JP6715663B2 - Steel pipe pile construction method - Google Patents

Description

The present invention relates to a method of constructing a steel pipe pile, and more particularly to a method of constructing a steel pipe pile that can be accurately constructed even in a place with a limited head or a narrow place.

Conventionally, steel pipe piles have been constructed by rotating and press-fitting long steel pipe piles vertically to the ground using an earth auger of a pile driver. However, when using such a pile driver to construct a long steel pipe pile in an upright state, a vast space is required above, for example, an empty head just below an existing structure. There was a problem that construction could not be done on site with restrictions.

Also, when constructing steel pipe piles using heavy equipment such as pile drivers and cranes, it is not possible to carry heavy equipment or long steel pipe piles into the site in the first place, and steel pipe piles cannot be constructed at narrow construction sites. There was a problem.

In order to solve such a problem, for example, in Patent Document 1, there is a construction method/apparatus in which a hollow pile 1 such as a steel pipe pile or a steel pipe sheet pile is driven into the ground by a reverse-type hollow digging method. A rotary excavator 2 having an excavation bit 13 at the tip of a pipe 12 is inserted and fixed inside a hollow pile 1, and the hollow pile 1 is press-fitted by a press-fitting device 4, and the tip of the hollow pile 1 is excavated by a drill bit. Then, the pile tip excavated earth and sand is sucked together with the supply water from the tip suction port of the drill pipe 12 and discharged to the ground, and the crushable bit 14 for rotation excavation provided at the tip suction port of the drill pipe 12 is used to remove the pile tip excavated soil A method for constructing a pile for crushing gravel is disclosed (see claim 1 of Patent Document 1, paragraphs [0030] to [0041] in the description, FIG. 1 of the drawings, etc.).

However, the method for constructing a pile described in Patent Document 1 can construct a steel pipe pile even under the limitation of the head, but requires a rotary excavator 2, a mud discharging device 3, a press-fitting device 4, etc., and supports them. There is a problem in that it takes time and labor to construct the supporting frame 33 that supports. In addition, there is a problem in that it is insufficient in terms of downsizing of the device, and that it cannot be installed in a narrow space.

And in patent document 2, the excavation blade 10 is attached to the lower end position inside the steel pipe 1, the pumping mud pipe 2 is inserted in the steel pipe 1, and the excavation blade 10 is penetrated, and the pumping mud pipe 2 is made into the steel pipe 1 and the excavation blade. It is placed in a state of being separated from 10. A steel pipe pile construction method in which a rotating force is applied to the steel pipe 1 to rotate the excavation blade 10 together with the steel pipe 1 to excavate the inside of the steel pipe 1 by the excavation blade 10, and the excavated soil is sucked by the pumped mud pipe 2 and discharged from the inside of the steel pipe 1. Are disclosed (refer to claim 1 of the claims of Patent Document 2, paragraphs [0025] to [0031] of the specification, and FIGS. 4 to 8 of the drawings).

However, even with the steel pipe pile construction method described in Patent Document 2, it is possible to construct a steel pipe pile even under the limitation of the head, but it is necessary to install a liner plate (mouth pipe 51) in advance, and a permanent steel pipe pile is constructed. The mechanism was complicated and the power transmission efficiency was low, such as connecting the pumped mud pipe 2 while rotating the steel pipe 1 together with the rotary press-fitting machine 8. For this reason, there is a problem that a large-scale mechanism is required as compared with the scale of the pile, and the cost increases accordingly.

JP 2004-68398 A JP 2004-211500 A

Therefore, the present invention has been devised in view of the above-mentioned problems, and the purpose thereof is to perform construction in a short time even at a site under narrow head or at a narrow site at a low cost by a simple mechanism. It is to provide a possible method of constructing a steel pipe pile.

A construction method of a steel pipe pile according to a first aspect of the present invention is a construction method of a steel pipe pile in which a steel pipe pile is newly installed directly below an existing structure, in which a press-fitting direction of the steel pipe pile is set before installing the steel pipe pile of main construction. While installing a guide pile with a diameter slightly smaller than the steel pipe pile that guides, install a press-fitting device that obtains a reaction force from the existing structure, using the installed press-fitting device, while assembling a steel plate into a cylindrical shape. After performing the guide pile press-fitting step of press-fitting the guide pile into the ground from the work ground to a predetermined depth, while guiding the press-fitting direction in the ground of the steel pipe pile with the guide pile, the steel plate is cylindrical from the steel plate by the press-fitting device. It is characterized in that the steel pipe pile is press-fitted while being assembled into a shape .

