JP5069873B2 - Steel pipe pile construction method - Google Patents

Description

  The present invention relates to a method for constructing a steel pipe pile, and more particularly, to a method for constructing a steel pipe pile having a tapered portion whose outer diameter is reduced from one end to the other end.

  In recent years, for example, as a ground reinforcement method when constructing small-scale buildings such as detached houses in soft ground areas, in addition to a deep mixed processing method (hereinafter referred to as a columnar improvement method) using a cement-based solidifying material, 40-200 mm There are an increasing number of cases where steel pipe piles with a small diameter having an outer diameter are installed in the ground to reinforce the ground. In addition, the deep mixing treatment method also has environmental problems such as elution of hexavalent chromium by mixing cement-based solidified material and volcanic ash soil, so it is simple and efficient using small-diameter steel pipe piles. Development of a new ground reinforcement method is desired.

As steel pipe piles of small diameter used for ground reinforcement, straight-shaped steel pipe piles and straight-shaped steel pipe piles having rotor blades at the tip are generally known, and these steel pipe piles reach the support layer at the tip. The foundation pile which obtains a desired supporting force is formed. On the other hand, as a steel pipe pile installed in the ground, by using a steel pipe pile provided with a tapered portion whose outer diameter is reduced from one end to the other end, the wedge effect of the tapered portion is driven. Although it becomes difficult, the technique which paid its attention to obtaining a big ground reaction force is disclosed (for example, refer patent document 1 and patent document 2).
Japanese Patent Laid-Open No. 11-181759 JP 2003-105757 A

However, all of the above methods for installing a steel pipe pile with a tapered portion in the ground apply striking force to the steel pipe pile after excavating the guide hole with an auger or the like or while excavating with an auger machine. Since the steel pipe pile is driven into the ground by a method of pressing, press-fitting, or rotary press-fitting, the surrounding ground is likely to be disturbed. In particular, as a steel pipe pile with a tapered portion, the outer diameter is not so large compared to the drilled diameter by an auger or the like, and when a steel pipe pile with a small diameter of about 50 to 300 mm is driven into the ground, By disturbing the ground, it is not only possible to secure a sufficient frictional force on the peripheral surface of the steel pipe pile and a desired supporting force can not be obtained, but also , for example, a ground resistance force against an external force during an earthquake is reduced.

  The present invention has been made by paying attention to such a conventional problem, and particularly when installing a steel pipe pile having a tapered portion in the ground with a tapered portion, the outer peripheral surface of the steel pipe pile without disturbing the ground. An object of the present invention is to provide a method for constructing a steel pipe pile capable of effectively adhering to the surrounding ground, ensuring a sufficient frictional force, and increasing the ground resistance against external force.

The present invention is used as a ground reinforcement method when constructing a small-scale building such as a detached house , and has an outer diameter having a tapered portion whose outer diameter is reduced from one end side toward the other end side. Is a steel pipe pile with a taper-shaped portion gradient of 1/50 to 1/100 . The outer peripheral surface of the steel pipe pile without disturbing the ground by pressing or rotating into the ground with a heavy press machine by driving into the ground only by pressing or rotating press without driving while excavating. The above object is achieved by providing a construction method of a steel pipe pile that forms a foundation pile capable of obtaining a desired supporting force by frictional force by closely adhering to the surrounding ground.

  And according to the construction method of the steel pipe pile of the present invention, a tip metal fitting provided with a displacement plate member is attached to the tip of the other end portion having a small outer diameter, and a boulder and an obstacle are pushed away by the tip metal fitting. It is preferable to press-fit the steel pipe pile.

  Moreover, according to the construction method of the steel pipe pile of the present invention, the steel pipe pile is press-fitted or rotationally pressed into the ground while another steel pipe pile is added above the steel pipe pile press-fitted or rotationally pressed into the ground, and the lower steel pipe pile is The lower steel pipe pile and the lower steel pipe pile are inserted and locked into the upper end straight joint pipe portion connected to the upper end portion having a large outer diameter. It is preferable that a joint portion with the upper steel pipe pile is formed.

Moreover, according to the construction method of the steel pipe pile of this invention, it is preferable that the press inputs at the time of press-fitting or rotary press-fitting the said steel pipe pile are 7t-8t .

