JP2003090036A - Ready-made pile and foundation pile structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To strengthen bending strength corresponding with high axial force capable of thickening the thickness t4 of a concrete section of the upper part of a pile thicker 30% or more than the lower end section, embedding a reinforcing steel bar in the section and reinforcing the upper end section of the pile. SOLUTION: Circular projections (outside diameter D2 ) 5 and 6 are formed in a lower shaft section (outside diameter D0 and thickness t0 ) 33, and an upper shaft section (outside diameter D1 and thickness t1 ) 43 is formed in succession to the upper side projection 6. A steel pipe (thickness t5 and outside diameter D3 ) 50 is fitted to the upper end section of the upper shaft section 43. In the upper shaft section 43, t3 is the thickness of the whole upper end section, t5 is the thickness of the steel pipe 50 and t4 is the thickness of a concrete part. The following formulas are obtained, t3 =t5 +t4 . D2 >D3 =D1 >D0 and t3 =t1 >t0 and t4 >t0 . The PC steel bar 37 is also embedded to the upper part of the pile as well as the lower part of the pile, and a reinforcing deformed steel bar 44 is embedded in parallel with the outside of the PC steel bar 37 inside of the vertical pile in a formed boundary section of the steel pipe section 50, and the ready-made pile 4 is constituted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foundation pile embedded in a pile hole having a root consolidation portion and a foundation pile structure in which a foundation pile is embedded in the pile hole.

[0002]

2. Description of the Related Art (1) First conventional example

In the construction of a joint pile of the upper pile 30 and the lower pile 32 which is usually carried out, SC piles (concrete piles in which a steel pipe 50 is wound to enhance bending performance) are used as the upper pile 30, and Is a configuration using a concrete pile with nodes (Fig. 8 (a), Japanese Patent No. 2651893, application of Fig. 1). Here, the shaft diameter (D ₃ ) of the upper pile 30 is set to the shaft diameter (D ₃ ) of the lower pile 32.
₀ ), and the wall thickness of the lower pile (t ₀ ) and the wall thickness of the upper pile (t ₃ ) are the same.

As described above, the method used to enhance the bending performance of the ready-made piles on the upper part of the pile foundation has the same outer and inner diameter (including wall thickness) shapes and dimensions for the upper and lower piles. Select the pile material type that satisfies the required axial force as the lower pile, and select the pile material type that satisfies the required bending moment and axial force from the same range as the lower pile for the lower pile. The method of satisfying is commonly used.

(2) Second conventional example

This is a structure in which a steel pipe 50 is wound on the upper part of a concrete pile, and a steel rod and a spiral reinforcing bar are embedded in the lower part in the axial direction (FIG. 8 (b). Japanese Utility Model Laid-Open No. 58-59842). And the top of the shaft diameter _{(D 3)} · thickness _{(t 3),} the lower portion of the shaft diameter _{(D 0)} · thickness _{(t 0)} is in the same geometry.

[0007] In this example, an outer shell steel pipe portion is provided at the upper end of the ready-made pile to improve the bending moment (performance) of the upper end of the pile foundation, but the lower part of the pile is a standard PC pile or PHC pile. In order to improve the stress transmission balance between the outer shell steel pipe section at the upper end and the concrete pile section at the lower part, the outer diameter and wall thickness of the upper and lower parts of the pile are the same.

(3) Third conventional example

After burying at a predetermined position in a concrete pile, carbon fiber is wound around the outer peripheral surface of the upper end of the pile and further covered with a protective material 52 such as mortar, and then a pile head reinforcing bar 53.
A structure in which the above is arranged is proposed (Japanese Patent Laid-Open No. 11-50448).
FIG. 8 (c). In addition, for the same purpose, a structure in which a pile head exposed and cut on the ground is wound with a double steel pipe or the like to be reinforced is proposed (Japanese Patent Laid-Open No. 2000-319875).

[0010]

In the first conventional example, the bending strength of the foundation is S having the same outer diameter as the shaft diameter of the lower end portion.
There was a problem that the bending range of the C pile was limited.

In the second conventional example, the upper portion secures the yield strength by the steel pipe, and the inner concrete portion is arranged to prevent buckling, and is a concrete layer having a thin wall thickness. Therefore, embedding a reinforcing material such as a steel rod or other deformed steel rod in the thin wall thickness of the upper end is not considered. Therefore, there is a problem that not only the strength at the lower edge of the steel pipe but also the strength quality of the upper and lower pile main parts cannot be sufficient, and the bending strength of this ready-made pile is eventually below the SC pile level equivalent to the outer diameter of the lower end. Has become.

Although the third conventional example is effective for reinforcing the pile head, it has a problem that after the pile burying work, many steps are required as a separate work for reinforcing the pile head. Further, it is also possible to embed a ready-made pile in which the pile head is reinforced in advance with a protective material 52 or the like so as to have a similar structure, but according to the outer diameter of the protective material 52 or the like, the entire pile hole, Since it is necessary to excavate a large diameter or to excavate only the upper end of the pile hole to a large diameter, there is a problem that the burden on the pile hole excavating work becomes large.

On the other hand, a soil pile having a solidification strength higher than that of the supporting ground is filled in the expanded root consolidation portion of the pile hole, and a ready-made pile having a projection is installed in the expanded bottom consolidation portion to make A foundation pile structure that achieves more than double the vertical bearing capacity (Japanese Patent Laid-Open No. 11-280067) and a foundation pile structure that achieves high vertical bearing capacity by fixing ready-made piles with rebar cages in the expanded root consolidation section (special Kaihei 11-61811) has also been proposed. In these foundation pile structures, compared with the vertical support force at the root consolidation part (lower end), the compressive strength and horizontal bearing capacity of the ready-made piles arranged in the pile hole shaft part are insufficient, and the foundation consolidation part and the pile It has been pointed out that the yield strength cannot be balanced at the upper part and the high vertical bearing capacity at the root consolidation part cannot be fully utilized.