Construction method for steel pipe pile according to the second invention, in the first invention, before installing the guide pile, said guide member for guiding the press-fitting direction of the guide piles while connecting the strip material longitudinal guide piles Press-fit into the ground until it reaches deeper than the bottom end of the guide member and fix the upper end of the guide member to the existing structure, and press-fit the guide pile into the ground while guiding the press-fitting direction with the guide member using the press-fitting device. It is characterized by doing.

A construction method of a steel pipe pile according to a third aspect of the present invention is a construction method of a steel pipe pile in which a steel pipe pile is newly installed directly below an existing structure, in which a press-fitting direction of the steel pipe pile is set before installing the steel pipe pile of main construction. While installing a guide pile that guides, install a press-fitting device that obtains a reaction force from the existing structure, and press-fit the steel pipe pile while guiding the press-fitting direction with the guide pile using the installed press-fitting device. The upper end of the guide pile is fixed to the existing structure.

In the method for constructing a steel pipe pile according to a fourth invention, in the third invention, the guide pile also serves as an inner pile of the steel pipe pile that is permanently installed, and an upper portion of the steel pipe pile has a double pipe structure. It is characterized by being

The method for constructing a steel pipe pile according to a fifth aspect of the present invention is the method according to any one of the first to third aspects of the present invention, in which high-pressure water is injected in parallel with the press-fitting of the steel pipe pile, and the soil is discharged by using a pump. It is characterized by excavating earth and sand in steel pipe piles.

According to the first invention to the fifth invention, it is possible to construct a steel pipe pile even in a site where the head is restricted or in a narrow space, and since the construction can be done in a short time with a simple mechanism, the installation cost of the steel pipe pile is reduced. be able to. Moreover, since the steel pipe pile is press-fitted while guiding the press-fitting direction with the guide pile, the construction accuracy of the steel pipe pile is improved.

In particular, according to the second aspect of the invention, the guide pile is press-fitted while guiding the press-fitting direction by the guide member, so the construction accuracy of the guide pile is improved. Therefore, the construction accuracy of the steel pipe pile is further improved.

In particular, according to the third aspect, the step of installing the guide member can be omitted, the construction period can be shortened, and the installation cost of the steel pipe pile can be reduced.

Particularly, according to the fourth invention, the guide pile also serves as the inner pile of the steel pipe pile of the permanent construction, and the upper portion of the steel pipe pile has the double pipe structure, so that the new steel pipe pile 1'is The thickness of the entire steel plate can be reduced.

Particularly, according to the fifth invention, it is possible to excavate the earth and sand in the steel pipe pile without using a large excavator or the like. For this reason, it is possible to easily perform the construction in a short time at a site where the head is limited or a narrow site.