According to the construction method of the steel pipe pile of the present invention, used as a ground reinforcing construction method for building small buildings such as detached houses, set up a steel pipe pile of small diameter with a tapered portion in the ground When reinforcing the foundation ground of a small-scale building, the outer peripheral surface of the steel pipe pile is effectively brought into close contact with the surrounding ground without disturbing the ground, and sufficient frictional force can be secured, and the ground resistance to external force Can be increased.

The construction method of the steel pipe pile which concerns on preferable one Embodiment of this invention is used as a ground reinforcement construction method at the time of constructing small-scale buildings, such as a detached house, for example in a soft ground area, FIG. 1 (a). , (B), a press-fit mechanism known as a heavy machine for driving a steel pipe pile 10 having a small diameter of about 100 to 145 mm toward the foundation ground 11, for example, a steel pipe pile or a PC concrete pile. Is used when forming a foundation pile of a small-scale building by press-fitting and installing using a press-fitting heavy machine 12.

  That is, the construction method of the steel pipe pile according to the present embodiment is obtained by changing the steel pipe pile 10 having the tapered portion 13 whose outer diameter is reduced from the one end 10a side toward the other end 10b side. By pressing or rotating press-fitting 10b downward into the ground using the press-fitting heavy machine 12, the outer peripheral surface of the steel pipe pile 10 is brought into close contact with the surrounding foundation ground 11 without disturbing the foundation ground 11, and friction force The foundation pile which can obtain the desired supporting force by is formed.

  In this embodiment, the steel pipe pile 10 is a steel member having a thickness of, for example, about 4.5 mm, which is formed into a cylindrical shape by, for example, a known steel pipe manufacturing method. The steel pipe pile 10 is a length that can reach the support layer, for example, with a formation layer having a sandy viscosity having an N value of about 9 existing at a depth of about 4.0 mm from the ground surface of the foundation ground 11. For example, it has a length of about 4.5 m. Further, the steel pipe pile 10 has a taper-shaped portion 13 in its entire length, and the outer diameter of one end portion having a large outer diameter is, for example, 145 mm, and the outer diameter of the other end portion having a small outer diameter is, for example, 100 mm. The gradient of the tapered portion is, for example, 1/100.

Here, the slope of the tapered portion 13 of the steel pipe pile 10, has a 1 / 50-1 / 100, particularly preferably in the 1 / 70-1 / 100.

  Moreover, in this embodiment, as shown in FIG. 2 (a), (b), it is press-fitting construction of the heavy machine 12 for press-fit into the steel pipe pile 10 continuously to the one end part (upper end part) 10a with a large outer diameter. For example, a straight pipe portion 15 made of a steel pipe having a length of about 400 to 500 mm having an outer diameter of 145 mm for mounting the jig 14 is attached by being integrally joined by welding or the like. When the straight pipe portion 15 is mounted on the press-fitting construction jig 14 of the press-fitting heavy machine 12, for example, the straight pipe portion 15 is locked in a locking groove provided in the press-fitting construction jig 14 to press-fit construction. Locking ribs 16 that prevent relative rotation of the straight tube portion 15 with respect to the jig 14 are provided so as to protrude inward. When the locking rib 16 is locked in the locking groove, the rotational force from the press-fitting heavy machine 12 can be reliably transmitted to the steel pipe pile 10 via the press-fitting construction jig 14. Can be performed smoothly.

  In addition, when installing the steel pipe piles 10 and 10 'in the ground while adding another steel pipe pile 10' above the steel pipe pile 10, as will be described later, 5 (a) and 5 (b)), the lower end straight joint pipe portion 21 constituting the joint portion 23 between the lower steel pipe pile 10 and the upper steel pipe 10 ′ can be used.

