JP2006090051A - Prefabricated concrete pile, manufacturing method of prefabricated concrete pile and foundation pile structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prefabricated concrete pile capable of maintaining high flexural proof stress of of an SC pile and high vertical bearing capacity by a lower inclined plane attached projection with the so-called SC pile (steel pipe coating concrete pile), contemplating an effective propagation of shear force toward the supporting ground by placing the projection in an enlarged bulb section so that vertical load and pull-out force can be further improved and easily forming the projection in an optional position of the outside of a steel pipe so that the projection can be formed in an appropriate position and the size in accordance with a ground characteristic, building required proof stress, required bearing capacity and shape, etc. of the enlarged bulb section. <P>SOLUTION: A projection forming member 10 of a steel material is welded and fixed to the lower end section of the steel pipe 5, and a closed space 41 is formed of the outside 6 of the steel pipe 5. The projection forming member 10 has a sideways trapezoid cross section forming up and down inclined planes 12 and 13 in both up and down sides of a vertical section 11 (b). The steel pipe 5 is installed in a centrifugal molding machine for a pile forming, and the prefabricated concrete pile 15 having the structure coating the steel pipe (an outside diameter D<SB>1</SB>and thickness t<SB>0</SB>) 5 is constituted on the circumference of a concrete body section (an inside diameter D<SB>2</SB>) 1 with manufacturing procedures of the usual SC pile (a). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a ready-made concrete pile related to a so-called SC pile in which the outer periphery of the concrete pile is covered with a steel pipe, a manufacturing method of the ready-made concrete pile, and a foundation pile structure in which the ready-made concrete pile is embedded in a pile hole.

  Conventionally, so-called SC piles in which the outer periphery of concrete is covered with steel pipes are prefabricated piles mainly strengthening bending strength against reinforced concrete piles (RC piles) and prestressed concrete piles (PC piles). Therefore, in the connection pile which joins and embeds many ready-made piles, it has mainly been arranged and used near the ground. Therefore, as a general idea, attempts have been made to form a node in the SC pile in order to simply increase the surface area and increase the frictional force with the ground, but naturally it has not been commercialized.

In the steel pipe pile, inventions have been proposed in which the diameter is locally increased from the inner side and a plurality of cylindrical protrusions are formed on the outer periphery (Patent Document 1, Patent Document 2). In this invention, a proposal has been made to line up with a fluidized solidifying agent to make the structure similar to an SC pile, but there is a problem in that the thickness of the protrusion becomes thin and the strength decreases.
JP 2000-129671 A JP2000-45274 Patent 3531099

(1) Problems of Cited Document 1 (Japanese Patent Laid-Open No. 2000-129671) In general, a joint pile is a ground having a small supporting force such as a soft ground, and is used as a foundation pile suitable for a load of a light building to be used.
Therefore, what is originally expected for the joint piles with protrusions formed on the entire length of the ready-made piles is the adhesive force with the surrounding ground, increasing the surface area of the outer surface of the ready-made piles, It is a grade used as a frictional force.
Therefore, it is not considered to make full use of the shearing force due to the protruding surface at the root consolidation part like foundation piles built on strong ground, and as concrete foundation piles with high bearing capacity (strength) The substance is not put into practical use.

(2) Problems of Cited Document 2 (Japanese Patent Laid-Open No. 2000-45274) The present invention is an outer shell steel pipe in which a steel pipe is processed and formed to form a rigid projection (for example, a node-like projection) and concrete is lined inside. It is a concrete pile, and the protrusion is formed at the lower end portion of the pile, and the protrusion at the lower end portion of the ready-made pile is installed at the widened root solidifying portion, thereby obtaining a large vertical support force.
However, in order to secure a high load propagation resistance with this protrusion, a high compressive force is required in the concrete portion inside the protrusion, and this protrusion requires factory production that is consistent with the ready-made pile.
For this reason, the flexibility for preparing and supplying ready-made piles with protrusions having dimensions and shapes corresponding to the ground characteristics at each construction site and the proof strength of the building, etc., corresponding to the required support force is inferior.
In addition, it is difficult to control the processing of the protrusions having a uniform thickness, and it is difficult to improve the yield strength and stability, and it is difficult to form protrusions that are thicker than the steel pipe.

