AU2014282262B2

AU2014282262B2 - Steel-pipe pile and steel-pipe pile construction method

Info

Publication number: AU2014282262B2
Application number: AU2014282262A
Authority: AU
Inventors: So Hirai; Yoshiaki Kikuchi; Takayuki Miyamoto; Takaaki Mizutani; Yoshiyuki Morikawa; Shunsuke Moriyasu; Yasuhide Nakamoto; Yukichi Suzuki; Kenji Takahashi; Masakazu Takeno; Hisao Yamashita; Hiroyasu Yokoyama
Original assignee: Nippon Steel Corp; Chowa Kogyo Co Ltd
Current assignee: Nippon Steel Corp; Chowa Kogyo Co Ltd
Priority date: 2013-06-19
Filing date: 2014-06-16
Publication date: 2016-09-22
Anticipated expiration: 2034-06-16
Also published as: JP6093923B2; AU2014282262A1; WO2014203858A1; JPWO2014203858A1

Abstract

This steel-pipe pile is equipped with: a pile body configured from steel pipe; a dividing member for dividing the cross-sectional surfaces of the pile body into a plurality of surfaces, and attached to the inside of the tip end of the pile body; a spray nozzle for selectively spraying water and a fluid solidification material, and mounted to the outer-circumferential surface of the tip end of the pile body and/or the inner-circumferential surface of the tip end of the pile body; and a pipe for selectively supplying the water and the fluid solidification material to the spray nozzle.

Description

[Document Type] Specification [Title of the Invention] STEEL PIPE PILE AND STEEL PIPE PILE CONSTRUCTION METHOD [Technical Field of the Invention] [0001]

The present invention relates to a steel pipe pile and a steel pipe pile construction method.

Priority is claimed on Japanese Patent Application No. 2013-128351, filed on June 19, 2013, the content of which is incorporated herein by reference.

[Related Art] [0002] A steel pipe pile can be classified into several types according to construction methods. For example, a pile driven by hammer is a steel pipe pile which is driven to a bearing stratum by a pile driving by hammer. A frictional force (an in-pipe frictional force) occurring between the inner peripheral surface of a leading end portion of a steel pipe pile and the ground increases in proportion to a pile diameter. On the other hand, the cross-sectional area (the closed cross-sectional area) of the leading end portion of the steel pipe pile increases in proportion to the square of a pile diameter. Therefore, the larger the pile diameter of the steel pipe pile, the smaller the in-pipe frictional force of the steel pipe pile becomes relatively with respect to the closed cross-sectional area of the steel pipe pile, and thus a sufficient leading end plugging effect cannot be obtained. As a result, the leading end bearing capacity of the steel pipe pile also decreases.

[0003]

In the related art, as a method of increasing the in-pipe frictional force of the steel pipe pile in order to improve the leading end plugging effect of the steel pipe pile, a method of increasing the total surface area of the leading end portion of the steel pipe pile by mounting a dividing member which divides a cross section of the steel pipe pile, on the inside of the lead ing end portion of the steel pipe pile, is known (refer to, for example, Non-Patent Document 1 described below).

[0004] FIG. 13 A is a diagram schematically showing a state where a dividing member 110 configured with a plurality of steel plates orthogonal to each other is mounted on the inside of a leading end portion of a steel pipe pile 100. The dividing member 110 is welded to the inner peripheral surface of the leading end portion of the steel pipe pile 100.

[0005]

In order to reliably improve the leading end plugging effect of the steel pipe pile 100, it is desirable that the length of the dividing member 110 in a length direction (an axial direction) of the steel pipe pile 100 is set to be greater than or equal to twice an outer diameter D of the steel pipe pile 100. However, in a case where the dividing member 110 having a length greater than or equal to twice the outer diameter D of the steel pipe pile 100 is mounted on the inside of the steel pipe pile 100, it is necessary for a worker to enter the inside of the steel pipe pile 100 and perform welding work. As a result, a problem in that the physical burden of the worker increases arises.

[0006]

Further, due to the mounting of the dividing member 110, the leading end plugging effect of the steel pipe pile 100 is improved and resistance occurring between the leading end portion of the steel pipe pile 100 which is driven into the ground by a pile driving by hammer and the ground also increases. As a result, even if impact force by the hammer is applied to the steel pipe pile 100, there is a case where penetration is not possible (driving becomes impossible) before the steel pipe pile 100 reaches a target bearing stratum.