  Further, in the present embodiment, the tip opening of the other end portion (lower end portion) 10b having a small outer diameter is closed, and the steel pipe pile 10 has a tip end as shown in FIGS. A metal fitting 17 is attached. For example, the tip metal fitting 17 is divided into a hollow interior of a cylindrical sleeve portion 17a whose inner peripheral surface has the same tapered shape as the lower end portion 10b of the steel pipe pile 10, and the upper portion thereof is connected to the steel pipe pile 10 with a partition plate 17b. The tip fitting portion is fixed to the steel pipe pile 10 by welding or the like with the tip portion of the steel pipe pile 10 fitted into the tip fitting portion. The cylindrical sleeve portion 17a below the partition plate 17b is disposed so as to cross the center of the cylindrical sleeve portion 17a in the diametrical direction, and has a substantially rectangular displacement plate that protrudes further downward than the cylindrical sleeve portion 17a. The member 18 is fixed and attached by welding or the like. This displacement plate member 18 rotates in accordance with the rotational press-fitting of the steel pipe pile 10, so that even if there are rolling stones or obstructions in the surface layer that prevent the steel pipe pile 10 from being pressed into the foundation ground 11, It is possible to continue to press-fit the steel pipe pile 10 while the steel pipe pile 10 is held substantially vertically while pushing out these rolling stones and the like by the retreating plate member 18.

  And in this embodiment, after carrying the steel pipe pile 10 provided with the above structures into the construction construction site of a detached house, for example, as shown to Fig.1 (a), a steel pipe is used using the press heavy machine 12 At the design hitting position of the pile 10, a tapered other end portion (lower end portion) 10b having a small outer diameter is installed in an inverted state with the vertical downward direction. After that, as shown in FIG. 2 (b), using the press-fitting heavy machine 12, the built-in steel pipe pile 10 is appropriately rotated and a pressure input of, for example, about 7 to 8 t is applied to support the foundation ground 11. The foundation pile by the steel pipe pile 10 which has a taper-shaped part is embed | buried and installed by press-fitting or rotating-pressing toward a layer.

  In this embodiment, for example, the foundation ground 11 above the support layer existing at a depth of about 4.0 mm from the ground surface is configured by a soft layer having an N value of 3 or less, for example. The steel pipe pile 10 is pressed into the soft layer easily and smoothly toward the support layer. Moreover, by the steel pipe pile 10 being press-fitted, consolidation of the soft layer is promoted, and the foundation ground 11 can be effectively compacted.

  When the steel pipe pile 10 is press-fitted to a predetermined depth reaching the support layer, as shown in FIGS. 4A and 4B, for example, the steel pipe pile 10 is supported by the press-fitted steel pipe pile 10 and a concrete foundation of a detached house above this. 19 is built. For example, after the foundation crushed stone 20 is laid on the ground surface of the foundation ground 11, the concrete foundation 19 is placed with reinforcing bars, formwork, etc., and the straight pipe portion 15 is filled with concrete while the upper part of the concrete foundation 19 is rolled up. The upper end of the steel pipe pile 10 can be formed as a fixed end (see FIG. 4A). Moreover, the concrete foundation 19 can also form the upper end of the steel pipe pile 10 as a free end, for example, by placing concrete only in the upper part without filling the straight pipe portion 15 with concrete (FIG. 4). (See (b)).

  And according to the construction method of the steel pipe pile of this embodiment provided with the above-mentioned structure, when installing the steel pipe pile 10 provided with the taper-shaped part 13 in the ground, the outer peripheral surface of the steel pipe pile 10 without disturbing the ground 11 Can be effectively brought into close contact with the surrounding foundation ground 11 to ensure a sufficient frictional force and to enhance the ground resistance against external forces.

That is, in this embodiment, the steel pipe pile 10 provided with the tapered portion 13 is driven into the ground by only press-fitting or rotary press-fitting without driving the guide hole by excavating the guide hole with an auger or the like while excavating with an auger machine. go. Therefore, even if the steel pipe pile 10 is a steel pipe pile 10 having a small diameter with an outer diameter of 100 to 145 mm, the outer diameter is not so large as compared with the drilled diameter by an auger or the like, the surrounding foundation ground 11 is disturbed. It is possible to install the steel pipe pile 10 in the ground, and the outer peripheral surface of the steel pipe pile 10 is firmly in contact with the surrounding ground while pushing the surrounding foundation ground 11 by the tapered wedge shape of the tapered portion 13. Will go. By these, a large frictional force can be secured on the outer peripheral surface of the steel pipe pile 10, and it becomes possible to obtain a large ground reaction force and a supporting force in combination with the wedge effect of the tapered portion 13.

  Further, for example, it is possible to increase the ground resistance against an external force at the time of an earthquake, and it is possible to increase the supporting force as a friction pile and improve the settlement of buildings.

