JP2018193686A - Construction method of support pile - Google Patents

Abstract

To increase pile strength and withdrawal resistance with simple construction.SOLUTION: A construction method of a support pile 1 includes: a steel pipe installing step of installing a steel pipe; an excavating step of excavating an inside of the steel pipe while installing or after installing the steel pipe; a concave forming step of expanding an inner wall of the steel pipe to form a concave portion 17a on an inner surface; a solidifying material filling step of filling concrete C in a range including the concave portion 17a in the steel pipe; and a pressurizing step of pressurizing the filled concrete C. In the pressurizing step, as a pressurizing device 19, a lid portion 20 installed in the supporting pile 1 is pressed by a press-fitting machine 3 through an inner pipe 21 to pressurize the concrete C, and forms an enlarged diameter bulb having a larger diameter than the steel pipe of the support pile 1 at a lower end portion of the support pile 1.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a construction method of a ground bite type support pile used for a foundation of a structure, for example.

Conventionally, support piles are used as pile foundations for foundation structures. The support pile has the tip reaching the support layer, and supports the load mainly by the tip support force acting on the tip of the pile.
For example, when the support pile described in Patent Document 1 is used to embed a steel pipe or concrete support pile in the ground, the support pile is formed by forming an enlarged diameter portion on the outer periphery of the lower end portion of the support pile. And is embedded in the root consolidation part, and the root consolidation liquid is injected into the root consolidation part and solidified. The concrete inside the support pile is filled with concrete and solidified.

  Moreover, in the construction method of the support pile described in patent document 2, a steel pipe is embed | buried to predetermined depth by casting, a press fit, or a rotary construction method, and the soil in a steel pipe is discharged to the predetermined depth. Then, a diameter expanding device is inserted into the steel pipe from the opening at the upper end, and the protruding portion that expands the diameter of the steel pipe from the inside and expands to the outer periphery is formed in multiple stages, and this protruding portion is pressed or penetrated into the natural ground surface.

Japanese Patent No. 3664361 JP 2000-120066 A

However, in the method for constructing a support pile described in Patent Document 1, a vertical hole is formed in advance by an excavator to form a large-diameter root-solidified portion in the support layer of the ground, and a root-setting liquid or After injecting the surrounding solidification liquid, the support pile with the enlarged diameter part is inserted at the lower end, so the pile will not enter unless the root solidification liquid or the surrounding solidification liquid for the volume of the support pile to be inserted comes out above the ground. . The support pile itself is surrounded by root hardening liquid and surrounding hardening liquid, and it is not the support pile that directly contacts the ground. That is, even if a multistage enlarged diameter portion is provided in the support portion, the friction with the ground has not been improved.
Moreover, since the construction method of the support pile described in patent document 2 forms a several enlarged diameter part in the longitudinal direction of the press-fitted steel pipe at predetermined intervals, in order to strengthen ground strength, pile strength, and drawing resistance Multi-stage enlarged diameter portions are formed at predetermined intervals in the longitudinal direction of the steel pipe. However, this construction method is a method to increase the peripheral friction of the pile to obtain a supporting force, and in most grounds, the middle is soft and there are many support layers below, so that it is not possible to obtain a sufficient supporting force There's a problem.

  This invention is made | formed in view of the situation mentioned above, Comprising: It aims at providing the construction method of the support pile which enabled it to increase pile strength and extraction resistance by simple construction.

That is, the construction method of the support pile according to the present invention includes a steel pipe placing process for placing a steel pipe, a drilling process for excavating the steel pipe while or after placing the steel pipe, and expanding the inner wall of the steel pipe. A recess forming step for forming a recess, a solidifying material filling step for filling the solidified material in a range including the recess in the steel pipe, and a pressurizing step for pressurizing the filled solidified material. .
According to the present invention, since the solidified material is pressurized and solidified after filling the solidified material including the recessed portion whose inner wall is expanded in the inside of the support pile, the concave portion has high integrity between the steel pipe and the solidified material. Pulling resistance can be increased by strength, and stress concentration does not occur because no slit is formed in the steel pipe.