It is process explanatory drawing which shows the prior preparation of the construction method of the steel pipe pile which concerns on 1st Embodiment of this invention. It is process explanatory drawing which shows the guide member installation process of the construction method of a steel pipe pile same as the above, (a) is the side view seen along the bridge axial direction, (b) is a top view. It is process explanatory drawing which shows the reaction force plate installation process of the construction method of a steel pipe pile same as the above, (a) is the side view seen along the bridge axial direction, (b) is a top view. It is process explanatory drawing which shows the press-fitting apparatus installation process of the construction method of a steel pipe pile same as the above. It is a front view showing the press fit device concerning an embodiment. It is a left side view showing a press fit device same as the above. It is process explanatory drawing which shows the guide pile press-fitting process of the construction method of the steel pipe pile which concerns on 1st Embodiment, (a) is the side view seen along the bridge axial direction, (b) is a top view. It is process explanatory drawing which shows the completion state of a guide pile press-fitting process same as the above, (a) is the side view seen along the bridge axis direction, (b) is a top view. It is process explanatory drawing which shows the press-fitting device rearrangement process of the construction method of a steel pipe pile same as the above. It is process explanatory drawing which shows the assembly condition of the steel pipe pile in the steel pipe pile press-fitting excavation process of the construction method of the same steel pipe pile, (a) is the side view seen along the bridge axis direction, (b) is a top view. is there. It is process explanatory drawing which shows the press fit situation of the steel pipe pile press fit excavation process same as the above. It is process explanatory drawing which shows the excavation earth discharge condition to the lower end vicinity of the guide pile of the steel pipe pile press-fitting excavation process same as the above. It is process explanatory drawing which shows the excavation earth removal condition at the time of excavating deeper than the lower end of the guide pile of the steel pipe pile press-fitting excavation process same as the above. It is process explanatory drawing which shows the press-fitting apparatus removal process of the construction method of a steel pipe pile same as the above. It is process explanatory drawing which shows the concrete placing process of the construction method of a steel pipe pile same as the above. It is process explanatory drawing which shows the steel pipe pile upper part construction process of the construction method of a steel pipe pile same as the above. It is process explanatory drawing which shows the prior preparation of the construction method of the steel pipe pile which concerns on 2nd Embodiment. It is process explanatory drawing which shows the ceiling crane installation process of the construction method of a steel pipe pile same as the above. It is process explanatory drawing which shows the reaction force plate installation process of the construction method of a steel pipe pile same as the above. It is process explanatory drawing which shows the press-fitting apparatus installation process of the construction method of a steel pipe pile same as the above. It is process explanatory drawing which shows the assembly condition of the steel pipe pile in the steel pipe pile press-fitting excavation process of the construction method of the same steel pipe pile, (a) is the side view seen along the bridge axis direction, (b) is a top view. is there. It is process explanatory drawing which shows the excavation earth removal situation of the steel pipe pile press-fitting excavation process same as the above. It is process explanatory drawing which shows the press-fitting device removal process of the steel pipe pile press-fitting excavation process same as the above. It is process explanatory drawing which shows the concrete placing process of the steel pipe pile press-fitting excavation process same as the above. It is process explanatory drawing which shows the steel pipe pile upper part construction process of the steel pipe pile press-fitting excavation process same as the above.

Hereinafter, an embodiment for carrying out a method for constructing a steel pipe pile according to the present invention will be described in detail with reference to the drawings.

[First Embodiment]
First, a method for constructing a steel pipe pile according to the first embodiment of the present invention will be described with reference to FIGS. The method for constructing a steel pipe pile according to the first embodiment is applied to a case where a new steel pipe pile is newly installed immediately below an existing structure. For example, since the water pipe P1 and the like are newly installed on the abutment B1 of the bridge, the steel pipe pile 1 that supports the load is preferably applied directly to the water pipe P1.

FIG. 1 is a process explanatory diagram showing prior preparation of a method for constructing a steel pipe pile according to a first embodiment of the present invention. The process explanatory drawing including Fig. 1 is a side view of the new construction work of the pile viewed along the bridge axis direction of the bridge, and shows the abutment B1 cut along a vertical plane orthogonal to the bridge axis direction of the bridge. ..

(1) Preliminary Preparation In the method for constructing a steel pipe pile according to the first embodiment of the present invention, as shown in FIG. 1, first, as a preliminary preparation, the surroundings and bottom of the abutment B1 are dug down so as to carry out a work space and material loading. Secure space for. In the illustrated form, a width of about 1 m is dug beside the abutment B1, and a part of the abutment B1 directly below the water pipe P1 is dug to secure a space of about 5 m in height. Needless to say, the size of this space may be appropriately set according to the size of the steel pipe pile 1 to be installed and the ground.

(2) Guide Member Installation Step Next, in the steel pipe pile construction method according to the first embodiment, as shown in FIG. 2, a guide member installation step of installing a guide member 2 for guiding a guide pile 5 described later is performed. .. The guide member 2 is a strip material in which H-shaped steels having a length of about 2 m that can be lifted by human power are connected along the longitudinal direction, and a reaction force for press-fitting a guide pile described later is applied to an existing structure (abutment B1). ) Has a function to get from.

In the guide member installation step according to the present embodiment, as shown in FIG. 2B, a total of four guide members 2 are installed in a cross shape on a plane centered on the axis of the new steel pipe pile 1. Specifically, in this step, the H-section steel is press-fitted into the ground at a predetermined position while connecting the H-section steels in the longitudinal direction by using a vibration press-fitting machine, a mini power shovel, or the like which is held by hand. In this embodiment, the lower end of the guide member 2 is press-fitted until it reaches a depth of 8 m from the working ground, which is deeper than the lower end of the guide pile 5 described later.

After that, the H-shaped steel is also connected to the upper side, and the upper end of the guide member 2 is fixed to the lower surface of the abutment B1 which is an existing structure using a post-installed anchor. The H-shaped steels of the guide member 2 are connected to each other by welding or bolt connection.

