JPH11256569A - Foundation pile structure and composite pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a more rational foundation pile structure corresponding to subsoil conditions and the like by securing a certain degree of adhesion of an upper pile to a filler, while taking advantages of a merit of the foundation pile structure which uses composite piles. SOLUTION: Composite piles comprising a joint node pile 1 serving as a lower pile and a projected steel pipe pile 2 serving as an upper pile connected to the lower pile are sunk into a curing agent 6 such as soil cement which fills a borehole 5. A foundation pile structure serving as an embedded pile is formed by the curing of the curing agent 6. The joint node pile 1 has shanks 1a and joint node parts 1b formed alternately and has a large vertical supporting force. The projected steel pipe pile 2 has projections 2a, 2b formed on its inner or outer surface and provides, in addition to high bending stress as a steel pipe, a peripheral face supporting force through the adhesion between the projections 2a, 2b and the curing agent 6. When necessary, the projected steel pipe pile 2 and the joint node pile 1 are also filled with the curing agent 6 to enable further enhancement of bending resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heterogeneous connection pile formed by joining a nodal pile and a steel pipe pile with a projection, and a foundation pile structure using the heterogeneous connection pile.

[0002]

2. Description of the Related Art Conventionally, as a basic pile structure, a pile body in which a cylindrical pile having a higher bending strength than a node pile, such as a steel pipe pile and an SC pile (steel-pipe concrete composite pile), is joined to a mortar,
Some piles are constructed in excavation holes filled with hardening material such as cement milk to build strong piles against horizontal forces such as seismic force.

For example, Japanese Patent Publication No. 5-47685 discloses a steel pipe pile 12 added to an upper part of a ready-made concrete knot pile 11 composed of a shaft portion 11a and a knot portion 11b as shown in FIG. I have. This is because a steel pipe pile 12 having a large bending strength is used for the upper ground where a relatively large horizontal strength is required, and a knotted pile 11 having excellent peripheral bearing capacity is used for the lower ground. A simple foundation pile structure is obtained.

[0004] When the steel pipe pile 12 is added to the upper part of the joint pile 11, the diameter of the steel pipe pile 12 is adjusted to the shaft part 1 of the joint pile 11.
In many cases, the diameter is almost the same as the diameter of 1a or the node 11b.

[0005]

By the way, in the foundation pile structure based on the above-mentioned principle, the vertical bearing capacity of the cylindrical pile as the upper pile is smaller than that of the node pile as the lower pile, Alternatively, the adhesive force with a filler such as mortar is smaller than that of the nodal pile.

[0006] As a result, if the adhesive force of the cylindrical pile portion is too small, a sufficient peripheral friction force cannot be exerted. Conversely, in order to secure the adhesive force, it is necessary to increase the strength of the filler. There is a problem that costs increase.

[0007] That is, while there is an advantage as a heterogeneous connection pile, depending on the ground conditions and other conditions, there may be a drawback in that the performance as a pile differs greatly between the lower pile and the upper pile.

[0008] The present invention makes use of the advantages of the conventional foundation pile structure using different types of connection piles, and secures a certain amount of adhesive force with the filler also for the upper pile, so that it is more rational in accordance with ground conditions and the like. It is an object of the present invention to provide a foundation pile structure and a heterogeneous connection pile which provide a general structure and economy.

[0009]

According to a first aspect of the present invention, there is provided a foundation pile structure in which a steel pipe pile having a projection on an inner surface and / or an outer surface of a steel pipe is joined to an upper part of a nodal pile to form a heterogeneous connection pile. The heterogeneous connecting pile is formed and set in an excavation hole filled with a hardening material such as cement milk or mortar, and the hardening material is hardened.

In the point that a pile having a large bending strength is used for the upper ground where a relatively large horizontal strength is required, and a knotted pile having excellent peripheral bearing capacity is used for the lower ground, the special ground described in the section of the prior art is used. Although it is the same as that of Japanese Patent Application Laid-Open No. 5-47685, in the present invention, since the upper pile is a steel pipe pile with projections, the pile can be designed with the peripheral surface supporting force included in the upper pile.

