JP4501249B2 - Steel pipe pile and its construction method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steel pipe pile whose end opening is closed and a construction method thereof, and more particularly, to a steel pipe pile and a construction method thereof effective when a large-diameter steel pipe concrete pile is constructed.
[0002]
[Prior art]
Steel pipe piles or concrete piles (hereinafter referred to as tip closed piles) closed by attaching a lid-like member to the tip opening to prevent intrusion of earth and sand when the steel pipe piles penetrate into the ground Several proposals have been made. In addition, the construction method of this tip blockage pile includes a hammering method in which the head of the pile body is struck and penetrates into the ground, a hole is excavated in advance in the ground where the pile body is installed, and a pile body is installed in the hole There is a pre-boring method or a method of rotating and embedding a pile body by the action of a wood screw attached to the vicinity of the tip of the pile body. Further, there has been proposed an invention in which a steel pipe pile having an open front end portion is dug and concrete is placed only at the front end portion.
[0003]
Tip blocking piles include those that attach excavation tip rods, and those that improve the bearing capacity characteristics of the tip ground due to the ground. Examples of these are shown below.
JP-A-55-119822 comprises a cylindrical portion inserted into the opening of the tip of a concrete pile, and a collar portion that is connected to the lower end portion of the cylindrical portion and is locked to the lower end surface of the concrete pile. A steel pipe member that reinforces the bearing capacity of a concrete pile is described.
Japanese Patent Application Laid-Open No. 55-155823 discloses a pile in which an enlarged shoe having a diameter larger than that of a bladed steel pipe and a triangular rib is attached to the tip of the bladed steel pipe.
[0004]
Japanese Laid-Open Patent Publication No. 60-55119 describes a ready-made pile in which an end plate having a diameter larger than that of the pile and having an earth rising port, a drilling blade and the like is attached to the tip opening of the pile. 62-29614 describes a ready-made pile with an anchor member secured to the lower end.
Furthermore, Japanese Patent Application Laid-Open No. 9-242068 describes cast-in-place piles having a bottom plate that has a drilling blade and is restrained from moving and turning upward at the tip opening of a steel pipe (these 5). The inventions are collectively referred to as Conventional Technology 1).
[0005]
Next, the method of hitting the closed end pile is applied to the head of the pile body with a hammer or the like, and with the hitting force, the earth and sand that constitutes the pile tip and the pile surface ground are moved in the depth direction and to the side. While eliminating, it is compacted and the pile body penetrates into the ground and is installed (Prior Art 2).
[0006]
In addition, the pre-boring method of the closed-end pile is made by drilling a hole in the ground with a drill or the like prior to the installation of the pile body, and normally filling the void with cement milk or the like to suppress the collapse of the geology, The body is built (Prior Art 3).
[0007]
Several methods have been put to practical use for small-diameter steel pipe piles by rotating and embedding pile bodies by acting as wing wood screws attached in the vicinity of the tip of the closed end pile.
The method of burying steel pipe piles described in Japanese Examined Patent Publication No. 2-62648 is that a bottom plate is fixed to the lower surface of a steel pipe pile main body, an excavating blade is provided on the bottom plate, and this is provided on the outer peripheral surface of the lower end of the pile main body. A steel pipe pile projecting approximately one turn of a spiral wing with a large blade width and having an outer diameter almost twice as large as the outer diameter of the pile body is pressed into the ground while rotating so as to be screwed into soft ground. Then, the soil at the tip of the pile body is softened by excavating the bottom of the pile body, and the spiral blades are bitten into the unexcavated soil on the side of the pile, and the softened soil is excavated and softened while rotating the pile body as the reaction force of the soil. The pile body is extruded and compressed on the side of the pile, and the pile body is screwed and installed in the ground without any soil (prior art 4).