  Further, it is possible to effectively avoid damage to the concrete foundation 19 and the steel pipe pile 10 due to a lateral load during an earthquake, etc., and reduce the horizontal displacement to reduce the influence of the earthquake on the superstructure. It becomes possible to do.

  Furthermore, according to the present embodiment, since the steel pipe pile 10 is installed on the foundation ground 11 by press-fitting with the press-fitting heavy machine 12, for example, the pressing force (press input) at the time of the press-fitting work or after the press-fitting work is finished. It is possible to measure as management data, and confirm the support capacity of the foundation pile by the steel pipe pile 10 from this management data, or estimate the support capacity. Also, since no cement-based solidifying material is used, it is possible to protect the surrounding environment.

  In addition, the supporting force of the steel pipe pile 10 immediately after press-fitting the steel pipe pile 10 of this embodiment using the press-fitting heavy machine 12, the outer diameter is 114.3 mm, the length is 4.5 m, and the wall thickness is 4.5 mm. When the straight steel pipe pile is compared with the support force immediately after press-fitting in a similar manner using the press heavy machine 12, the support force by the steel pipe pile 10 of the present embodiment having the tapered portion 13 is It was confirmed that a considerable supporting force of about 2 to 2.5 times was obtained as compared with the supporting force by the straight steel pipe pile.

  5 (a) and 5 (b) show, for example, when a support layer on the foundation ground 11 is deep, while another steel pipe pile 10 ′ is added above the steel pipe pile 10 that has been press-fitted or rotationally pressed into the ground, , 10 'will be explained in the case of press-fitting or rotary press-fitting into the ground. That is, when installing the steel pipe piles 10 and 10 ′ in the ground while adding them, the upper steel pipe pile 10 ′ is connected to the upper end straight joint pipe portion 21 connected to the upper end portion 10 a having a large outer diameter of the lower steel pipe pile 10. By inserting and locking the lower end straight joint pipe portion 22 connected to the lower end portion 10b having a small outer diameter, a joint portion 23 between the lower steel pipe pile 10 and the upper steel pipe pile 10 ′ is formed.

  The upper end straight joint pipe portion 21 connected to the upper end portion 10a of the lower steel pipe pile 10 is, as described above, the straight pipe portion 15 on which the press fitting jig 14 of the press heavy machine 12 is mounted as it is, the upper end straight joint pipe. It can be used as part 21. The lower end straight joint pipe portion 22 connected to the lower end portion 10b ′ of the upper steel pipe pile 10 ′ is, for example, approximately twice as thick as the inner diameter of the upper end straight joint pipe portion 21 and has an outer diameter smaller than that of the upper end straight joint pipe portion 21. A straight pipe portion having a length similar to that of the joint pipe portion 21, and an L-shaped joint locking groove 24 is provided on the outer peripheral surface thereof.

  When the lower steel pipe pile 10 is press-fitted until its upper end portion 10 a is close to the ground surface of the foundation ground 11, the lower end straight joint pipe portion 22 of the upper steel pipe pile 10 ′ is connected to the upper end straight joint pipe portion 21 of the lower steel pipe pile 10. Then, the joint locking groove 24 is inserted while being matched with the locking rib 16 (see FIG. 5B). After the lower end straight joint pipe portion 22 is inserted into the upper end straight joint pipe portion 21 of the lower steel pipe pile 10, the upper steel pipe pile 10 ′ is slightly rotated so that the locking ribs 16 are formed in the L-shaped joint locking grooves 24. The lower steel pipe pile 10 is joined by, for example, welding to the base end portion of the lower end straight joint pipe portion 22 of the upper steel pipe pile 10 ′ while being engaged with the hook-shaped portion and at the upper end of the upper straight joint pipe portion 21. The upper steel pipe pile 10 'is firmly connected to the upper side of the upper side.

  When the upper steel pipe pile 10 ′ is added above the lower steel pipe pile 10, the press fitting jig 14 of the press heavy machine 12 is attached to the straight pipe portion 15 ′ at the upper end of the upper steel pipe pile 10 ′. Similarly, the joined steel pipe piles 10 and 10 'are press-fitted or rotationally press-fitted into the ground, and the same effects as described above are exhibited.

