JPS6151096B2 - - 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, although this RC pile has an advantage in terms of supporting capacity, it has the disadvantage of being weak against bending and prone to cracking on the concrete surface. Of course, when cracks occur, buckling is more likely to occur in that area, 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 of RC piles, which tend to crack easily, PC piles, which pre-stress the concrete, were later proposed, but PC piles have the advantage of being less prone to cracking. On the other hand, since the steel wire is under tension and lacks so-called viscosity, there is a problem in that if a bending moment larger than a predetermined value is applied, the prestressed steel wire will break and the prestressing will be meaningless.

On the other hand, there are also concrete piles in which flat steel materials are arranged radially on the surface of the pile body so that their end faces are in contact with the outer peripheral surface or have a small overlap, and these flat steel materials prevent cracks on the surface of the pile body. It is known (Japanese Patent Publication No. 52-49247) that this pile is designed to strengthen the crack resistance of the pile surface due to horizontal loads by using the strong axis direction of the flat steel materials. The problem is that the steel is bent in the direction of the weak axis, resulting in poor adhesion between the concrete and steel, which easily causes cracks.

In response to these problems with concrete piles, steel pipe piles have an advantage over concrete piles because they are elastic themselves and have sufficient horizontal force in addition to bearing capacity, but in addition to the problem of high cost, The problem is that when buried underground, corrosion occurs on the surface due to the influence of groundwater and acidic soil. The problems caused by this corrosion have recently received particular attention due to the phenomenon that stray currents grounded underground from various facilities in urban areas and railways electrolyze groundwater, accelerating the corrosion process. There is.

In addition, in steel pipe composite piles in which the inside of the steel pipe is filled with concrete, in addition to the corrosion problem mentioned above, in the pile cap cutting process after the pile driving work is completed, the outer steel pipe is first fused at high heat. The problem is that the crystalline structure of the inner concrete is destroyed by the thermal insulation, and at that stage the function as a composite pile filled with concrete is lost.

As a result of studying the problems of conventional concrete piles and the problems of steel pipe piles as described above, the present invention combines the advantages of concrete piles, especially PC piles, which are less susceptible to cracking and corrosion, and the elasticity of steel pipe piles. The purpose of the present invention is to provide a new type of foundation pile that can compensate for each other's shortcomings by combining the various advantages.

The foundation pile according to the present invention is basically a type of concrete pile, particularly a PC pile, for the purpose of preventing corrosion when buried underground. Of course, although the concrete pile of this invention is based on the type of PC pile, its properties are plastic and lack viscosity, so steel is used to compensate for the viscosity. However, the steel used in the concrete pile of the present invention is different from the steel material used in conventional concrete piles, which simply compensates for the tensile force of the concrete.
It is used for the purpose of obtaining sufficient horizontal force required as a pile function. A large number of flat steel plates such as strips are used as steel materials, but each flat steel plate has a problem in that the steel plane is parallel to the radial direction of the pile cross section in the axial direction within the cross section of the concrete pile body. are arranged by placing Therefore, when a horizontal force acts on the pile body, among the arranged flat bars, each of the flat bars oriented parallel to the direction in which the horizontal force acts exerts a strong resistance force against the horizontal force. It is to give it to the pile body. Of course, since the flat bars are arranged radially within the cross section of the pile body, they can exhibit the same resistance to horizontal forces from any direction within 360 degrees of the circumference of the pile body.

Next, the concrete pile of the present invention will be explained with reference to illustrated embodiments. FIG. 1 is a sectional view showing the structure of the pile body cross section, and the pile body 1 made of concrete 3
A large number of flat bars 2 are arranged at predetermined intervals as reinforcing members along the axial direction of the pile in the cross section of the pile. These flat bars 2 are different from the round rod shaft reinforcing bars in conventional concrete piles, and as the name suggests, the plate width W is the same as the wall thickness h.
It is a strip that has at least twice the number of
The respective planes are arranged in a direction parallel to the radial direction of the cross section of the pile, that is, in a radial manner with respect to the inside of the pile as a whole. As shown in FIG. 2, these flat bars 2 are arranged in a radial manner with a fixed end plate 4 at both ends of the pile, a ring reinforcement 6 arranged at the inner end of each flat bar 2, and an outer end of the flat bar 2. It is firmly held and fixed by the spiral muscle 7 wrapped around the
The reinforcement is arranged so as to be sufficiently wrapped inside the concrete 3 of the cross section of the pile body.