[0008]
In addition, the steel pipe pile embedding method described in Japanese Examined Patent Publication No. 4-58850 closes the lower end portion of the steel pipe pile with a bottom plate having a drilling blade and a grout spout, and has an outer diameter almost twice the outer diameter of the steel pipe. A steel pipe pile in which a spiral wing with a diameter is fixed to the outer peripheral surface of the lower end of the steel pipe pile in a single turn is used to reinforce the peripheral ground by ejecting cement milk from the grout outlet during and after the rotary burial. Yes (prior art 5).
[0009]
Furthermore, as a construction method in which a steel pipe pile having an open end portion is dug and concrete is placed only at the end portion, there is one described in Japanese Patent Publication No. 5-517305. In this construction method, the ground is excavated, a steel pipe is built in the hole, the support layer is excavated at the bottom, concrete is placed at the tip, and the excavated soil is backfilled in the steel pipe ( Prior art 6).
[0010]
[Problems to be solved by the invention]
Each front-end blockage pile of prior art 1 cannot move or remove the lid-like member attached to the front-end | tip part in the middle of construction in the pile body direction. For this reason, excavation of a pile body front-end | tip part cannot be performed using another means during construction.
[0011]
In the hitting method of Prior Art 2, when the pile diameter is increased, the penetration resistance of the peripheral ground is increased by the pile diameter, but since the tip of the pile body is blocked, the penetration resistance of the tip ground is the pile diameter. It increases in proportion to the square. For this reason, with a closed end pile with an outer diameter of 600 mm or more, it is practically impossible to penetrate the ground to a predetermined depth, in particular, to punch out a hard intermediate layer or to insert it into the tip support layer.
[0012]
Moreover, in the pre-boring method of the prior art 3, when the pile diameter is increased, the amount of soil by the pre-excavation increases, and the cement milk filled in the hole prior to the pile installation is not With the installation, only the volume of the pile body will be discharged, and processing of the discharged soil and cement milk will be very expensive.
[0013]
In the method of embedding a steel pipe pile with a wing attached to the tip, the method according to the prior art 4 has been widely put into practical use in the range where the outer diameter of the steel pipe pile is less than 300 mm. This embedding method can secure a relatively large tip support force because the tip of the steel pipe is closed by the bottom plate, but the torque required for rotational penetration is high because the reaction force received by the spiral blade from the ground is large. Not only becomes very large, but also the penetration efficiency deteriorates. According to the field test conducted by the inventors, the torque required for the penetration of the support layer increases to 3 to 5 times the torque when the soft ground penetrates.
[0014]
For this reason, a motor with a large capacity for rotating the pile body and a base machine for mounting the same are required, and the torsional moment of the pile body is increased, resulting in a thickness larger than the thickness required for the design. Steel pipes are often required for construction. Also, concrete piles that are vulnerable to torsion cannot be applied. Furthermore, if the outer diameter of the steel pipe exceeds 600 mm, the torque required for the construction becomes too large and a special large machine is required, which is not practical.
[0015]
In the steel pipe pile embedding method of the prior art 5, cement milk is jetted from the tip of the pile body and mixed with the earth and sand by the spiral blade, so that the disturbance of the support layer ground due to the spiral blade is somewhat recovered. However, since the rotation for stirring and mixing is only one direction of the spiral blade, sufficient stirring of earth and sand and cement milk cannot be expected. In particular, when the ground is a viscous soil, the stirring and mixing tends to be uneven. In addition, although the rotational torque can be slightly reduced as compared with the case where cement milk is not ejected, the earth and sand in the vicinity of the closed pile tip portion are difficult to move, and thus a significant reduction in rotational torque cannot be expected. Furthermore, the range of stirring and mixing of the earth and sand is only the spiral blade portion, and only the ground supporting force corresponding to the area of the spiral blade can be expected.
[0016]
In the construction method of Prior Art 6, it is necessary to excavate all the earth and sand at the position where the pile is installed in order to open the tip. Not only the amount of excavated soil increases, There is a risk of deteriorating the bearing capacity characteristics.
[0017]
The present invention was made in order to solve the above-described problems, and a large-diameter steel pipe pile with a closed end opening portion can be installed in the ground, and the original supporting ability of the upper ground is exhibited. Steel pipe pile and its construction Direction The purpose is to provide a law.