The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, as shown in FIG. 6, for example, the joint portion when the upper steel pipe pile 10 'is added above the lower steel pipe pile 10 is formed by shortening the lower end straight joint pipe portion 22 of the upper steel pipe pile 10'. By providing the male screw portion 25 on the surface and screwing and fastening the male screw portion 25 to the female screw portion 26 provided on the upper inner surface of the upper end straight joint pipe portion 21 ′ of the lower steel pipe pile 10, the lower steel pipe The pile 10 and the upper steel pipe pile 10 'can be connected and integrated.

Furthermore, if the ground into which the steel pipe pile is press-fitted or rotationally-fitted is a ground in which the steel pipe pile can be press-fitted or rotationally pressed without excavating with an auger or the like, the N value is 3 or less except for the support layer at the tip portion. It is not always necessary for the ground to be, for example, a ground having a ground supporting force from below the foundation of 2 m to 50 kN / m ² or less and a soft layer having an N value of 3 or less continuing below it. .

(A), (b) is the schematic side view explaining the construction method of the steel pipe pile which concerns on preferable one Embodiment of this embodiment. (A) is the partial side view which shows the state which provided the straight pipe part for mounting | wearing with the press-fitting construction jig of the press-fitting heavy machine continuously to the one end part of a steel pipe pile, (b), (a) It is the top view seen from the upper part. (A) is a fragmentary sectional view explaining the state which attached the tip metal fitting provided with a displacement plate member to the other end part of a steel pipe pile, and (b) is a perspective view of a tip metal fitting. (A), (b) is the fragmentary sectional view explaining the state which built the concrete foundation above this by making the steel pipe pile installed in the ground into a foundation pile. (A) is a side view explaining the state which added the upper steel pipe pile above the lower steel pipe pile, (b) is a partial side view explaining the structure of the joint part of a lower steel pipe pile and an upper steel pipe pile. It is a fragmentary perspective view explaining the composition of other joint parts of a lower steel pipe pile and an upper steel pipe pile.

Explanation of symbols

10 Steel pipe pile (downward steel pipe pile)
10a One end of steel pipe pile (upper end)
10b The other end of steel pipe pile (lower end)
10 'Lower steel pipe pile 11 Foundation ground (ground)
DESCRIPTION OF SYMBOLS 12 Press fitting heavy machine 13 Taper-shaped part 14 Press fitting construction jig 15 Straight pipe part 16 Locking rib 17 End metal fitting 17a End metal fitting cylindrical sleeve part 17b End metal fitting partition plate 18 Retraction plate member 19 Concrete foundation 19a End face contact plate Locking slit 20 Basic crushed stone 21, 21 'Upper end straight joint pipe part 22, 22' Lower end straight joint pipe part 23 Joint part 24 Joint locking groove 25 Male thread part 26 Female thread part

Claims (4)

It is used as a ground reinforcement method when constructing small-scale buildings such as detached houses , and has an outer diameter of 100 to 145 mm having a tapered portion with an outer diameter reduced from one end side toward the other end side. , Drive the steel pipe pile with a taper-shaped portion gradient of 1/50 to 1/100 with the other end with a small outer diameter facing down and drilling the guide hole in advance or drilling with an auger machine Without damaging the ground, the outer peripheral surface of the steel pipe pile is surrounded by the surrounding ground by pressing or rotating into the ground using a press heavy machine. A steel pipe pile construction method that forms a foundation pile that can be brought into close contact with each other to obtain a desired supporting force by frictional force.   The steel pipe according to claim 1, wherein a tip fitting having a displacement plate member is attached to a tip of the other end portion having a small outer diameter, and the steel pipe pile is rotationally press-fitted while pushing away a boulder or an obstacle by the tip fitting. Pile construction method.   An upper end straight joint in which the steel pipe pile is press-fitted or rotary-fitted into the ground while another steel pipe pile is added above the steel pipe pile that has been press-fitted or rotationally pressed into the ground, and is connected to the upper end portion of the lower steel pipe pile that has a large outer diameter A joint part between the lower steel pipe pile and the upper steel pipe pile is formed by inserting and locking the lower end straight joint pipe part connected to the lower end part having a small outer diameter of the upper steel pipe pile in the pipe part. The construction method of the steel pipe pile of 1 or 2.   The construction method of the steel pipe pile according to any one of claims 1 to 3, wherein the pressure input when the steel pipe pile is press-fitted or rotationally press-fitted is 7t to 8t.

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