Further, in the pressurizing step, it is preferable that the solidified material is protruded from the lower end portion of the support pile to form the expanded portion of the solidified material that is larger than the diameter of the steel pipe.
The strength and pull-out resistance of the support pile can be further improved by forming a diameter-enlarged portion of the solidified material that is expanded from the diameter of the steel pipe at the lower end portion of the support pile.
In addition, according to the present invention, the peripheral ground tends to decrease in the collapse direction from the original state due to the strength of the groundwater and the soil of the excavation surface when it is a method of expanding the expanded diameter portion by excavation, Since the peripheral ground is consolidated in the pressurizing step, the peripheral ground can be strengthened.

Further, in the pressurizing step, it is preferable to cause the solidified material protruding from the lower end of the steel pipe to bite into the support ground.
By causing the pressurized solidified material protruding from the lower end portion of the support pile to bite into the support ground, the strength and pull-out resistance of the support pile can be further improved without forming an enlarged diameter portion.

Moreover, you may make it pressurize solidification material with a pressurization apparatus in a pressurization process.
Specifically, the pressurizing device can press the solidified material by a press-fitting machine.
By pressurizing the solidified material in the steel pipe through the lid with a press-fitting machine used for press-fitting the support pile, the solidified material can be efficiently pressed without using a separate facility. Moreover, the resistance at the time of pressing is only the frictional resistance between the inner surface of the support pile and the solidified material, and the solidified material can be easily pressed.

Moreover, a pressurization apparatus may make it pressurize solidification material by fixing a cover part in a steel pipe, and pushing a steel pipe with a press-fitting machine.
Since the lid portion is fixed to the upper surface of the solidified material in the support pile, the lid portion is also pushed by pressing the steel pipe with a press-fitting machine, so that the solidified material can be pressurized.

The pressurizing device may fix the cylinder device in the steel pipe and pressurize the solidified material by the cylinder device.
The solidified material can be pressurized by pushing the solidified material through the lid with a cylinder device fixed in the support pile, and the resistance when pushing is only the frictional resistance between the inner surface of the support pile and the solidified material. Easy to press.

According to the construction method of the support pile according to the present invention, since the solidified material is filled in the concave portion formed in the support pile and then pressed and solidified, the integrity of the support pile and the solidified material is increased. However, the pulling resistance can be increased with high strength.
And since it is not necessary to form a multistage projection part in a support pile at predetermined intervals, a construction man-hour and cost can be reduced.

It is a figure which shows the excavation process of the support pile by 1st embodiment of this invention. It is a figure which shows the soil removal process inside a support pile. It is a figure of the diameter-expansion process and projection part which form a projection part in a support pile. It is a figure of the process of filling a support pile with concrete. It is a figure of the process of pressurizing the concrete in a support pile. It is a figure which shows the other method of pressurizing concrete, (a) is a figure of the pressurization method which fixes a cover part with a jack and press-fits a support pile, (b) is the pressurization method which pressurizes concrete with a press-fit cylinder FIG. It is explanatory drawing of the support pile constructed by this embodiment. It is a figure which shows the construction method of the support pile by 2nd embodiment of this invention, and shows a soil removal process. It is explanatory drawing of the support pile constructed by this 2nd embodiment. It is explanatory drawing of the pressurized support pile.

Hereinafter, the construction method of the support pile by each embodiment of this invention is demonstrated with an accompanying drawing.
FIG. 1 thru | or FIG. 7 is a figure which shows the construction method of the support pile by 1st embodiment of this invention.
The construction method of the support pile 1 by this embodiment is a method of press-fitting or rotationally press-fitting into the ground 2 using the press-fitting machine 3, for example. The support pile 1 is placed in order to fix a structure such as a breakwater on the ground 2. The support pile 1 consists of a pile of steel pipes as shown in FIG. 1, and the excavation tooth 1a is formed in the lower end part. The press-fitting machine 3 installs the clamp 4 on the reaction force weight 5 or the existing support pile 1 to take the reaction force, and drives the steel pipe as the support pile 1.

