JPS58185827A - Joining of head and footing of concrete pile - Google Patents

Abstract

PURPOSE:To prevent the breakage of the head of a pile to be caused by the earthquake by a method in which a fixing bar is vertically provided at the spherical top of the pile head, and concrete for footing is placed above the spherical face of the pile head so as to join the head and footing of the pile through only the fixing bar. CONSTITUTION:A spherical metal 4 having a fixing bar 3 erected at its top is fixed to the top plate 2 of the pile 1 penetrated into the ground, and then a frictional force-reducing treatment using asphalt, etc., is applied to the pile head S to form a frictional force-reduced layer (a). Then, concrete for footing 10 is placed above the pile head S to join the head S and the footing 10 through only the fixing bar 3. By this, the frictional force between the pile head S and the footing 10 is reduced by the layer (a) to form a pin-joint and thereby the relative movement between the pile head S and the footing 10 by horizontal force caused by earthquake is made possible and the load to a structure on the ground's surface is diffused over the whole area of the pile head S, thus preventing the local breakage of the pile head.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention proposes a method for connecting the pile cap and footing of a concrete pile, which is effective in preventing the pile head from being destroyed by horizontal force during an earthquake.

There are two ways to connect the pile cap and footing: one using l1411 knots and the other using pins.

When the pile cap and footing are rigidly connected, the horizontal force generated due to the relative movement between the ground and the above-ground structure during an earthquake causes
The largest bending moment acts on the pile head, but when a pin is used, no bending moment acts on the pile head, as shown in Figure 1 (b).

Therefore, in order to bring the bending moment of the pile head due to horizontal force during an earthquake to as close to zero as possible, it is desirable to bring the pile head condition close to a pin state. Regarding piles, a method for connecting pile caps and footings has not yet been established so that the pile cap conditions become a clear pin from the time the footing is completed.

For example, in the case of a foundation made of PC piles, even if the pile head is considered to be a pin in the design, the construction of the joint between the head and footing is
This is usually done by removing the concrete pile head to expose a large number of PC steel members buried at equal intervals in the circumferential direction of the concrete, and using these as anchoring bars for the footing.

In this method, the pile cap and footing are connected together! A is rather close to the size, and at least it is not a clear bin state at the time of completion of the footing change πj.

In the event of an earthquake, it is thought that the horizontal force is first resisted by the fixed hangings, and the balance gradually collapses, resulting in a pin state in terms of KJI, but at the time when this bin-hanging position is reached. Now, the pile head of Mr. Footing 1 has already been broken to #, and as a result, the specified bearing capacity cannot be obtained, and even though there is a difference in the culm (9), it is enough to cause a kind of uneven settlement. is assumed.

In addition, methods to prevent pile heads from being destroyed by horizontal forces during earthquakes include increasing the number of piles, increasing the pile diameter, or integrating piles 1IJ1 with cast-in-place concrete. Methods 4.1!4 have been proposed in the past, such as locally reinforcing the pile head by pouring concrete around the head, but none of these methods stiffen the pile head condition. This is a failure at the 4M point, which attempts to increase the horizontal strength of the pile head where the largest bending moment acts, and it goes without saying that it is disadvantageous in terms of construction costs.

Therefore, the present invention is designed to improve the condition of the pile head of a concrete pile by footing! - Pile heads and footings can be connected so that they form a clear bin from the time construction is completed, and while securing the specified bearing capacity, the pile heads can be prevented from being destroyed by horizontal forces during earthquakes, especially for above-ground structures. This method provides a method for connecting pile caps and footings that can effectively prevent local crushing of one side of the pile cap due to loads I. With the fixed shield reinforcement for the footing erected only at the apex of the spherical part, concrete for the footing was placed above the lower edge of the spherical part described in @IJ, and the pile cap and footing were removed. It is characterized by being connected only through the joints.

In addition, in the present invention, the footing is constructed at a position above the lower edge of the spherical portion, so that the footing and the pile head can be moved relative to each other without creating a #i hole as a structure of the footing paper or the pile head. 69. From this meaning, Bunten, which is located above the lower edge of the butterfly face part, is
Although it should be interpreted as a device, an example of the collar of the present invention will be explained briefly with reference to the drawings.

