JP6932544B2 - Construction method of support pile - Google Patents

Description

The present invention relates to a method for constructing a ground-cutting type support pile used for, for example, the foundation of a structure.

Conventionally, support piles have been used as pile foundations for foundation structures. The tip of the support pile reaches the support layer, and the load is supported mainly by the tip bearing force acting on the tip of the pile.
For example, the support pile described in Patent Document 1 has a diameter-expanded portion formed on the outer periphery of the lower end portion of the support pile when the support pile made of steel pipe or concrete is buried in the ground. It is inserted into the root-consolidating part and embedded in the root-consolidating part, and the root-consolidating liquid is injected into the root-consolidating part to solidify and fix it. Then, the inside of the support pile is filled with concrete and solidified.

Further, in the method of constructing the support pile described in Patent Document 2, the steel pipe is buried to a predetermined depth by driving, press-fitting, rotary construction, or the like, and the soil in the steel pipe is discharged to a predetermined depth. Then, a diameter-expanding device is inserted into the steel pipe through the opening at the upper end, the diameter of the steel pipe is expanded from the inside to form a multi-stage protrusion that bulges to the outer circumference, and this protrusion is crimped or penetrated into the ground surface.

Japanese Patent No. 3664361 Japanese Unexamined Patent Publication No. 2000-120066

However, in the method of constructing a support pile described in Patent Document 1, a standing hole is formed in advance by an excavator to form a large-diameter rooting portion in the support layer of the ground, and a rooting liquid or a rooting liquid is formed in the standing hole. After injecting the surrounding solidifying liquid, the support pile with the enlarged diameter formed at the lower end is inserted, so the pile will not enter unless the root hardening liquid and the surrounding solidifying liquid for the volume of the supporting pile to be inserted come out to the ground part. .. Further, it is the root hardening liquid and the surrounding hardening liquid that surround the support pile itself, and it is not the support pile that is in direct contact with the ground. That is, even if the support portion is provided with a multi-stage enlarged diameter portion, the friction with the ground is not improved.
Further, in the method of constructing a support pile described in Patent Document 2, since a plurality of enlarged diameter portions are formed at predetermined intervals in the longitudinal direction of the press-fitted steel pipe, in order to strengthen the ground strength, pile strength and pull-out 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 of increasing the peripheral friction of the pile to obtain bearing capacity, and in most grounds, the middle is soft and there is often a support layer below, so it is said that sufficient bearing capacity cannot be obtained. There's a problem.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for constructing a support pile so that pile strength and pull-out resistance can be increased by simple construction.

That is, the method for constructing the support pile according to the present invention includes a steel pipe driving process for driving a steel pipe, an excavation process for excavating the inside of the steel pipe while driving or after driving the steel pipe, and expanding the diameter of the inner wall of the steel pipe. It is characterized by including a recess forming step of forming a recess, a solidifying material filling step of filling a solidified material in a range including the recess in the steel pipe, and a pressurizing step of pressurizing the filled solidified material. ..
According to the present invention, since the solidifying material is pressure-solidified after filling the solidifying material including the region of the recess in which the inner wall is enlarged in diameter inside the support pile, the solidification is highly integrated between the steel pipe and the solidifying material due to the recess. In addition to being able to increase pull-out resistance with strength, stress concentration does not occur because slits are not formed in the steel pipe.

Further, in the pressurizing step, it is preferable to project the solidifying material from the lower end of the support pile to form an enlarged diameter portion of the solidifying material whose diameter 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 an enlarged diameter portion of the solidifying material whose diameter is larger than that of the steel pipe at the lower end portion of the support pile.
In addition, in the method of expanding the enlarged diameter portion by excavation, the strength of the peripheral ground tends to decrease in the collapse direction from the original state due to the strength of the groundwater and the soil on the excavated surface, whereas according to the present invention. Since the peripheral ground is compacted in the pressurizing process, the peripheral ground can be strengthened.

Further, in the pressurizing step, it is preferable that the solidifying material protruding from the lower end of the steel pipe bites into the supporting ground.
By allowing the pressurized solidifying material protruding from the lower end 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 a diameter-expanded portion.