(3) Problem In addition, the applicant installs a support pile having an annular projection at the lower end in the root consolidation portion of a pile hole filled with a high-strength root consolidation liquid, and has about twice the conventional support force. Proposed construction method (Patent No. 3531099) and has made many construction results. In this case, we could demonstrate unprecedented large support force in the root consolidation part, but we adopted a high strength upper pile with high bending strength etc. commensurate with the support force obtained by burying the lower pile in the root consolidation part Normally, large piles are connected and reinforced, but if the outer diameter is not increased and the upper pile has the same outer diameter as the lower pile, the outer periphery of the upper pile is made of steel pipe. It was necessary to employ a coated SC pile (having high bending strength).

  In addition, when a concrete pile is used as the lower pile for the root consolidation part and the pulling force acts on the foundation pile connected with the SC pile as the upper pile, the lower pile has a small pulling force of the pile material itself, The high pullout strength of SC pile could not be utilized.

  In this way, when the upper pile is an SC pile, the lower pile can be balanced with a more stable vertical support force and pull-out force by aligning the structure with the same outer diameter as the SC pile. High yield strength can be expected. Therefore, it is required to propose an SC pile having an annular rib and capable of effectively transmitting a shearing force toward the supporting ground within the rooting portion.

In view of the problems of the large frame as described above, it is an object of the present invention to realize a balanced high-strength ready-made pile that is commensurate with the high supporting force of the root-sealed portion in which the ready-made pile with protrusions is embedded.
(a) Pile structure commensurate with the high axial force of the root consolidation part.
(b) Pile structure that matches the high pulling force of the root consolidation part.
(c) Nodal shape that can withstand high bearing capacity (shearing force).
(d) Node mounting position where high bearing capacity can be developed.
(e) Versatile ready-made piles with protrusions.
(f) A versatile ready-made pile that can flexibly respond to the ground characteristics for each construction ground and the required proof stress for each building structure.
(g) A production system that can provide a stable supply at the SC pile production plant.

  However, the present invention is a ready-made pile in which the outer periphery of a cylindrical concrete base is covered with a steel pipe, and the outer surface of the steel pipe is made of steel, and at least the lower surface has a protrusion having an inclined surface inclined upward in the radial direction. Since the prefabricated concrete pile was formed, the above problems were solved.

  That is, the present invention is a prefabricated pile in which the outer periphery of a cylindrical concrete base is covered with a steel pipe, and a protrusion is formed at least on the lower end of the outer periphery of the steel pipe, and is positioned at least at the lowest end of the protrusion The protrusion to be made of steel is a ready-made concrete pile characterized in that an inclined surface inclined upward in the radial direction is formed on at least the lower surface.

  Another invention is a ready-made pile in which the outer periphery of a cylindrical concrete base is covered with a steel pipe, and a protrusion is formed at least at the lower end of the outer periphery of the steel pipe, and the protrusion is made of a steel material. The ready-made concrete pile is characterized in that an inclined surface inclined upward in the radial direction is formed on at least the lower surface.

Moreover, in the above, it is a ready-made concrete pile characterized by having the following structure as a protrusion.
(1) It is formed in an annular shape and has an upper inclined surface and a lower inclined surface.
(2) When a load is applied downward, the shear force propagates in a conical shape obliquely downward from the lower inclined surface.
(3) When a pulling force is applied upward, the shear force propagates in an inverted conical shape obliquely upward from the upper inclined surface.