[0007]

In this case, as a countermeasure, it is conceivable to increase a striking force which is applied to the steel pipe pile 100. However, in a case of adopting a pile driving by hammer, heavy machinery such as a pile driver is increased in size. For this reason, an increase in facility cost or a decrease in workability is caused. Further, a large amount of noise and vibration are generated, and therefore, in an area in which environmental regulations are strict, like an urban area, it is difficult to simply increase a striking force. Therefore, even if the dividing member 110 is mounted on the steel pipe pile 100 having a large pile diameter (the outer diameter D), there is a case where it becomes difficult to drive the steel pipe pile 100 to a bearing stratum by a pile driving by hammer.

[0008]

On the other hand, in an area in which environmental regulations are strict, an inner excavation method or a bored pile method, in which it is possible to suppress noise and vibration occurring during the driving of a steel pipe pile, is widely used.

In these construction methods, in a state where a drilling rod is inserted into the inside of a steel pipe pile, drilling of the ground by the drilling rod and sinking of the steel pipe pile are performed at the same time, and a fluidity solidifying material (cement milk or the like) is injected into a bearing stratum disturbed by the drilling rod. The fluidity solidifying material injected into the bearing stratum is solidified, whereby a foot protection block is constructed so as to cover a leading end portion of the steel pipe pile. Due to the construction of the foot protection block, the leading end portion of the steel pipe pile is plugged and the ground disturbed by the drilling rod is restored (refer to, for example. Patent Documents 1 to 5 described below and NonPatent Document 1 described below).

[0009] FIG. 13B is a diagram schematically showing a state where the steel pipe pile 100 is driven by an inner excavation method. The ground is dug by a drilling rod 120 inserted into the inside of the steel pipe pile 100, until the leading end portion of the steel pipe pile 100 reaches a bearing stratum. After the leading end portion of the steel pipe pile 100 reaches the bearing stratum, a fluidity solidifying material (cement milk or the like) is injected from a leading end portion of the drilling rod 120 into the bearing stratum disturbed by the drilling rod 120 and the leading end portion of the steel pipe pile 100, and thus a foot protection block 130 is constructed.

[0010]

By adopting the inner excavation method or the bored pile method, it is possible to suppress noise and vibration occurring during the driving of the steel pipe pile 100, and therefore, it is possible to drive the steel pipe pile 100 in an area in which environmental regulations are strict, such as an urban area. However, as described above, in the inner excavation method and the bored pile method, it is necessary to insert the drilling rod 120 into the inside of the steel pipe pile 100, and therefore, it is not possible to mount the dividing member 110 for increasing the leading end plugging effect on the steel pipe pile 100.

[0011]

The leading end portion of the steel pipe pile 100 driven by the inner excavation method or the bored pile method is confined by a frictional force occurring between soil cement filled into the leading end portion of the steel pipe pile 100 and the surface of the steel pipe pile 100. This confining force exerts the leading end plugging effect.

[0012] The larger the outer diameter D of the steel pipe pile 100, the further the leading end plugging effect decreases. Therefore, in order to obtain the above-described confining force, it is necessary to increase the length of the soil cement (the length of the foot protection block) on the inside of the leading end portion of the steel pipe pile 100. Further, it is necessary to inject a large amount of cement milk or the like into the steel pipe pile 100 and the ground according to the extension of the foot protection block, and therefore, construction hours become longer, and construction costs increase.

[Patent Document] [0013] [Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2009-057817 [Patent Document 2] Japanese Unexamined Patent Application, First Publication No. 2009- 068326 [Patent Document 3] Japanese Unexamined Patent Application, First Publication No. 2010- 209516 [Patent Document 4] Japanese Unexamined Patent Application, First Publication No. 2012-097511 [Patent Document 5] Japanese Unexamined Patent Application, First Publication No. 2012-127082 [Non-Patent Document] [0014] [Non-Patent Document 1] "Steel pipe pile-design and construction thereof (12th edition revised on April I, 2009) issued by the Japanese Technical Association for Steel Pipe Piles and Steel Sheet Piles, pp 328 to 329 and 469 to 470 [0015] In recent years, under strict environmental regulations, applications of the inner excavation method or the bored pile method in which it is possible to suppress noise and vibration occurring during the driving of a steel pipe pile have increased. However, unlike in the pile driving by hammer, in the inner excavation method or the bored pile method, it is necessary to insert the drilling rod into the inside of the steel pipe pile, and therefore, it is not possible to attach the dividing member for increasing the leading end plugging effect, to the inside of the leading end portion of the steel pipe pile.