[0018]
[Means for Solving the Problems]
The steel pipe pile according to the present invention is a steel pipe pile whose tip is closed by a lid, A rod is fixed to the center of the upper surface of the lid, Even during the construction of steel pipe piles By rotating the rod by an external operation, Detachable lid And can be pulled out It is configured.
Moreover, said steel pipe pile is comprised with the winged screwed-type steel pipe pile.
[0019]
Moreover, the construction method of the steel pipe pile according to the present invention includes a step of penetrating the steel pipe pile into the ground, and the steel pipe pile is left in the ground when the tip of the steel pipe pile reaches the support layer or the vicinity thereof. A step of extracting the lid body from the steel pipe pile in a state of being made, a step of excavating a support layer by inserting a drum bucket into the steel pipe pile left in the ground, a step of extracting the drum bucket, the excavation part and And a process of placing concrete in the steel pipe pile.
[0020]
Furthermore, in the construction method of the steel pipe pile described above, when the tip of the steel pipe pile reaches the hard ground or its vicinity before reaching the support layer, the lid is placed in the state where the steel pipe pile is left in the ground. A step of extracting from the pile, a step of excavating the hard ground by inserting a drum bucket into a steel pipe pile left in the ground, and a step of extracting the drum bucket when the excavation of the hard ground is finished, And a step of closing the tip opening of the steel pipe pile again with a lid.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
[Embodiment 1]
FIG. 1 is a cross-sectional explanatory view of a main part of a steel pipe pile according to Embodiment 1 of the present invention.
In the figure, reference numeral 2 denotes a steel pipe constituting a steel pipe pile 1 having an open end, and an internal thread 3 is provided on the inner peripheral surface near the end. Reference numeral 5 denotes a lid that opens and closes the front end opening of the steel pipe 2, and a male screw 6 that is screwed into the female screw 3 of the steel pipe 2 is provided on the outer periphery. Reference numeral 7 denotes a rod fixed to the center of the upper surface of the lid 5.
[0022]
Next, an example of a construction method of the steel pipe pile 1 configured as described above will be described with reference to FIGS. In this example, the steel pipe pile 1 is installed on the ground composed of the soft layer S and the support layer B by a hammering method. In addition, as shown in FIG. 1, the steel pipe pile 1 is provided at the tip, and the screw 6 of the lid 5 is screwed into the screw 3 so that the tip opening is closed.
[0023]
(1) First, as shown in FIG. 2 (a), the steel pipe pile 1 is penetrated into the ground by a striking method, and its tip is positioned in the support layer B as shown in FIG. 2 (b).
(2) Next, the rod 7 is attached to a drive motor mounted on a base machine or the like (not shown), and the rod 7 is rotated to connect the male screw of the lid 5 to the steel pipe 2 as shown in FIG. Remove from the female screw 3 and pull it up.
(3) Next, as shown in FIG. 2 (d), the drum bucket 15 is inserted into the steel pipe pile 1 and rotated to excavate the support layer.
[0024]
As shown in FIG. 4, the drum bucket 15 is provided with a drum-shaped main body 16 and a lower excavating blade 17 that is provided at the bottom of the drum bucket 15 so that it can be opened and closed by an external operation. And a plurality of side excavation blades 18 that are provided on the outer wall and expand in the left-right direction by an external operation. Reference numeral 19 denotes a rod that rotates with one end attached to the top surface of the main body 16 and the other end attached to, for example, a drive motor mounted on a base machine.
[0025]
(4) Then, as shown in FIG. 2 (e), the side excavation blade 18 of the drum bucket 15 is gradually expanded to rotate the rod 19, and the support layer B is excavated together with the lower excavation blade 17 to expand the bottom portion. 25 is created, and at the same time, earth and sand are taken into the main body 16 from the bottom.
When the excavation of the expanded bottom portion 25 is finished, the side excavation blade 18 is returned to the original position, and the drum bucket 15 is pulled out from the steel pipe pile 1.