Further, in the above, the protrusion is a ready-made concrete pile characterized in that a closed space is formed between the inner surface of the protrusion and the outer surface of the steel pipe.
Moreover, another invention is a manufacturing method of the ready-made concrete pile characterized by shape | molding in the following procedures.
(1) An annular steel material capable of forming an annular protrusion is fixed to at least the lower end portion of the outer surface of the integrally or divided steel pipe, and a closed space is formed between the annular protrusion and the outer surface of the steel pipe.
(2) The steel pipe is installed in a centrifugal molding machine for concrete pile molding.
(3) A predetermined concrete is poured into the steel pipe and centrifugally formed.

Further, in another foundation, in a foundation pile structure in which a ready-made concrete pile whose outer periphery is covered with a steel pipe is embedded in a drilling hole, the ready-made concrete pile has at least one protrusion formed at a lower end, At least one projecting portion of the ready-made concrete pile is disposed in the root consolidation portion formed at the lower end portion of the excavation hole, the projection portion is made of steel, and obliquely toward the support ground in the root consolidation portion. It is a foundation pile structure characterized by having a structure having an inclined lower surface that enables propagation of a shearing force downward.

  The “concrete” in the above is a hydraulic material mainly composed of cement. Therefore, mortar is included regardless of the presence or absence of coarse aggregate, and the presence or absence of aggregate is not limited as long as it has a predetermined strength.

(1) A so-called SC pile with the outer periphery of a cylindrical concrete base covered with a steel pipe, and a protrusion made of steel material was formed on the outer periphery of the steel pipe, and the lower slope of the predetermined protrusion was formed. If a projection is placed on the enlarged bulb part of the borehole while maintaining the vertical bearing force, effective propagation of shearing force toward the supporting ground will occur in the enlarged bulb part when a vertical load is applied. Can withstand vertical loads.

(2) Since the concrete base is covered with a steel pipe and the protrusions of the steel material are placed on the outer surface of the steel pipe in the proper dimensions and in the proper position, they are equivalent to the high bearing capacity foundation pile structure using PC piles. High bearing capacity can be expressed. At the same time, as the pile material, it is possible to use more than 5 times higher pulling force than the concrete ready-made piles for root-tightening bulbs. .

(3) Since it is a projection made of steel, it can be easily attached to any position on the outer surface of the steel pipe, so it is suitable for the ground characteristics, the required strength of the building, the required supporting force, the shape of the enlarged bulb, etc. -There is an effect that a protrusion can be formed in a size. Therefore, ready-made piles adapted to the required conditions can be easily supplied. That is, it is possible to easily meet a desired requirement by fixing a projection having a predetermined shape and dimension to a normal SC pile.

  In addition, since a projection made of another steel material is retrofitted on the outer surface of the steel pipe, a projection having a uniform thickness is formed and each proof stress is stabilized. Furthermore, since a thicker projection than the steel pipe can be easily formed, it is possible to cope with a required high strength foundation.

(1) The projection forming member 10 made of steel is welded and fixed to the lower end portion of the steel pipe 5, and the closed space 41 is formed by the projection forming member 10 and the outer surface 6 of the steel pipe 5.

  The protrusion forming member 10 has a trapezoidal cross-sectional shape and rises from the upper edge 11a of the ring-shaped vertical portion (position corresponding to the upper base of the trapezoid) 11 toward the outer surface 6 side (center side) of the steel pipe 5. An upper slope 12 is formed, and a lower slope 13 descending from the lower edge 11b of the vertical portion 11 toward the outer surface 6 side (center side) of the steel pipe 5 is formed (that is, the lower slope 13 is directed in the radial direction). Formed with an upward slope). The inner peripheral edge 12a of the upper inclined surface 12 and the inner peripheral edge 13a of the lower inclined surface 13 are in contact with the outer surface 6 of the steel pipe 5, and are welded at the contact line (FIG. 3 (b)). In addition, a flange etc. can be formed in the end of the up-and-down slopes 12 and 13 irrespective of welding, and it can also fix with a volt | bolt etc. (not shown).

