JPS6225812B2 - - 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 of RC piles, which tend to crack easily, PC piles, which apply prestress to concrete, were later proposed. However, while PC piles have the advantage of being less prone to cracking, steel wire There is a problem in that the prestress is applied to the prestressed wire, and since it lacks so-called viscosity, the prestressed wire will break if a bending moment larger than a predetermined value is applied, rendering the prestressing point meaningless.

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 in addition to the PC steel material, it can be used as a concrete reinforcing reinforcement material to fully exhibit the viscosity of the pile, like the shaft reinforcement material in conventional concrete piles. The purpose of this project is to use a special type of steel that can sufficiently provide the horizontal bearing capacity required as a function of the pile, rather than simply compensating for the tensile force of the concrete.

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 a pile body, in which a large number of tapered steel members 2 with trapezoidal cross sections are arranged in the axial direction of the pile within the cross section of the concrete layer 3 of the pile body 1 which is centrifugally formed with concrete. They are arranged at predetermined intervals as reinforcing bars. Unlike the round rod shaft reinforcing bars in conventional concrete piles, these shaped steel members 2 have a thickness at the bottom end 5 that is greater than the thickness at the top end 4, as shown in Figure 2 a, b, and c. A plate having a vertically elongated trapezoidal cross section with a plate width W larger than the plate thickness H is used. In addition, this shaped steel material 2 is oriented such that the bottom end 5, which has a large plate thickness, is located on the outer peripheral side of the concrete layer 3 in the cross section of the concrete layer 3, and the bottom end 5 and the top end 4
The center lines L connecting the piles are arranged in a direction parallel to the radial direction of the pile cross section, that is, in a radial direction with respect to the center of the pile as a whole. Furthermore, type steel material 2
Since it is preferable to arrange the bottom ends 5 in the direction of the outer periphery, the tip end surface of the bottom ends 5 of each shaped steel material 2 is formed in an arc shape, as shown in FIG. 2. The reason for this is to prevent an unfilled part of concrete from forming on the back side of the bottom end 5 when viewed from the center of the pile cross section when the concrete layer 3 is compacted by centrifugal force, and to prevent an unfilled part of concrete from forming on the back side of the bottom end 5 when viewed from the center of the pile cross section. This is to make it convenient for

As shown in FIG. 4, these shaped steel members 2 are fixed to each other by fixed end plates 6 at both ends of the piles so that the above-mentioned radial arrangement is maintained. Furthermore, as shown in FIG. 1, when arranging the shaped steel materials 2, the prestressed steel materials 7 are arranged between the respective shaped steel materials 2, so that the shaped steel materials 2 and the prestressed steel materials 7 are arranged.
A spiral reinforcement 8 is wrapped around the outside of the pile body, and the top end 4 of each type steel member 2 is firmly held and fixed by this spiral reinforcement 8, so that it is sufficiently wrapped inside the concrete layer 3 of the cross section of the pile body. Reinforcement is arranged.

FIG. 3 shows the structure of a pile cross-section according to another embodiment, in which a tapered steel material 2 with a triangular cross-section is used as the shaft reinforcing material. In the case of this shaped steel material 2 with a triangular cross section, it may be in the shape of a vertically elongated isosceles triangle where the plate width W is larger than the plate thickness H, as shown in Fig. 2c.
Alternatively, as shown in FIG. 2d, the bottom end 5 may be bulged in an arc shape so that the width W is larger than the plate thickness H, so that it has a substantially equilateral triangular shape. As with the case of the trapezoidal cross section, these shaped steel members 2 having a triangular cross section are also oriented such that the bottom end 5 is located on the outer circumferential side of the concrete layer 3, and the center line L connecting the bottom end 5 and the top end 4 is a pile. They are arranged in a direction parallel to the radial direction of the cross section. Furthermore, the bottom end 5 is formed into an arc shape and is reinforced together with the prestressing steel material 7, as in the case of the previous embodiment.

As described above, the concrete pile according to the present invention has a large number of shaped steel members 2 having trapezoidal or triangular cross sections in the cross section of the concrete layer 3 of the concrete pile body 1, with their center lines L parallel to the radial direction of the pile cross section. Because they are arranged at intervals, when a horizontal force is applied in the direction of the arrow as shown in Fig. 1, the parts 2a and 2b in the direction parallel to the horizontal force are particularly affected by the horizontal force. will be resisted. In this case, the shaped steel materials 2a and 2b
The cross section is vertically long along the center line L, and
When the bottom end 5 is located on the outer circumferential side of the concrete layer 3 as in the embodiment, the thickness of the bottom end 5 is large and the neutral axis P when viewed as a cross section is located outside the center line L, that is, the concrete layer 3 Furthermore, since both sides are tapered surfaces at equal angles to the center line L, it has strength against bending parallel to the center line L when viewed as a cross section. For this reason, it exhibits an extremely strong resistance against the horizontal force. Especially the third
When the shaped steel members 2 have a cross section close to an equilateral triangle as in the example shown in the figure, not only the shaped steel members 2a and 2b that directly resist the horizontal force but also almost all of the shaped steel members 2 are arranged. The horizontal force will be resisted depending on the cross-sectional shape at the position, and all the shaped steel materials can exhibit strong bending strength and elasticity as a whole pile.

In addition, in this concrete pile, prestress is introduced into the concrete by the PC steel material 7 placed between the tapered surface steel materials 2, but the bottom end 5 of each steel material 2 is Since the arrayed state is maintained and fixed, even if prestress is introduced into the concrete between the shaped steel members 2, the radial arrayed state of each shaped steel member 2 will not be deformed.

In addition, by applying a consolidation effect due to prestress to the concrete between each type steel 2,
The concrete between the shaped steel members 2 is subjected to a consolidation action not only in the axial direction of the pile but also in the horizontal direction with respect to the lateral direction of each shaped steel member 2, and due to the consolidation action of this concrete, the radial direction of each shaped steel member 2 is The arrangement becomes even stronger.

Furthermore, as the concrete layer between each type steel material 2 is subjected to the consolidation effect due to prestress, not only chemical adhesion force but also physical adhesion force is added between the concrete layer and each type 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 prestress introduced state as described above is combined with the viscosity as a pile body imparted by the shaped steel material 2, and the conventional simple
Compared to PC piles, it has the advantage of significantly improving the toughness of piles.

[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, Fig. 2 a, b, c, d
3 is a sectional view showing the configuration of a pile cross section in another embodiment, and FIG. 4 is a sectional view taken along the line - in FIG. 1. FIG. In the figure, 1: pile body, 2: shaped steel material, 3: concrete layer, 4: bottom end of shaped steel material, 5: top end of shaped steel material,
6: Fixed end, 7: PC steel material, 8: Spiral bar.

Claims (1)

[Claims] 1 A tapered surface type steel material with a large number of trapezoidal or triangular sections with a thicker bottom end is oriented so that the center line connecting the bottom end and the top end is parallel to the radial direction of the pile cross section, and the bottom end is made of concrete. These steel molds are arranged at intervals so as to be located on the outer circumferential side of the layer, and the bottom ends of each of these steel molds are tied together with spiral reinforcements so that the above arrangement is fixed. The steel material is placed as the main axial reinforcing material so that it is wrapped inside the concrete of the pile body cross section, and the PC steel material, which is fixed between the fixed end plates of the shaped steel materials at both ends of the pile, is placed in the middle between each of the shaped steel materials. A concrete pile characterized in that the prestressed concrete pile is prestressed by the prestressed steel material.