JPH0243848B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a method of integrating footings with underground structures such as piles and underground continuous walls, and more specifically, the present invention relates to a method of integrating footings with underground structures such as piles and underground continuous walls. This relates to a construction method that integrates a buried underground structure with a footing formed by pouring concrete.

Conventionally, in the construction method of integrating the so-called PC pile and footing, for example, by burying prestressing steel in concrete in a tensioned state and introducing prestress force into the concrete pile, the PC pile is driven into the ground. The upper end was cut off together with the prestressing steel material, and the pile head was slightly exposed above the ground before being joined to the footing.

However, when the top end of the pile is cut off in this way, the prestress at the pile head is reduced, and the area near the joint with the footing does not become a PC pile.

For this reason, a method of reinforcing the portion where the prestress has decreased, as shown in FIG. 1 or 2, has been proposed.

In other words, in the construction method shown in Fig. 1, the PC steel material 1
A PC pile 14 made of 0 and concrete 12 is driven into the ground 16 to a predetermined depth, and the pile head 18 is cut off to a state slightly protruding above the ground.
A hole 20 of a predetermined depth is excavated around the outer periphery of the PC pile 14, and a part of reinforcing reinforcing bar 22 is inserted into this hole 20 and then built into the hole 20 and the filling concrete part 21. After pouring concrete, the footing 24 is finished with concrete and integrated.

In addition, in the construction method shown in FIG. 2, the steps from driving the PC pile 14 to cutting off the pile head 18 are similar to the construction method described above, but after this, reinforcing reinforcing steel is inserted into the hole 20 inside the PC pile 14. 22 is partially inserted, and after pouring concrete for the intermediate concrete portion 21, the footing 24 is finished with concrete and integrated.

However, in this construction method,
Although the joint state between the PC pile and the footing 24 is reinforced to some extent, the reduction in prestress at the pile head 18 is not recovered, and the fundamental problem has not been solved.

In addition, as mentioned above, drilling holes 20 on the outer periphery or inside of the PC pile 14 and erecting reinforcing bars 22 are disadvantageous in that they become an obstacle to shortening the construction period and increase costs. It had the following characteristics.

This invention was made to focus on the drawbacks of the conventional method as described above and to solve them.
The purpose of this is to have an economical advantage in that it can be constructed without adding reinforcement members or excavation work, and also to be able to recover the decrease in prestress even if the head of the PC pile is cut off.
The purpose of this invention is to provide a construction method for integrating footings with underground structures that can strengthen the connection between PC piles, underground continuous walls, and footings.

In order to achieve the above object, this invention has the following features. In a construction method that integrates a footing with an underground structure consisting of prestressed concrete piles, cast-in-place piles, or underground continuous walls in which steel materials for prestressed concrete are buried, the steel materials for prestressed concrete are removed from the base of the underground structure. projecting upward, forming the footing by pouring concrete around the outer periphery of the projecting portion, and making the end of the steel material slightly project from the upper end of the footing;
and by forming an anchoring part on the outer periphery of the steel material, and applying a prestress force by tensioning the steel material using a fixing tool within the anchoring part, thereby integrating the underground structure and the footing. Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

In the following explanation, parts that are the same as or equivalent to the conventional construction method described above will be referred to as
The same reference numerals are given.

3 to 6 show an embodiment of the method of integrating an underground structure and a footing according to the present invention.

The integrated construction method shown in the figure is suitable for underground structures.
This figure shows a case in which the PC pile 14 and the footing 24 are integrated.

In the integrated construction method, first, multiple pieces of PC steel 10 were buried under tension in concrete 12.
A PC pile 14 is driven into the ground 16 to a predetermined depth.

At this time, the upper end 26 of the PC pile 14 exposed above the ground is cut off to leave the pile head 18 slightly protruding above the ground, which is the same as in the conventional construction method (see Figures 3 and 4). .

Then, the footing 24 and PC pile 1 shown in the same figure
The integrated construction method with 4 has the following features compared to the conventional construction method described above.

That is, the upper end 26 of the frame of the PC pile 14
When cutting off the steel material 10 for PC,
Without cutting, the protruding portion 28 is left as it is as shown in FIG. 4, and concrete is poured around the outer periphery of this portion to form the footing 24.

In this case, the tip of the protruding portion 28 is made to protrude from the upper end surface of the formed footing 24, and a concave fixing portion 30 is formed on the outer periphery of the protruding portion 28 (see FIG. 5).

In addition, at this time, the concrete 12 is placed in a state in which a screw is previously installed around the tip side of the protruding portion 28 of the steel material 10 for PC, which matches the fixing device 32 described later.
If it is buried inside, the fixing work will be easier.

In addition, the thickness of the footing 24 to be formed in advance, the length of the PC pile 14 buried in the ground 16, the length of the pile head 18 to be protruded, etc. are calculated, and a predetermined length of the PC pile is placed on the upper end of the PC pile 14. Projecting portion 2 of steel material 10
It is also possible to perform construction with 8 formed.
This eliminates the need for the above-mentioned cut-off operation, which is also economically advantageous.

After this, the fixing tool 32 is inserted into the fixing section 30 and the prestressing steel material 10 is tensed, thereby introducing a prestress force between the pile head 18 and the footing 24, and thereby tightening the PC pile 14. The footing 24 is integrated with the footing 24 (see FIG. 6).