  The protrusion forming member 10 is an annular member that is installed on the outer surface 6 of the steel pipe 5. However, when mounting, a semicircular protrusion forming member piece divided in two in the diameter direction can be used in combination. (Not shown). The upper slope 12 and the lower slope 13 are formed symmetrically with respect to a horizontal line passing through the center of the vertical portion 11.

(2) Then, according to the procedure for manufacturing a normal SC pile, the steel pipe 5 is installed in a centrifugal molding machine for pile forming (not shown).

(3) According to the procedure for manufacturing a normal SC pile, concrete is poured into the steel pipe 5, centrifugally formed, demolded and cured, and a normal SC pile is obtained. That is, the outer periphery of the concrete main body (inner diameter D ₂ ) 1 is covered with the steel pipe (outer diameter D ₁ , thickness t ₀ ) 5.

(4) The ready-made concrete pile 15 of this invention is comprised as mentioned above (FIG. 3, FIG.5 (c)).

For example, the ready-made concrete pile 15 and the protrusion forming member 10 have the following numerical values, for example.
-Ready-made concrete pile 15 (lower pile 35)
Shaft diameter (outer diameter of steel pipe) D ₀ = 600 mm
Diameter D ₁ of the annular projection 17 portion = 750 mm
Length from the bottom of the pile to the lowermost annular projection L ₂ = 500 mm
Length from pile bottom to second annular protrusion L ₃ = 1500mm
Interval L _{4 in} the vertical direction of each annular projection 17 = 1000 mm
Steel pipe thickness t ₀ = 6 mm
Steel pipe outer diameter D ₁ = 600 mm
Steel pipe + concrete part thickness D ₄ = 90 mm
Projection forming member 10 Angle θ ₁ = 45 ° formed by horizontal and upper slope 12
Angle θ ₂ = 45 ° between horizontal and lower slope 12
From the outer surface 6 of the steel pipe 5 to the vertical part 11
Radial length (projection height) D ₃ = 75 mm
Steel thickness t ₁ = 9 mm (SKK400 material)
Height L ₆ of the vertical part 11 = 75 mm
Height of upper slope 12 L ₇ = 75 mm
Lower slope 13 height L ₈ = 75 mm

(5) when formed in dimensions such as described above, in the steel tube 5 and the annular projection 17 (projection forming member 10) cross-sectional area of the weld at the junction between 33929Mm ^2, stress 79.7N / mm ² of the weld It is possible and can bear 2704 kN with one annular protrusion, so that it can exhibit a short-term support force of about 7510 kN (safety factor 1.70) as a foundation pile.

(6) Here, when the ready-made concrete pile 15 is placed in the excavation hole 31 having the enlarged bulb portion 33, when the shear force is effectively propagated, for example, the excavation hole has the following size and shape. It is desirable to store the ready-made concrete pile 15 in a predetermined position (FIG. 3A).
・ Drilling hole 31
Drilling diameter D ₁₀ of the shaft portion 32 = 780 mm
Excavation diameter D ₁₁ = 1100 mm of the enlarged bulb portion 33
Length L ₁₁ of the expanded bulb portion 33 = 2500 mm
From the bottom 34 of the enlarged bulb 33
Distance L ₁₂ = 500 mm of the lower surface 16 of the ready-made concrete pile 15
From the upper end 34a of the enlarged bulb 33
Distance to the annular protrusion 17 located on the lower side L ₁₃ = 500 mm

(7) Other configurations

(a) In the above, since the protrusion forming member 10 is formed as a separate member from the steel pipe 5 (not formed by bulging from the steel pipe 5), it can be formed in a desired and uniform thickness. . In addition, the thickness t ₁ can be appropriately set according to each required yield strength regardless of the thickness t ₀ of the steel pipe 5.

(b) Since the angles θ ₁ and θ _{2 in the above} are about 30 to 45 ° in the propagation angle of the shearing force in the enlarged bulb portion (root consolidation portion) when a vertical load or a pulling force is applied, In view of this, it is desirable to select and set as appropriate at 30 to 45 degrees so that the propagation destination of the shear force is generated from the upper and lower slopes 12 and 13 at an angle close to a radial shape.

