JP2003232033A - Foundation pile structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foundation pile structure which allows a foundation pile suitable for properties of ground to be installed at a low cost. <P>SOLUTION: In this foundation pile structure for supporting various types of structures, the foundation pile 1, which is formed by coupling a steel pipe pile 2 to a prestressed concrete (PC) pile in a required position on the foundation pile 1, is installed in the ground G by a construction method for driving various types of existing piles. Thus, the foundation pile 1 can be constructed at a cost lower than ever before and can be installed by the construction method suitable for an environment of a job site for execution of work and the properties of the ground G. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a foundation pile structure for supporting various structures.

[0002]

2. Description of the Related Art For various structures such as building structures and civil engineering structures including railways and harbors, for example, pre-stressed concrete piles (PC piles) or other ready-made piles are used. It is common practice to support a structure by reaching the support ground, which is a solid ground. One or more ready-made piles are connected and used according to the ground condition such as the depth position of the supporting ground,
Among the ready-made piles, PC piles are widely used because the cost is low with respect to the required strength.

Prestressing force is applied to PC piles in the order of Class A, Class B, and Class C so that appropriate piles can be used according to the magnitude of horizontal force acting at the time of an earthquake that is assumed during design. Larger pile types are set, and among these pile types, those of type B or C are generally used according to the strength required in the pile head where the normal conditions are the most severe. .

If the horizontal force and bending moment expected on the pile head are too large for a C type PC pile to withstand,
Corresponding by connecting the concrete pile with steel pipe with outer shell (SC pile), which has high horizontal and bending strength in which centrifugal concrete is placed inside the steel pile, to the pile head of the foundation pile by connecting it to the PC pile Often.

As described above, first, the PC is used as the lower pile of the foundation pile.
When piles are piled up, and when piles are piled up by adding SC piles to PC piles as pile heads, PC piles and SC piles are generally end hardware provided in advance at the ends of the piles. In addition to joining them by welding, they are joined by a method such as using a screw joint or a crimp metal fitting.

[0006]

By the way, the SC pile is
For example, since it is manufactured through the steps of pouring concrete into the steel pipe prepared by attaching the end metal fittings and the mold, molding and curing, and then removing the mold, it is very troublesome to manufacture. It is expensive because of the cost. In the conventional technology in which the high-priced SC piles are added to the PC piles in this way, even if an inexpensive PC pile is used to construct a pile foundation that does not cost much, the cost is increased by adopting the expensive SC piles. It has a problem that it becomes such a pile foundation.

Further, when the PC pile is installed by a hammering driving method due to the surrounding environment, the property of the ground, construction cost, etc., the PC pile is driven into the supporting ground to reach the supporting ground. Although its actual depth can be known, it is often necessary to finish the driving at an earlier stage than expected at the time of design due to the fact that the supporting ground is unplanned. In this case, the pile head is generally cut at an appropriate position to adjust the pile length at the construction site. However, when the SC pile is used for the pile head, the rigidity of the SC pile is very large and it is basically difficult to cut it at the construction site. Therefore, when the SC pile is used for the pile head, the driving method is used. It has another problem that it is difficult to adopt.

An object of the present invention is to provide a foundation pile structure which can solve the above-mentioned problems of the prior art.

[0009]

To solve the above problems, according to the invention of claim 1, there is provided a foundation pile structure for supporting various structures, wherein the foundation pile is formed from steel pipe piles and ready-made concrete piles. There is proposed a foundation pile structure characterized by using the steel pipe pile at a required position of the foundation pile.

According to the invention of claim 2, in the invention of claim 1, there is proposed a foundation pile structure in which the foundation pile is installed by a method of installing various ready-made piles.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An example of an embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view showing an example of an embodiment of the present invention. A foundation pile 1 according to the structure of the present invention supports the structure on the ground G by allowing the weight of the structure to reach the supporting ground G1. Therefore, it is installed in the excavation hole A formed in the ground G. Reference numeral 2 is a steel pipe pile used near the ground in the ground G, and reference numerals 3 and 4 are prestressed concrete piles of ready-made concrete piles used below the steel pipe pile 2. (PC pile)
Is. Here, one steel pipe pile 2 and two PC piles 3,
4 and the foundation pile 1 is constructed and connected to the footing B of the structure.