Further, in the pressurizing step, the solidifying material may be pressurized by a pressurizing device.
Specifically, the pressurizing device can pressurize the solidified material by a press-fitting machine.
By pressurizing the solidifying material in the steel pipe through the lid with a press-fitting machine used for press-fitting the support pile, the solidifying material can be efficiently pressurized without using separate equipment. Moreover, the resistance at the time of pushing is only the frictional resistance between the inner surface of the support pile and the solidifying material, and the solidifying material can be easily pressurized.

Further, the pressurizing device may press the solidified material by fixing the lid portion in the steel pipe and pushing the steel pipe with a press-fitting machine.
Since the lid is fixed to the upper surface of the solidifying material in the support pile, the lid can be pressed by pushing the steel pipe with the press-fitting machine to pressurize the solidifying material.

Further, the pressurizing device may fix the cylinder device in the steel pipe and pressurize the solidified material with the cylinder device.
The solidifying material can be pressurized by pushing the solidifying material through the lid with a cylinder device fixed in the support pile, and the resistance at the time of pushing is only the frictional resistance between the inner surface of the support pile and the solidifying material, and the solidifying material is added. The pressure is easy.

According to the method for constructing a support pile according to the present invention, since the recess formed inside the support pile is filled with the solidifying material and then pressurized and solidified, the unity between the support pile and the solidifying material is improved and the support pile is solidified. Is high strength and can increase pull-out resistance.
Moreover, since it is not necessary to form multi-step protrusions on the support piles at predetermined intervals, the construction man-hours and costs 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 earth removal process in the support pile. It is a figure of the diameter expansion process which forms a protrusion on a support pile, and the protrusion. It is a figure of the process of filling concrete in a support pile. It is a figure of the process of pressurizing concrete in a support pile. It is explanatory drawing of the support pile constructed by this embodiment. It is a figure which shows the other method of pressurizing concrete, (a) is the figure of the pressurizing method which fixes the lid part with a jack and press-fits a support pile, (b) is the figure of a pressurizing method which presses concrete with a press-fitting cylinder. It is a figure of. It shows the construction method of the support pile by the 2nd Embodiment of this invention, and is the figure which shows the earth removal process. It is explanatory drawing of the support pile constructed by this 2nd Embodiment. It is explanatory drawing of the pressure | pressure support pile.

Hereinafter, a method of constructing a support pile according to each embodiment of the present invention will be described with reference to the accompanying drawings.
1 to 7 are views showing a method of constructing a support pile according to the first embodiment of the present invention.
The construction method of the support pile 1 according to the present embodiment is, for example, a method of press-fitting or rotating press-fitting into the ground 2 using a press-fitting machine 3. The support pile 1 is driven to fix a structure such as a breakwater to the ground 2. As shown in FIG. 1, the support pile 1 is made of a steel pipe pile, and excavation teeth 1a are formed at the lower end portion. 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, a method of constructing the support pile 1 using a steel pipe will be described.
In the steel pipe driving process 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. Upon press-fitting, as shown in FIG. 2, the support pile 1 excavates the ground 2 until it reaches the harder support ground 7. After that, the support pile 1 is pulled up by a predetermined stroke a for forming the enlarged diameter bulb made of concrete (see FIG. 4). In this case, a portion without a steel pipe is formed between the lower end 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 soil removal step in the support pile 1 shown in FIG. 2, the inside of the support pile 1 is excavated by the excavator 9 to discharge the soil. The inside of the support pile 1 may be excavated after the press-fitting of the steel pipe is completed, or the excavation may be performed while press-fitting and the soil may be discharged.
After the soil removal in the support pile 1 is completed, the process shifts to the diameter expansion process. As shown in FIG. 3, a diameter expanding device 11 for increasing the inner diameter of the steel pipe is inserted into the support pile 1. Here, the diameter expanding device 11 has a pressing portion 13 that is provided in the apparatus main body 12 and is capable of advancing and retreating in the inner wall direction of the steel pipe, that is, in the radial direction, and a jack portion 14 that advances and retreats the pressing portion 13. Moreover, a suspension portion 15 including a wire for stabilizing the posture and raising and lowering in the vertical direction and a hydraulic hose for operating the diameter-expanding device is connected to the device main body 12.