(c) Usually, no projection is formed near the lower surface 16 of the ready-made concrete pile 15, but the lower slope 13 is formed even when the projection forming member 10 is fixed and the annular projection 17 is formed near the bottom of the pile. It is desirable to maintain the inclination angle. For example, when the bottom surface of the pile is leveled, the annular protrusion 17 is easily deformed at the time of burying and transferring the pile, and the stability is not good from the viewpoint of load propagation strength.

(d) In the above description, the protrusion forming member 10 forms a closed space 41 between the outer surface 6 of the steel pipe 5 and the closed space 41 is hollow. ) And high-strength concrete of the same level as the concrete main body 1 can be filled in the closed space 17 (not shown). Moreover, it can also be filled with concrete that is not so strong other than high-strength concrete. When various kinds of concrete are filled in the closed space 41, it is desirable because the load can be smoothly propagated and formed into a shape having a strength that does not deform by the load, and versatility can be improved.

  However, the operation of forming an opening (injection port) in the protrusion forming member 10 and filling various concrete is not efficient, and it is difficult to maintain the quality of the concrete to be solidified. When the rigidity is further strengthened, the thickness and size of the protrusion forming member 10 itself are set so that the protrusion forming member 10 itself can exhibit necessary strength and rigidity while keeping the closed space 41 hollow. It is desirable to ensure it in order to ensure the strength. Of course, the protrusion forming member 10 itself can be a steel block.

(e) In the above description, the two projection forming members 10 are provided. However, when the ready-made concrete pile 15 is embedded in the excavation hole with the enlarged bulb portion, at least one annular projection 17 is arranged in the enlarged bulb portion. If so, high yield strength is achieved (not shown). For example, there are a plurality according to certainty and required proof stress, three (FIG. 5 (b)), four (FIG. 4 (a)), five (FIG. 5 (e)), and six (FIG. 5 (a) ( d)) It can also be fixed.

(f) In the above, the upper end 7 and the lower end 8 of the steel pipe 5 have the same diameter, but the upper end 7 side can also be formed with a large diameter _DT (FIGS. 4B and 5B). (D) (e)). For example, a small-diameter steel pipe 5 is inserted and configured inside the upper outer diameter _DT steel pipe 5. In this case, the protrusion forming member 10 can be fixed to the stepped portion 43 whose outer diameter changes (FIGS. 4B, 5B, and 5D).

(g) In the above description, the distance L ₄ between the protrusion forming members 10 and 10 is such that the stress does not concentrate and the shear force does not overlap when installed on the enlarged bulb 33, and the shear force propagates effectively. It is set so that it is equally spaced so that it is possible. In this case, since the projection forming member 10 is formed of a member different from the steel pipe 5, an optimum position can be selected and attached depending on the required support force and the properties of the enlarged bulb portion.

  Note that the protrusion forming member 10 that is not disposed on the enlarged bulb portion can achieve its purpose if it is appropriately disposed so as to ensure a necessary outer surface area.

  Embodiments of the present invention will be described with reference to the drawings.

[1] Composition of ready-made concrete piles

(1) The ready-made concrete pile 15 of this invention is covered with a steel pipe (outer diameter D ₁ ) having a thickness t _{0 over} the entire length of the outer periphery of the concrete main body (length L ₁ , inner diameter D ₂ ). The protrusion-forming members 10 and 10 made of steel material having a thickness t ₁ are welded and fixed from the lower end 8 to the positions of the lengths L ₂ and L ₃ on the outer surface 6 (FIG. 3B). Here, over the entire length of the steel pipe 5, at regular intervals L _4, it is fixed to four protrusions forming member 10 (Figure 4 (a)).