[0016] For this reason, in a case of adopting the inner excavation method or the bored pile method, in order to improve the confining force of the steel pipe pile by the foot protection block constructed by the solidification of the fluidity solidifying material, it is necessary to increase the length of the foot protection block in the leading end portion of the steel pipe pile as the outer diameter of the steel pipe pile becomes larger. In a case where the length of the foot protection block is not appropriate with respect to the outer diameter of the steel pipe pile, it is not possible to obtain the bearing capacity of the steel pipe pile from the bearing stratum to a maximum extent. For this reason, it is necessary to increase the number of steel pipe piles in order to obtain the required bearing capacity for the entire structure, and thus an economical burden such as an increase in construction costs and a prolonged construction period increases.

[0017] There is a need for a steel pipe pile and a steel pipe pile construction method in which leading end bearing capacity can be obtained to a maximum extent by increasing a confining force of a steel pipe pile by a foot protection block constructed by solidification of a fluidity solidifying material.

OBJECT OF THE INVENTION

[0017a] It is an object of the present invention to at least substantially satisfy the foregoing need.

SUMMARY OF THE INVENTION

[0018] (l)An aspect of the present invention provides a steel pipe pile comprising: a pile main body configured with a steel pipe; a dividing member which is joined to the inside of a leading end portion of the pile main body, thereby dividing a cross section of the pile main body into a plurality of sections; an injection nozzle which is mounted on at least one of an outer peripheral surface of the leading end portion of the pile main body and an inner peripheral surface of the leading end portion of the pile main body and selectively injects water and a fluidity solidifying material; and a pipe which selectively supplies the water and the fluidity solidifying material to the injection nozzle, wherein the dividing member is a member for constructing a foot protection block by solidification of the fluidity solidifying material, wherein the dividing member is a steel plate joined to the inside of the leading end portion of the pile main body so as to be parallel to an axial direction of the pile main body, and wherein another injection nozzle is mounted on the dividing member.

[0019] [This paragraph is left intentionally blank] [0020] [This paragraph is left intentionally blank] [0021] (2) In an embodiment, the injection nozzle may be mounted on the dividing member as well.

[0022] (3) In an embodiment, an injection direction of the injection nozzle may be parallel to an axial direction of the pile main body and may be directed to the inside of an inner peripheral surface of the pile main body.

[0023] (4) In an embodiment, a plurality of the injection nozzles may be mounted on at least one of the outer peripheral surface and the inner peripheral surface of the leading end portion of the pile main body, and each injection direction of the plurality of injection nozzles may intersect an axial direction of the pile main body.

[0024] (5) In an embodiment, the outer peripheral surface of the pile main body may be provided with a projection.

[0025] (6) In an embodiment, the dividing member and the inner peripheral surface of the pile main body may be provided with a projection.

[0026] (7) In an embodiment, the dividing member may be provided with a through-hole.

[0027] (8) In an embodiment, a length of the dividing member in an axial direction of the pile main body may be less than twice an outer diameter of the pile main body.

[0028] (9) In an embodiment, the injection nozzle and the pipe may be detachably mounted on the pile main body.

[0029] (10) There is also disclosed herein a steel pipe pile construction method including a process of driving the steel pipe pile according to any one of (1) to (8) to a maximum drilling depth in a bearing stratum while injecting the water from the injection nozzle, a process of pulling up the steel pipe pile to a predetermined pull-up depth while injecting the fluidity solidifying material from the injection nozzle, a process of driving the steel pipe pile to a fixing depth in the bearing stratum while continuing to inject the fluidity solidifying material from the injection nozzle, and a process of constructing a foot protection block of the steel pipe pile by solidification of the fluidity solidifying material.

