JP7119892B2 - Construction methods of structures and structures - Google Patents

Description

The present invention relates to structures and construction methods for structures .

In the foundations of structures such as steel towers and condominiums with a high tower-to-tower ratio, when inertial force due to an earthquake or horizontal force due to wind load is generated, a pull-out force may occur in the foundation. Pull-out resistance is required.

The inner-digging expansion foot protection pile construction method (hereinafter also referred to as the inner-digging construction method) is used as the foundation of building structures and civil engineering structures because it can achieve low noise, low vibration, and high bearing capacity. In the inner excavation method, cement milk is used to construct an improved body of soil cement on the peripheral surface of the pile to obtain peripheral surface resistance, thereby increasing the pull-out resistance.

However, in the method of constructing while improving the pile peripheral surface, the construction period may be prolonged and the material cost may increase compared to the case where the improvement is not performed. In addition, when it is necessary to resist greater horizontal force, the number of piles is increased or enlarged piles are used. becomes an issue.

On the other hand, as a technique for increasing the pull-out resistance of the foundation pile without using the inner excavation method, for example, in Patent Document 1, the steel pipe pile body is formed of a large-diameter upper steel pipe and a small-diameter lower steel pipe, and the lower part A notch is formed at the tip of the side steel pipe in a spiral shape, a spiral blade having at least one turn or less is provided corresponding to the notch form of the spiral shape, and a second at or near the diameter expansion boundary portion of the steel pipe pile body. Techniques for providing helical vanes have been described.

Japanese Patent Application Laid-Open No. 2002-61180

However, in the technique described in Patent Document 1, penetrating a steel pipe having a spiral blade at its tip to a solid support layer deep in the ground does not allow an intermediate layer existing before reaching the support layer. It is not easy compared to penetrating into a wall, and there is still room for improvement at least in terms of workability.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a new and improved structure and a method of constructing a structure that can increase the pull-out resistance while improving the workability of foundation piles.

According to one aspect of the present invention, a foundation pile that penetrates into the ground is provided. The foundation pile consists of a tubular inner pile body, a foot protection portion formed at the tip of the inner pile body, and a larger diameter than the inner pile body, shorter than the inner pile body, and arranged concentrically with the inner pile body. and a wing portion formed at the tip of the outer pile body and positioned shallower than the foot protection portion in the ground.

In the foundation pile described above, the foot protection part may be formed in the supporting layer of the ground, and the wing part may be located in a layer shallower than the supporting layer.

According to another aspect of the present invention, there is provided a foundation structure comprising the foundation pile described above and a concrete structure integrating the respective heads of the inner pile body and the outer pile body.

The above foundation structure may further comprise reinforcing bars joined to the outer pile body and embedded in the concrete structure.

According to still another aspect of the present invention, there is provided a structure in which the above foundation pile is used as a foundation at the outer edge portion extending in the long side direction in plan view.

According to yet another aspect of the present invention, there is provided a method of constructing the foundation pile described above. A foundation pile construction method includes a first step of penetrating the inner pile body into the ground, and a second step of penetrating the outer pile body into the ground outside the inner pile body after the first step. Alternatively, the foundation pile construction method includes a first step of penetrating the outer pile body into the ground, and a second step of penetrating the inner pile body into the ground inside the outer pile body after the first step. include.

In the above configuration, the outer pile body having the wing portion formed at the tip exerts pull-out resistance even if it does not penetrate as deeply into the ground as the inner pile body. Therefore, the workability can be improved by making the outer pile body shorter than the inner pile body and penetrating only to a shallower layer while increasing the pull-out resistance by the outer pile body and the wing portions.