As the pressing portion 13, an appropriate toe portion such as a tapered conical shape or a polygonal pyramid shape can be adopted. It is preferable that the tip of the pressing portion 13 has a round chamfer or the like so that a notch hole communicating with the outside is not formed in the steel pipe when the diameter is expanded.
When a notch hole or the like is formed in the support pile 1, stress is concentrated to reduce the pile strength, and water, earth and sand, etc. from the surrounding ground 2 flow into the support pile 1 to deteriorate the quality of the filled concrete. There is a risk of causing it. Further, when the lower end of the support pile 1 reaches the support ground 7, which is a hard ground, a large resistance is applied to the excavated teeth 1a, stress concentration occurs in the notch hole, and the pile strength decreases. Moreover, the processing process is necessary. In that respect, in the present embodiment, since the steel pipe in the normal state in which the notch hole is not formed in the steel pipe can be used, it is possible to suppress the decrease in pile strength and prevent the inflow of water and earth and sand from the surrounding ground 2. The cost is also cheaper.

Although the number of the pressing portion 13 and the jack portion 14 can be appropriately set, it is preferable to arrange them in pairs so as to take a reaction force during plastic working of the steel pipe. Further, the protrusion 17 and the recess 17a formed on the support pile 1 have a substantially triangular cross section, but the shape is not limited to such a shape, and an appropriate shape can be adopted. Further, the protrusions 17 may have a continuous shape.
By forming the recess 17a on the inner surface of the support pile 1, it is sufficient that high integrity can be ensured when the support pile 1 is filled with concrete and solidified.

In the diameter-expanding step (recess forming step) shown in FIG. 3, the diameter-expanding device 11 can be moved to an arbitrary position in the support pile 1 in the length direction by lowering the suspension portion 15 in the support pile 1. By operating the jack portion 14 at that position, the inner surface of the steel pipe is pressed by the pressing portion 13 to plastically deform the steel pipe, and the recess 17a can be formed by expanding the diameter on the inner surface of the support pile 1. In the present embodiment, six protrusions 17 are formed at predetermined intervals in the circumferential direction of the support pile 1.
Then, after the diameter expanding device 11 is pulled up from the inside of the support pile 1, concrete C is filled as the solidifying material in the solidifying material filling step shown in FIG. The filling amount of the concrete C shall be set so that the concrete surface C1 is located above the recess 17a even after the concrete C is pressurized in the next step. In the case of non-collapsed ground, concrete may be filled after the pile is pulled up.

In the pressurizing step shown in FIG. 5, the concrete C filled in the support pile 1 is pressurized before solidification. As the pressurizing means of the concrete C, an appropriate device can be adopted. For example, the pressurizing device 19 shown in FIG. 5 has a lid portion 20 installed on the concrete surface C1 in the support pile 1 and a support member connected to the lid portion 20 and extending upward from the opening of the upper end portion of the support pile 1. For example, the inner tube 21 is provided. The inner pipe 21 is supported by the grip portion of the press-fitting machine 3 for press-fitting the support pile 1, and the lid portion 20 can be pressed by the inner pipe 21. For the lid portion 20, a plate material such as metal having a disk shape having substantially the same outer diameter as the inner diameter of the support pile 1 can be adopted.

In the pressurizing step, the concrete C is pressurized in the stationary support pile 1 by pressing the lid portion 20 through the inner pipe 21 by the press-fitting machine 3. Since the pressure concrete C protruding from the lower end opening of the support pile 1 has a pressure higher than the pressure of the surrounding ground 2, it flows into the space b, expands the ground 2 and expands, and the volume is expanded like a bulb. 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, the diameter of the compacted enlarged diameter sphere 23 in which the concrete C is expanded from the diameter of the support pile 1 with the support ground 7 is expanded by the width E in the radial direction. Is formed. In this case, pressurization can be performed only by the frictional resistance that the concrete contacts in the pile of the concrete C.
Moreover, by pressing the concrete C inside the support pile 1 with the pressurizing device 19, the moisture inside the concrete is pushed out and the volume of the concrete is compressed. As a result, the strength of the concrete C becomes stronger, the support pile 1 and the concrete C inside can be brought into close contact with each other, and the adhesive strength with the recess 17a can be improved. Further, the earth pressure of the surrounding ground 2 is increased by the pressure of the enlarged bulb 23 of the pressurized concrete C protruding from the tip opening of the support pile 1 to balance each other. In other words, it also improves the surrounding ground.