[0011] In particular, when the supporting force is insufficient only by the tip supporting force and the peripheral surface supporting force of the node pile as the lower pile, a certain degree of peripheral surface supporting force can be obtained even for the upper pile composed of the projected steel pipe pile. Thus, a foundation pile structure having more excellent support performance can be obtained.

The steel pipe pile with projections may have a projection only on the inner surface, a projection only on the outer surface, or a projection on both inner and outer surfaces. Such a steel pipe pile with projections can be manufactured by, for example, making a spiral pipe from a rolled steel sheet having striped or mesh-like projections. However, when a projection is provided only on the inner surface, it is premised that stress is transmitted between the steel pipe pile with the projection and the hardened material by filling the interior with the hardened material.

The hardening material in the drilling hole is a soil cement, and when excavating with an auger or the like, cement milk is injected and mixed with the excavated soil by stirring to thereby mix the soil into the drilling hole. A cement mixture is created, and the heterogeneous connecting piles can be submerged in the soil cement mixture to form a foundation pile by curing the soil cement.

In the case of soil cement, although the strength of the hardening material is lower than that of mortar or the like, the steel pipe pile with projections constituting the upper pile of the heterogeneous connection pile can be expected to have a peripheral surface supporting force. It can compensate for low strength and improve workability and economy.

A third aspect of the present invention is the case where the inside of the steel pipe pile with projections is filled with a hardening material. When the projection has a projection on the inner surface of the steel pipe pile, the rigidity of the upper pile portion can be further increased. Further, when the stress state near the joint becomes unstable due to a sudden cross-sectional change from the lower pile to the upper pile, a foundation structure with more excellent stability can be obtained.

When the knot as a lower pile is hollow and the upper part is open, the inside of the knot can be filled with a hardening material.

According to a fourth aspect of the present invention, there is provided a heterogeneous connection pile for use in the above-described foundation pile structure, wherein a steel pipe pile with a projection having a projection on an inner surface and / or an outer surface of a steel pipe is provided above a nodal pile. It is characterized by being joined.

The joint pile as the lower pile and the steel pipe pile with a projection as the upper pile are settled in a joined state, and the upper pile is joined in a state in which the lower pile is set to some extent and further settled. There are cases. The joining of these dissimilar piles
When a steel end plate is provided at the end of the knot, it can be performed by welding or the like. When the pile diameters of the lower pile and the upper pile are different from each other, the lower pile and the upper pile may be joined by interposing a tapered connecting pipe or the like.

[0019]

FIG. 1 shows an embodiment of a foundation pile structure according to the present invention, in which different connection piles are set in a hardening material 6 such as soil cement filled in an excavation hole 5.

The heterogeneous connection pile is formed by joining a projecting steel pipe pile 2 as an upper pile to an upper part of a node pile 1 as a lower pile.

In this example, the knotted pile 1 is a knotted pile made of hollow concrete, and the shaft portions 1a and the knotted portions 1b are formed alternately, and have a large vertical supporting force.

On the other hand, the projecting steel pipe pile 2 has projections 2 on its inner and outer surfaces.
a and 2b are formed, and in addition to the high bending strength as a steel pipe, the peripheral surface supporting force is exerted by the adhesive force between the projections 2a and 2b and the hardening material 6. In this example, the hardening material 6 is also filled in the inside of the projected steel pipe pile 2 and the knotted pile 1.

2 (a) to 2 (d) show one embodiment of the heterogeneous connecting pile of the present invention.

FIG. 2A shows the case where the protrusion 2a is formed only on the outer surface of the steel pipe pile 2 with protrusions, and FIG. 2B shows the case where the protrusion 2b is formed only on the inner surface of the steel pipe pile 2 with protrusions. , FIG. 2
(c) is a case where the protrusions 2a and 2b are formed only on the inner and outer surfaces of the steel pipe pile 2 with protrusions.