Even if the above-mentioned conventional examples for strengthening the pile head are applied to the foundation pile structure which exerts a high vertical supporting force at such a consolidation portion, a pile head suitable for the consolidation portion can be obtained. The strengthening could not be realized.

[0015]

According to the present invention, however, an upper shaft portion having a large diameter is formed above the lower shaft portion, the lower shaft portion is positioned at the root consolidation portion of the pile hole, and the steel pipe is attached to the upper shaft portion. The above problem was solved because the steel pipe was fitted and the steel pipe was positioned at the upper end of the pile hole.

That is, the present invention is a concrete ready-made pile having a hollow portion embedded in a pile hole in which a pile hole consolidation portion is formed below a pile hole shaft portion, and a lower portion located in the pile hole consolidation portion. An upper shaft portion having an outer diameter larger than that of the lower shaft portion is formed above the shaft portion via a dimension adjusting portion, and a protrusion is formed on an outer surface of the lower shaft portion, and at least the upper shaft portion is formed. A steel rod is embedded in an upper end portion, and a steel pipe is fitted to at least an upper end portion of the upper shaft portion, which is a ready-made pile.

Another aspect of the present invention is a concrete prefabricated pile having a hollow portion embedded in a pile hole in which a pile hole root consolidation portion is formed below a pile hole stem portion. It is composed of a lower pile arranged and one or a plurality of upper piles joined to the upper part of the lower pile, and the lower pile has a dimension adjusting portion above the lower shaft portion located in the pile hole root consolidation portion. An upper shaft portion having an outer diameter larger than that of the lower shaft portion is formed, a protrusion is formed on an outer surface of the lower shaft portion, and the upper shaft portion has an upper end portion having the same diameter as or an upper portion of the upper shaft portion. It is an off-the-shelf pile characterized in that an upper pile having a diameter larger than that of a shaft portion is joined, a steel rod is embedded in at least the upper end of the uppermost upper pile, and a steel pipe is fitted at least outside the upper end.

In the prefabricated pile, the outer diameter of the steel pipe is formed larger than the outer diameter of the lower shaft portion and smaller than the outer diameter of the protruding portion of the lower shaft portion. In addition, it is a ready-made pile in which the wall thickness of the upper shaft portion is thicker than the wall thickness of the lower shaft portion.

Further, another invention is a structure in which a cement solidified material is filled in a pile hole formed by forming a root consolidation portion at the lower end of the pile hole shaft portion, and a ready-made pile is embedded in the pile hole. In the ready-made pile, an upper shaft portion having a diameter larger than that of the lower shaft portion is formed above the lower shaft portion having the protrusion through the dimension adjusting portion, and the steel pipe is fitted to at least the upper end portion of the upper shaft portion. In the foundation pile structure, the lower shaft portion and the dimension adjusting portion of the ready-made pile are located in the root consolidation portion of the pile hole, and the steel pipe is located near the ground of the pile hole.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION A single pile, which is a ready-made pile, is constructed as follows. (1) An upper shaft portion having a diameter larger than that of the lower shaft portion is continuously provided above the lower shaft portion having a protrusion such as an annular rib. The wall thickness of the upper shaft portion is made thicker than the wall thickness of the lower shaft portion. (2) The upper shaft portion is embedded with a steel rod such as a PC steel rod and / or a deformed steel rod over the entire length including the upper end portion. (3) A steel pipe having a larger diameter than the lower shaft and smaller than the outer diameter of the protrusion is fitted on the upper end of the upper shaft. (4) In addition, by connecting the upper shaft part with a larger diameter than the lower shaft part and forming the upper shaft part thicker than the lower shaft part, the inner diameters of the lower shaft part and the upper shaft part are increased. Have the same dimensions.
By making the inner diameters of the upper and lower shaft parts the same, the wall thickness of the ready-made pile can be effectively used to obtain the desired bearing capacity, etc. When applied, the excavation rod can be smoothly raised and lowered in the ready-made pile. Therefore, it is possible to make ready-made piles that are optimal for the medium excavation method.

Further, the joint pile, which is a ready-made pile, is constructed as follows. (1) In the lower pile, an upper shaft portion having a diameter larger than that of the lower shaft portion is continuously provided above the lower shaft portion formed with a protrusion such as an annular rib. The wall thickness of the upper shaft portion is made thicker than the wall thickness of the lower shaft portion. (2) The upper pile has the same shape as the upper shaft part or a large diameter, and the steel pipe is fitted over the entire length. Further, the upper pile has steel bars such as PC steel bars and / or deformed steel bars buried over the entire length.

Further, prefabricated piles are buried in the pile holes to form a foundation pile structure as follows. (1) A pile hole is formed by forming an enlarged root consolidation portion at the lower end of the pile hole shaft. (2) After filling cement milk or soil cement into the pile holes, or burying prefabricated piles while filling them, a foundation pile structure is created. (3) For an off-the-shelf pile, an upper shank with a larger diameter than the lower shank is formed above the lower shank with protrusions, and the lower shank and the size adjuster expand the pile hole. Located in the root consolidation area. (4) A steel pipe is fitted on at least the upper end of the upper shaft of the ready-made pile, and the steel pipe is located near the ground above the shaft of the pile hole.