According to the construction method of the support pile 1 according to the present embodiment, as shown in FIG. 6, a diameter-expanded bulb 23 of pressure concrete having a diameter larger than that of the support pile 1 can be formed at the tip of the support pile 1, and the support pile can be formed. The concrete C and the enlarged diameter stake 23 in 1 were compacted. Further, the consolidation strength between the recess 17a of the support pile 1 and the pressure concrete C can be improved. Therefore, even if a large pulling force acts on, for example, a steel tower as an existing structure installed on the support pile 1, it can be undertaken by the increased pulling resistance.

Further, since the protrusion 17 does not form a notch such as a slit, the strength of the support pile 1 can be improved without inflowing water, earth and sand, etc. from the external ground 2 and deteriorating the quality of the concrete C. In addition, the pile strength is high because stress concentration does not occur due to the notch.
By pressurizing the concrete C, the surrounding ground 2 can be compressed by the enlarged bulb 23 to balance with the concrete strength, and the strength of the pressurized concrete C can be increased. Therefore, the strength of the support pile 1 and the pull-out 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 compacted in the recess 17a of the support pile 1, the degree of adhesion of the concrete C to the steel pipe is increased and the concrete strength is increased. Therefore, pile strength and pull-out resistance can be improved.
Moreover, by pressurizing the concrete C to form the enlarged bulb 23 at the lower end of the support pile 1, the support force and the pull-out resistance of the support pile 1 can be further increased together with the recess 17a.
Further, since the press-fitting machine 3 is used as the construction method of the support pile 1, the diameter-expanding amount E of the enlarged-diameter bulb 23 can be controlled by controlling the press-fitting stroke of the concrete, and the concrete is compacted by controlling the pressing force of the concrete. You can control the strength.

The method of constructing the support pile 1 according to the present invention is not limited to the above-described embodiment, and various changes and replacements can be made without departing from the gist thereof. Included in the technical scope. Hereinafter, other embodiments and modifications of the present invention will be described with reference to the same or similar parts and members as those in the above-described embodiment.

In the present invention, a pressurizing device different from the pressurizing device 19 using the press-fitting machine 3 may be adopted, and this will be described with reference to FIG.
The pressurizing device 25 shown in FIG. 7A is used by pulling up the support pile 1 by a predetermined stroke. In the pressurizing device 25, the lid portion 20 is installed on the concrete surface C1 filled in the support pile 1, and a pair of pressing members capable of advancing and retreating in the direction of the inner wall of the jack portion 26 and the support pile 1 on the upper surface of the lid portion 20. A pressing device 28 provided with 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 downhill member 30 is gripped by the gripping portion of the press-fitting machine 3. The downhill member 30 has a columnar portion 30a having a diameter larger than the steel pipe diameter and an intrusion portion 30b having a diameter smaller than the steel pipe diameter protruding from the tip surface thereof, and the columnar portion 30a opens at the upper end of the support pile 1. The tip surface is seated, and the penetration portion 30b is fitted into the support pile 1 through the tip opening.
Then, in the pressurizing step, the press-fitting machine 3 pushes down the down member 30 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 pressurized 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 applied to the pressure input. The pressing force of the concrete C is set by the difference between the pressure input of the support pile 1 and the pulling force (friction resistance of the peripheral surface of the pile). It is preferable that the support pile 1 is pushed down by a predetermined stroke that is pulled up.

Further, in the pressurizing device 32 shown in FIG. 7B, the cylinder device 33 is fixed to the jack portion 26 in the pressing device 28 described above, and the lid portion 20 is connected to the tip of the rod 34 provided in the cylinder device 33. There is. Moreover, the jack portion 26 can be supplied with flood control via a hydraulic tube extending outward from the opening at the upper end 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 to be locked, the rod 34 is pushed 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. 8 to 10.
The construction method of the support pile 1A according to the second embodiment relates to, for example, a construction method in a case where a bearing capacity can be obtained without expanding the diameter of the very hard ground 2. The support pile 1A is made of the steel pipe shown in FIG. 1 as in the first embodiment, and the steel pipe is press-fitted into a predetermined construction position by press-fitting or rotary press-fitting using the press-fitting machine 3 as the support pile 1A. In the excavation process, as shown in FIG. 8, the support pile 1A is excavated in the ground 2 by the press-fitting machine 3, and the support ground 7 of the hard ground is excavated. The support pile 1A is stopped in a state where the tip bites into the support ground 7, and the space b is not formed between the support pile 1A and the support ground 7 because the ground 2 may collapse.