FIG. 2 (d) shows a case where the outer diameter of the steel pipe 2 with the projection is larger than the outer diameter of the shaft portion 1a of the knot 1. In this case, the connecting pipe 4 having a taper is interposed. hand,
Joined by welding or the like. In the case of welding, knot 1
Attach a metal fitting such as a steel end plate to the end of.

FIGS. 3 (a) to 3 (c) show an example of a construction procedure of the foundation pile structure according to the present invention, and can be performed basically in the same manner as a conventional embedded pile.

First, a drilling hole 5 is drilled by using a drilling device such as a spiral auger 7 (see FIG. 3A). At this time, cement milk is injected from the tip of the spiral auger 7 and stirred and mixed with excavated earth and sand by a stirring blade to obtain soil cement.

The knot pile 1 is laid down in the soil cement as the hardening material 6, and the steel pipe pile 2 with the projection is joined thereon (see FIG. 3 (b)). 6
As a result, the foundation pile structure of the present invention is formed (see FIG. 3 (c)).

The drilling equipment and the hardening material for drilling are merely examples, and are not limited to those described above.

[0030]

According to the present invention, a rational pile structure can be achieved by using a pile having a large bending strength in the upper ground where relatively large horizontal strength is required, and using a knotted pile having an excellent peripheral bearing capacity in the lower ground. Further, in the present invention, since the upper pile is a steel pipe pile with projections, the pile can be designed in a form that also takes into account the peripheral surface supporting force of the upper pile, and a larger vertical supporting force can be obtained.

The stress state in the vicinity of the joint is unstable due to insufficient supporting force or a sudden cross-sectional change from the lower pile to the upper pile only with the tip supporting force and the peripheral surface supporting force of the node pile as the lower pile. In this case, a certain level of peripheral surface support force can be obtained for the upper pile made of the steel pipe pile with projections, so that a foundation pile structure having more excellent support performance and stability can be obtained.

Since the adhesive force can be easily secured also for the upper pile, the cost of the hardening material can be reduced by using poorly-mixed soil cement, etc.
This leads to improved economics.

By filling the inside of the pile with a hardening material,
Greater bending strength can be obtained.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view showing one embodiment of a foundation pile structure of the present invention.

FIGS. 2A to 2D are front views (partially cutaway sectional views) showing one embodiment of the heterogeneous connection pile of the present invention.

FIGS. 3A to 3C are vertical sectional views showing an example of a construction procedure.

FIGS. 4 (a) and 4 (b) are vertical sectional views showing a foundation pile structure using a conventional heterogeneous connection pile.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Knotted pile, 1a ... Shaft part, 1b ... Knotted part, 2 ... Steel pipe pile with projection, 2a ... Outer side projection, 2b ... Inner side projection, 3 ... Joint, 4 ... Connection pipe, 5 ... Drilling hole, 6 ... hardened material, 7 ... spiral auger, 11 ... knotted pile, 12 ... steel pipe pile, 13 ... joint, 14 ... connecting pipe, 15 ... drilled hole, 16 ... hardened material

Claims (4)

[Claims] A steel pipe pile having projections on an inner surface and / or an outer surface of a steel pipe is joined to an upper part of a nodal pile to form a heterogeneous connection pile, and the heterogeneous connection pile is formed in an excavation hole filled with hardening material. A foundation pile structure wherein a pile is laid down and the hardening material is hardened. 2. The foundation pile structure according to claim 1, wherein said hardening material is soil cement. 3. The foundation pile structure according to claim 1, wherein a hardening material is also filled in the inside of the steel pipe pile with projections. 4. A heterogeneous connection pile comprising a jointed steel pipe pile having a projection on an inner surface and / or an outer surface of a steel pipe on an upper part of a nodal pile.