In the foundation pile structure thus constructed, the wall thickness of the upper portion of the pile can be increased, so that the concrete portion of the upper portion of the pile main body can be thickened, and a reinforcing material such as a deformed steel bar can be provided inside the pile with a margin. Since the steel pipe material of the outer shell can be made of a thicker plate material than ever before, the axial strength and bending strength of the upper pile can be selected in a wide range that has never existed before, and a higher strength foundation pile can be constructed.

In addition to the above, as a method of designing a pile foundation adopting the foundation pile structure, regarding the outer shell steel pipe concrete pile portion of the pile upper portion having the above-mentioned structure, mainly the axial force of the pile upper portion of the pile upper portion is used. The concrete section will bear the burden, and
It is possible to further improve the bending resistance by mainly having the outer shell steel pipe portion bear the bending resistance.

According to the present design method, since it is possible to adopt an upper pile having an outer diameter larger than the shaft diameter of the lower pile of the pile hole shaft located at the lower portion of the pile upper portion (outer shell steel pipe concrete portion), The selection range of the axial force and bending strength can be further expanded.

In addition, in each of the above-mentioned embodiments and each of the examples described later, after burying the ready-made pile, cement milk having a higher solidification strength than the cement milk filled in the root consolidation portion is newly injected into the hollow part of the ready-made pile. Then, the compressive strength that the ready-made pile should bear can be increased, and the yield strength of the entire foundation pile structure can be increased to a predetermined value. In this case, over the entire length of the ready-made pile,
It is desirable to fill with high strength cement milk,
At least the upper end (pile head) of the ready-made pile may be filled with high-strength cement milk.

When the hollow portion is filled with cement milk, the excavated soil is sandy soil or the like, and when it is good, the excavated soil and cement milk are mixed to fill the soil cement with a predetermined solidification strength. , It is also easy to control the foundation pile structure with a predetermined strength.

Further, when filling the hollow portion of the ready-made pile with cement milk or the like, when the soil cement already filled in the pile hole enters from the lower end of the ready-made pile, it is stirred with desired cement milk. It can also be mixed or replaced with cement milk.

[0029]

Embodiment 1 An embodiment of the present invention will be described with reference to FIG. The case of a single pile will be described.

In the lower shaft portion (outer diameter D ₀ , wall thickness t ₀ ) 33,
Two annular protrusions (outer diameter D ₂ ) 5 and 6 are formed, and the upper shaft portion (outer diameter D ₁ and wall thickness t ₁ ) 4 is continuous with the upper protrusion 6.
3 is formed. At the upper end of the upper shaft portion 43, a steel pipe (wall thickness t
₅ , the outer diameter D ₃ ) 50 is fitted.

In the upper shaft portion 43, the thickness of the entire upper end portion is
t_ThreeAnd t_ThreeThickness t of inner steel pipe 50₅Without the
The thickness of the cleat part is t_FourAnd That is, "t_Three= T₅
+ T _FourIt has become.

In the upper shaft portion 43, the PC steel rod 37 is extended to the upper end portion of the pile in the same manner as the lower portion of the pile, and is parallel to the outer side of the PC steel rod 37 in the upper and lower portions of the pile at the boundary portion where the steel pipe portion 50 is formed. A deformed steel bar 44 for reinforcement is formed to reinforce the pile.
Since the thickness of the pile at the upper end is about 60% larger than that of the general-purpose SC pile, the deformed steel rod 44 can be extended to the upper portion of the protrusion 6 at the lower portion of the pile for further strength reinforcement.

The respective dimensions have the following values, for example. D ₂ > D ₃ > D ₁ > D ₀ t ₃ > t ₄ = t ₁ > t ₀ D ₀ = 600 mm D ₁ = 700 mm D ₂ = 750 mm D ₃ = 740 mm D ₄ = 420 mm t ₃ = 160 m t ₀ = 90 mm t ₅ = 20 mm t ₄ = t ₁ = 140 mm

The ready-made pile 4 of the present invention is constructed as described above (FIG. 1).

This ready-made pile 4 is such that the outer diameter D ₃ of the pile upper end is 20% or more larger than the shaft diameter D ₀ of the pile lower end of the root consolidation part, and the concrete outer diameter of the pile upper end. To have the same dimension as the pile shaft diameter D ₁ of the upper layer of the foundation, and to make the outer shell steel pipe concrete pile portion having a smaller diameter than the projection outer diameter D ₂ of the lower portion, and the pile inner diameters are all the same dimension, The wall thickness of the part is 70% or more greater than the bottom end of the pile.

In designing the pile foundation, the axial force at the upper end of the pile is mainly borne by the concrete pile portion whose wall thickness is increased by 50% or more, without excavating a new large-diameter pile hole. Since a thick steel material that cannot be obtained by a conventional SC pile or the like can be used as the outer shell steel pipe portion, it is possible to provide an unprecedented high bending resistance corresponding to the high axial force of the root consolidation portion.

In the case of the conventional so-called SC pile, when the outer diameter is 700 mm, the inner diameter is 500 mm, and the pile wall thickness is 100 mm.
mm, and within the wall thickness, the steel pipe part (4.5 mm-1
9 mm) and concrete part (excluding steel pipe part)
And are included.

[0038]

[Embodiment 2] An embodiment of the present invention will be described with reference to FIG.

Similar to the first embodiment, the lower shaft portion (outer diameter D ₀ ,
The wall thickness t ₀ ) 33, the two annular protrusions (outer diameter D ₂ ) 5,
6 is formed, and an upper shaft portion (outer diameter D ₁ , thickness t ₁ ) 43 is formed continuously with the upper protrusion 6. A recessed portion 49 is formed on the surface of the upper end portion of the upper shaft portion 43, and a steel pipe (wall thickness t ₅ , outer diameter D ₃ ) 50 is fitted into the recessed portion 49.