Next, in the soil removal step inside the support pile 1A, the inside of the support pile 1A is excavated by the excavator 9 to discharge the soil. The inside of the support pile 1A may be excavated after the press-fitting of the steel pipe is completed, or the excavation may be performed while press-fitting and the soil may be 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 shifts to the diameter expansion process. Similar to 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 inner surface of the support pile 1A can be pressed to plastically deform the support pile 1A to form a recess 17a on the inner surface of 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 the 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 recess 17a even after the concrete C is pressurized in the next diameter expansion step.
Next, in the pressurizing step, the concrete C in the support pile 1A is pressurized using, for example, the pressurizing device 19 (or the pressurizing 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 compacted even in the recess 17a to be more firmly integrated with the support pile 1A. At the lower end of the support pile 1A, the lower end of the pressure concrete C bites into the support ground 7 and is firmly joined, and the support ground 7 is also improved.

By pressurizing the concrete C in the support pile 1A in this way, 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 enlarged bulb 23 is not formed at the lower end of the support pile 1A, but the lower end of the support pile 1A is made to bite into the support ground 7 to pressurize the concrete C and make a recess. Since it is brought into close contact with 17a, it is possible to improve the pull-out resistance with high strength as in the first embodiment.

In each of the above-described embodiments, one-stage recesses 17a are formed in the support piles 1 and 1A, but a plurality of-stage recesses 17a may be formed in the longitudinal direction of the support piles 1. In this case, the support piles 1 and 1A have higher strength and the pull-out resistance can be increased.
Further, in the first embodiment of the present invention, the enlarged diameter bulb 23 is formed as the enlarged diameter portion at the lower end portion of the support pile 1, but the enlarged diameter bulb 23 does not necessarily have to be provided. Similarly, in the second embodiment of the present invention, the lower end portion of the support pile 1A is made to bite 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. You may. Even in these cases, high strength and pull-out resistance can be obtained by filling the recesses 17a of the protrusions 17 of the support piles 1 and 1A press-fitted into the ground 2 with the pressure concrete C.
The supporting ground 7 may be an existing underground structure. Further, the recess 17a may be contained in the supporting ground 7 or the existing structure.

1, 1A Support pile 2 Ground
3 Press-fitting machine 7 Supporting ground 9 Excavator 11 Diameter-expanding device 13 Pressing part 14, 26 Jack part 17 Protruding part 17a Recession 19, 25, 32 Pressurizing device 20 Lid part 23 Diameter-expanding bulb 33 Cylinder device C Concrete b Space

Claims (5)

The steel pipe placing process for placing steel pipes and
An excavation process in which the inside of the steel pipe is excavated while or after the steel pipe is driven.
A recess forming step of expanding the diameter of the inner wall of the steel pipe to form a recess,
A solidifying material filling step of filling a range including the recess in the steel pipe with a solidifying material,
A pressurizing step of pressurizing the filled solidified material and
Equipped with a,
In the pressurizing step, the solidifying material is pressurized by a pressurizing device.
A method for constructing a support pile, wherein the pressurizing device pressurizes the solidifying material with a press-fitting machine. The method for constructing a support pile according to claim 1 , wherein the pressurizing device has a lid fixed in the steel pipe and presses the steel pipe with a press-fitting machine to pressurize the solidifying material. The steel pipe placing process for placing steel pipes and
An excavation process in which the inside of the steel pipe is excavated while or after the steel pipe is driven.
A recess forming step of expanding the diameter of the inner wall of the steel pipe to form a recess,
A solidifying material filling step of filling a range including the recess in the steel pipe with a solidifying material,
A pressurizing step of pressurizing the filled solidified material and
Equipped with a,
In the pressurizing step, the solidifying material is pressurized by a pressurizing device.
The pressurizing device is a method for constructing a support pile, characterized in that a cylinder device is fixed in the steel pipe and the solidifying material is pressurized by the cylinder device. The support pile according to claim 1 or 3 , wherein in the pressurizing step, the solidifying material is projected from the lower end of the steel pipe to form an enlarged diameter portion of the solidifying material whose diameter is larger than the diameter of the steel pipe. Construction method. The method for constructing a support pile according to claim 1 or 3 , wherein in the pressurizing step, the solidifying material protruding from the lower end of the steel pipe bites into the support ground.

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