[0030] (11) there is also disclosed herein a steel pipe pile construction method including a process of driving the steel pipe pile according to (9) to a maximum drilling depth in a bearing stratum while injecting the water from the injection nozzle, a process of pulling up the steel pipe pile to a predetermined pull-up depth while injecting the fluidity solidifying material from the injection nozzle, a process of driving the steel pipe pile to a fixing depth in the bearing stratum while continuing to inject the fluidity solidifying material from the injection nozzle, a process of separating the injection nozzle and the pipe from the steel pipe pile in a state where injection of the fluidity solidifying material from the injection nozzle is temporarily stopped, a process of pulling up the injection nozzle and the pipe to the ground while injecting the fluidity solidifying material from the injection nozzle, and a process of constructing a foot protection block of the steel pipe pile by solidification of the fluidity solidifying material.

[0031] (12) There is also disclosed herein a steel pipe pile construction method including a process of driving the steel pipe pile according to (9) to a maximum drilling depth in a bearing stratum while injecting the water from the injection nozzle, a process of pulling up the steel pipe pile to a predetermined pull-up depth while injecting the fluidity solidifying material from the injection nozzle, a process of driving the steel pipe pile to a fixing depth in the bearing stratum while continuing to inject the fluidity solidifying material from the injection nozzle, a process of separating at least a portion of the pipe from the steel pipe pile in a state where injection of the fluidity solidifying material from the injection nozzle is temporarily stopped, a process of pulling up a portion of the separated pipe to the ground while injecting the fluidity solidifying material from a leading end of the separated pipe, and a process of constructing a foot protection block of the steel pipe pile by solidification of the fluidity solidifying material.

[0032] (13) In an embodiment, after the process of driving the steel pipe pile to the maximum drilling depth and before the process of pulling up the steel pipe pile to the pull-up depth, a process of pulling up the steel pipe pile while injecting the fluidity solidifying material or the water from the injection nozzle, and then driving the steel pipe pile, may be performed at least once.

[0033] According to at least a preferred embodiment, the contact area between the foot protection block constructed by the solidification of the fluidity solidifying material and the inside of the leading end portion of the pile main body (the leading end portion of the pile main body and the dividing member) increases, and therefore, it is possible to increase the confining force of the steel pipe pile on the foot protection block.

Therefore, according to at least a preferred embodiment, in a case where the outer diameter of the steel pipe pile (the pile main body) is large, even if the length of the foot protection block on the inside of the pile main body is shortened, the contact area is secured, and thus it is possible to sufficiently obtain the confining force of the steel pipe pile. Therefore, according to at least a preferred embodiment, it is possible to obtain the leading end bearing capacity of the steel pipe pile from the bearing stratum to a maximum extent.

[Brief Description of the Drawings] [0033a] Preferred embodiments of the invention will be described hereinafter, by way of examples only, with reference to the accompanying drawings.