In the upper shaft portion 43, the wall thickness of the entire upper end portion is t _3, and the wall thickness of the concrete portion excluding the wall thickness t ₅ of the inner steel pipe 50 at t ₃ is t ₄ . That is, “t ₃ = t ₅ +
t ₄ ”.

In the upper shaft portion 43, the PC steel rod 37 is also arranged at the upper end portion of the pile in the same manner as the lower portion of the pile, and for reinforcement in parallel with the outside of the PC steel rod 37 inside the upper and lower piles at the steel pipe forming boundary. Deformed steel bar 44 is formed.

The dimensions are, for example, the following values. D ₂ > D ₃ > D ₁ > D ₀ t ₃ > t ₁ > t ₄ > t ₀ D ₀ = 600 mm D ₁ = 700 mm D ₂ = 750 mm D ₃ = 720 mm D ₄ = 420 mm t ₃ = 150 mm t ₀ = 90 mm t ₅ = 20 mm t ₄ = 130 mm t ₁ = 140 mm

The ready-made pile 4 of the present invention is constructed as described above (FIG. 2).

The inner diameters of the piles are all the same, the concrete wall thickness t ₄ at the top of the pile is 40% or more thicker than the wall thickness t _{0 at the} bottom end of the pile, and the deformed steel bar 44 for reinforcement is formed at the top of the pile. Is also an easy size. Since the thickness t ₁ of the pile shaft portion just above the nodal protrusion 6 and the thickness t ₃ of the pile upper end portion are both 50% or more thicker than the lower end wall thickness t ₀ dimension, the reinforcing deformed steel bar 44 is attached to the lower portion of the pile. It is possible to extend it just above the protrusion 6 to strengthen the strength of the pile above the protrusion.

Regarding the upper end of the pile, the outer diameter D of the pile_ThreeThe root
Shaft diameter D at the lower end of the pile at the solidification part₀About 20% larger diameter
Outer diameter D of the lower protrusion_TwoSmaller diameter, the inner diameter of the pile is
Over the circumference, the same size as the lower end of the pile, and the upper end of the pile
Thickness t_ThreeIs the bottom wall thickness t of the pile ₀More than 50% larger
And the concrete wall thickness t at the top of the pile_FourThe con
Shaft wall thickness t at the bottom of the cleat pile₀More than 40% outer shell
Steel pipe concrete precast piles are formed.

As for the strength design of the pile foundation, the axial force at the upper end of the pile is mainly borne by the concrete pile part, and the wall thickness of the steel pipe part is also thicker than that of conventional SC piles to achieve high axial force. It can provide a correspondingly large bending resistance.

[0047]

Third Embodiment Another embodiment of the present invention will be described with reference to FIG.

Similar to the second embodiment, the lower shaft portion (outer diameter D ₀ ,
The wall thickness t ₀ ) 33, the two annular protrusions (outer diameter D ₂ ) 5,
6 is formed, and an upper shaft portion (outer diameter D ₁ , thickness t ₁ ) 43 is formed continuously with the upper protrusion 6. A concave portion is formed on the surface of the upper end portion of the upper shaft portion 43, and a steel pipe (thickness t
₅ , the outer diameter D ₃ ) 50 is fitted.

In the upper shaft portion 43, the wall thickness of the entire upper end portion is t _3, and the wall thickness of the concrete portion excluding the wall thickness t ₅ of the inner steel pipe 50 at t ₃ is t ₄ . That is, “t ₃ = t ₅ +
t ₄ ”.

The PC steel rod 37 is formed on the upper part of the pile in the same manner as the lower part of the pile, and the deformed steel bar 44 for reinforcement is formed parallel to the outside of the PC steel rod 37 inside the upper and lower piles at the boundary portion where the steel pipe portion 50 is formed. is doing.

The respective dimensions are, for example, the following values. D ₂ > D ₃ = D ₁ > D ₀ t ₃ = t ₁ > t ₀ , t 4> t ₀ D ₀ = 600 mm D ₁ = 700 mm D ₂ = 750 mm D ₃ = 700 mm D ₄ = 420 mm t ₃ = t ₁ = 140 mm t ₀ = 90 mm t ₅ = 20 mm t ₄ = 120 mm

The ready-made pile 4 of the present invention is constructed as described above (FIG. 3).

Regarding the upper end of the pile, the outer diameter D ₃ of the pile is 15% or more larger than the axial diameter D _{0 of the} lower end of the pile of the consolidation portion, and is substantially the same as the diameter D ₁ of the pile shaft portion of the upper portion of the consolidation portion. The size of the pile is smaller than the outer diameter D ₂ of the lower protrusion, the inner diameter of the pile is substantially the same as the lower end of the pile, and the thickness of the upper end of the pile is 50% or more greater than the lower end of the pile. Outer shell steel tube concrete is a ready-made pile.

All the inner diameters of the piles are the same, and the concrete part wall thickness t ₄ at the top of the pile is 30% or more thicker than the bottom end of the pile, so that it is easy to form the deformed steel bar 44 for reinforcement at the top of the pile. It is a dimension. Since the pile wall thicknesses t ₁ and t ₃ of the shaft portion above the bottom end portion of the pile are both 50% or more thicker than the t ₀ dimension, the reinforcing deformed steel bar 44 is extended to the upper part of the nodal protrusion 6 at the bottom of the pile if necessary. It is also possible to form it to reinforce the strength.

Further, the axial force at the upper end of the pile is mainly borne by the concrete part, and the wall thickness of the steel pipe part is adopted which is thicker than that of conventional SC piles and the like, and bending strength corresponding to high axial force can be provided. .