In this step, in addition to the installation of the guide member 2, about four cranes C, which are electric hoist type cranes, are installed on the four circumferences of the steel pipe pile 1 as a temporary lifting device. Specifically, four runways made of shaped steel such as H-shaped steel and I-shaped steel are fixed to the lower surface of the structure (abutment B1) with post-installed anchors, and the overhead crane C can be driven on each of the runways. Stop it.

(3) Reaction Plate Installation Step Next, in the steel pipe pile construction method according to the first embodiment, as shown in FIG. 3, a reaction plate installation step of installing a reaction plate is performed. The reaction force plate 3 is a steel plate in the shape of a block (brick shape) that is a rectangular plate that is long in the lateral direction and serves as a locking projection that locks the press-fitting device 4 described later, and guides the reaction force when press-fitting with the press-fitting device. It has a function of obtaining from the existing structure (abutment B1) through the member 2.

In this step, first, in accordance with the height at which the press-fitting device 4 is mounted (in this embodiment, the height is about 2.5 m above the work ground), the two-step cross shape is formed so that the interval between the guide members 2 is not shortened. The spacing member 30 made of H-shaped steel is attached to the. Then, the reaction force plate 3 is bolted to the outer side surface of the guide member 2 via the pressure bearing plate 31. The bolt holes of the reaction force plate 3 are counterbored holes, and the bolt heads do not project so that the press-fitting device 4 can be easily hooked.

(4) Press-fitting device installation step Next, in the steel pipe pile construction method according to the first embodiment, as shown in FIG. 4, a press-fitting device installation step of installing four press-fitting devices 4 at predetermined positions is performed.

As shown in FIGS. 5 and 6, this press-fitting device 4 is mainly composed of a hydraulic expansion/contraction jack 40, and is a device for press-fitting a guide pile 5 or a steel pipe pile 1 described later by expanding/contracting a piston rod 41 by hydraulic pressure. Is. The press-fitting device 4 includes a pair of upper and lower leg portions 42 and an upper leg portion 43, and the lower leg portion 42 is formed with a recessed groove 44 to which the reaction force plate 3 is hooked. The upper leg portion 43 has a function of a pressure support plate that supports the press-fitting device 4 so as not to rotate vertically.

In this step, the recessed groove 44 is fitted into the reaction force plate 3 to position the lower leg portion 42 of the press-fitting device 4 and the upper leg portion 43 is fixed to the outer surface of the guide member 2 so that the press-fitting device 4 is fixed. Install so that it is vertical. This is because the piston rod 41 of the telescopic jack 40 is installed so as to be capable of vertically telescopic movement, and the steel pipe pile 1 is press-fitted with high accuracy. Further, the four press-fitting devices 4 simultaneously press the guide piles 5 and the like through the ring member 45 made of a ring-shaped steel material to press-fit them (see FIG. 4 ).

(5) Guide pile press-fitting step Next, in the steel pipe pile construction method according to the first embodiment, as shown in FIG. 7, a guide pile press-fitting step of press-fitting the guide piles 5 is performed. The guide pile 5 is a steel pile made up of a plurality of four-divided cylindrical steel plates 50 having a diameter (in the present embodiment, 1.456 mm) which is slightly smaller than the steel pipe pile 1 that is permanently installed and has a height of about 1.5 m. It has a function of guiding the press-fitting direction of the steel pipe pile 1.

In this step, first, a set of steel plates 50 is carried in through a gap having a width of 1 m on the side of the abutment B1. Then, on the work ground, while lifting by using the overhead crane C, the end faces of the steel plates 50 are brought into contact with each other around the guide member 2 to be combined, and welded in the longitudinal direction along the joint surface to form a cylindrical shape. To do. Then, the expansion jack 40 of the press-fitting device 4 is operated to press-fit the guide pile 5 into the ground via the ring member 45.

After that, the additional steel plate 50 is carried in, the guide pile 5 is assembled and welded above the guide pile 5 press-fitted into the ground, and then the press-fitting device 4 press-fits it as described above. As shown in FIG. 8, this assembly welding and press fitting are repeated to press fit the guide pile 5 to a predetermined depth. In this embodiment, the lower end of the guide pile 5 is press-fitted from the work ground until it reaches 6.5 m, which is more than 1/3 of the total length 17 m of the steel pipe pile 1 that is permanently installed.

