner pipe is the outer pipe. The large-diameter lower part has approximately the same diameter as the lower large-diameter part of the outer tube, and this large-diameter lower part protrudes downward from the lower end of the outer tube. It is something that can be done.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an embodiment of the device of the present invention, FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1, FIG. 3 is a cross-sectional view taken along line B-B in FIG. 1, and FIG. FIG. 1 is a sectional view taken along line C-C, FIG. 5 is a front view of another embodiment showing the connection between the upper body and the lower body, FIG. 6 is a sectional view of another device of the present invention, and FIG. 7 is a sectional view taken along line D-D in Figure 6, and Figure 8.
The figure is a cross-sectional view taken along the line E-E in Figure 6, and Figure 9 is a cross-sectional view taken along the line E-E in Figure 6.
-F line sectional view, Figures 10a, b, and c are explanatory diagrams showing the order of insertion of the loading pipes into the ground, Figure 11 is a sectional view of an example in the case of a cast-in-place expanded bottom pile, Figure 1
Figure 2 is a cross-sectional view of a conventional example, where 1 is an outer pipe, 2 is an inner pipe, 3 is a loading pipe, 4 is a ground,
5 is a loading device, 6 is a large diameter part, 7 is concrete,
8 is a large-diameter lower part, and 9 is a borehole.

Claims (1)

[Scope of Claims] 1. A loading pipe configured by moving the inner pipe into the outer pipe so that the lower part protrudes downward from the outer pipe is inserted into the ground, and the outer pipe is pushed upward by the loading device. Pile loading characterized by applying a force and simultaneously applying the reaction force of the pushing up force to the inner pipe as a pushing down force, and checking the amount of upward movement of the outer pipe and the amount of pushing movement of the inner pipe into the ground. Test method. 2. Insert the loading pipe, which consists of a movable inner pipe so that the lower part protrudes downward from the outer pipe, and a large diameter part at the lower part of the outer pipe, into a hole formed in the ground, and Concrete is placed in the cavity in the borehole on the outer periphery of the outer pipe above the large diameter part of the pipe, and after the concrete hardens, a loading device applies an upward pushing force to the outer pipe and at the same time a reaction force of the pushing up force is applied. A pile loading test method characterized by applying a downward force to the inner pipe and examining the amount of upward movement of the outer pipe and the amount of movement of the inner pipe into the ground. 3. Insert the inner tube movably into the outer tube, make the lower part of the inner tube the same diameter as the outer tube to form a large diameter lower part, and make the large diameter lower part protrude downward from the lower end of the outer tube,
A pile loading test device comprising a loading device for applying an upward pushing force to an outer tube and simultaneously applying a reaction force of the pushing force to an inner tube as a downward force. 4. Insert the inner tube movably into the outer tube, make the lower part of the outer tube a large diameter part, make the lower part of the inner pipe approximately the same diameter as the large diameter part of the lower part of the outer pipe, and configure the large diameter lower part. A loading device is provided to project the lower diameter portion downward from the lower end of the outer tube and apply an upward pushing force to the outer tube and at the same time apply a reaction force of the pushing force to the inner tube as a downward force. Features: Pile loading test equipment.