JPS6225813B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to concrete piles.

Conventionally known foundation piles for structures can be roughly divided into concrete RC piles, PC piles,
In addition, there are steel pipe piles and composite piles of steel pipes and concrete. RC out of concrete pile
Piles have been used in large quantities for a long time because they are easy to manufacture and the advantage of concrete's high compressive force can be effectively utilized as the supporting force of the pile. However, while this RC pile has an advantage in terms of supporting capacity, it has the disadvantage of being weak against bending and prone to cracks on the concrete surface. Of course, when cracks occur, buckling becomes more likely to occur in those areas, and the internal reinforcement corrodes due to the intrusion of groundwater, eventually causing the pile to lose its function.

In order to compensate for the disadvantage that RC piles tend to crack easily, PC piles, which apply prestress to concrete using the tension of steel wires, were later proposed, but the advantage of PC piles is that they are less prone to cracking. On the other hand, since the concrete is only given tension by the steel wire and lacks so-called viscous force, if a bending moment greater than the specified value is applied, the prestressed steel wire will break, meaning that prestress is applied. There is a problem in that it disappears.

In addition, as a method other than PC piles to prevent concrete cracking, a large number of flat steel members are arranged radially on the surface of the pile body so that the end surface touches the outer circumferential surface or has a small overlap. However, concrete piles are also known in which these flat steel materials are used to prevent cracks on the surface of the pile body (Japanese Patent Publication No. 49247/1983). However, although this pile is intended to strengthen the crack resistance of the pile body surface due to horizontal loads by using the strong axis direction of the flat steel members, the outer end surface of each flat steel member is almost exposed near the pile body surface. Because the connection between each steel material is weak,
Under vertical loads, the flat steel material easily bends in the direction of its weak axis, resulting in a lack of adhesion between the concrete and the steel material, which easily causes cracks.

The present invention aims to provide a new type of concrete pile that can solve the problems of RC piles and PC piles as described above.

The concrete pile according to the present invention basically depends on the type of PC pile, but it uses a PC steel material with a flat steel cross section as the PC steel material, and the flat steel material is given tension and is simply concreted. It not only has the meaning of compensating for the tensile force of
A new type of concrete pile that is constructed to serve as concrete reinforcing reinforcement to fully demonstrate its viscosity as a pile, thereby providing sufficient horizontal bearing capacity required as a pile function, even though it is a PC pile. The purpose is to provide concrete piles.

Next, the concrete pile of the present invention will be explained with reference to illustrated embodiments. Figure 1 is a cross-sectional view showing the structure of the pile body cross section. In the concrete layer 3 cross section of the pile body 1 centrifugally formed with concrete, a PC steel material 2 with many cross sections formed into a flat steel shape is attached to the pile shaft. They are arranged at predetermined intervals as reinforcing bars along the direction.
These prestressed steel materials 2 are formed by hot rolling killed steel and stretching or other methods, similar to conventional prestressed concrete prestressed concrete steel bars. Although it differs from the conventional round bar shape in that it is molded into a steel shape,
Various mechanical properties such as yield point load and tensile load are the same as conventional PC steel bars. The cross-sectional shape may be a trapezoidal one in which the bottom end 4 is thicker than the top end 5, as shown in FIG.

Both ends 12 of these PC steel materials 2 are fixed by welding to the fixed end plates 6 that constitute both ends of the pile in the process before forming.
The PC steel materials 2 are arranged so that the center line L along the longitudinal direction of each cross section is parallel to the radial direction of the pile cross section, that is, in a radial manner with respect to the center of the pile as a whole. In addition, when the plate thicknesses at both ends are made different as in the case of the PC steel material 2 shown in FIG. 3, it is desirable to arrange the plates so that the thicker bottom end 4 is located on the outer circumferential side of the concrete layer 3. Also the third
As shown in the figure, the bottom end 4 of each PC steel material 2
The tip end surface of the pile should be formed into an arc shape in order to prevent an unfilled part of concrete from forming on the back side of the bottom end 4 when viewed from the center of the pile cross section when the concrete layer 3 is compacted by centrifugal force. is desirable.

After these PC steel members 2 are temporarily fixed to each other by the fixed end plates 6 at both ends of the piles so as to maintain a radial arrangement state as described above, the PC steel members 2 are
A spiral reinforcement 7 is wound around the outside of the steel material 2, and the outer end of each PC steel material 2 is firmly held and fixed by the spiral reinforcement 7. Further, the PC steel material 2 and the spiral reinforcement 7 are arranged so as to be sufficiently wrapped inside the concrete layer 3 of the cross section of the pile body.