1 is a schematic perspective view of a foundation pile according to one embodiment of the invention; FIG. FIG. 2 is a sectional view taken along line II-II of FIG. 1; It is a figure which shows the 1st example of the construction method of the foundation pile which concerns on one Embodiment of this invention. It is a figure which shows the 2nd example of the construction method of the foundation pile which concerns on one Embodiment of this invention. It is a figure which shows the 1st example of the foundation structure containing the foundation pile which concerns on one Embodiment of this invention. FIG. 5 is a diagram showing a second example of a foundation structure including foundation piles according to one embodiment of the present invention; FIG. 5 is a diagram showing a third example of a foundation structure including foundation piles according to one embodiment of the present invention; It is a figure which shows the 4th example of the foundation structure containing the foundation pile which concerns on one Embodiment of this invention. It is a figure which shows the 5th example of the foundation structure containing the foundation pile which concerns on one Embodiment of this invention. 1 is a plan view of a foundation portion of a structure using foundation piles as a foundation according to one embodiment of the present invention; FIG.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the present specification and drawings, constituent elements having substantially the same functional configuration are denoted by the same reference numerals, thereby omitting redundant description.

(Composition of Foundation Pile)
FIG. 1 is a schematic perspective view of a foundation pile according to one embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II of FIG. As shown in FIGS. 1 and 2, a foundation pile 1 penetrating into the ground consists of a tubular inner pile body 2, a foot protection portion 3 formed at the tip of the inner pile body 2, and a tubular outer pile body. 4 and a vane portion 5 formed at the tip of the outer pile body 4 . Here, the outer pile body 4 has a larger diameter than the inner pile body 2, is shorter than the inner pile body 2, and is arranged concentrically with the inner pile body 2. - 特許庁Therefore, as shown, the outer pile body 4 is arranged to cover the inner pile body 2 halfway. The cross-sectional centers of the inner pile body 2 and the outer pile body 4 do not need to be exactly aligned.

The foot protection portion 3 is a portion where soil cement constructed by injecting cement milk into the ground is fixed to the tip portion of the inner pile main body 2 . That is, the tip of the inner pile main body 2 is embedded in the foot protection portion 3 after construction. The blade portion 5 is a plate-like member projecting radially outward from the tip portion of the outer pile main body 4, and is formed in a spiral shape with a predetermined pitch in the axial direction of the outer pile main body 4 in this embodiment. . The blade portion 5 does not necessarily have to be formed from the tip surface of the outer pile main body 4, and may be formed from a position close to the tip surface. As described above, since the outer pile main body 4 is shorter than the inner pile main body 2, the blade portion 5 is shallower than the foot protection portion 3 when the foundation pile 1 is penetrated into the ground.

In the illustrated example, the spiral blade portion 5 makes one turn around the outer pile body 4, but the blade portion 5 may be formed to go around the outside pile body 4 more than one turn. . Further, the blade portion 5 may have a shape other than a spiral shape as long as it is possible to increase the pull-out resistance of the foundation pile 1 as will be described later. If the blades 5 are shaped like a spiral with a pitch in the axial direction of the outer pile body 4, by rotating the outer pile body 4 around its axis, it is possible to obtain propulsion in the ground. can. Also, in the illustrated example, the outer diameter of the blade portion 5 is larger than the outer diameter of the foot protection portion 3, but this size relationship may be reversed. Alternatively, the blade portion 5 and the foot protection portion 3 may have the same outer diameter.

FIG. 3 is a diagram showing a first example of a method for constructing foundation piles according to one embodiment of the present invention. In the illustrated example, first, as shown in (A), the outer pile main body 4 is connected to the all-around rotating machine 6 and is made to penetrate into the ground while being rotated about its axis. At this time, it is possible to obtain a driving force for penetrating the outer pile body 4 into the ground by means of the helical blade portion 5 formed at the tip portion of the outer pile body 4 . Alternatively, a pile driver may be connected to the outer pile main body 4 and pressed into the ground while being rotated about its axis. In this case, the load required for press-fitting can be reduced by disturbing the ground by the vanes 5 . By this process, as shown in (B), the outer pile main body 4 penetrates over the surface layer 7 of the ground to the intermediate layer 8, and the blade portion 5 is positioned in the intermediate layer 8.