[0056]

Fourth Embodiment Next, with reference to FIGS. 4 and 5 (a), an embodiment of a joint pile constituted by an upper pile 30 and a lower pile 32 of the ready-made pile of the present invention will be described.

The lower pile 32 has a lower shaft portion (outer diameter D ₀ , wall thickness t
₀ ) 33, two annular protrusions (outer diameter D ₂ ) 5 and 6 are formed, and the upper shaft portion (outer diameter D ₁ ,
A wall thickness t ₁ ) 43 is formed. The upper shaft portion 43 has a connection portion (end plate) 34 with the upper pile at the upper end (FIG. 4).

The upper pile 30 has end plates 31 for connection at the upper and lower ends,
31 has a steel pipe (wall thickness t
₅ , the outer diameter D ₃ ) 50 is fitted.

In the upper pile 30, the entire outer diameter D ₃ (which is the same as the outer diameter of the steel pipe 50) and the total wall thickness t ₃ are defined as t _3.
The wall thickness of the concrete portion excluding the wall thickness t ₅ of the inner steel pipe 50 of ₃ is defined as t ₄ . That is, “t ₃ = t ₅ + t ₄ ” (FIG. 5A).

Deformed steel rod 4 is placed in the concrete shaft.
4, 44 are embedded and fixed to the upper and lower end plates 31, 31 (FIG. 4).

The respective dimensions are, for example, the following values. D ₂ > D ₃ > D ₁ > D ₀ t ₃ > t ₁ = t ₄ > t ₀ D ₀ = 600 mm D ₁ = 700 mm D ₂ = 750 mm D ₃ = 740 mm D ₄ = 420 mm t ₃ = 160 mm t ₀ = 90 mm t ₅ = 20 mm t ₄ = t ₁ = 140 mm

The upper and lower piles 30 constructed as described above,
32 is joined and the ready-made pile 4 of this invention is comprised (FIG. 4).

With respect to the upper end portion of the upper pile 30, its outer diameter D
_ThreeIs the shaft diameter D at the bottom end of the pile at the root consolidation part ₀More than 20% larger
Diameter, outer diameter D of protrusion of lower pile 32_TwoSmaller diameter and above the pile
The outside diameter of the concrete part at the end is the diameter of the pile shaft part at the upper layer of the root consolidation part
D₁And the pile inner diameter is the same for both the upper and lower piles.
And the wall thickness of the upper end of the pile is 70% or more greater than the lower end of the pile.
Outer shell steel pipe concrete precast piles are formed.

The PC steel rod 37 of the lower pile 32 is formed from the lower end of the pile to the upper end of the connecting portion 43. In the vicinity of the upper end of the lower pile, the deformed steel rod is parallel to the outside of the PC steel rod 37. 44
Are formed for reinforcement. Further, since the pile wall thickness t ₁ of the upper shaft portion 43 of the lower pile is increased by 50% or more of the wall thickness t ₀ of the lower end portion of the pile, if it is desired to further increase the thickness, it is possible to deform the upper portion of the nodular projection 6 The steel rod 44 can also be extended and formed to reinforce.

In the upper pile 30, the axial force of the pile is mainly used and the wall thickness t ₄ of the concrete portion having the same dimension as the wall thickness t _{1 of the} lower pile connecting portion.
It is an outer shell steel pipe concrete pile that is borne by the company, and the bending strength is enhanced by the steel pipe wall thickness t _{5 which is} larger in size than general-purpose SC piles, and the high bending corresponding to the high axial force of the pile foundation root consolidation part. Providing a strong pile foundation.

[0066]

[Embodiment 5] Next, an embodiment of a joint pile constituted by an upper pile 30 and a lower pile 32 of the ready-made pile of the present invention will be described with reference to FIGS. 4 and 5 (b).

Using the same lower pile 32 as in Example 4,
The upper pile 30 also has the same configuration as that of the fourth embodiment (FIG. 4). However, in the upper pile of Example 4, t ₄ (thickness of the concrete portion) = t ₁ (thickness of the upper shaft portion of the lower pile), but in this Example, t ₄ <t ₁ <t ₃ (outer diameter of steel pipe = outer diameter of entire upper pile) (FIG. 5 (b)).

The respective dimensions are, for example, the following values. D ₂ > D ₃ > D ₁ > D ₀ t ₃ > t ₁ > t ₄ > t ₀ D ₀ = 600 mm D ₁ = 700 mm D ₂ = 750 mm D ₃ = 740 mm D ₄ = 420 mm t ₃ = 160 mm t ₀ = 90 mm t ₅ = 20 mm t ₁ = 140 mm t ₄ = 130 mm

Regarding the upper pile 30, the outer diameter D of the pile at the upper end thereof
_ThreeIs the shaft diameter D at the bottom end of the pile at the root consolidation part ₀20% larger diameter
So, the pile shaft diameter D of the upper layer of the root consolidation part₁Larger diameter,
And the outer diameter D of the lower protrusion_TwoThe smaller the diameter, the inner diameter of the pile is
Approximately the same size over the entire length of the upper and lower piles, and the meat of the upper end of the pile
Thickness t_ThreeIs the bottom wall thickness t of the pile₀Outside 50% larger than
Shell steel tube concrete precast piles are formed.

The PC steel rod 37 of the lower pile 32 is formed from the lower end of the pile to the upper end of the connecting portion 43. In the vicinity of the upper end of the lower pile, the deformed steel rod is parallel to the outside of the PC steel rod 37. 44
Are formed for reinforcement. Moreover, since the pile thickness t ₁ of the connecting portion 43 in the upper part of the lower pile is increased by 50% or more of the wall thickness t ₀ of the lower end of the pile, there is a margin of the thickness dimension when it is desired to further increase the knot shape. The deformed steel rod 44 may be extended to the upper portion of the protrusion 6 to be reinforced.