Hereinafter, the method of constructing the support pile 1 using a steel pipe will be described.
In the steel pipe placing step shown in FIG. 1, the steel pipe is buried as a support pile 1 at a predetermined construction position using a press-fitting machine 3. The support pile 1 is buried by press-fitting or rotary press-fitting. At the time of press-fitting, the support pile 1 is excavated in the ground 2 until reaching the harder support ground 7 as shown in FIG. Thereafter, the support pile 1 is pulled up by a predetermined stroke a for forming an expanded bulb with concrete (see FIG. 4). In this case, a portion without the steel pipe is formed between the lower end portion of the support pile 1 and the support ground 7, but the ground 2 does not collapse because concrete is contained. When the support pile 1 reaches the support ground 7, the strength of the support ground 7 can be confirmed by the pressure of the press-fitting machine 3 at the time of press-fitting.

Next, in the earth removal process in the support pile 1 shown in FIG. 2, the inside of the support pile 1 is excavated and excavated by the excavator 9. The excavation inside the support pile 1 may be performed after the press-fitting of the steel pipe, or may be excavated while being pressed and discharged.
After the soil removal in the support pile 1 is completed, the process proceeds to the diameter expansion process. As shown in FIG. 3, a diameter expanding device 11 for expanding the inner diameter of the steel pipe is inserted into the support pile 1. Here, the diameter expansion device 11 includes a pressing portion 13 that is provided in the device main body 12 and can be advanced and retracted in the inner wall direction of the steel pipe, that is, in the radial direction, and a jack portion 14 that advances and retracts the pressing portion 13. In addition, a suspension portion 15 including a wire that stabilizes the posture and moves up and down in the vertical direction and a hydraulic hose for operating the diameter expansion device is connected to the apparatus main body 12.

The pressing portion 13 can employ an appropriate toe portion such as a tapered cone shape or a polygonal cone shape. The tip of the pressing portion 13 is preferably formed with a round chamfer or the like so that a notched hole communicating with the outside is not formed in the steel pipe when the diameter is expanded.
When notched holes are formed in the support pile 1, the stress is concentrated and the strength of the pile is reduced, and the quality of the concrete that is filled with water and earth and sand from the surrounding ground 2 flows into the support pile 1 is deteriorated. There is a risk of causing. Moreover, when the lower end part of the support pile 1 reaches the support ground 7 which is a hard ground, a large resistance is added to the excavation tooth 1a, stress concentration is generated in the notch hole, and the pile strength is lowered. Moreover, the process is required. In that respect, in this embodiment, since the steel pipe in a normal state in which notched holes are not formed in the steel pipe can be used, it is possible to suppress the decrease in pile strength and prevent the surrounding ground 2 from flowing in water and earth and sand. Cost is also reduced.

Although the number of the press parts 13 and the jack parts 14 can be set suitably, it is preferable to carry out a pair opposing arrangement so that reaction force can be taken at the time of plastic processing of a steel pipe. Moreover, although the projection part 17 and the recessed part 17a formed in the support pile 1 are cross-sectional substantially triangular shapes, the thing of an appropriate shape is employable, without being limited to such a shape. Moreover, the shape where protrusion part 17 continues may be sufficient.
By forming the recess 17a on the inner surface of the support pile 1, it is only necessary to ensure high integrity when the support pile 1 is filled with concrete and solidified.

In the diameter expansion process (recess formation process) shown in FIG. 3, the diameter expansion device 11 can be moved to any position in the length direction in the support pile 1 by lowering the suspension part 15 in the support pile 1. By operating the jack portion 14 at the position, the inner surface of the steel pipe is pressed by the pressing portion 13 to plastically deform the steel pipe, and the concave portion 17a can be formed on the inner surface of the support pile 1 by expanding the diameter. In the present embodiment, six protrusions 17 are formed at predetermined intervals in the circumferential direction of the support pile 1.
And after raising the diameter expansion apparatus 11 from the inside of the support pile 1, concrete C is filled as a solidification material by the solidification material filling process shown in FIG. The filling amount of the concrete C is set so that the concrete surface C1 is positioned above the concave portion 17a even after the concrete C is pressed in the next step. In the case of non-disintegrating ground, concrete may be filled after lifting the pile.