(5) As shown in FIG. 2 (f), the raised drum bucket 15 opens the lower excavating blade 17 in the vicinity of the steel pipe pile 1 or at a predetermined location, and the earth and sand 31 taken into the main body 16 is grounded. To discharge. Further, if necessary, the steel pipe pile 1 is penetrated until the tip of the steel pile 1 reaches the vicinity of the center of the bottom expanded portion 25 at this time or after placement of the concrete 30 described later.
[0026]
(6) Next, as shown in FIG. 3 (a), the tremely pipe 14 is inserted into the steel pipe pile 1, and the concrete 30 is cast to the full length or a predetermined height within the expanded base 25 and the steel pipe pile 1. Create concrete piles.
(7) And as shown in FIG.3 (b), the tremy pipe 14 is pulled up, and the earth and sand 31 is thrown in in the steel pipe pile 1 as shown in FIG.3 (c) as needed.
[0027]
In the above description, the case where the drum bucket 15 is used for excavation of the expanded bottom portion 25 and the removal of earth and sand has been shown, but a grab bucket may be used instead of the drum bucket 15. For example, as shown in FIG. 5, the grab bucket 20 has a digging blade 21 that is opened and closed by an external operation. The digging blade 21 digs a support layer and rotates the digging blade 21 in the center direction. It is made to carry the earth and sand and carry it out to the outside. In addition, the apparatus used for excavation of the support layer B, formation of the expanded bottom portion 25, and unloading of the earth and sand is not limited to the drum bucket 15 and the grab bucket 20 described above, and other apparatuses may be used (hereinafter, These are collectively called drum buckets).
[0028]
According to the construction method as described above, a large-diameter steel pipe pile can be installed at a high speed with a small amount of soil removal, and a large tip support force can be obtained. In the above description, the bottom portion 25 is formed by the drum bucket and the concrete 30 is placed in the bottom portion 25 and the steel pipe pile 1. However, the bottom portion 25 is omitted and the steel pipe pile 1 is provided. Concrete 30 may be placed.
[0029]
In the above description, the case where the steel pipe pile 1 according to the present embodiment is installed on the ground composed of the soft layer S and the support layer B has been described. However, as shown in FIG. In some cases, an intermediate layer I of ground that is harder than the soft layer S exists between the support layer B and the support layer B.
In such a case, as shown in FIG. 6 (a), the steel pipe pile 1 is penetrated into the soft layer S by the striking method with the end opening closed by the lid 5. And when the front-end | tip part of the steel pipe pile 1 reaches the intermediate | middle layer I or its vicinity as shown in FIG.6 (b), the rod 7 is rotated, the cover body 5 is removed from the steel pipe pile 1, and it raises and pulls up. .
[0030]
Next, as shown in FIG. 6 (c), the drum bucket 15 is inserted into the steel pipe pile 1, the intermediate layer I is excavated by the lower excavating blade 17, and the steel pipe pile 1 is penetrated. When passing through the intermediate layer I, the drum bucket 15 is pulled up and the earth and sand taken into the main body 16 are discharged to the outside. And as shown in FIG.6 (d), the cover body 5 is inserted in the steel pipe pile 1, and it mounts | wears with a front-end | tip part, and penetrates into the next soft layer S in the state which closed the front-end | tip opening part again. Hereinafter, the construction is performed by the processes after (b) described in FIGS. In addition, when the hard ground exists up to the support layer B following the intermediate layer I, the ground may be excavated by the drum bucket 15 without lifting the drum bucket 15.
[0031]
7 and 8 show another example of the steel pipe pile according to the present embodiment. In the steel pipe pile 1 of FIG. 7, the lower surface of the lid 5 is formed in an inverted conical shape in the steel pipe pile 1 of FIG. It is easy to penetrate into the ground.