Introducing tension force into the PC steel material 10 can be done before the concrete placed in the footing 24 is completely solidified.
If necessary, it is also possible to cover the protruding portion 28 with a sheath made of steel pipe or the like and carry out the process after the poured concrete has solidified.

Now, with the above configuration, the footing 24 and
In the construction method of integrating the PC pile 14, even if the prestress of the pile head 18 is reduced by cutting off the upper end 26 of the PC pile 14 as in the conventional construction method described above, the PC steel material 10 is not tensed again. As a result, the prestress is recovered and the PC pile 14
Since prestress is introduced into the joint between the footing 24 and the footing 24, the joint is much stronger than the conventional reinforcing reinforcing bar 22, and the problems associated with cut-off can be fundamentally solved. .

Further, the configuration for exhibiting the above-mentioned effects includes the formation of the fixing section 30 and the fixing tool 3.
The addition of 2 is relatively simple, and it also has economic advantages such as shortening the construction period and reducing costs.

FIG. 7 shows a second embodiment of the present invention, and to explain only its features, it is different from the first embodiment in that it is buried in advance by cutting off the upper end 26 of the PC pile 14. Whereas the upper side of the PC pile 14 is exposed to form the protruding portion 28, in this embodiment, the outer periphery of the PC steel material 10 is
One end is buried as a dead anchor part 36,
A relatively short steel material 33 for connecting PC is provided so that the other end thereof becomes the protrusion 28 .

Even in the case of a PC pile with such a configuration, it is driven into the ground 16 until the pile head 18 is slightly exposed, a footing 24 is formed on the top, and a fixing device 32 is used for the connecting PC steel material 33. By applying pre-stress by applying tension, the above-mentioned effects can be achieved.

FIG. 8 shows a third embodiment of the present invention. To explain only its features, both the first and second embodiments are constructed by driving an existing PC pile 14 into the ground 16. In this embodiment, the underground structure is a so-called cast-in-place pile 3, which is formed by excavating a vertical hole at the construction site and pouring concrete into the vertical hole.
This is applied to 4.

As shown in the figure, in this embodiment, the prestressing steel material 10 to be buried in the cast-in-place pile 34 is placed in advance so as to protrude from the pile head 18.
This protruding portion becomes the protruding portion 28,
In other respects, integration with the footing portion 24 is performed in the same steps as in the first embodiment.

Further, FIG. 9 shows a fourth embodiment of the present invention.

The integration method shown in the figure is applied to the case of integrating the footing 24 and an underground continuous wall 35 as an underground structure. The lower end of the PC steel material 10 that has been buried in advance in the 35 is in a state where it is buried as a dead anchor part 36.

It goes without saying that even in the case where the lower end portion of the PC steel material 10 is made into the dead anchor portion 36 in advance, the effects described in the above-mentioned embodiments can be exhibited.

As described above, according to the method of integrating an underground structure and a footing according to the present invention, it is possible to recover from the decrease in prestress caused by cut-off of a PC pile, and also to strengthen the connection between the underground structure and the footing. can be made to become

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are cross-sectional views showing a prestressed concrete pile and a footing formed by a conventional method. Figures 3 to 6 are cross-sectional views showing each step of the first embodiment of the method for integrating an underground structure and footing according to the present invention in order. 6
This is done in the order shown. Fig. 7 shows a second embodiment of the present invention, in which Fig. 7a is a sectional view and Fig. 7b is a top view of the pile. FIG. 8 is a sectional view showing a third embodiment in which the present invention is applied to the integration of a cast-in-place pile and a footing. FIG. 9 is a sectional view showing a fourth embodiment in which the present invention is applied to the integration of a footing with an underground continuous wall. 10... Steel material for PC, 12... Concrete,
14...PC pile, 16...underground, 18...pile head,
20... Hole, 22... Reinforcing bar, 24... Footing, 26... Upper end, 28... Projecting part,
30...Fixing part, 32...Fixing tool, 35...Underground continuous wall, 36...Detsut anchor part.

Claims (1)

[Scope of Claims] 1. In a construction method that integrates a footing with an underground structure consisting of prestressed concrete piles, cast-in-place piles, or underground continuous walls in which steel materials for prestressed concrete are embedded, the steel materials for prestressed concrete are buried in the ground. The footing is made to protrude upward from the frame of the medium structure, and the footing is formed by pouring concrete around the outer periphery of this protruding portion, and the end of the steel material is slightly protruded from the upper end of the footing, and the outer periphery of the steel material is made to protrude upward from the frame of the medium structure. An underground structure characterized in that an anchoring section is formed in the anchoring section, and a prestressing force is introduced by tensioning the steel material using an anchoring tool within the anchoring section, thereby integrating the underground structure and the footing. A construction method that integrates the structure and footing. 2. In the construction method described in claim 1,
A method for integrating an underground structure and a footing, characterized in that the protruding portion is formed by cutting off an upper end portion of the underground structure. 3. In the construction method described in claim 1,
An underground structure and a footing characterized in that a connecting prestressing steel material whose lower part is buried is provided near the upper end of the underground structure, and the connecting prestressing steel material serves as the protruding part. Integrated construction method. 4. In the construction method described in claim 1,
Integration of an underground structure and a footing, characterized in that the upper end of the steel material for prestressed concrete is arranged in advance in a state that projects upward from the upper end of the underground structure, and this part is used as the projecting part. Chemical method.