First, as shown in Part 2 (A), after inserting the PC pile 1, which is an example of a concrete pile, into the ground to a depth of 191 feet, the top surface of the PCC10 top plate 2 is formed in a spherical shape, and The hardware 4 on which seven fixed shield lines 3 are erected is fixed, and the spherical part S is made of asphalt q cloth, Teflon (trade name) recoating, and glass fiber impregnated with Teflon. Apply k-vibration force reduction treatment by covering with cloth or other methods. Tstd, 11ii, the friction force reduction layer in the second layer is removed. This rubbing force reduction treatment may be performed after the metal fittings 4 are solidified on the top plate 2.
As shown in Fig. 8, No. 4, the 0 marking hardware 4 has a hole 5 formed in the center and holes 6 formed at a predetermined pitch around the hole 5. It has...

Then, thread a constant WaS made of threaded reinforcing bar or threaded reinforcing bar into the hole 5 of the medium heat section, install it in a state where it is prevented from coming out with a pair of nuts 7... and washers 8, and then immerse it in the hole 6. Bolts 9 inserted into... are attached to the top plate 2.
(It is desirable to use the hole for fixing one end of the PC steel material to the top plate 2 or the hole for applying tensile force to the PCY4 material in the manufacturing process of II'i PC pile as is.) It is screwed in and attached as shown in Figure 2 U). As shown in the figure, the hole 5ri in the center is of a type having an inner ring surface of an inverted circular female fold, and the fixing b3 can swing within the gap between the inner surface of the hole 5 and the footrest 6. Although this configuration is very preferable in terms of suppressing constant *63 folding, it is not an essential configuration.

Next, as shown in FIG. Fixing duties 3
They are connected only through.

According to the above configuration, the pile cap and the footing 10 are connected only by the seven rods 7d, and the load force between the pile cap (that is, the dimension S) and the footing 10 is Oi
Since it was reduced by □j a in the I period, it becomes a bin connection, and the +1 pair movement between the footing 10 and the pile η due to the horizontal force at the time of the earth'IM is iJ function. Also, Kui 47 lk
Since l is equal to 1 and 1, when the relative movement described in J: occurs, the ground Md transmitted through the footing 10
Since the objects 4=i= are dispersed over the entire area of the spherical enclosing portion S and supported by a ladle or the like, local pressure plates can be prevented.

FIG. 5 shows another embodiment, in which a flat metal fitting 4' with fixed i#as erected is opened and opened on the top plate 2 of the PC pile 1.
The feature is that by forming the mortar tube 11 on the metal fittings 4', the upper circumference of the pile is formed into a ball rfr+down shape.

FIG. 6 shows another embodiment, which is characterized in that one side of the concrete pile itself is formed into a round shape.

In addition, as in each of the above-mentioned examples of interpolation, it is desirable to apply frictional force reduction treatment to the ball IU downside part to ensure a clear separation from the footing J, but this treatment is not necessarily required.

The present invention differs from the above-described structure in that the pile cap and the footing have seven parts.
Since they are connected only by the fixed shield 6 of the book, and the bottom of the footing is located above the lower edge of the spherical part of the pile top surface, it becomes a clear bottle connection from the time the footing finishes dyeing, and when the ground is ``S'' This method is effective in preventing destruction of the pile head due to horizontal force, and since the surface of the pile head is formed into a spherical shape, when relative movement between the pile head and the ground structure occurs during an earthquake, it is transmitted through the footing. The loading area of the above-ground structure is distributed and evenly supported over the entire area of the pile wall, which has the effect of preventing localized compression.

[Brief explanation of drawings]

Figure 1 (A) and (B) are bending moment diagrams, Figure 2)
. (B) is a vertical cross-sectional view showing an embodiment of the present invention; FIGS. 8181 and 4 are a side view and a plan view of the hardware; FIGS. 6 is a longitudinal sectional view. 1... Concrete pile (PC pile), 10-... Footing, S... Spherical method part. Figure 1 (d) (b) Figure 2 (a) Figure 2 (b) Figure 3 Figure 4 Figure 5 Figure 6 132-

Claims (1)

[Claims] Concrete pile jiff K-plane shaped like a sphere 1
1, and with a fixture for the footing erected only at the apex of this spherical section, pour concrete for the footing at a position above the lower edge of the spherical section, and connect the pile cap and footing. A method for connecting a pile cap and a footing of a concrete pile, characterized in that the pile cap and footing are connected only through N nil anchorage.