Further, the steel pipe pile 1 of FIG. 8 is provided with one or a plurality of inverted L-shaped key grooves 8 on the side wall of the drum-shaped lid body 5 and a key groove on the inner peripheral surface in the vicinity of the tip of the steel pipe 2. A key 9 is provided corresponding to 8. And when closing the front-end | tip opening part of the steel pipe pile 1, after turning the cover body 5 and fitting the key groove 8 to the key 9, it rotates, and the key 9 is located in the horizontal part of the key groove 8. FIG. Thereby, the lid 5 is held in that position and does not move in the vertical direction.
Moreover, when removing the cover body 5 from the steel pipe 2, if the cover body 5 is rotated in the opposite direction and pulled up, it can be easily removed.
[0032]
According to the present embodiment, a lid 5 that is detachable even during construction is provided at the tip of the steel pipe pile 1, and the steel pipe pile 1 is penetrated into the ground with the tip opening closed, and the pile tip When reaching the intermediate layer I or the support layer B, which is a hard ground, or the vicinity thereof, the steel pipe pile 1 is left in the ground, the lid 5 is removed and pulled up, and the ground excavation means is placed in the steel pipe pile 1 By inserting the drum bucket 15 and excavating the steel pipe pile 1 having a large diameter can be easily penetrated even on hard ground. In addition, since the excavated earth and sand are taken into the drum bucket 15 and discharged to the outside, the earth and sand do not enter the steel pipe pile 1 and can be easily put by placing the concrete 30 as it is. Steel pipe concrete piles can be created.
Further, the lid 5 is pulled up, the drum bucket 15 is inserted into the steel pipe pile 1, and the bottom portion 25 is formed in the support layer B so that the concrete 30 is placed. Can be created. In addition, in this Embodiment, although the case where the steel pipe pile 1 was penetrated by the hammering method was shown, you may penetrate the steel pipe pile 1 by a press-fitting method.
[0033]
[Embodiment 2]
FIG. 9 is a cross-sectional explanatory view of a main part of a steel pipe pile according to Embodiment 2 of the present invention. In addition, the same code | symbol is attached | subjected to this and the same part as the steel pipe pile demonstrated in FIG. 1, and description is abbreviate | omitted.
In this embodiment, the steel pipe pile 1 according to the first embodiment shown in FIG. 1 is provided with a wing 11 on the outer periphery of the lower portion of the steel pipe 2 to form a winged screwed steel pipe pile 10 (hereinafter referred to as a winged steel pipe pile). It is a thing.
[0034]
An example of the wing | blade 11 provided in the steel pipe pile 10 with a wing | blade in FIG. 10, FIG. 11 is shown. In the example of FIG. 10, steel blades 11a and 11b made of fan-shaped flat plates are joined to the outer periphery in the vicinity of the tip portion of the steel pipe 2 so as to intersect at the same height position by welding, thereby forming the blade 11. .
In the example of FIG. 11, the spiral blade 12 formed by cutting and bending one portion of a donut-shaped steel plate is joined to the outer periphery in the vicinity of the distal end portion of the steel pipe 2 by welding to configure the blade 11. Is.
[0035]
An example of the wing 11 has been described with reference to FIGS. 10 and 11. However, the present invention is not limited to this, and may be a polygonal shape in addition to the flat plate shape and the spiral shape described above, or these may be divided into a plurality of pieces. A thing etc. can be selected suitably. Moreover, the attachment position can also be set suitably and you may provide multiple steps | paragraphs in an axial direction as needed. In addition, as for the wing | blade 11, it is desirable to use the thing whose outer diameter is about 1.5 to 3.0 times the outer diameter of the steel pipe 2. FIG.
[0036]
Next, an example of the construction method of the winged steel pipe pile 10 according to the present embodiment will be described with reference to FIGS.
(1) First, the pile head of the winged steel pipe pile 10 whose end opening is closed by the lid 5 is attached to a drive motor mounted on a base machine or the like (not shown) installed on the ground. As shown in FIG. 12 (a), the steel pipe pile 10 is rotated and propelled by the action of the wood screw of the wing 11, penetrates into the ground, and supports its tip as shown in FIG. 12 (b). Located in or near layer B. In addition, it may replace with a pile head and you may make it attach a drive motor to the trunk | drum of the winged steel pipe pile 10. FIG.