Since the guide pile 5 is not a permanently installed pile, the joining of the steel plates 50 is not limited to welding, and other joining methods such as bolding may be used. Also, the guide pile 5 is exemplified by dividing the circumference of the cylinder into four, but of course, depending on the size of the carry-in port and the diameter of the guide pile 5, the circumference is divided into other than four such as two or three. It does not matter if it is done.

(6) Press-fitting device refilling step Next, in the steel pipe pile construction method according to the first embodiment, as shown in FIG. 9, a press-fitting device refilling step of horizontally moving the four press-fitting devices 4 to the outside is performed. ..

In this process, after the press-fitting device 4 is once removed, as shown in FIG. 9, an additional member 46 such as a grooved steel plate or a thick steel plate is attached to the outside of the reaction force plate 3 and the pressure bearing plate 31 to enlarge it. , The press-fitting device 4 is rearranged and fixed to a position corresponding to the diameter of the steel pipe pile 1 that is permanently installed. Also, the ring member is replaced with a ring member 45' having a diameter slightly larger than the ring member 45. By this reassembling work of the press-fitting device 4, it becomes possible to install the press-fitting device 4 directly above the upper end of the steel pipe pile 1, and the press-fitting of the steel pipe pile 1 by the press-fitting device 4 can be performed accurately and in a short time in a subsequent process. become.

(7) Steel pipe pile press-fitting excavation step Next, in the steel pipe pile construction method according to the first embodiment, as shown in FIGS. 10 and 11, while the steel pipe pile 1 is being press-fitted into the ground, the earth and sand inside the steel pipe pile 1 is pressed. The steel pipe pile press-fitting excavation process is performed. The steel pipe pile 1 is a steel-made permanent pile made of a four-division cylindrical arc steel plate 10 having a predetermined diameter and a predetermined thickness according to the structural design. In the steel pipe pile 1 according to the present embodiment, as shown in FIG. 10, one lot has an outer diameter of 1700 mm and a height of 1500 mm.

In this process, similarly to the above-mentioned guide pile press-fitting process, the arc steel plates 10 are carried in from a gap having a width of 1 m on the side of the abutment B1, and the arc steel plates 10 are combined and welded around the guide pile 5 on the work ground. The steel pipe pile 1 has a cylindrical shape. After that, the tip end of the piston rod 41 of the press-fitting device 4 and the upper end of the assembled steel pipe pile 1 are connected to each other, and the expansion jack 40 of the press-fitting device 4 is operated to press-fit the steel pipe pile 1 into the ground.

After that, an additional circular arc steel plate 10 is carried in, a new steel pipe pile 1 is assembled and welded above the steel pipe pile 1 press-fitted into the ground, and then the press-fitting device 4 press-fits it. As shown in FIG. 11, the assembly welding and press fitting are repeated to press fit the steel pipe pile 1 to a depth such that the lower end of the steel pipe pile 1 is below the lower end of the guide pile 5.

However, unlike the guide pile press-fitting step, in this step, as shown in FIG. 12, the sand inside the steel pipe pile 1 and the guide pile 5 is excavated and discharged in parallel with the press-fitting of the steel pipe pile 1. This is because in order to surely support the steel pipe pile 1 on the support ground, concrete is placed as a filler at the lower end of the steel pipe pile 1 as a tip treatment.

Here, as shown in FIG. 12, up to the vicinity of the lower end of the guide pile 5, while excavating while ejecting a water jet, a soil discharging device such as a soil discharging pump sucks the water. Thereby, the earth and sand in the steel pipe pile 1 can be excavated and discharged without using a large-sized device.

In addition, as shown in FIG. 13, when digging deeper than the lower end of the guide pile 5, it is assumed that the water pressure of the water jet alone cannot dig and excavate the soil. Therefore, excavation is performed by a plurality of nozzles that eject jet water of higher pressure, and excavation and soil removal is performed by the MJP method or the air lift method. Of course, when digging only on the water pressure of the water jet on soft ground such as a clay layer, it goes without saying that the water jet alone may be used for digging.

As described above, in this process, the assembly welding and press-fitting are repeated to press-fit the steel pipe pile 1 to a predetermined depth to reach the support layer, and excavate and remove the earth and sand in the steel pipe pile 1.

(8) Press-fitting device removing step Next, in the steel pipe pile construction method according to the first embodiment, as shown in FIG. 14, a press-fitting device removing step of removing the press-fitting device 4 and the reaction plate 3 is performed. At this time, the guide member 2 may be removed together. However, since the strength of the steel pipe pile 1 does not decrease due to the presence of the guide member 2, the guide member 2 may be left in place without being removed.