[0034] FIG. 1A is a side view of a steel pipe pile 1 according to an embodiment of the present invention. FIG. IB is a cross-sectional view as seen from a direction of arrow A-A of the steel pipe pile 1 shown in FIG. 1A. FIG. 2A is a first diagram schematically showing a method of constructing the steel pipe pile 1 according to the embodiment of the present invention. FIG. 2B is a second diagram schematically showing the method of constructing the steel pipe pile 1 according to the embodiment of the present invention. FIG. 2C is a third diagram schematically showing the method of constructing the steel pipe pile 1 according to the embodiment of the present invention. FIG. 3 is a diagram schematically showing a foot protection block FPB constructed by the method of constructing the steel pipe pile 1 according to the embodiment of the present invention. FIG. 4 is a diagram schematically showing a modified example in which injection nozzles 4 are mounted on both an outer peripheral surface 2b and an inner peripheral surface 2a of a leading end portion of a pile main body 2. FIG. 5 is a diagram schematically showing a modified example in which a plurality of through-holes 3 a is provided in a dividing member 3. FIG. 6A is a diagram schematically showing a modified example in which the injection nozzles 4 are disposed on the outer peripheral surface 2b of the pile main body 2 and the cross section of the pile main body 2 is divided into three sections by three dividing members 6 (flat steel plates) joined to each other at the center of the pile main body 2. FIG. 6B is a diagram schematically showing a modified example in which the injection nozzles 4 are disposed on the outer peripheral surface 2b of the pile main body 2 and the cross section of the pile main body 2 is divided into three sections by two arc-shaped dividing members 7. FIG. 7A is a diagram schematically showing a modified example in which the injection nozzles 4 are disposed on the outer peripheral surface 2b and the inner peripheral surface 2a of the pile main body 2 and the cross section of the pile main body 2 is divided into three sections by the three dividing members 6 (flat steel plates) joined to each other at the center of the pile main body 2. FIG. 7B is a diagram schematically showing a modified example in which the injection nozzles 4 are disposed on the outer peripheral surface 2b and the inner peripheral surface 2a of the pile main body 2 and the cross section of the pile main body 2 is divided into three sections by the two arc-shaped dividing members 7. FIG. 8 is a diagram schematically showing a modified example in which two injection nozzles 4 are also disposed on both sides of the dividing member 3 which is a sheet of flat steel plate as shown in FIG. 1B. FIG. 9A is a diagram schematically showing a modified example in which one injection nozzle 4 is disposed on one side of each of the three dividing members 6 as shown in FIG. 6A. FIG. 9B is a diagram schematically showing a modified example in which one injection nozzle 4 is disposed on one side of each of the two arc-shaped dividing members 7 as shown in FIG. 6B. FIG. 10 is a diagram schematically showing a modified example in which injection directions of a plurality of injection nozzles 4 intersect an axial direction AX of the pile main body 2. FIG. 11A is a schematic diagram when the pile main body 2 with four projections 11 (steel plates) provided on the outer peripheral surface 2b is viewed from the axial direction AX. FIG. 11B is a schematic diagram when the pile main body 2 with four projections 11 (steel plates) provided on the outer peripheral surface 2b is viewed from a direction orthogonal to the axial direction AX. FIG. 12 is a diagram schematically showing a modified example in which a projection 12 (a reinforcing bar) is provided at the dividing member 3 which is a sheet of flat steel plate. FIG. 13 A is a diagram schematically showing a state where a dividing member 110 configured with two steel plates orthogonal to each other is mounted on the inside of a leading end portion of a steel pipe pile 100. FIG. 13B is a diagram schematically showing a state where the steel pipe pile 100 is driven into the ground by an inner excavation method.

[Embodiments of the Invention] [0035]

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0036] FIG. 1A is a side view of a steel pipe pile 1 according to an embodiment of the present invention. FIG. IB is a cross-sectional view as seen from a direction of arrow A-A of the steel pipe pile 1 shown in FIG. 1 A. As shown in FIGS. 1A and IB, the steel pipe pile 1 according to this embodiment is provided with a pile main body 2, a dividing member 3, a plurality of (for example, six) injection nozzles 4, and a plurality of (for example, six) pipes 5.

[0037]

The pile main body 2 is configured with a steel pipe having an outer diameter D which is constant along an axial direction AX. In the following, an end portion on one side on which the dividing member 3 is mounted, in two end portions of the pile main body 2, is referred to as a leading end portion, and an end portion on the other side is referred to as a rear end portion.

[0038]

The dividing member 3 is a single flat steel plate having a rectangular shape. The dividing member 3 is mounted so as to divide the cross section of the pile main body 2 into two sections on the inside of the leading end portion of the pile main body 2. The dividing member 3 is welded to an inner peripheral surface 2a of the pile main body 2 so as to be parallel to the axial direction AX of the pile main body 2. As will be described later, it is preferable that a length L of the dividing member 3 in the axial direction AX of the pile main body 2 be less than twice the outer diameter D of the pile main body 2.

[0039]

As described above, as the dividing member 3, it is preferable to use a flat plate-shaped metal member. In particular, it is preferable that a steel plate which is used as the dividing member 3 have a strength and a plate thickness capable of withstanding driving of the steel pipe pile 1 and a pile leading end bearing capacity. A method of joining the dividing member 3 to the pile main body 2 is not particularly limited. For example, it is possible to adopt a bolt joint. However, as a method of joining the dividing member 3 to the pile main body 2, welding is preferable. In this case, it is preferable that the quality of a material of a steel plate which is used as the dividing member 3 be the same as the quality of a material of the pile main body 2. However, as long as it is the quality of a material having good weldability, the quality of a material which is different from that of the pile main body 2 is also acceptable.