  In the pressurizing step shown in FIG. 5, the concrete C filled in the support pile 1 is pressed before solidification. An appropriate apparatus can be adopted as the pressing means for the concrete C. For example, the pressure device 19 shown in FIG. 5 includes a lid 20 installed on the concrete surface C <b> 1 in the support pile 1, and a support member connected to the lid 20 and extending upward from the upper end opening of the support pile 1. For example, an inner tube 21 is provided. The inner pipe 21 is supported by the gripping part of the press-fitting machine 3 for press-fitting the support pile 1, and the lid part 20 can be pressed by the inner pipe 21. The lid portion 20 can employ a plate material made of metal or the like having a disk shape having substantially the same outer diameter as the inner diameter of the support pile 1.

In the pressurizing step, the concrete C is pressed in the stationary support pile 1 by pressing the lid portion 20 through the inner tube 21 by the press-fitting machine 3. Since the pressurized concrete C protruding from the lower end opening of the support pile 1 is higher than the pressure of the surrounding ground 2, it flows into the space b, expands and expands the ground 2, expands into a bulb shape, and has a volume. Increase. Further, the concrete surface C1 is lowered by the height e. On the lower end side of the support pile 1, as shown in FIG. 6, a constricted expanded bulb 23 in which the concrete C is expanded from the diameter of the support pile 1 between the support ground 7 is expanded in the radial direction by a width E. Formed. In this case, pressure can be applied only by the frictional resistance with which the concrete contacts the concrete C pile.
And the concrete C inside the support pile 1 is pressed with the pressurization device 19, and the moisture inside the concrete is pushed out to compress the volume of the concrete. As a result, the strength of the concrete C is increased, so that the support pile 1 and the concrete C inside can be brought into closer contact with each other, and the adhesion strength with the concave portion 17a can be improved. Furthermore, the earth pressure of the surrounding ground 2 increases by the pressure of the diameter expanding bulb 23 of the pressurized concrete C protruding from the front end opening of the support pile 1 and balances with each other. In other words, it also improves the surrounding ground.

  According to the construction method of the support pile 1 according to this embodiment, as shown in FIG. 6, the expanded concrete bulb 23 having a diameter larger than that of the support pile 1 can be formed at the tip of the support pile 1. The concrete C in 1 and the expanded bulb 23 were consolidated. Furthermore, the consolidation strength between the concave portion 17a of the support pile 1 and the pressed concrete C can be improved. Therefore, even if a large pulling force is applied to, for example, a steel tower as an existing structure installed in the support pile 1, it can be accepted with an increased pulling resistance.

Furthermore, since notches such as slits are not formed in the protrusions 17, the strength of the support pile 1 can be improved without water or earth and sand flowing in from the external ground 2 and deteriorating the quality of the concrete C. Moreover, since the stress concentration by the notch does not occur, the pile strength is high.
By compressing the concrete C, the surrounding ground 2 can be compressed with the expanded bulb 23 to balance the concrete strength, and the strength of the pressed concrete C can be increased. Therefore, the strength of the support pile 1 and the pulling resistance of the concrete C can be improved.

As described above, according to the construction method of the support pile 1 according to the present embodiment, since the pressurized concrete C is consolidated in the concave portion 17a of the support pile 1, the degree of adhesion of the concrete C to the steel pipe increases and the concrete strength increases. Therefore, pile strength and pull-out resistance can be improved.
Moreover, pressurizing the concrete C to form the enlarged bulb 23 at the lower end of the support pile 1 can further increase the support force and the pull-out resistance by the support pile 1 together with the recess 17a.
Moreover, since the press-fitting machine 3 was used for the construction method of the support pile 1, the expansion amount E of the enlarged bulb 23 can be controlled by managing the press-fitting stroke of the concrete, and the consolidation of the concrete by managing the pressure of the concrete. Strength can be controlled.

  In addition, the construction method of the support pile 1 by this invention is not limited to the above-mentioned embodiment, A various change, substitution, etc. are possible in the range which does not deviate from the summary, These cases are also of this invention. Included in the technical scope. In the following, other embodiments and modifications of the present invention will be described using the same reference numerals for the same or similar parts and members as those of the above-described embodiments.