For example, as shown in FIG. 1, the arrangement of the flat bars 2 is such that two equally spaced flat bars 2 are evenly arranged with an isolation space twice that of the spacing between them. Inside, a PC steel wire 5 is arranged at an intermediate part between two adjacent flat bars 2,
Both ends of the PC steel wire 5 are fixed by fixed end plates 4. Note that the arrangement relationship between the flat bars 2 and the PC steel bars 5 is not limited to the arrangement shown in FIG. 1; for example, the flat bars 2 may be arranged at equal intervals as shown in FIG. A PC steel wire 5 is provided in the middle of the flat bars 2, 2 at equal intervals, and
The steel wires 5 may be arranged in a numerically uniform relationship. In addition, when arranging the flat bars 2 and PC steel wires 5 at equal intervals, each flat bar 2 and
As shown in FIG. 3, it is preferable that the PC steel wires 5 are arranged in an even number so that the flat steel wires 2 are arranged in positions facing each other.

In the concrete pile according to the present invention, as described above, a large number of flat bars 2 are arranged at intervals within the cross section of the concrete pile body 1 with their planes parallel to the radial direction of the pile cross section. When a horizontal force is applied from the direction of the arrow as shown in FIG. 1, the portions of the flat bars 2a and 2b that are oriented parallel to the direction of the horizontal force particularly resist the horizontal force. In addition, not only the flat bars 2a and 2b in the specific portions but also all the flat bars 2 exhibit elasticity as a whole, and although it is a concrete pile, it is possible to obtain a horizontal force comparable to that of a steel pipe pile.

In addition, in this concrete pile, prestress is introduced into the concrete by the PC steel wire 5 placed between the flat bars 2, but each flat bar 2 has ring reinforcements 6 at the inner end and spiral reinforcements 7 at the outer end. Since the radial arrangement state is maintained and fixed, even if prestress is introduced into the concrete between the flat bars 2,
The radial arrangement state of each flat bar 2 is not deformed. In addition, by applying a compressive action due to prestress to the concrete between each flat steel 2,
The concrete between the flat bars 2 is consolidated not only in the axial direction of the pile but also in the horizontal direction with respect to the plane of both flat bars 2, and the radial arrangement of each flat bar 2 is caused by the consolidation action of the concrete. becomes even stronger.

Furthermore, as the concrete between each of the flat bars 2 is subjected to the consolidation action due to prestress, not only chemical adhesion but also physical adhesion is added between the concrete 3 and each of the flat bars 2, and this prestress is introduced. This ensures the effect of preventing surface cracks. Therefore, in this concrete pile, the above-mentioned state of introducing prestress is combined with the viscosity as a pile body imparted by the flat steel 2, and the concrete pile has a higher performance as a pile than a conventional simple PC pile. It has the advantage of significantly improving toughness.

In addition, in this concrete pile, the steel materials arranged within the pile cross section are flat bars, and each flat bar is arranged radially with respect to the center of the pile, so when compacting concrete by centrifugal force, This also has the advantage that there is no unfilled part of concrete between the outer part of the flat steel, that is, between the flat steel and the matrix, and the steel and concrete can be synthesized without any problem.

Since the concrete pile according to the present invention has a steel part inside, it can obtain bending strength not found in conventional concrete piles, so it can be used not only as a pile but also as a pillar material for above-ground structures. It also has the advantage of being widely available.

[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.
FIG. 3 is a cross-sectional view showing the structure of a pile cross-section in another embodiment. In the figure, 1: pile body, 2: flat steel, 3: concrete, 4: fixed end plate, 5: PC steel wire, 6: ring reinforcement, 7: spiral reinforcement.

Claims (1)

[Claims] 1 A large number of flat bars are arranged at intervals so that their planes are parallel to the radial direction of the cross section of the pile, and the inner and outer ends of each of these flat bars are formed by ring reinforcements, spiral reinforcements, etc. as described above. These flat bars are tied together so that their arrangement is fixed, and each of these flat bars is placed so as to be wrapped inside the concrete of the cross section of the pile body as the main reinforcement in the axial direction, and is fixed between the fixed end plates of the flat bars at both ends of the pile. A concrete pile characterized in that a prestressing steel material is placed in an intermediate portion between the flat steels, and a prestress is applied to the pile concrete by the prestressing steel material.