[0037]
(2) Next, the drive motor is removed from the winged steel pipe pile 10, the rod 7 of the lid 5 is attached to the drive motor, the rod 7 is rotated, and the lid 5 is removed from the steel pipe 2, as shown in FIG. Pull up to the outside.
(3) Next, as shown in FIG. 12 (d), the drum bucket 15 with the rod 19 attached to the drive motor is inserted into the winged steel pipe pile 10 and rotated to excavate the support layer B.
(4) Then, as shown in FIG. 12 (e), a bottom expanded portion 25 is formed in the support layer B, the drum bucket 15 is pulled out from the winged steel pipe pile 10, and as shown in FIG. 12 (f), the drum bucket The earth and sand taken in 15 is discharged.
[0038]
(5) Next, as shown in FIG. 13 (a), the tremy pipe 14 is inserted into the winged steel pipe pile 10, and the concrete 30 is driven to the full length of the bottom expanded part 25 and the winged steel pipe pile 10 or to a predetermined height. Set up.
(6) Next, as shown in FIG.13 (b), the tremy pipe 14 is pulled up and a steel pipe concrete pile is formed. Then, the winged steel pipe pile 10 is attached again to the drive motor and rotated, and penetrates until the tip part reaches the vicinity of the center part of the bottom expanded part 25.
In addition, as shown in FIG.13 (c), the earth and sand 31 is thrown in in the steel pipe concrete pile 10 as needed.
[0039]
According to the construction method as described above, it is possible to install a large-diameter winged steel pipe pile 10 in the ground with low vibration, low noise, and a small amount of soil removal, and earth and sand may enter the inside of the pile. Therefore, it is possible to construct a steel pipe concrete pile by placing concrete without discharging earth and sand. Moreover, the large tip support force can be obtained with a small amount of use of the concrete by the concrete 30 placed on the wing 11 and the expanded bottom portion 25.
Also in the present embodiment, when the intermediate layer I exists in the ground, as explained in the construction method of FIG. 6 of the first embodiment, the tip of the winged steel pipe pile 10 is the intermediate layer I or When the vicinity is reached, the lid body 5 is pulled up and the drum bucket 15 is inserted. After excavating the intermediate layer I, the lid body 5 is inserted again and attached.
[0040]
14 and 15 show another example of the screw-type steel pipe pile according to the present embodiment. In the example of FIG. 14, the lower surface of the lid body 5 of FIG. 9 is formed in an inverted conical shape.
Further, in the example of FIG. 15, one or a plurality of inverted L-shaped key grooves 8 are provided on the side wall of the drum-shaped lid 5, and the key grooves 8 are formed on the inner peripheral surface near the tip of the steel pipe 2. Correspondingly, a key 9 is provided, and its action is the same as that of the steel pipe pile described in FIG.
[0041]
Although the embodiment of the present invention has been described above, the lid body 5 that opens and closes the tip opening of the steel pipe pile 1 or the winged steel pipe pile 10 according to the present invention is used when the steel pipe pile 1 or the winged steel pipe pile 10 penetrates. Since it is for preventing soil and sand from entering the inside, the tip opening may not be completely closed, and a part thereof may be opened.
Moreover, the attachment / detachment mechanism of the lid 5 with respect to the steel pipe pile 1 or the winged steel pipe pile 10 is not limited to the above-described example, and can be attached and detached by an external operation during the construction of the steel pipe pile 1 or the winged steel pipe pile 10. Other means may be used as long as it is.
[0042]
Further, an excavation blade may be provided on the lower surface of the lid 5 or an injection hole for injecting water, cement milk or the like into the ground may be provided in the lid 5. Furthermore, you may make it raise the adhesive force of concrete by providing a rib and other convex parts in the inner peripheral surface near the front-end | tip part of the steel pipe pile 1 or the winged steel pipe pile 10, or any one.