Next, as shown in (C), after the inner pile body 2 is penetrated into the ground using the pile driver 9, the inside of the inner pile body 2 is excavated using the screw auger 10, and the screw auger Cement milk is injected into the ground near the tip of the inner pile body 2 from the tip of 10 . The ground injected with cement milk becomes soil cement that constitutes the foot protection part 3 . By this process, as shown in (D), the inner pile body 2 penetrates to the support layer 11 deeper than the intermediate layer 8 of the ground, and the foot protection part 3 is positioned in the support layer 11 . Since the support layer 11 is generally harder than the intermediate layer 8, it is not easy to penetrate the outer pile body 4 with the wings 5 formed thereon. On the other hand, the inner pile main body 2, which has a smaller diameter than the outer pile main body 4 and does not have a wing portion, can be penetrated to the support layer 11 relatively easily.

FIG. 4 is a diagram showing a second example of a method for constructing a foundation pile according to one embodiment of the present invention. In the illustrated example, first, as shown in (A), the pile driver 9 is used to penetrate the inner pile body 2 into the ground, and then the screw auger 10 is used to push the inner side of the inner pile body 2. By excavating and injecting cement milk into the ground near the tip of the inner pile body 2 from the tip of the screw auger 10, the foot protection part 3 is formed. Next, as shown in (B), the outer pile main body 4 is connected to the full-circumferential turning machine 6 and penetrated into the ground while being rotated about its axis. At this time, the propulsive force may be obtained by the blade portion 5, or the outside pile main body 4 may be press-fitted while the ground is disturbed by the blade portion 5. As a result, as shown in (C), the inner pile body 2 penetrates to the support layer 11 of the ground, the foot protection part 3 is formed in the support layer 11, and the outer pile body 4 is an intermediate layer shallower than the support layer 11. Penetrating up to 8, the blade part 5 is located in the intermediate layer 8. - 特許庁

Although not shown, in the example shown in FIGS. 3 and 4, when the upper ends (pile heads) of the inner pile body 2 and the outer pile body 4 are penetrated to a position deeper than the ground surface, By using a jig such as a casing as necessary, construction can be performed while protecting the surrounding ground.

In the foundation pile 1 according to this embodiment as described above, the inner pile body 2 formed with the foot protection portion 3 mainly bears the vertical bearing force, and the outer pile body 4 formed with the blade portion 5 It mainly bears the pull-out force. As a result, the foundation pile 1 can efficiently obtain a high resistance of the pile. Further, by penetrating the outer pile body 4, which has a larger outer diameter than the inner pile body 2, into the ground, the horizontal resistance of the foundation pile 1 as a whole increases. The outer pile body 4 having the wing portion 5 formed at the tip thereof can exert pull-out resistance without penetrating to the support layer 11 of the ground shown in the examples of FIGS. The workability can be improved by only penetrating. On the other hand, as for the inner pile body 2 having the foot protection portion 3 formed at its tip, by penetrating up to the support layer 11, a high vertical bearing capacity can be obtained. Moreover, when the ground strength of the intermediate layer 8 is relatively low, both the outer pile body 4 and the inner pile body 2 can be constructed using the pile driver 9 .

(Configuration of foundation structure)
FIG. 5 is a diagram showing a first example of a foundation structure including foundation piles according to one embodiment of the present invention. In the illustrated example, the foundation structure includes the foundation pile 1 described above, a footing 12 which is a concrete structure that integrates the respective heads of the inner pile body 2 and the outer pile body 4 of the foundation pile 1, It includes reinforcing bars 13 and 14 joined to the inner pile body 2 and the outer pile body 4 respectively and embedded in the footing 12, a filling reinforcing bar 15, and filling concrete 16. - 特許庁The reinforcing bars 13, 14 are joined to the inner pile body 2 and the outer pile body 4, respectively, by welding or mechanical joining using connecting members, for example. In the illustrated example, the inner pile body 2 and the outer pile body 4 are integrally connected via the footing 12, so that loads such as vertical pushing and pulling, horizontal forces, and bending moments are applied to the foundation pile. 1 can certainly resist.

