JPH01268921A - Connecting structure for base pile and superstructure - Google Patents

Abstract

PURPOSE:To meet the design of pile without application of horizontal force and bending moment to the top of pile by a method in which an airtight bag packed with compressed air is interposed between the top of a base pile and a superstructure. CONSTITUTION:Pressure support plates 4 and 4' are fixed through anchor bolts 3 and 3' between the upside of the footing or base slab 2 of a superstructure and the downside of a base pile 1. An airtight bag 7 of rubber or synthetic resin, packed with compressed air, is set between the plates 4 and 4'. Also, a ringed laminate material formed by alternately laminating and bonding metal pieces 8 and rubber or resin pieces 9 is placed on the periphery of the bag 7 between the plates 4 and 4'. Springs 11 are thrust through the holes 10 of the laminate material and its upper and lower both ends are fixed to the plates 4 and 4'.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a connection structure between the head of a ready-made pile used as a foundation pile and a cast-in-place pile and a superstructure.

(Prior Art) Conventionally, the pile head of a foundation pile and the footing or foundation slab of a superstructure are rigidly connected directly into one body.

(Problem A to be Solved by the Invention) Vertical force, horizontal force, and bending moment generally act on the foundation pile from the superstructure to the pile head. Therefore, pile foundations must be safe against these external forces, and are designed so that the bearing capacity determined from the ground, the stress generated in the pile, and the pile tl displacement are below the allowable values, and the pile cross-sectional area and amount of reinforcing bars are can be determined. Particularly in the event of an earthquake, failure of the foundation structure can cause fatal damage to the superstructure.

Furthermore, since the footing connected to the antibody is generally a rigid footing, the thickness of the footing becomes large, which is extremely uneconomical.

Furthermore, in reality, a fixed end moment is generated at the pile cap due to the connection with the superstructure, but in conventional design and construction, this is dealt with by increasing the rigidity of the foundation beams, foundation slabs, etc. As a result, the cross sections of foundation beams and foundation slabs become excessively large, making them uneconomical.

The present invention was proposed in view of the problems of the prior art, and its purpose is to reduce the horizontal force on the pile head.
The object of the present invention is to provide a connection structure between a foundation pile and a superstructure, which allows for advantageous pile design without applying a bending moment.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the connection structure between a foundation pile and a superstructure according to the present invention provides a connection structure between the superstructure and the head of the foundation pile. It is constructed by interposing an airtight bag body filled with pressurized air.

(Function) As described above, in the present invention, an airtight bag body containing pressurized air is interposed between the pile head of the foundation pile and the structure, and Since the upper structure is supported on the upper structure, the vertical force from the upper structure is supported by the pressure inside the bag, and when horizontal force or bending stress from the upper structure is applied, the pressure inside the bag is The air layer absorbs the stress and deformation and does not transmit it to the head.

(Example) The present invention will be described below with reference to the illustrated embodiments.

(1) is the foundation pile, (2) is the footing or MliJ slab of the superstructure, and the footing or foundation slab (
2) The upper surface and the lower surface of the foundation pile (1) are connected to the bearing plate (
4) (4') is fixed.

In the figure, (5) (5') are anchor play 1・, (6) (
6') is a nut for fastening the anchor bolt (3) (3') to the anchor brake (505').

An airtight bag body (7) made of rubber, synthetic resin, etc. and filled with pressurized air is interposed between the opposing pair of bearing plates (4) (4'), and the bag body (7) The superstructure is supported on the pile head via.

On the outer periphery of the airtight bag (7), surrounding the bag (7), is a ring-shaped laminate formed by alternately laminating metal pieces (8) and rubber or resin pieces (9). , the bearing plate (4
) (4”).

Vertical through holes (10) are bored at required locations in the ring-shaped laminate, and spring materials (11) are passed through each of the vertical through holes (10), with the upper and lower ends of each of the bearing plates f4) ( 4'), and the spring material (11) applies a frictional force between the metal pieces (8) of the laminate so that the upper structure does not horizontally displace at all times. Also, even if the pressure of the bag body (7) decreases, the laminate will not absorb the vertical force! Designed to allow U.

Furthermore, the pressure of the bag (7) is constantly monitored by an external monitor (12).
) is monitored and controlled. (13) in the figure is the air injection/monitoring piping.

Since the illustrated embodiment is constructed as described above, the horizontal force during an earthquake is handled by the horizontal displacement of the bag body (7), and the bending moment caused by this causes the member angle to be Processed by expanding the spaces between the laminated metal pieces (8) in the foundation pile (
Neither horizontal force nor bending moment acts on 1), and only vertical force acts on the foundation pile (11).

As a design example to prevent horizontal force and bending stress from acting on the foundation pile (1), it is possible to support the superstructure on the foundation pile (1) with rollers, but when bending deformation is applied, 1 There is a problem that stress is concentrated at a point. On the other hand, according to the illustrated embodiment, the pressurized air within the bag body (7) can follow any deformation, and when bending deformation is applied, stress will not be concentrated at one point. Vertical force is supported by air pressure, and when bending stress or horizontal force is applied, the air layer inside the bag absorbs the stress and deformation, preventing it from being transmitted to the pile head.

Next, the horizontal displacement of the upper structure is always controlled by the spring material (
Here is an example of a design that is inhibited by 11).

As shown in Figure 3, an axial force of 250 t is applied to the pile head, resulting in a relative deformation angle of θ-2,0×10-3 rad (the value of θ is based on the Architectural Institute of Japan's Architectural Foundation Design Guidelines). Assume.

Due to the uneven settlement (relative displacement), an axial force P acts on the laminated material on a straight line connecting the pile heads. The force of this P is P=250X5inθ=250X(sin 2.0
xlO-')-8.7kg Therefore, in order to prevent horizontal displacement, the spring material (1
The force N applied to 1) is 8,7<μ.・N, the coefficient of static friction between the laminated layers μ. By setting (≠0), the spring material (
11) is determined.

(Effects of the Invention) According to the present invention, an airtight bag body containing pressurized air is interposed between the pile head of the foundation pile and the superstructure,
By supporting the superstructure on the pile head through the bag, no horizontal force or bending moment acts on the pile head, and therefore only vertical force is transmitted to the foundation pile, simplifying the design. The pile cross-sectional area and amount of reinforcing bars are reduced, and the fixed end moment does not occur at the pile head unlike in conventional structures, so the cross-sections of foundation beams and foundation slabs can be reduced compared to conventional structures. Furthermore, by monitoring and controlling the air pressure inside the bag, the function of the connecting structure can be maintained at all times.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of a connection structure between a foundation pile and a superstructure according to the present invention, and FIG. 2 is a cross-sectional plan view thereof.
FIG. 3 is an explanatory diagram showing a design example of a spring material. (1)...Foundation pile, (2)...Footing or foundation slab of the superstructure, (7)...Airtight bag. Agent: Patent attorney: Shige Okamoto (2 persons)

Claims (1)

[Claims] A connection structure between a foundation pile and a superstructure, characterized by interposing an airtight bag containing pressurized air between the pile head of the foundation pile and the superstructure.