(9) Concrete Placing Step Next, in the steel pipe pile construction method according to the first embodiment, as shown in FIG. 15, concrete is poured into the lower portion of the steel pipe pile 1 press-fitted using a pressure pump or the like. Perform the placing process.

In this step, first, the sand on the inner peripheral surface of the steel pipe pile 1 is thoroughly washed using a water jet or the like, and the soil is discharged and drained by an earth discharge pump or the like to remove slime and the like below the steel pipe pile 1.

Then, a concrete portion having a predetermined height for transmitting stress to the support layer is constructed under the steel pipe pile 1 using a pressure pump or the like.

(10) Steel Pipe Pile Upper Construction Step Next, in the steel pipe pile construction method according to the first embodiment, as shown in FIG. 16, a steel pipe pile for constructing the remaining steel pipe pile 1 above the press-fitted steel pipe pile 1. Perform the upper construction process.

In this process, similarly to the steel pipe pile press-fitting excavation process, the circular arc steel plate 10 is carried in from a gap having a width of 1 m on the side of the abutment B1, placed as it is on the pressed steel pipe pile 1, assembled and welded.

In this way, assembly and welding are repeated until the bottom surface of the abutment B1 which is an existing structure is reached, and the steel pipe piles 1 of the remaining lot are constructed above the steel pipe piles 1 press-fitted under the working ground.

(11) Backfilling step Finally, in the steel pipe pile construction method according to the first embodiment, although not shown, the remaining temporary overhead crane C and the like are removed and excavated for the work space and the like in advance. The backfilling step of backfilling the soil with sand and sand is performed, and the method for constructing the steel pipe pile according to the present embodiment ends.

According to the method for constructing a steel pipe pile according to the first embodiment described above, the construction of a steel pipe pile can be performed only by a simple mechanism such as the press-fitting device 4 mainly including the hydraulic expansion/contraction jack 40, a water jet, and an earth pump. It will be possible. For this reason, not only can steel pipe piles be easily constructed on sites with limited head space or on narrow sites, but large-scale heavy machinery and equipment for rotary excavation, support frames, etc. are not required, so temporary and leasing costs can be reduced. Therefore, the installation cost of the steel pipe pile can be reduced as a result. Further, since the steel pipe pile 1 is press-fitted after the guide pile 5 for guiding the press-fitting direction of the steel pipe pile 1 is installed in advance, the press-fitting direction of the steel pipe pile 1 is accurate, and the steel pipe pile 1 is accurately installed at a predetermined position. be able to.

[Second Embodiment]
Next, a method for constructing a steel pipe pile according to the second embodiment of the present invention will be described with reference to FIGS. Similar to the construction method of the steel pipe pile according to the first embodiment, when a water pipe P1 and the like are newly installed on the abutment B1 of the bridge, a steel pipe pile 1'supporting the load is newly installed directly under the water pipe P1. Will be described as an example.

(1) Preliminary Preparation In the method for constructing a steel pipe pile according to the second embodiment of the present invention, as shown in FIG. 17, as in the case of the method for constructing a steel pipe pile according to the second embodiment, as a preliminary preparation, around the abutment B1. Digging down the bottom to secure a working space and a space for material loading. In the illustrated form, a width of about 1 m is dug beside the abutment B1, and a part of the abutment B1 directly below the water pipe P1 is dug to secure a space of about 5 m in height.

(2) Overhead Crane Installation Step Next, in the method for constructing a steel pipe pile according to the second embodiment, as shown in FIG. 18, an overhead crane C is installed which is an electric hoist type crane as a temporary lifting device. Perform the installation process. Specifically, four runways made of shaped steel such as H-shaped steel and I-shaped steel are fixed by post-installation anchors at four positions of the steel pipe pile 1'on the lower surface of the structure (abutment B1), The overhead cranes C are fixed to the runways so that they can travel.

(3) Reaction Force Plate Installation Step Next, in the steel pipe pile construction method according to the second embodiment, as shown in FIG. 19, a reaction force steel plate installation step of installing a reaction force plate is performed.

In this step, first, the upper part of the inner pile 5 ′ similar to the above-mentioned guide pile 5 is constructed on the work ground. In the procedure for constructing the inner pile 5', similarly to the above, a plurality of four-divided cylindrical steel plates 50' are carried in through a gap having a width of 1 m on the side of the abutment B1. Then, while hoisting using the overhead crane C on the working ground, the end faces of the steel plates 50' are brought into contact with each other at the installation position of the steel pipe pile 1'of the permanent installation, and combined, and then vertically along the joint surface. Weld into a cylindrical shape.