In this invention, you may employ | adopt the pressurization apparatus different from the pressurization apparatus 19 using the press injection machine 3, and this is demonstrated with reference to FIG.
The pressurizing device 25 shown in FIG. 7A uses the support pile 1 with a predetermined stroke. In the pressurizing device 25, a pair of pressing members are installed on the concrete surface C <b> 1 in which the lid portion 20 is filled in the support pile 1, and can be moved forward and backward in the direction of the inner wall of the jack portion 26 and the support pile 1 on the top surface of the lid portion 20. 27 is installed. The pressing member 27 is provided with a plurality of engaging claws consisting concave protrusions on the surface, it is linked by engaged to the inner wall of the supporting piles 1 by advancing the pressing member 27 radially outward by the jack unit 26.

Further, the lowering member 30 is gripped by the gripping portion of the press-fitting machine 3. The lowering member 30 has a cylindrical portion 30a having a diameter larger than the diameter of the steel pipe and an intrusion portion 30b having a diameter smaller than the diameter of the steel pipe projecting from the tip surface thereof. The front end surface is seated, and the penetration portion 30b is inserted into the support pile 1 from the front end opening.
In the pressurizing step, the lowering member 30 is pushed down by the presser 3 to push the support pile 1 into the ground 2. Then, since the pressing device 28 also descends integrally with the support pile 1, the concrete C can be pressed through the lid portion 20. In this case, the peripheral frictional resistance with the ground 2 over the entire length of the support pile 1 is added to the pressure input. The pressurizing force of the concrete C is set by the difference between the pressure input of the support pile 1 and the pulling force (peripheral frictional resistance of the pile). The support pile 1 is preferably pushed down by a predetermined stroke.

Further, the pressurizing device 32 shown in FIG. 7B has a cylinder device 33 fixed to the jack portion 26 in the pressing device 28 described above, and a lid portion 20 is connected to the tip of a rod 34 provided in the cylinder device 33. Yes. Moreover, hydraulic pressure can be supplied to the jack portion 26 through a hydraulic tube extending outward from the upper end opening of the support pile 1.
Therefore, in a state where the pressing member 27 of the pressing device 28 is pressed against the inner surface of the support pile 1 by the jack portion 26 and pressed, the rod 34 is pressed down from the cylinder device 33 and the concrete C is pressed by the lid portion 20. Can be pressurized. In this case, the concrete C can be pressurized only by the frictional resistance of the concrete C.

Next, the construction method of the support pile 1A according to the second embodiment of the present invention will be described with reference to FIGS.
The construction method of the support pile 1A according to the second embodiment relates to a construction method in the case where it is likely that a supporting force can be obtained without expanding the diameter on the very hard ground 2, for example. The support pile 1A is made of a steel pipe shown in FIG. 1 as in the first embodiment, and the steel pipe is pressed into a predetermined construction position by press-fitting or rotational press-fitting using the press-fitting machine 3 with the support pile 1A. In the excavation process, as shown in FIG. 8, the support pile 1 </ b> A is excavated in the ground 2 by the press-fitting machine 3 and excavated to the support ground 7 of the hard ground. The support pile 1 </ b> A is stopped in a state where the tip bites into the support ground 7, and since there is a possibility of the ground 2 collapsing, no space b is formed between the support pile 1 </ b> A.

Next, in the earth removing process inside the supporting pile 1A, the inside of the supporting pile 1A is excavated by the excavator 9 and discharged. The excavation inside the support pile 1A may be performed after the press-fitting of the steel pipe or may be excavated while being pressed and discharged.
After the soil removal in the support pile 1A is completed, the support ground is excavated so as to be integrated with the support ground. Next, the process proceeds to the diameter expansion process. As in the first embodiment, the diameter expanding device 11 for expanding the inner diameter of the steel pipe is inserted to an appropriate height position in the support pile 1A, and the jack portion 14 is operated to advance the pressing portion 13 to the outside. The recess 17a can be formed on the inner surface of the support pile 1A by pressing the inner surface of the support pile 1A to plastically deform the support pile 1A.

