JPS6233927A - Concrete pile having short large-diameter concrete-steel tube composite - Google Patents

Abstract

PURPOSE:To enhance the bearing capacity of the tip of bored pile by a method in which concrete is integrated with the inside of a steel tube, the upper and lower parts of the concrete are protected by steel plates integrated with the steel tube, and a pile is connected to the upper part of the concrete-steel tube composite. CONSTITUTION:External force from the upper part of a pile is transmitted through a steel plate 4 to a concrete 1 having a steel plate 5 on its lower part. The concrete pile 1 is of a structure that a steel plate 4 is provided on the upper part and a steel tube 2 integrated with the concrete 1 is provided around the concrete 1. Holes 6 and 7 of a smaller diameter than the inside diameter of the concrete 1 are drilled in the centers of the steel plates 4 and 5. The concrete pile can settle even into the ground where piles are hard to settle by buoyancy. The bearing capacity of the concrete pile can thus be increased, and the pile can be easily settled exactly to given depths.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to ready-made piles buried underground to support buildings, etc., and particularly to foundation concrete piles with improved tip bearing capacity.

BACKGROUND OF THE INVENTION Conventionally, when a ready-made pile is buried underground to support a building, etc., a 4/'A large bulbous concrete section is formed at the bottom of the pile on site to increase the supporting capacity.

Problems to be Solved by the Invention In order to form an enlarged bulb part at the bottom of a pile at the site, it was thought that a large enlarged bulb part would have a large supporting capacity. Cement milk with a high moisture content before and after is commonly used. However, even with ready-made embedded piles with enlarged bulbs formed from moths, only a small branching force can be obtained compared to driven piles in which the ready-made piles are directly embedded into the ground by impact.

An object of the present invention is to provide a ready-made pile for foundations that can improve the tip bearing capacity of conventional embedded piles.

Means for Solving the Problems The concrete pile having a large diameter and short concrete steel pipe composite part of the present invention has a structure in which a concrete pile is connected to the upper part of the concrete steel pipe composite part, and the structure of the concrete steel pipe part is In this case, concrete 1 has a length of 40~
It is integrated with a steel pipe 2 in a copper pipe 2 of 80 crn, and the upper and lower parts of the concrete 1 are protected by steel plates 4 and 5, and in the center of each of the steel plates 4 and 5,
It has a structure in which holes 6 and 7 with a diameter smaller than the inner diameter of the concrete 1 are opened, and a structure in which concrete 1 and piles 8 with an outer diameter smaller than the outer diameter of the concrete steel pipe composite part are connected. This is a characteristic pile.

The concrete part 1 of the concrete steel pipe composite part of the concrete pile having a short concrete steel pipe composite part with a large diameter according to the present invention is integrated with a steel pipe in a steel pipe 2 having a length of 40 to 80 eyn. In order to integrate steel pipes and concrete in this way, it is necessary to mix an expanding admixture such as magnesium oxide, calcium sulfur aluminate, or gypsum lime with the concrete raw material, and use the expansion force to ensure that the concrete is integrated with the steel pipes. is preferable, and the length of the steel pipe must be at least 40 crn for such integration, and even if the length exceeds 80 α, the amount of steel pipe etc. used will be large, which will be uneconomical. Generally, about 50 crn can be optimally used. The trench steel pipe 2 may have a thickness that can withstand deformation due to pressure from the top of the pile, etc., and is generally 3 to 20 mm thick.
Steel pipes with a thickness of mm are used depending on their diameter. The thickness of the concrete 1 is 5 to 10 crn depending on the outer diameter of the steel pipe 1.
A range of is commonly used.

Further, the upper and lower parts of the concrete 1 are protected by a steel plate 4.5 that is integrated with the steel pipe 2 by welding or the like.

The outer diameter of the steel plate 4.5 is equal to the inner diameter of the steel pipe 2 in order to protect the concrete 1 from external forces applied to the concrete-steel pipe composite part K, and its thickness is preferably 5 to 20 mm.

Note that a hole 6.7 with a diameter smaller than the inner diameter of the concrete 1 must be formed in the center of the steel plate 4.5. This hole is necessary in order to prevent the pile from being unable to sink due to buoyancy if it is sealed, and is generally more than 1/10 of the outer diameter of the steel pipe 2 of the concrete steel pipe composite part and less than 120 mm. (However, if the outer diameter of the steel pipe 2 is larger than 200mm, 1
Even if it is 20 mm larger, it is allowed up to 115 mm or less of the outer diameter of the steel pipe 2. ), and about 100 mm is optimally used. Further, the size of the holes 6 and 7 is preferably smaller than the inner diameter of the concrete 1 in order to prevent the concrete 1 from being damaged by earth and sand flowing downward. Further, as shown in FIGS. 1 and 2, if the hole 7 is provided at a position recessed from the steel plate 5, it becomes easier for earth and sand to flow downward.