  The protrusion forming member 10 has a ring shape in which a vertical portion 11 and upper and lower slopes 12 and 13 are formed above and below the vertical portion 11, respectively, and constitutes an annular protrusion 17 as a whole. The protrusion forming member 10 has a vertical portion 11 having the largest diameter at the center and a vertical outer periphery, and an upper slope having a small diameter from the upper end 11a of the vertical portion 11 toward the center (inner periphery) obliquely upward. 12 and a lower slope 13 having a small diameter from the lower end 11b of the vertical portion 11 toward the center (inner peripheral edge) obliquely downward.

  The upper slope 12 and the lower slope 13 are formed symmetrically with respect to a horizontal plane passing through the center of the vertical portion 11.

[2] Foundation pile structure 50

Next, the foundation pile structure of this invention which uses a ready-made concrete pile is demonstrated.

(1) The lower pile 35 has the same structure as described above, and the ready-made concrete pile 15 (four annular protrusions 17, 17 is formed by covering the outer periphery of the concrete main body 1 with the steel pipe 5, fixing the protrusion forming member 10, and forming four annular protrusions 17, 17. Shaft outer diameter D ₀ , inner diameter D ₂ , and protrusion outer diameter D ₁ ). The upper pile 36 has the same shaft outer diameter D ₁ and inner diameter D _{2 as} the lower pile 35, and is a straight-shaped (no annular protrusion 17) ready-made concrete pile in which the outer periphery of the concrete main body 1 is covered with a steel pipe 5. (Conventional so-called SC pile) (FIGS. 1 and 3).

(2) The excavation rod 20 used in the present invention is constructed by connecting an intermediate rod 24 with a spiral blade 25 attached to the lower end of a rod body 21 and further connecting an excavation head 26 therebelow. The rod body 21 has stirring bars 22 and 22 and kneading drums 23 and 23 attached thereto. The excavation head 26 is configured by swingably attaching excavation arms 29 and 29 having excavation blades 30 and 30 at the lower end to a head main body 27 having fixed excavation blades 28 and 28 at the lower end (FIG. 2).

(3) Attach the excavating rod 20 to the auger drive device of the pile driving machine, stir the inside of the hole while kneading the drilling fluid from the tip of the excavating head 26 at a predetermined position on the ground 39, and knead the mud into the hole wall. The shaft portion 32 of the excavation hole 31 is excavated. After excavating with a positive rotation to a predetermined depth, the excavating rod 20 is repeated up and down, sufficiently stirred, and the hole wall is kneaded to build the excavating hole 31 (FIG. 1A).

(4) The excavation rod 20 is reversed and the excavation arms 29 and 29 are swung to the other side to increase the excavation diameter from the tip of the excavation hole 31 to a predetermined length section. Excavate (root consolidation part) 33. Next, rooting solution 45 (cement milk with water / cement ratio = 60%, 4 weeks compressive strength = 20 N / mm ² , predetermined amount of excavation volume) is injected into this range, and the excavation mud is replaced and stirred and mixed, The enlarged bulb part 3 filled with the root hardening liquid is constructed (FIG. 1 (b)).

For example, the following numerical values are adopted as the formulation of the root hardening liquid 45 in accordance with, for example, the bore diameter to be excavated. Here, normally, Portland cement is usually used as the cement, but early-strength cement, blast furnace cement, silica cement, and the like may be used as necessary.

(5) Pile circumference fixing liquid 46 (water cement ratio = 60% cement milk, 4 weeks compressive strength = 20 N / mm ² ) is injected from the tip of the excavation hole 31, and the inside of the excavation hole 31 is mixed and stirred. Then, the excavation rod 20 is pulled up (FIG. 1 (d)).

Moreover, the following numerical value is employ | adopted for the mixing | blending of the pile periphery fixing liquid 46 according to a drilling diameter. At this time, the injection amount is an amount that considers the volume of the upper and lower piles 35 and 36, and the portion where the projection forming member 10 is fixed and the annular projection 17 is formed is 20% of the volume in the hole and the straight without the annular projection 17 In the part, 10% of the volume in the hole is standard.