After the diameter expanding device 11 is pulled up from the inside of the support pile 1A, concrete C is filled as a solidifying material in the solidifying material filling step shown in FIG. The filling amount of the concrete C is set so that the concrete surface C1 is located above the concave portion 17a even after the concrete C is pressed in the next diameter expansion step.
Next, in the pressing step, the concrete C in the supporting pile 1A is pressed using, for example, the pressing device 19 (or the pressing devices 25 and 32) shown in FIG. By dehydrating the water in the concrete C by pressurization, the strength becomes high and becomes close to the strength of the steel pipe, and the concrete C is consolidated even in the concave portion 17a so that it is more firmly integrated with the support pile 1A. At the lower end portion of the support pile 1A, the lower end portion of the pressure concrete C bites into the support ground 7 and is firmly joined, and the support ground 7 is also improved.

  Thus, by pressing the concrete C in the support pile 1A, the support pile 1A having high strength can be constructed as shown in FIG. In the construction method of the support pile 1A according to the second embodiment, the expanded bulb 23 is not formed at the lower end portion of the support pile 1A, but the lower end portion of the support pile 1A is bitten into the support ground 7 to press the concrete C to be recessed. Since it is closely attached to 17a, the pull-out resistance can be improved with high strength as in the first embodiment.

In each of the above-described embodiments, the one-step recessed portion 17 a is formed in the support piles 1, 1 </ b> A, but a plurality of recessed portions 17 a may be formed in the longitudinal direction of the support pile 1. In this case, the support piles 1 and 1A are further strengthened, and the pulling resistance can be increased.
In the first embodiment of the present invention, the enlarged bulb 23 is formed at the lower end of the support pile 1 as the enlarged portion, but the enlarged bulb 23 is not necessarily provided. Similarly, in the second embodiment of the present invention, the lower end portion of the support pile 1A is bitten into the support ground 7, but if the design does not consider the pulling force, the tip portion does not necessarily bite into the support ground 7. May be. Even in these cases, high strength and extraction resistance can be obtained by filling the concave concrete 17a of the projection 17 of the support pile 1 and 1A press-fitted into the ground 2 with the pressurized concrete C.
The supporting ground 7 may be an existing underground structure. Moreover, the recessed part 17a may be in the support ground 7 or the existing structure.

1, 1A Support pile 2 Ground
DESCRIPTION OF SYMBOLS 3 Press-fit machine 7 Support ground 9 Excavator 11 Diameter expansion apparatus 13 Press part 14,26 Jack part 17 Protrusion part 17a Recessed part 19,25,32 Pressurization apparatus 20 Lid part 23 Diameter expansion bulb 33 Cylinder apparatus C Concrete b Space

Claims (7)

A steel pipe placing process for placing the steel pipe;
An excavation step of excavating the steel pipe while or after the steel pipe is cast;
A recess forming step of forming a recess by expanding the inner wall of the steel pipe;
A solidifying material filling step of filling the solidified material in a range including the concave portion in the steel pipe;
A pressing step of pressing the filled solidified material;
A support pile construction method characterized by comprising:   The construction method of the support pile according to claim 1, wherein, in the pressurizing step, the solidified material is protruded from a lower end portion of the steel pipe to form a diameter-expanded portion of the solidified material that is larger than the diameter of the steel pipe. .   The construction method of the support pile described in Claim 1 which made the said solidification material which protrudes from the lower end part of the said steel pipe bite into a support ground in the said pressurization process.   The construction method of the supporting pile described in any one of Claim 1 to 3 which was made to pressurize the said solidification material with a pressurization apparatus in the said pressurization process.   The construction method of the support pile according to claim 4, wherein the pressurizing device pressurizes the solidified material by a press-fitting machine.   The said pressurization apparatus fixes the cover part in the said steel pipe, The construction method of the support pile described in Claim 4 made to pressurize the said solidification material by pushing the said steel pipe with a press-fitting machine.   The said pressurization apparatus fixes the cylinder apparatus in the said steel pipe, The construction method of the support pile described in Claim 4 which was made to pressurize the said solidification material with this cylinder apparatus.

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