FIG. 6 is a diagram showing a second example of a foundation structure including foundation piles according to one embodiment of the present invention. In the example shown in FIG. 6, interstitial concrete 17 is added between the inner pile body 2 and the outer pile body 4 as compared with the example shown in FIG. By providing the interstitial concrete 17, for example, the integrity of the inner pile body 2 and the outer pile body 4 against horizontal force can be further enhanced. In addition, the filling concrete 17 may not be placed near the tip of the outer pile main body 4 as in the illustrated example, but may be placed partway. Further, high fluidity mortar or the like may be used instead of the interfilling concrete 17 .

FIG. 7 is a diagram showing a third example of a foundation structure including foundation piles according to one embodiment of the present invention. In the example shown in FIG. 7, compared to the example shown in FIG. 5, the reinforcing bars 13 joined to the inner pile body 2 and the filling reinforcing bars 15 are omitted. As described above, in the foundation pile 1, the inner pile main body 2 in which the foot protection portion 3 is formed mainly bears the vertical bearing force. Since the vertical bearing force acts on the foundation structure as a compressive force, in the example of FIG. On the other hand, a reinforcing bar 14 is joined to the outer pile main body 4 which mainly bears the tensile force so that the tensile force can also be transmitted from the footing 12 . The reinforcing bars 14 may be joined to the outer pile body 4 by welding or the like before the outer pile body 4 is penetrated into the ground.

FIG. 8 is a diagram showing a fourth example of a foundation structure including foundation piles according to one embodiment of the present invention. In the example shown in FIG. 8, interstitial concrete 17 similar to the example in FIG. 6 is added between the inner pile body 2 and the outer pile body 4 as compared with the example shown in FIG. Even in the case where only compressive force can be mainly transmitted from the footing 12 to the inner pile body 2, by providing the filling concrete 17, for example, the integration of the inner pile body 2 and the outer pile body 4 against horizontal force can be prevented. You can increase your sexuality.

FIG. 9 is a diagram showing a fifth example of a foundation structure including foundation piles according to one embodiment of the present invention. In the example shown in FIG. 9, anti-slip members 18 are added to the inner and outer peripheral surfaces of the inner pile body 2 and the inner peripheral surface of the outer pile body 4, compared to the example shown in FIG. ing. The anti-slip member 18 is, for example, an annular rib joined to the peripheral surface of each pile body, specifically a flat steel, deformed steel bar, round steel, or a welded protrusion, etc., from the peripheral surface of the pile body. By protruding and fixing to the filling concrete 16 or the filling concrete 17, slippage between the concrete and the pile body is prevented.

(Structure configuration)
FIG. 10 is a plan view of a foundation portion of a structure using foundation piles as a foundation according to one embodiment of the present invention. In the illustrated example, the planar shape of the structure is rectangular, and the foundations are arranged in the long side direction and the short side direction, respectively. For example, a large horizontal force and pull-out force act on the outer edge portion extending in the long side direction in the plan view, that is, the foundation shown as group E in FIG. Therefore, the above-described foundation piles 1 may be used only for the foundations of Group E. As described above, the foundation pile 1 can efficiently obtain the high resistance of the pile including the pull-out force and the horizontal force, but in the part where the pull-out force and the horizontal force acting are small, the normal foundation pile, specifically For example, it is economical to use a foundation pile that uses only the inner pile body 2 and the foot protection portion 3 of the foundation pile 1 . In addition, when the horizontal force and pull-out force acting as a whole are small, the foundation pile 1 may be used only at the rectangular corners in the planar shape of the structure, that is, at the foundations shown as group C in FIG.

Next, examples of the present invention will be described. In this example, the foundation pile 1 described above as one embodiment of the present invention was designed, and the ultimate resistance indicating resistance to pull-out was calculated.