This assembly and welding work is repeated until the upper end of the inner pile 5′ reaches the lower surface of the abutment B1, the cylindrical guide piles 5 are stacked to build the upper portion of the guide pile 5, and the upper end is existing so that reaction force can be obtained. It is fixed to the abutment B1 which is a structure. Since the press-fitting device 4 is installed on the peripheral surface of the guide pile 5 having a height of about 2.5 m above the work ground, the reaction force plate 3'corresponding to the reaction force plate 3 is installed at the height. Install. The reaction plate 3'according to the present embodiment is a strip-shaped thick steel plate that is curved to form a four-divided cylinder, and is welded to the peripheral surface of the guide pile 5 in advance. Needless to say, the reaction plate 3'may be welded on site.

The inner pile 5'also serves as the upper structure of the new steel pipe pile 1'. Therefore, the pile upper part where bending stress is concentrated in the pile can be handled by the double pipe structure of the steel pipe pile 1′ and the inner pile 5′, and the thickness of the entire steel plate of the new steel pipe pile 1′ can be reduced. It can be reduced.

(4) Press-fitting device installation step Next, in the steel pipe pile construction method according to the second embodiment, as shown in FIG. 20, four press-fitting devices 4′ similar to the above-described press-fitting device 4 are installed at predetermined positions. Perform the press-fitting device installation process.

(5) Steel Pipe Pile Press-Fit Excavation Process Next, in the steel pipe pile construction method according to the second embodiment, as shown in FIGS. 21 and 22, the steel pipe pile 1 ′ is pressed into the ground while the steel pipe pile 1 ′ is A steel pipe pile press-fitting excavation process for excavating earth and sand is performed. The steel pipe pile 1′ is a steel-made permanent pile made of a four-division cylindrical arc steel plate 10′ having a predetermined diameter and a predetermined thickness according to the structural design, similarly to the above-described steel pipe pile 1 (FIG. 21 ( See b)). Further, in the steel pipe pile 1'according to the present embodiment, as shown in FIG. 21(a), one lot has an outer diameter of 1700 mm and a height of 1500 mm. However, as described above, since the pile head portion is reinforced by the inner pile 5′, the steel pipe pile 1′ has a thin steel plate.

In this process, similarly to the steel pipe pile press-fitting excavation process of the method for constructing a steel pipe pile according to the first embodiment, an arc steel plate 10′ is carried in from a gap having a width of 1 m on the side of the abutment B1 and the inner pile 5′ on the work ground. The circular arc steel plates 10' are combined around and welded to form a cylindrical steel pipe pile 1'. Then, as shown in FIG. 22, the expansion jack of the press-fitting device 4'is operated to press-fit the steel pipe pile 1'into the ground through the ring member. This assembly welding/press fit is repeated to press fit the steel pipe pile 1'to a predetermined depth.

However, in this process, unlike the steel pipe pile press-fitting excavation process of the steel pipe pile construction method according to the first embodiment, the steel pipe pile 1'is press-fitted below the inner pile 5'corresponding to the guide pile 5 and excavated. Therefore, excavation and soil removal is performed from the beginning by the above-mentioned MJP or air lift method. Needless to say, when digging only on the water pressure of a water jet on soft ground such as a clay layer, the water jet alone may be used for digging.

(6) Press-fitting device removing step Next, in the steel pipe pile construction method according to the second embodiment, as shown in FIG. 23, a press-fitting device removing step of removing the press-fitting device 4'is performed.

(7) Concrete Placing Step Next, in the method for constructing a steel pipe pile according to the second embodiment, as shown in FIG. 24, concrete is placed under the steel pipe pile 1'press-fitted using a pressure pump or the like. Perform concrete placing process.

In this step, first, a water jet or the like is used to wash away the soil on the inner peripheral surface of the steel pipe pile 1', and the soil is discharged and drained by an earth-discharging pump or the like to remove slime and the like below the steel pipe pile 1'.

Then, below the steel pipe pile 1', a concrete portion having a predetermined height for transmitting stress to the support layer is constructed under the steel pipe pile 1'using a pressure pump or the like.