The diameters of the steel pipe pile 2 and the PC piles 3 and 4 are substantially the same, and the steel pipe pile 2 and the PC pile 3 are
As shown in FIG. 1, end metal parts 2A and 3A made of steel are fixed to the respective ends, and a steel pipe pile 2 and a PC pile 3 are provided.
Are joined by an appropriate method such as welding these end metal parts 2A, 3A to each other. Also, PC pile 3 and P
The C pile 4 is joined by a method similar to the conventional method of constructing a foundation pile by adding PC piles by the end metal fittings 3B and 4A provided in advance at the respective ends.

It is needless to say that the steel pipe pile 2 needs to have a diameter dimension and a thickness dimension corresponding to the required yield strength in consideration of the corrosion allowance. Further, the steel pipe pile 2 can be cut at the site because it is made of only steel plates unlike the concrete pile with outer shell steel pipe (SC pile) that has been conventionally used for the pile head, and in comparison with SC piles. It is an inexpensive member.

In the foundation pile, generally, a large horizontal force or the like is applied to the pile head near the ground, so that the pile head is required to have a large horizontal proof strength.
Since the steel pipe pile 2 having a larger allowable stress than the piles 3 and 4 is used for the pile head, it is possible to construct a pile that is strong against horizontal force from the ground generated during an earthquake or the like.

Further, since the steel pipe pile 2 can be cut at the construction site, the foundation pile 1 is driven by the driving method, and the PC pile 4 reaches the supporting ground G1 at a depth position shallower than expected at the time of design. , Even if it is necessary to finish the driving at an earlier stage to cut the pile head, the steel pile 2 used for the pile head is cut at an appropriate position at the construction site to construct the foundation pile 1 as a structure. It can be adjusted to have the optimum pile length to support.

Further, since the steel pipe pile 2 and the PC piles 3 and 4 have substantially the same diameter, the steel pipe pile 2 and the PC pile 3 and P pile.
A large level difference does not occur in the transmission of the horizontal force between the C pile 3 and the PC pile 4, and smooth transmission is performed, and a large horizontal proof strength can be maintained as the entire foundation pile 1.

Next, an example of a construction procedure for installing the foundation pile 1 on the ground will be described. Basically, it can be performed in the same manner as the conventional driving method.

First, the PC pile 4 is built in a predetermined position on the ground G, and the PC pile 4 is hit with a hammer etc.
Then, the end metal fittings 4A and the end metal fittings 3B of the PC pile 3 are joined by a known method such as welding or joining with a screw joint or a crimp metal fitting to join the PC pile 3 to the PC pile 4 and the same. Drive into. Next, attach the steel pipe pile 2 to the end hardware 2
A and 3A are added to the PC pile 3 by an appropriate means such as welding and driven, and the tip end of the PC pile 4 reaches the support ground G1 in the ground G.

As described above, the foundation pile 1 using the steel pipe pile 2 in the vicinity of the ground of the ground G and the PC piles 3 and 4 in the lower portion is constructed in the ground G.

The foundation pile 1 constructed as described above is different from the case where a foundation pile using only steel pipe piles is placed as a whole.
Since a large supporting force can be expected to be generated in the foundation pile 1 due to the tip supporting force and the peripheral frictional force, the foundation pile 1 can be installed on the ground G by a pre-boring method suitable as a method for installing the pile in the city area. A rotary press-fitting method of statically screwing the pile has been devised in recent years. According to this method, a wing-shaped member is provided at the tip of the pile and the pile is screwed while excavating the ground. It takes a lot of time and money to attach the parts.

Next, an example of a construction procedure for installing the foundation pile 1 in the ground G by the preboring method will be described. Basically, it can be performed in the same manner as the case of installing by the conventional preboring method.

First, the excavation hole A is bored using an excavation device such as a swipe auger. At this time, cement milk is injected from the tip of the excavator and mixed with excavated earth and sand to obtain soil cement. The PC pile 4 is submerged in the soil cement as a hardening material, and the PC pile 3 is joined on it. Since the PC pile 4 and the PC pile 3 are connected by a known method such as welding as in the case of the driving method described above, further detailed description will be omitted here. The joined PC pile 3 is also sunk in the excavation hole A, and the steel pipe pile 2 is joined thereon. The PC pile 3 and the steel pipe pile 2 are joined to each other by appropriate means such as welding in the same manner as in the case of the driving method described above, using the end metal parts 3A and 2A provided in advance at the respective end portions. . After the steel pipe pile 2 is sunk to a predetermined depth, the foundation pile 1 is installed by hardening the soil cement.

It should be noted that the drilling device for punching and the hardening material are only examples and are not limited to the above.

In the present embodiment, the case where PC piles are used as ready-made concrete piles has been described, but the present invention is not limited to this, and concrete piles are more suitable than PC piles depending on the ground, horizontal bearing capacity, vertical bearing capacity, and the like. Reinforced concrete piles with low strength (RC piles) and high-strength prestressed concrete piles with greater concrete strength than PC piles (PH
C pile) may be used.