The axial force of the upper pile 30 is mainly borne by the concrete pile portion, and the steel pipe portion 50 of the upper pile has a steel pipe wall thickness t ₅ larger than that of the general-purpose SC pile to increase the bending strength. We provide pile foundations with high bending strength that match the high axial force of the foundation foundation.

[0072]

[Embodiment 6] Next, an embodiment of a joint pile constituted by an upper pile 30 and a lower pile 32 of the ready-made pile of the present invention will be described with reference to FIGS. 4 and 5 (c).

Using the same lower pile 32 as in Example 4,
The upper pile 30 also has the same configuration as that of the fourth embodiment (FIG. 4). However, in the upper pile of Example 4, t ₄ (thickness of the concrete portion) = t ₁ (thickness of the upper shaft portion of the lower pile), but in this Example, t ₁ = t ₃ (steel pipe) Outer diameter = outer diameter of the entire upper pile) (FIG. 5 (c)).

The respective dimensions have the following values, for example. D ₂ > D ₃ = D ₁ > D ₀ t ₃ = t ₁ > t ₀ D ₀ = 600 mm D ₁ = 700 mm D ₂ = 750 mm D ₃ = 700 mm D ₄ = 420 mm t ₃ = t ₁ = 140 mm t ₀ = 90 mm t ₄ = 120 mm t ₅ = 20 mm

With respect to the upper pile, the outer diameter D ₃ of the pile is 15% or more larger than the shaft diameter D _{0 of the} lower end portion of the pile of the root consolidation portion, and the pile shaft portion (connecting portion) of the upper portion of the root consolidation portion of the lower pile. ) 43 is substantially the same as the shaft diameter D ₁ and smaller than the protrusion outer diameter D ₂ of the lower pile, and the inner diameter of the pile is substantially the same as the lower end of the pile,
Further the thickness t ₃ of該杭upper portion from the pile bottom end the wall thickness t ₀ 50
% Of the outer shell steel pipe concrete prefabricated piles are formed.

The PC steel rod 37 of the lower pile is formed from the lower end of the pile to the upper end of the connecting portion 43. Near the upper end of the lower pile, the deformed steel rod 44 is parallel to the outside of the PC steel rod 37. Are formed for reinforcement. Also, the connecting portion 4 on the upper part of the lower pile
Since the pile wall thickness t ₁ of _No. 3 is increased by 50% or more of the wall thickness t ₀ of the lower end portion of the pile, if it is desired to further strengthen it, the deformed steel bar 44 is extended to the upper part of the nodular projection 6 to reinforce it. You can also do it.

The upper pile has a wall thickness t of the outer shell steel pipe concrete pile.
_{Since 3} is 50% or more larger than the wall thickness t _{0 of the} lower end of the lower pile and has the same dimension as the wall thickness t ₁ of the connecting portion 43, the axial force of the upper pile can be borne by the entire outer shell concrete pile. In addition, the steel pipe portion 50 of the upper pile can also have an increased bending strength by using the steel pipe portion wall thickness dimension t ₅ which is thicker than the general-purpose SC pile,
It is possible to provide a pile foundation having a high bending strength corresponding to the high axial force of the pile foundation consolidation portion.

Further, depending on the required yield strength required from the building, since the strength of the connecting portion 43 of the lower pile is reinforced by the deformed steel rod 44 in this structure, the outer diameter D _{3 of the} upper pile is increased.
And the outer diameter D ₁ of the connecting portion 43 of the lower pile are made the same size, and additionally, if the upper pile wall thickness t ₃ is selected to be larger than the lower pile wall thickness t ₀ , the inner diameters of both piles are different. Is also possible. That is, even if the outer shell steel pipe concrete pile in which the inner diameter of the upper pile is smaller than the inner diameter of the lower pile is used, it is possible to provide a pile foundation having a more balanced axial force and bending strength than ever before.

[0079]

[Embodiment 7] Next, a foundation pile structure 10 in which the above-mentioned ready-made piles are buried in pile holes will be described.

(1) Structure of ready-made pile 4

The prefabricated pile 4 of this embodiment has the shaft portion 2 of the pile hole 1.
It is a hollow concrete pile composed of one or a plurality of upper piles 30 used in the portion located in the lower part and a lower pile 32 used in the part located in the pile hole 3 (FIG. 4).

The upper pile 30 has an outer diameter D ₃ (= 700 mm),
Wall thickness t ₃ (= 140 mm), concrete compressive strength 1
Example formed at 00 N / mm ² (FIG. 5C)
Will be described below.

The lower pile 32 has a shaft portion (lower shaft portion 3
3 outer diameter D ₀ (= 600 mm), shaft thickness t ₀ (90 m
m), protrusions (outer diameter D ₂ = 750 m) at the lower end and the middle part
m) Two 5 and 6 are formed, the upper end portion forms a straight pile-shaped upper shaft portion 43 having an outer diameter D ₁ , and the upper end portion of the upper shaft portion 43 is connected to the upper pile 30 (outer diameter D). ₁ = 700 mm) 34
Is formed, and the connection portion has a wall thickness t ₁ (= 140 mm) and a concrete strength of 100 N / mm ² .

Since the upper shaft portion 43 is integrally formed on the upper surface of the upper protrusion 6, the lower shaft portion 33 does not appear,
Since the upper shaft portion 43 having the outer diameter D ₁ is formed continuously with the outer diameter D ₂ of the annular rib 6, an annular surface is formed obliquely upward on the upper surface 6c of the outer peripheral portion of the protrusion 6. (FIG.7 (b)).