(6) The lower pile 35 (the ready-made concrete pile 15) is set in the excavation hole 31 with its own weight or while rotating, and is held to the ground 39 in a state where it is set to a predetermined depth. It joins, it is set as a connection pile, a holding | maintenance is cancelled | released, and a connection pile (upper pile 36 + lower pile 35) is subsequently laid (FIG.1 (e)).

(7) Finally, it press-fits or rotationally sinks and installs the connection pile (upper pile 36 + lower pile 35) at a predetermined depth (FIG. 1 (f)). In this case, the two annular protrusions 17 and 17 of the lower pile are disposed in the enlarged bulb portion 33 (FIG. 1 (f) and FIG. 4 (a)).

(8) The foundation pile structure 50 of this invention is comprised as mentioned above (FIG.1 (f)).
here,
-Ready-made concrete pile 15 (lower pile 35)
Shaft diameter D ₀ = 600 mm
Diameter D ₁ of the annular projection 17 portion = 750 mm
Length L ₂ = 500 mm from the pile bottom 16 to the lowermost annular projection 17
Length L ₃ from the pile bottom 16 to the second annular protrusion 17 = 1500 mm
Interval L _{4 in} the vertical direction of each annular projection 17 = 1000 mm
・ Drilling hole 31
Drilling diameter D ₁₀ of the shaft portion 32 = 780 mm
Excavation diameter D ₁₁ = 1100 mm of the enlarged bulb portion 33
Length L ₁₁ of the expanded bulb portion 33 = 2500 mm
From the bottom 34 of the enlarged bulb 33
Distance L ₁₂ = 500 mm to the bottom 16 of the ready-made concrete pile 15
From the upper end 34a of the enlarged bulb 33
Distance to the annular protrusion 17 located on the lower side L ₁₃ = 500 mm
Distance to the annular protrusion 17 located on the upper side L ₁₄ = 500 mm

[4] Test example

(1) Ground characteristics, pile length, pile configuration, etc. Lower pile 35 Ready-made concrete pile 15 of the present invention FIG. 4 (a)
Pile length L ₁ = 5m
Number of annular protrusions 4
Upper pile 36 SC pile
Pile length 44m
Steel pipe outer diameter D ₁ = 600 mm
Tip ground Soil Sand, N value 32.5

(2) Drilling hole 31
Enlarged bulb 33
Length L ₁₁ = 2500mm
Diameter D ₁₁ = 1100mm
Pile under length L ₁₂ = 500mm
Width between node and bulb top L ₁₃ = 500mm

(3) Drilling hole 31
Shaft 32 (depth 42m)
Drilling diameter D ₁₀ = 780 mm

(4) The root hardening liquid 45 and the pile circumference fixing liquid 46 are the same as in the above embodiment.

(5) Loading test result It became 7492 kN at the time of the maximum load, and demonstrated the same high bearing force as the case where it was embed | buried in the same excavation hole 31 by making a lower pile into a PC pile.

(5) Peeling strength of pile material:
Concrete pile (φ600): 57t / piece (A type), × 2 (C type) ... Conventional SC pile (φ600, t = 12mm), 480t / piece, 240t / piece (t = 6mm)
More than 5 times the capacity of conventional concrete piles.

[4] Other embodiments

(1) In the said Example, it consists of an upper pile, a middle pile, and a lower pile, the lower pile 35 is made into the ready-made concrete pile 15 of this invention which has the cyclic | annular protrusion 17, and the upper pile 36 and the middle pile 37 are normal SC piles. However, if the ready-made concrete pile 15 of this invention which has the cyclic | annular protrusion 17 is used for the lower pile 35 (FIG.6 (c)), the structure of a connection pile is arbitrary.

  For example, a connection pile is comprised by the combination of the lower pile 35, the middle pile 37, and the upper pile 36 (FIG. 6, FIG. 7), and this whole which has the cyclic | annular protrusion 17 of the lower pile 35, the middle pile 37, and the upper pile 36. Use the ready-made concrete pile 15 of the invention (FIG. 6A), use the ready-made concrete pile 15 of the present invention having the annular protrusion 17 as the lower pile 35 and the middle pile 37, and make the upper pile 36 the SC pile. (FIG. 6B).