Furthermore, as shown in Figures 2 and 3, the upper steel plate 4 is connected to a pile with a small diameter, so it is easy to receive external force from the side, so the upper steel plate 4 is connected to a steel pipe. It is more preferable to use a map-shaped steel plate 4 having a portion 10 that slightly protrudes from the outer periphery of the steel plate 2.

With this structure, even if the integration between the steel pipe 2 and the steel plate 4 becomes weak, the structure can sufficiently withstand external forces. This cap-shaped steel plate 4 may have a projecting portion 10 integrally formed therein as shown in FIG.
0 and the steel plate 4 may be made into separate bodies and integrated by welding. In the latter case, if you weld at three points on the outer circumference and inner circumference,
There are fewer weaknesses in integration compared to those welded only on the outer periphery. Further, in this case, it is preferable that the outer diameter of the steel plate 4 is large enough to fit on the upper part of the overhanging part 10.

Furthermore, the length of the overhanging portion 10 extending below the steel plate 4 must be at least 2 cm due to its structure, and a length of more than 7 cm should be avoided from the economic point of view, and its thickness should be 5 to 2 cm.
It is about 0 order.

When these cap-shaped overhanging parts 10 are provided, it is preferable that the overhanging parts 10 and the steel pipe 2 are integrated by welding as shown in FIGS. 2 and 3.

As shown in FIGS. 1 to 3, the short concrete-steel pipe composite section detailed above is constructed by attaching the end plate 11 of the concrete pile 8 and the steel plate 4 to the concrete pile 8, which has a small outer diameter. are integrally connected by welding to form a welded portion 9. Furthermore, it is preferred that the outer diameter of the concrete pile 8 is 5 to 15 m smaller than the maximum outer diameter of the concrete steel pipe composite section. This is because it is uneconomical to make the concrete pile 8 thick, and if it is too thin, there will be too much clearance between it and the maximum outer diameter of the concrete-steel pipe composite section.

In addition, the ready-made concrete IJ-to piles 6 to be connected are concrete piles such as reinforced concrete piles and prestressed concrete piles, but in order to further increase the bearing capacity, it is preferable to use concrete piles with a compressive strength of 800 Kp/1w2 or more. . Further, in this case, it is preferable that the compressive strength of the concrete 1 of the concrete-steel pipe composite part is equal to or higher than the compressive strength of the upper concrete pile, so the compressive strength is preferably 800 Ky/cm2 or more. Concrete with such high compressive strength is
It can be obtained by curing concrete 1 restrained by steel pipes 2 in an autoclave.

In addition, the concrete 1 of the concrete steel pipe section is integrated with the steel pipe 2 on the outside thereof, and the concrete pile 8
The compressive force from can be borne via the steel plate 4, so
The inner diameter of the concrete 1 may be set to a size that overlaps the outer diameter of the concrete IJ-to pile 8 by at least 1 crn on both sides thereof. Therefore, from the viewpoint of practicality, it is generally preferable for the concrete 1 to have a hollow shape in the center.

An example of manufacturing such a short concrete-steel pipe composite section is the following manufacturing method. In other words, the concrete raw material containing an expanding agent is applied to the upper steel plate 4 using a centrifugal force forming method or the like.
and the lower steel plate 5 are formed in a steel pipe of an appropriate length that is integrated by welding or the like, and then the steel pipe and concrete are integrated by the expansion action of an expanding agent during curing.

The concrete 1 of the concrete-steel-pipe composite part, which has a short action, is protected by steel plates 4 and 5 at its upper and lower parts, and by a steel pipe at its outer periphery. Even when external forces such as the weight of a building are applied from above, the concrete 1 is protected and will not be damaged.

In particular, the structure is such that the external force on the upper part of the pile is transmitted to the concrete 1 which has a steel plate 5 at the bottom via the steel plate 4, and the external force from the bottom is transmitted to the steel plate 4 upward via the steel plate 5. In addition, the steel pipe 2 integrated with the concrete is present on the outer periphery of the concrete 1, so the structure is strong against external forces. In particular, since the concrete 1 is integrated with the steel pipe 2,
Even if an external force such as a bending force that separates the steel pipe 2 and the concrete 1 is applied to the concrete-steel pipe composite part, sufficient and reliable supporting force can be exerted without damaging the integration.

In addition, in the center of each of steel plates 4 and 5, concrete IJ-1
The structure in which the hole 6.7 has a diameter smaller than the inner diameter of the
If the lower end is sealed due to the presence of groundwater, the buoyancy allows the buoyant to be easily sunk into ground that is difficult to sink into, and it also has resistance to earth and sand flowing downward. The pile of the present invention is used by closing the hollow part with cement mortar or the like after being sunk. When the hollow part is closed in this way, the lower end becomes a sealed structure, and the surrounding concrete 1 is larger than the diameter of the concrete pile 8, and as mentioned above, it is solid, so it is definitely large. It can demonstrate supporting capacity.