Since the pile used as the upper pile 30 usually has a large amount of pre-stress, the wall thickness of the upper and lower piles, concrete compressive strength, etc. are adjusted to satisfy the required axial force. . The space between the annular ribs 5 and 6 of the lower pile 32 is such that the annular rib 5 is formed at a position of 500 mm from the bottom surface 8a of the lower pile 32 and the annular rib 6 is formed at a position of 1500 mm. Further, the lower pile 32 is a bar arrangement in which spiral steel rebars 38 are provided around PC steel rods 37, 37 arranged at equal intervals along the circumference of the shaft portion 33. In addition, at the upper end portion of the upper shaft portion 43, the deformed rebars 44, 44 fixed to the joint end plate 45 are attached.
Are arranged in a ring. (FIGS. 7A and 7B).

By disposing the deformed steel rods 44 on the outer periphery of the PC steel rods 37 in this way, the pile head is prevented from being broken against vertical loads and bending moments acting from the above-ground structures and upper piles. can do. Further, in the case of the connecting pile, the vertical load (axial force) propagating from the upper pile 30 to the lower pile 32 can be transmitted to the consolidation portion 3 substantially uniformly.

Also in the upper pile 30, similarly to the upper end of the lower pile, the PC steel rod 37 and the deformed steel rod 44 may be arranged on the outer periphery of the thick wall portion of the lower pile to uniformly propagate the axial force. it can. At this time, it is desirable that the PC steel rod 37 rebar position of the upper pile 30 and the deformed steel bar 44 rebar position match.

(2) Foundation pile structure (burying method of foundation pile)

The pile hole 1 having the diameter D ₀₀ (= 780 mm) of the shaft portion 2 and the diameter D ₁₁ (= 1100 mm) of the expanded bottom portion 3 is excavated,
A predetermined solidifying strength (20 N / m
m ² ) cement milk is injected and soil cement mixed and mixed with the excavated soil is filled, and the shaft portion 2 of the pile hole 1 is injected with cement milk having a solidification strength (20 N / mm ² ) and stirred with the excavated soil.・ Mixed and soil cement (1.0N / mm
² ) to the pile hole mouth (Fig. 6 (a)).

Subsequently, the lower pile 32 is lowered while being rotated if necessary so as not to adhere dirt to the pile surface (FIG. 6 (b)), and the upper pile 30 is connected to the connecting portion 34 of the lower pile 32. It is connected and lowered (Fig. 6 (c)).

The lower pile 32 of the ready-made pile 4 is provided in the expanded bottom portion 3 of the pile hole 1.
Install the bottom edge of. Here, the bottom surface of the lower pile 32 of prefabricated pile 4 (the lowermost end face) 8a is placed at a height _D H1 (about 50 cm) from the ground bottom surface 11 of拡底portion 3. Also, lower pile 3
Interval _D H2 from the annular rib 6 uppermost of 2 to the horizontal plane X of the top of拡底section 3 (about 50 cm) is provided, connecting surface 3
4a (lower edge 31 of the upper pile, upper edge of the lower pile) is the shaft portion 2 of the pile hole 1
It is installed inside. By solidifying the soil cement, the pile structure 10 in which the ready-made piles 4 are buried in the pile holes 1 is constructed (Fig. 6 (d)).

In the pile structure 10 constructed as described above, the bottom face 8a and the downward faces 5a and 6a of the annular ribs 5 and 6 act on the vertical load (axial force). hand,
A significant increase in vertical load (axial force) can be achieved.

The annular ribs 5 and 6 are also resistant to the pulling force.
The upwardly directed surfaces 5a, 6c and the like act to obtain a high pulling resistance.

Further, the size and shape adjusting portion (protrusion 6 and its peripheral portion) adapted to connect the lower pile 32 and the upper pile 30.
That is, the shaft diameter changing part is arranged in the bottom expanding part 3 of the pile hole 1, and the stress of the dimension / shape adjusting part is absorbed by the entire layer of the bottom expanding part 3 to enhance the proof stress of the part. As mentioned above, the lack of proof stress due to stress concentration at the dimensional shape change part formed on the shaft part 2 is solved, and it is possible to form a pile having a higher vertical support force (axial force) and bending strength on the upper pile 30 than ever before. It has a basic pile structure that holds a certain degree.

[0095]

[Effects of the Invention] When a prefabricated pile having a projection is buried in a pile hole root-consolidated portion that has been excavated from the bottom and a pile structure with good quality by integrating the prefabricated pile and soil cement is constructed, one pile foundation is formed. The vertical load (axial force) and pull-out force that should be borne can be significantly (about twice) increased compared to conventional general construction methods, but bending strength can be similarly enhanced by adding the present invention to the pile construction. It is possible to provide a high yield strength pile having a good balance of axial strength, pulling strength and bending strength.

Further, specifically, a protrusion is provided in the root-consolidating portion, and the diameter of the upper shaft portion in the root-consolidating portion is adjusted to be larger than the lower-end portion shaft diameter and smaller than the protruding portion outer diameter, and the shape dimension is adjusted. The so-called adjustment part to be changed is also formed in the root consolidation part,
By embedding both in the high-quality expanded bottom root consolidation part to reinforce the strength of the adjusting part, and by adopting the outer shell steel pipe pile of the present invention specifications as the pile above this large diameter upper shaft diameter, , It is not necessary to excavate a shank of enlarged diameter dimension in the upper part of the pile hole, and the wall thickness of the concrete part of the pile shank can be made larger than the shaft diameter of the lower end part. You can also form and reinforce steel rods,
At the same time, the thickness of the steel pipe part can be made thicker than that of the conventional SC pile. Moreover, since the axial force of the upper part of the pile foundation is mainly applied to the concrete portion of the pile and the bending moment performance of the steel pipe can be selectively used, a wide range of pile yield strength can be selected.