The tension force is applied to each PC steel material 2 on the fixed end plate 6 as shown in FIG.
Tension bolts 9 are inserted into the locking holes 8 opened between the welded parts.
This is done by attaching the tension bolts 9 and pulling the tension bolts 9 using jacks (not shown). In addition, when applying tension to the prestressed steel material 2, a spiral reinforcement 7 is wound and fixed in advance around the outer periphery of the prestressed steel material 2, but due to its shape characteristics, the spiral reinforcement 7
Since it does not cause any hindrance to the elongation of the PC steel material 2,
Tension can be applied to the PC steel material 2 without any problem.

As described above, the concrete pile according to the present invention has a large number of cross sections in the concrete layer 3 of the concrete pile body 1 having a flat steel shape or a trapezoidal cross section.
By arranging the prestressed steel materials 2 and applying tension to these prestressed steel materials 2, the concrete pile body 1 will be able to resist cracking by transmitting the tension of these prestressed steel materials 2 after the concrete layer 3 has hardened. This allows the strong PC pile to perform its original functions.

In addition, the cross section of each PC steel material 2 is a flat steel shape or a trapezoid, which is different from the conventional round bar shape, and the
Plate width W of steel material 2 within the cross section of concrete layer 3
Since the planes forming the pile are arranged radially parallel to the radial direction of the pile cross section and spaced apart from each other, when a horizontal force is applied from the direction of the arrow as shown in Figure 1, The PC steel members 2a and 2b in the parts parallel to the direction of the horizontal force exhibit particularly strong resistance against the horizontal force, and all the PC steel members have strong bending strength against the entire pile. It can give elasticity.

Note that when the prestressing steel material 2 is shaped like a trapezoid and the thick bottom end 4 is located on the outer circumferential side of the concrete layer 3 as in the embodiment shown in FIG. Because it is located on the outside of the concrete layer 3, that is, on the outer peripheral side of the concrete layer 3, and because both side surfaces are tapered surfaces at equal angles to the center line L, the cross-sectional strength against bending parallel to the center line L is high. Because of this, it exhibits an extremely strong resistance against the horizontal force.

In addition, this concrete pile uses a flat steel prestressing steel material 2 with a rectangular or trapezoidal cross section as the shaft reinforcing material, and its outer periphery is fixed in a radial arrangement state by the spiral reinforcing bars 7. With prestress introduced into the concrete layer 3 by applying tension to the PC steel material 2,
The radial arrangement state of each PC steel material 2 is not deformed.

In addition, by applying a consolidation effect due to prestress to the concrete between each prestressing steel material 2, the concrete between these prestressing steel materials 2 is not only in the axial direction of the pile but also in the horizontal direction with respect to the side surface of each prestressing steel material 2. Consolidation is also applied to the concrete, and due to the consolidation effect of concrete, each PC
The radial arrangement of the steel materials 2 becomes even stronger.

Furthermore, as the concrete layer between each prestressing steel material 2 is subjected to the consolidation action due to prestress, not only chemical adhesion force but also physical adhesion force is added between the concrete layer and each prestressing steel material, and this prestress By introducing this, the effect of preventing cracks on the surface can be ensured. Therefore,
In this concrete pile, the above-mentioned state of introducing prestress is combined with the viscosity of the pile body provided by the prestressing steel material 2, which increases the toughness of the pile compared to a conventional simple prestressing pile. It has the advantage that it can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of the concrete pile cross section according to the present invention, and FIG.
3 is a sectional view showing the structure of a pile cross section in another embodiment, and FIG. 4 is a partial sectional view showing an embodiment for imparting tension to prestressing steel. In the figure, 1: pile body, 2: PC steel material, 3: concrete layer, 4: bottom end of steel material, 5: top end of steel material,
6: Fixed end plate, 7: Spiral muscle, 8: Locking hole, 9: Tension bolt.

Claims (1)

[Claims] 1 Between both fixed end plates of the pile end, PC steel materials with a flat steel cross section or a trapezoidal cross section are arranged at intervals so that the center line along the longitudinal direction of each cross section is parallel to the radial direction of the pile cross section. Then, the outer peripheries of these prestressed steel materials with a rectangular cross section are tied together with spiral reinforcement so that the above arrangement is fixed, and the prestressed steel materials are placed as axial main reinforcing materials wrapped inside the concrete of the pile body cross section. A concrete pile characterized in that the tension applied to the prestressing steel material is introduced as prestress into the concrete pile body.