  Moreover, it is also possible to use a pile having different outer diameters in the lower pile 35 and the upper pile 36 by using the middle pile 37 in which the stepped portion 43 is formed so that the outer diameter is different between the upper and lower sides (FIG. 6D (E)).

(A)-(f) is the general | schematic sectional drawing explaining the embedding method of the foundation pile of the Example of this invention. It is a front view of the excavation rod used for the Example of this invention. It is a ready-made pile of the Example of this invention, (a) is a partial front view, (b) is a partially expanded longitudinal cross-sectional view. (A) (b) is a front view of the ready-made pile of another Example. (A)-(e) is a front view of the ready-made pile of another Example, (f) (g) is a front view of the conventional ready-made pile used combining in an Example. (A)-(e) is a front view of the foundation pile structure of this invention. (A)-(c) is a front view of another foundation pile structure similarly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Concrete body part 5 Steel pipe 6 Outer surface 7 of a steel pipe Upper end 8 of a steel pipe Lower end 10 of a steel pipe 10 Protrusion forming member 11 Vertical part 12 Upper slope 13 Lower slope 15 Ready-made concrete pile 16 Lower face 17 of ready-made concrete pile Annular protrusion 20 Excavation rod 21 Rod body 24 intermediate rod 26 excavation head 27 head main body 28 fixed excavation blade 29 excavation arm 30 excavation blade 31 excavation hole 32 excavation hole shaft portion 33 excavation hole enlargement bulb portion 34 enlargement bulb portion lower end 34a enlargement bulb portion upper end 35 lower pile 36 Upper pile 37 Middle pile 39 Above ground 41 Closed space 45 Root solidification liquid 46 Pile circumference fixing liquid 50 Foundation pile structure

Claims (6)

The outer periphery of a cylindrical concrete base is covered with a steel pipe, and at the outer periphery of the steel pipe, at least the lower end portion is a ready-made pile having a protrusion,
A protrusion located at the lowest end among the protrusions is made of a steel material, and an inclined surface inclined upward in the radial direction is formed on at least a lower surface of the ready-made concrete pile. The outer periphery of a cylindrical concrete base is covered with a steel pipe, and at the outer periphery of the steel pipe, at least the lower end portion is a ready-made pile having a protrusion,
The protrusion is made of steel, and has an inclined surface inclined upward in the radial direction on at least the lower surface. The ready-made concrete pile according to claim 1, wherein the protrusion has the following configuration.
(1) It is formed in an annular shape and has an upper inclined surface and a lower inclined surface.
(2) When a load is applied downward, the shear force propagates in a conical shape obliquely downward from the lower inclined surface.
(3) When a pulling force is applied upward, the shear force propagates in an inverted conical shape obliquely upward from the upper inclined surface. The ready-made concrete pile according to claim 1, wherein the protrusion forms a closed space between the inner surface of the protrusion and the outer surface of the steel pipe. The manufacturing method of the ready-made concrete pile characterized by shape | molding in the following procedures.
(1) An annular steel material capable of forming an annular protrusion is fixed to at least the lower end portion of the outer surface of the integrally or divided steel pipe, and a closed space is formed between the annular protrusion and the outer surface of the steel pipe.
(2) The steel pipe is installed in a centrifugal molding machine for concrete pile molding.
(3) Pour predetermined concrete into the steel pipe and perform centrifugal forming. In the foundation pile structure in which a ready-made concrete pile whose outer periphery is covered with a steel pipe is buried in the excavation hole,
The ready-made concrete pile has at least one protrusion formed on the lower end,
In the root consolidation part formed in the lower end part of the excavation hole, at least one projection part of the ready-made concrete pile is arranged, the projection part is made of a steel material, toward the support ground in the root consolidation part, A foundation pile structure characterized by having a structure having an inclined lower surface that allows shearing force to propagate obliquely downward.

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