[0043]
【Example】
Next, the Example about the construction method of FIG. 12, FIG. 13 by the steel pipe pile with a wing | blade of Embodiment 2 is demonstrated.
The winged steel pipe pile 10 has a female thread 3 on the inner peripheral surface of the tip, and has an outer diameter of 1800 mm, a long inner diameter of 1008 mm, and a short inner diameter of 1000 mm on the outer periphery of the tip of the steel pipe 2 having an outer diameter of 1000 mm, a plate thickness of 12 mm, and a length of 31 m. A steel wing made of a flat plate obtained by dividing a donut-shaped steel plate having a thickness of 40 mm into two was crossed at the same height position and joined by welding to form a wing 11.
[0044]
Further, the lid 5 was constituted by a drum-shaped steel material having a thickness (height) of 40 mm having the screws 6 on the outer periphery, and the rod 7 was attached to the center of the upper surface. The ground to be constructed was a soft layer with an N value of 3 up to 23 m from the ground surface, a soft layer with an N value of 7 up to 23 to 32 m, and a support layer with an N value of 50 after that.
[0045]
First, the lid body 5 was inserted into the steel pipe 2 from the upper opening, the rod 7 was rotated, the male screw 6 was screwed onto the female screw 3 of the steel pipe 2, and the tip opening was closed.
Next, the pile head of the winged steel pipe pile 10 was attached to the drive motor of the base machine installed on the ground, and it was squeezed while rotating and propelled through the soft layer by the wood screw action of the wing 11 to penetrate.
When the tip of the pile reaches the support layer, the drive motor is detached from the winged steel pipe pile 10 and attached to the rod 7 of the lid 5, and the rod 7 is rotated to engage with the female screw 3 of the steel pipe 2. And the lid 5 was pulled up with the winged steel pipe pile 10 left in the ground.
[0046]
Next, the rod 19 of the drum bucket 15 is attached to the drive motor and inserted into the winged steel pipe pile 10, and the drum bucket 15 is rotated to excavate the support layer by the lower excavation blade 17, and the side excavation blade 18 is Gradually expanded to excavate a bottom expansion 25 having a depth of 35 m from the surface and a maximum outer diameter of 2000 mm. When the excavation of the expanded bottom portion 25 was finished, the side excavation blade 18 was returned to the original state, the drum bucket 15 was lifted up, and the earth and sand taken into the drum bucket 15 was discharged.
[0047]
Then, the tremy pipe 14 was attached to the drive motor, the concrete 30 was placed in the widened portion 25 and the winged steel pipe pile 10, and the tremy pipe 14 was pulled up. The casting height of the concrete 30 was 4 m from the bottom of the expanded bottom portion 25.
Next, the winged steel pipe pile 10 was attached to a drive motor and rotated, and penetrated until the tip portion reached the vicinity of the center portion of the expanded bottom portion 25. As a result, the blade 11 is located in the expanded bottom portion 25.
[0048]
By the above procedure, a low-vibration, low-noise, large-diameter winged steel pipe pile can be installed in the ground in a short period of time with a small amount of soil removed. Combined with the existence of wings, we were able to obtain a large tip support force.
[0049]
【The invention's effect】
The steel pipe pile according to the present invention is a steel pipe pile whose tip is closed by a lid, A rod is fixed to the center of the upper surface of the lid, Even during the construction of steel pipe piles By rotating the rod by an external operation, Detachable lid And can be pulled out In addition, because the above steel pipe pile was composed of a winged screw-in type steel pipe pile, the lid body was pulled out even during construction, and another excavation means was inserted inside, and the ground near the tip of the steel pipe pile was removed. Can be excavated.
[0050]
Furthermore, the construction method of the steel pipe pile according to the present invention includes the step of penetrating the steel pipe pile into the ground, and the steel pipe pile is left in the ground when the tip of the steel pipe pile reaches the support layer or the vicinity thereof. In the state of extracting the lid from the steel pipe pile, inserting the drum bucket into the steel pipe pile left in the ground, excavating the support layer, extracting the drum bucket, and in the excavation part and the steel pipe pile Therefore, a large-diameter steel pipe pile can be installed in the ground, and a large tip supporting force can be obtained with less soil and less concrete.