Further, in the present embodiment, the foundation pile 1 is formed by connecting one steel pipe pile 2 to two PC piles 3 and 4, but the depth of the supporting ground G1 in the ground G is reduced. Depending on the ground properties such as the position and the supporting force required at each length position of the pile, the required number of PC piles and steel pipe piles may be added and connected to each other.

FIG. 2 is a sectional view showing another embodiment of the present invention. In FIG. 2, the foundation pile 1'is configured by sandwiching the steel pipe pile 2'between the PC pile 3'and the PC pile 4 ', and
Ground G'is a hard layer GC between the soft layer GA and the soft layer GB.
It is different from the case shown in FIG. 1 in that it is configured so as to sandwich. The foundation pile 1'is connected to the footing B'of the structure to support the structure.

PC pile 3'and steel pipe pile 2'and steel pipe pile 2 '
The PC pile 4'and the steel pile 2 and the PC pile 3 shown in FIG. 1 are the end metal fittings 3A 'and 2A' and the end metal fittings 2B 'and 4A' which are provided in advance at the respective ends. In the same manner as in the case of joining, they are joined and joined by joining.

In the ground G ′, the boundary surface 10 between the soft layer GA and the hard layer GC and the boundary surface 11 between the hard layer GC and the soft layer GB are different from each other due to the difference in the soil properties above and below each surface. The rigidity has changed significantly. Therefore, it is assumed that the ground condition is different between the upper and lower sides of the boundary surfaces 10 and 11 in the event of an earthquake, etc. In this case, a very large horizontal force is applied to the foundation pile 1'at a position in contact with the boundary surfaces 10 and 11. Occur. Steel pipe pile 2'with high horizontal yield strength and high toughness
Can be installed in the foundation pile 1 ′ so as to be in contact with each other through the two boundary surfaces 10 and 11 so that the structure can be firmly supported.

As described above, according to the foundation pile 1 ', the steel pipe pile 2'is connected to the PC piles 3', 4'of ready-made concrete piles at the required positions of the foundation pile 1'according to the ground property. It is possible to use the steel pipe pile 2'corresponding to the part where the rigidity of the ground is different and a large horizontal force is applied to the foundation pile 1 ', and the same effect as when used for the pile head shown in Fig. 1 is obtained. Can be expected.

[0031]

According to the present invention, as described above, in the foundation pile structure, the steel pipe pile is connected to the ready-made concrete pile at the required position of the foundation pile, and the foundation pile thus formed is installed by various ready-made piles. Since it was installed on the ground by using, it is not an expensive SC pile in a part requiring a large stress that is difficult to withstand with ready-made concrete piles,
Since steel pipe piles, which are cheaper than SC piles, are used, the cost for foundation construction can be significantly reduced.

Further, since steel pipe piles and ready-made concrete piles can be cut at the construction site of foundation piles, unlike the conventional method of using SC piles at the pile heads, the foundation pile structure of the present invention has a driving method. Can be adopted.

Further, unlike the case of placing a foundation pile using only steel pipe piles as a whole, according to the foundation pile having the structure of the present invention, a large bearing force is exerted on the pile due to the tip supporting force and the peripheral frictional force. Since it can be expected to occur, it is possible to install the foundation piles using the pre-boring method, which is suitable as the method for installing foundation piles in urban areas. That is, the foundation pile according to the structure of the present invention can be installed by using a construction method of a ready-made pile, whether it is a steel pipe pile or a ready-made concrete pile, and be installed by a method suitable for the environment of the construction site and the properties of the ground. You can

Further, the foundation pile according to the structure of the present invention is designed to fill the gap in the region in which both the steel manufacturer producing steel pipe piles and the pile manufacturer producing ready-made concrete piles are used. You can

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of an embodiment of the present invention.

FIG. 2 is a sectional view showing another embodiment of the present invention.

[Explanation of symbols]

1,1 'foundation pile 2,2 'steel pipe pile 3,3 ', 4,4' PC pile A drilling hole G ground G1 support ground GA soft layer GB Soft layer GC hard layer

Claims (2)

[Claims] 1. A foundation pile structure for supporting various structures, wherein a foundation pile is formed from steel pipe piles and ready-made concrete piles, and the steel pipe piles are used at required positions of the foundation piles. Foundation pile structure. 2. The foundation pile structure according to claim 1, wherein the foundation pile is installed by a method of installing various ready-made piles.