(Example 1)
In Example 1, in the foundation pile 1, the inner pile main body 2 had a diameter of 600 mm, a length of 40 m, and an outer diameter of the foot protection portion 3 of 1,200 mm. The outer pile main body 4 has a diameter of 800 mm, a length of 16 m, and an outer diameter of the blade portion 5 of 1,600 mm. The ground is clay with an N value of 2 at a depth of 0 to 10 m and an unconfined compressive strength of 30 kN/m ² , sandy soil with an N value of 15 at a depth of 10 to 20 m, and an N value of 4 at a depth of 20 to 40 m. , clay with a uniaxial compressive strength of 50 kN/m ² , and the deeper part is a support layer with an N value of 50. When the foundation pile 1 is penetrated into such ground, the tip of the inner pile body 2 is positioned in the support layer, and the foot protection portion 3 is formed in the support layer.

Regarding the inner pile main body 2 and the foot protection part 3, the calculation formula described in the catalog "TN-X construction method, tip expansion steel pipe pile construction method" (March 2013) published by Nippon Steel & Sumitomo Metal Co., Ltd. and Tenox Co., Ltd. Substituting the above conditions into , the vertical bearing capacity is 11,196 kN. On the other hand, with regard to pull-out resistance, when the pull-out resistance of the foot protection portion 3 is not taken into account, a pile penetrated into a sandy, viscous ground has a pile peripheral resistance of 15 kN/m ² due to peripheral friction. Therefore, the pile circumferential surface resistance force obtained by the inner pile body 2 is 15×0.6 (pile diameter)×π×24 (the length of the portion ahead of the outer pile body 4)=678 kN.

On the other hand, regarding the outer pile main body 4 and the blade part 5, according to the catalog "Rotational press-fit steel pipe pile NS Ecopile (registered trademark) foundation structure" (August 2006) issued by Nippon Steel & Sumikin Engineering Co., Ltd. In the piles that have been stretched, a circumferential resistance of 0.27 times the uniaxial compressive strength per unit area is obtained due to circumferential friction. In addition, for piles penetrated into sandy ground, the value is equivalent to 1.13 times the average number of impacts per unit area of the ground around the pile in a standard penetration test of sandy ground due to peripheral friction. is obtained as a circumferential resistance expressed in units of kN/m ² . In addition, the peripheral surface resistance is not taken into account in the range from the tip of the pile to twice the outer diameter of the blade. Calculating the pull-out resistance due to the peripheral friction of the outer pile main body 4 according to the above resistance conditions, the pile peripheral resistance obtained in the cohesive soil portion is 203 kN, and the pile peripheral surface resistance obtained in the sandy soil portion is 203 kN. The resistance is 119kN. Furthermore, the pull-out resistance by the blade part 5 is the average N value of the ground in the section twice the blade diameter from the pile tip to the pull-out direction bearing force coefficient κ (= 92) of the pile tip (15 ) and the effective cross-sectional area of the pile tip (1.131 m ² in the case of Example 1), resulting in 1,560 kN. Therefore, summing up the pull-out resistance of the inner pile body 2, the outer pile body 4, and the blade portion 5, the pull-out resistance of the foundation pile 1 in Example 1 is 2,560 kN.

On the other hand, as a conventional foundation pile, assuming a foundation pile using only the inner pile body 2 and the foot protection part 3 of the foundation pile 1, the pull-out resistance in the same ground as in Example 1 corresponds to the inner pile body 2. If the pile has a diameter of 600 mm and a length of 40 m, it will be 1,130 kN. Therefore, in Example 1, the pull-out resistance of the foundation pile 1 is increased to approximately double the pull-out resistance of the conventional foundation pile in the same ground by providing the outer pile main body 4 and the blade portion 5 .

(Example 2)
In Example 2, the dimensions of the foundation pile 1 were the same as in Example 1, but the ground conditions were changed. Specifically, the ground is liquefied sand with an N value of 2 at a depth of 0 to 10 m, non-liquefied gravel with an N value of 20 at a depth of 10 m to 20 m, and N at a depth of 20 m to 40 m. It is non-liquefied gravel with a value of 10 and the deeper part is a support layer with an N value of 50. Since the foot protection part 3 is formed in the supporting layer, the vertical bearing force obtained by the inner pile main body 2 and the foot protection part 3 is 11,196 kN in the second embodiment as in the first embodiment. On the other hand, the pull-out resistance is 15 kN/m ² for sandy and viscous ground other than the liquefied layer, when the pull-out resistance by the foot protection part 3 is not taken into account and the circumferential friction force in the liquefied layer is also ignored. of pile circumferential surface resistance is obtained. Since the ground is not a liquefaction layer in the portion ahead of the outer pile body 4 of the inner pile body 2, the peripheral surface resistance force obtained by the inner pile body 2 is 678 kN as in the first embodiment.