Therefore, it is possible to enhance the axial force and bending performance of the pile foundation of the pile hole shaft portion and to adapt it to a wide range of required proof strengths, so that economical and high strength which could not be selected with conventional SC piles etc. We can provide high quality pile foundation.

Further, in a prefabricated pile in which the upper shaft portion has a larger diameter than the lower shaft portion, if the wall thickness of the upper shaft portion is thicker than that of the lower shaft portion, the inner diameter of the prefabricated pile is increased from the upper shaft portion to the lower shaft portion. It is possible to make them the same and to secure hollow portions having the same cross-sectional shape. Therefore, in the prefabricated pile or foundation pile structure of the present invention, it is possible to use the advantages of the medium excavation method such as less vibration and less damage to the prefabricated pile, and further to select the excavation rod to be used when applied to the medium excavation method. The width can be increased.

Further, according to the present invention, since a large-diameter and high-strength steel pipe is inserted into the upper shaft portion of the ready-made pile and the inside of the wall thickness of the concrete of the ready-made pile is reinforced by the deformed steel bar, the ready-made pile is provided. By filling the hollow part with cement milk or soil cement having a predetermined solidifying strength, the yield strength of the shaft portion of the foundation pile structure can be easily increased and the yield strength can be controlled to a desired value.

[Brief description of drawings]

FIG. 1 is a front view in which a part of a foundation pile (single pile) according to a first embodiment of the present invention is cut away.

FIG. 2 is a front view in which a part of a foundation pile (single pile) of Example 2 of the present invention is cut away.

FIG. 3 is a front view in which a part of a foundation pile (single pile) of Embodiment 3 of the present invention is cut away.

FIG. 4 is a front view of a foundation pile (joint pile) according to Examples 4 to 6 of the present invention.

5 (a) to (c) are enlarged front views of the joint portion of the foundation piles of Examples 4 to 6. FIG.

6 (a) to 6 (d) are vertical sectional views for explaining the construction of the foundation pile structure of the present invention.

FIG. 7 is a lower pile used for the foundation piles of Examples 4 to 6,
(A) is an enlarged cross-sectional view, (b) is a partial front view, and (c) is a schematic front view for explaining the reinforcement.

8 (a) to (c) are front views in which a part of a ready-made pile of a conventional example is cut away.

[Explanation of symbols]

1 pile hole 2 Shaft part of pile hole 3 Bottom expansion of pile holes 4 Ready-made piles 5 protrusions 6 Protrusion (Dimension adjustment part) 8a Bottom of ready-made pile 10 pile structure 11 Support ground surface 30 Upper pile 31 End pile end plate 32 Lower pile 33 Shaft of lower pile 34 Connection of lower pile 37 PC steel rod 38 spiral rebar 39 Deformed steel bar 43 Upper shaft of lower pile 44 Deformed steel bar 45 joint end plate 49 Recessed part 50 steel pipe

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2D041 AA02 BA12 BA13 BA17 CA03                       DB05 DB11                 2D046 CA01

Claims (5)

[Claims] 1. A concrete prefabricated pile having a hollow portion embedded in a pile hole in which a pile hole consolidation portion is formed below the pile hole stem portion, the lower shaft portion being located in the pile hole consolidation portion. An upper shaft portion having an outer diameter larger than that of the lower shaft portion is formed above the lower shaft portion via a size adjusting portion, and a protrusion is formed on an outer surface of the lower shaft portion, and at least an upper end portion of the upper shaft portion is formed. A prefabricated pile in which a steel rod is buried and a steel pipe is fitted to at least the upper end portion of the upper shaft portion. 2. A prefabricated concrete pile having a hollow portion embedded in a pile hole in which a pile hole consolidation portion is formed below a pile hole shaft portion, the lower pile being arranged in the pile hole consolidation portion. And one or a plurality of upper piles joined to the upper portion of the lower pile, the lower pile being above the lower shaft portion located in the pile hole root consolidation portion, the lower shaft being provided with a dimension adjusting portion. Forming an upper shaft portion having an outer diameter larger than that of the upper shaft portion, and forming a protrusion on the outer surface of the lower shaft portion, and having a diameter equal to or larger than that of the upper shaft portion at the upper end portion of the upper shaft portion. A prefabricated pile, characterized in that the upper pile is joined to the uppermost pile, a steel rod is embedded in at least the upper end of the uppermost pile, and a steel pipe is fitted at least outside the upper end. 3. The ready-made pile according to claim 1 or 2, wherein the outer diameter of the steel pipe is formed larger than the outer diameter of the lower shaft portion and smaller than the outer diameter of the protruding portion of the lower shaft portion. 4. The ready-made pile according to claim 1, wherein the thickness of the upper shaft portion is larger than that of the lower shaft portion. 5. A structure in which a cement pile is filled and a prefabricated pile is embedded in a pile hole formed by forming a root consolidation portion at the lower end of the pile hole shaft portion, wherein the prefabricated pile is a protrusion. An upper shaft portion having a diameter larger than that of the lower shaft portion is formed above the lower shaft portion having a portion through a size adjusting portion, and a steel pipe is fitted to at least an upper end portion of the upper shaft portion to form the pile. A foundation pile structure characterized in that a lower shaft portion and a dimension adjusting portion of a ready-made pile are located in a root consolidation portion of a hole, and a steel pipe is located near the ground of the pile hole.