An annular steel plate with an outer diameter of 536n and a wall thickness of 12mm and a length of 50 threads was welded at three points on the outer circumference and inner surface of a steel plate with a hole 6 of an inner diameter of 10crn and a diameter of 53-τ and a wall thickness of 12mm. A cap-shaped steel plate having a slightly protruding portion 10 as shown in Fig. 2 is prepared, and a steel plate 5 with an outer diameter of 50 crn and a wall thickness of 12 cm is recessed downward by 10 cnl from a direct fll = 28 m, with an inner diameter in the center. A steel plate with a 10 m hole 7 was prepared.

These steel plates were welded together with a steel pipe with an outer diameter of 50cy++, a wall thickness of 4.5fi, and a length of 50m, as shown in Figure 2, and the thickness was adjusted using a thickness adjustment sheet corresponding to the thickness of the cap, and then divided into two. It was set in a cylindrical formwork. Into the steel pipe 2 in this state, concrete raw material mixed with magnesium oxide was injected under the action of centrifugal force so that the diameter of the hollow part of the concrete was 3.5 cyn, and after curing with atmospheric pressure steam, it was cured in an autoclave. did.

At the top of this approximately 50 cr JT long concrete steel pipe complex is a type of concrete pile with an outer diameter of 40 cr.

An AH8-gile manufactured by Mukasei Kogyo Co., Ltd. with an inner diameter of 27 crn was attached to the end plate of the AHS pile and the upper steel plate of the concrete steel pipe composite, with the antibiotic core aligned with the center line of the concrete steel pipe composite #A. The piles were connected by welding to create a pile with a composite section of concrete and steel pipes with a short enlarged diameter.

Next, this pile was sunk as a foundation pile in a hole with a diameter of 53 m that had been previously excavated and reached the supporting ground. The piles were erected by their own weight; however, when the piles could not be erected by their own weight due to partial collapse or bending of the hole, the upper part of the pile was struck. Furthermore, if the hole is deep and one concrete pile at the top is not enough, a concrete pile can be welded to the top as in the previous technique, and finally a pipe can be used from above the anti-resistance cavity to connect the hollow part of the concrete-steel pipe complex. The area was closed by injecting cement mortar.

Since most of the structure of the pile was based on the present invention, the pile arrived at the bottom of the hole without freezing.

28 foundation piles having the structure of the present invention were sunk in this manner.
After several days, an external force was applied to the upper part of the pile, and the bearing capacity of the lower part of the pile leading to settlement and failure was measured.

Even when an external force of 110 tons was applied to the foundation pile having the structure of the present invention, it only sank by about 1 hu and did not cause any failure phenomenon.

As a comparative example, cement mortar was injected from below into an excavation hole under the same conditions as in the example to form a cement layer with a depth of 506 nm, on top of which the AHS pile used in the example was deposited, and 28 days later the pile was When an external force was applied from the top and the bearing capacity below the pile was measured to cause settlement and failure, the amount of settlement increased rapidly around 60 tons, and by the time it reached 80 tons, the cement layer at the bottom had been destroyed.

Effects of the Invention The concrete pile of the present invention has a large bearing capacity, is easy to sink, and can be reliably sunk to a predetermined depth.

[Brief explanation of drawings]

1, 2 and 3 show the right half of the concrete pile of the present invention in cross-section. 1... Concrete 1, 2... Steel pipe 4.5... Steel plate 6.7... Hole 8... Concrete pile Patent applicant Asahi Kasei Kogyo Co., Ltd. Procedural amendment (voluntary) 1985, 1985 Commissioner of the Patent Office Michibe Uga 1, Indication of the case 1985 Patent Application No. 172386 2, Name of the invention Large diameter short concrete -I- Concrete Pitch 3 Having a Steel Pipe Composite Part, Relationship with the Amendment Case Patent Applicant: 1-2-6 Dojimahama, Kita-ku, Osaka-shi, Osaka Prefecture (1) The scope of claims in the specification is as attached. correct. (2) Claims on page 3, line 3, line 13, and line 20 of the specification

Claims (1)

[Claims] A concrete 1 is integrated into a steel pipe 2 having a length of 40 to 80 cm, the upper and lower parts of the concrete 1 are protected by steel plates 4 and 5 integrated with the steel pipe 2, and each of the steel plates 4 and 5 is has a large diameter short concrete steel pipe composite part with holes 6 and 7 having a diameter smaller than the inner diameter of the concrete 1 in the center thereof, and above the concrete steel pipe composite part, the concrete steel pipe composite part A concrete pile having a large diameter short concrete steel pipe composite part, characterized in that it has a structure in which a concrete pile 8 having a diameter smaller than the outer diameter of is connected.