On the other hand, when ignoring the peripheral frictional force in the liquefaction layer for the outer pile body 4 and the vanes 5, pull-out resistance due to peripheral friction in the outer pile body 4 is obtained at a depth of more than 10m and the gravel layer. The length is 2.8m if the range of twice the blade diameter (3.2m) is subtracted from the tip of the pile without considering the peripheral resistance force. If the pile peripheral surface resistance force in this section is calculated in the same manner as in Example 1, it is 386 kN. As in Example 1, the pull-out resistance by the blade part 5 is the average N value (Example In the case of 2, it is calculated by multiplying 20) and the effective cross-sectional area of the tip of the pile (1.131 m ² in the case of Example 2), resulting in 2,416 kN. Therefore, summing up the pull-out resistance of the inner pile body 2, the outer pile body 4, and the blade portion 5, the pull-out resistance of the foundation pile 1 in Example 2 is 3,480 kN.

On the other hand, as a conventional foundation pile, assuming a foundation pile using only the inner pile body 2 and the foot protection part 3 of the foundation pile 1, the pull-out resistance in the same ground as in Example 2 is the inner pile body 2. If the pile has a diameter of 600 mm and a length of 30 m (10 m is a liquefaction layer, the pile peripheral resistance cannot be obtained), it becomes 848 kN. Therefore, in Example 2, the pull-out resistance of the foundation pile 1 is increased to about four times the pull-out resistance of the conventional foundation pile in the same ground by providing the outer pile main body 4 and the blade portion 5 .

The examples of the present invention as described above show that the foundation pile according to the embodiment of the present invention can efficiently obtain a higher pull-out resistance than the conventional foundation pile.

Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention belongs can conceive of various modifications or modifications within the scope of the technical idea described in the claims. It is understood that these also naturally belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1... Foundation pile, 2... Inner pile body, 3... Foot protection part, 4... Outer pile body, 5... Wing part, 6... Circumference turning machine, 7... Surface layer, 8... Intermediate layer, 9... Pile driver, DESCRIPTION OF SYMBOLS 10... Screw auger, 11... Supporting layer, 12... Footing, 13, 14... Reinforcement bar, 15... Filling reinforcing bar, 16... Filling concrete, 17... Filling concrete, 18... Slip prevention member.

Claims (6)

A structure in which a foundation pile that penetrates the ground is used as a foundation,
The foundation pile is
a tubular inner pile body;
a foot protection portion formed at the tip of the inner pile body;
a tubular outer pile body having a larger diameter than the inner pile body and shorter than the inner pile body and arranged concentrically with the inner pile body;
a wing portion formed at the tip portion of the outer pile body and positioned shallower than the foot protection portion in the ground ;
A structure in which the foundation pile is used as a foundation in a planar shape limited to the outer edge . The foot protection part is formed in the support layer of the ground,
2. The structure according to claim 1, wherein said vane portion is located in a layer shallower than said support layer. The basic structure is
the foundation pile;
A structure according to claim 1 or 2, comprising: a concrete structure integrating the respective heads of the inner pile body and the outer pile body. 4. The structure of claim 3 , wherein the foundation structure further comprises rebar joined to the outer pile body and embedded in the concrete structure , and wherein the inner pile body is not joined to the rebar . A construction method for a structure according to any one of claims 1 to 4,
a first step of penetrating the inner pile body into the ground;
and a second step of penetrating the outer pile body into the ground outside the inner pile body after the first step. A construction method for a structure according to any one of claims 1 to 4,
a first step of penetrating the outer pile body into the ground;
and a second step of penetrating the inner pile body into the ground inside the outer pile body after the first step.

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