(8) Steel Pipe Pile Upper Construction Step Next, in the steel pipe pile construction method according to the second embodiment, as shown in FIG. 25, a steel pipe for constructing the remaining steel pipe pile 1 ′ above the press-fitted steel pipe pile 1 Perform the pile top construction process.

In this process, similarly to the above-described steel pipe pile press-fitting excavation process, the circular arc steel plate 10' is carried in from the gap of 1 m width on the side of the abutment B1 and placed as it is on the pressed steel pipe pile 1'and assembled. Weld.

In this way, assembling and welding are repeated until the bottom surface of the abutment B1 which is an existing structure is reached, and the steel pipe pile 1'of the remaining rod is constructed above the steel pipe pile 1'press-fitted under the working ground.

(9) Backfilling step Finally, in the method of constructing a steel pipe pile according to the first embodiment, although not shown, the temporary overhead crane C and the like are removed, and the excavated portion for working space and the like is prepared in advance for earth and sand. The backfilling step of backfilling is performed, and the steel pipe pile construction method according to the present embodiment ends.

According to the method for constructing a steel pipe pile according to the second embodiment described above, in addition to the effects of the method for constructing a steel pipe pile according to the first embodiment, the pile head portion is reinforced by the inner pile 5′, The steel pipe pile 1′ can have a thinner steel plate than the steel pipe pile 1′. Further, according to the method for constructing a steel pipe pile according to the second embodiment, compared with the method for constructing a steel pipe pile according to the first embodiment, since there is no guide member installation step, etc., the construction period is shortened and Installation costs can be reduced.

Although the construction method of the steel pipe pile according to the embodiment of the present invention has been described above in detail, the above-described or illustrated embodiments are merely examples showing one embodiment embodied in carrying out the present invention. However, the technical scope of the present invention should not be limitedly interpreted by these. In particular, the abutment B1 is an example of a structure requiring a steel pipe pile, and other structures such as a foundation footing of a pier may be used.

1, 1': Steel pipe pile 10, 10': Arc steel plate 2: Guide member 3, 3': Reaction force plate 30: Spacing member 31: Bearing receiving plate 4, 4': Press-fitting device 40: Expansion jack 41: Piston Rod 42: Lower leg 43: Upper leg 44: Grooves 45, 45', 45": Ring member 46: Additional member 5: Guide pile 50, 50': Arc steel plate B1: Abutment (existing structure)
P1: Water pipe C: Overhead crane

Claims (5)

A method of constructing a steel pipe pile, in which a steel pipe pile is newly installed directly below an existing structure,
Before installing the steel pipe pile of the permanent installation, a guide pile having a diameter slightly smaller than the steel pipe pile for guiding the press-fitting direction of the steel pipe pile is installed, and a press-fitting device for obtaining a reaction force from the existing structure is installed. Then
Using the press-fitting device installed , after performing a guide-pile press-fitting step of press-fitting the guide pile into the ground from the working ground to a predetermined depth while assembling it from a steel plate into a cylindrical shape, the ground of the steel pipe pile is provided by the guide pile. A method for constructing a steel pipe pile, which comprises press-fitting the steel pipe pile while assembling a steel plate into a cylindrical shape by the press-fitting device while guiding the press-fitting direction inside . Before installing the guide pile, a guide member that guides the press-fitting direction of the guide pile while connecting the strips in the longitudinal direction is press-fitted into the ground until it reaches deeper than the lower end of the guide pile, and the upper end of the guide member was fixed to the existing structure, construction method of a steel pipe pile according to claim 1, characterized in that press-fitting the guide piles while guiding the press-fit direction by the guide member with the press-fitting apparatus in soil .. A method of constructing a steel pipe pile, in which a steel pipe pile is newly installed directly below an existing structure,
Before installing the steel pipe pile of the permanent installation, while installing a guide pile that guides the press-fitting direction of the steel pipe pile, install a press-fitting device that obtains a reaction force from the existing structure,
While press-fitting the steel pipe pile while guiding the press-fitting direction with the guide pile using the press-fitting device installed ,
The steel pipe pile construction method, wherein the upper end of the guide pile is fixed to the existing structure. The method for constructing a steel pipe pile according to claim 3, wherein the guide pile also serves as an inner pile of the steel pipe pile that is permanently installed, and the upper portion of the steel pipe pile has a double pipe structure. .. The steel pipe pile according to any one of claims 1 to 4, wherein high pressure water is injected in parallel with the press-fitting of the steel pipe pile to discharge the soil by using a pump to excavate the earth and sand in the steel pipe pile. Construction method.

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