[0051]
In the construction method of each steel pipe pile, when the tip of the steel pipe pile reaches the hard ground or its vicinity before reaching the support layer, the lid is placed in the state where the steel pipe pile is left in the ground. The process of extracting from the steel pipe pile, the process of excavating the hard ground by inserting the drum bucket into the steel pipe pile left in the ground, the process of extracting the drum bucket when the hard ground is excavated, and the tip opening of the steel pipe pile And the step of closing the part again with the lid, it is possible to easily penetrate a large-diameter steel pipe pile even when a hard ground such as an intermediate layer exists before reaching the support layer.
[Brief description of the drawings]
FIG. 1 is a cross-sectional explanatory view of a steel pipe pile according to a first embodiment of the present invention.
2 is an explanatory view of another construction method of the steel pipe pile of FIG. 1. FIG.
FIG. 3 is an explanatory view of another construction method of the steel pipe pile of FIG. 1;
4 is an explanatory diagram of an example of a drum bucket used in the construction method of FIGS. 2 and 3. FIG.
FIG. 5 is an explanatory diagram of an example of a grab bucket used in the construction method of FIGS. 2 and 3;
6 is an explanatory view of still another construction method of the steel pipe pile of FIG. 1. FIG.
7 is a cross-sectional explanatory view of another example of the steel pipe pile according to the first embodiment. FIG.
FIG. 8 is an explanatory diagram of still another example of the steel pipe pile according to the first embodiment.
FIG. 9 is a cross-sectional explanatory view of a winged steel pipe pile according to a second embodiment of the present invention.
FIG. 10 is an explanatory diagram showing an example of a wing according to a second embodiment.
FIG. 11 is an explanatory view showing another example of the wing of the second embodiment.
12 is an explanatory diagram of another example of the construction method of the winged steel pipe pile of FIG. 9; FIG.
13 is an explanatory view of another example of the construction method of the winged steel pipe pile of FIG. 9; FIG.
FIG. 14 is an explanatory diagram of another example of a winged steel pipe pile according to the second embodiment.
FIG. 15 is an explanatory diagram of still another example of the winged steel pipe pile according to the second embodiment.
[Explanation of symbols]
1 Steel pipe pile
2 Steel pipe
3 Female thread
5 lid
6 Male thread
8 Keyway
9 keys
10 Winged steel pipe pile
11 Wings
14 Tremy Tube
15 drum bucket
20 Grab bucket
25 Widened bottom
30 concrete

Claims (4)

A steel pipe pile whose tip is closed by a lid , wherein a rod is fixed to the center of the upper surface of the lid, and the rod is rotated by an external operation even during construction of the steel pipe pile , A steel pipe pile characterized in that the lid can be detached and pulled up to the outside . The steel pipe pile according to claim 1, wherein the steel pipe pile is a winged screw-type steel pipe pile. A step of penetrating the steel pipe pile of claim 1 or 2 into the ground;
When the tip of the steel pipe pile reaches the support layer or the vicinity thereof, the step of extracting the lid from the steel pipe pile with the steel pipe pile left in the ground; and
Inserting a drum bucket into a steel pipe pile left in the ground and excavating a support layer; and extracting the drum bucket;
A method for constructing a steel pipe pile, comprising the step of placing concrete in the excavation part and the steel pipe pile. When the tip of the steel pipe pile reaches the hard ground or its vicinity before reaching the support layer, the step of extracting the lid from the steel pipe pile with the steel pipe pile left in the ground; and
A step of excavating the hard ground by inserting a drum bucket into the steel pipe pile left in the ground, and a step of extracting the drum bucket when the excavation of the hard ground is completed;
The construction method of the steel pipe pile of Claim 3 provided with the process of closing again the front-end | tip opening part of the said steel pipe pile with a cover body.

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