[0040]

The six injection nozzles 4 are mounted at regular intervals along a circumferential direction of the pile main body 2 on an outer peripheral surface 2b of the leading end portion of the pile main body 2. Each of the injection nozzles 4 selectively injects water and a fluidity solidifying material (for example, cement milk) along the axial direction AX of the pile main body 2. That is, an injection direction JD of each of the injection nozzles 4 is a direction parallel to the axial direction AX and outward in the axial direction AX. In a case where the water is injected from each of the injection nozzles 4, the ground which is included in a drilling range 4a shown in Fig. 1B is dug. In this embodiment, each of the injection nozzles 4 is detachably mounted on the pile main body 2.

[0041]

The six pipes 5 correspond to the six injection nozzles 4 on a one-to-one basis. That is, one pipe 5 is connected to one injection nozzle 4. Each of the pipes 5 is disposed so as to extend along the axial direction AX of the pile main body 2 on the outer peripheral surface 2b of the pile main body 2. The water and the fluidity solidifying material are selectively supplied to the injection nozzle 4 through the pipe 5. In this embodiment, each of the pipes 5 is detachably mounted on the pile main body 2, similarly to the injection nozzle 4. In addition, in the steel pipe pile 1 according to the embodiment of the present invention shown in FIGS. 1A and IB, an example in which the pipes 5 and the injection nozzles 4 correspond to each other on a one-to-one basis is shown. However, there is no limitation thereto, and pipes branched from one pipe may be connected to the plurality of injection nozzles 4, and a plurality of pipes may be connected to one injection nozzle 4.

[0042]

Next, a method of constructing the steel pipe pile 1 according to this embodiment configured as described above will be described.

First, as shown in a first process in FIG. 2A, after the steel pipe pile 1 is provided to be erect on a surface of ground GS in a state where the leading end portion of the steel pipe pile 1 (that is, the leading end portion of the pile main body 2) is in contact with the surface of ground GS. a vibratory hammer BH is mounted on a rear end portion of the steel pipe pile 1 (that is, a rear end portion of the pile main body 2). The vibratory hammer BH is suspended by a crane (not shown).

[0043]

Further, each of the pipes 5 of the steel pipe pile 1 is connected to a fluid supply device (not shown). The fluid supply device has a function to selectively supply the water and the fluidity solidifying material to each of the pipes 5 according to an operation by a worker. At this point of time, a fluid which is supplied from the fluid supply device to each of the pipes 5 is set to be the water.

[0044]

Subsequently, as shown in a second process in FIG 2A, vibration which acts in the axial direction AX is applied to the steel pipe pile 1 by the vibratory hammer BH while high-pressure water (water jet) WJ is injected from each of the injection nozzles 4 of the steel pipe pile 1. The ground which is present in a driving direction (a vertically downward direction) from the steel pipe pile 1 is dug by the injection of the high-pressure water WJ and the vibration of the steel pipe pile 1, and thus a driving hole DH of the steel pipe pile 1 is formed along the driving direction. The steel pipe pile 1 settles along the driving hole DH due to its own weight and the weight of the vibratory hammer BH.

[0045]

Subsequently, as shown in a third process in FIG. 2A, if the leading end portion of the steel pipe pile 1 reaches the maximum drilling depth in a bearing stratum, the injection of the high-pressure water WJ by each of the injection nozzles 4 is stopped and a vibration generating operation of the vibratory hammer BH is also stopped. In this way, the steel pipe pile 1 is stopped at the maximum drilling depth.

In a state where the steel pipe pile 1 has been stopped at the maximum drilling depth in this manner, the fluid which is supplied from the fluid supply device to each of the pipes 5 is switched from the water to the fluidity solidifying material (for example, cement milk).

[0046]

Subsequently, as shown in a fourth process in FIG. 2B, the vibration generating operation of the vibratory hammer BH is resumed, and while a fluidity solidifying material SM is injected from each of the injection nozzles 4 of the steel pipe pile 1, the vibratory hammer BH is pulled up by the crane until the steel pipe pile 1 returns to a predetermined pull-up depth. When the steel pipe pile 1 is pulled up from the maximum drilling depth to the pull-up depth in this manner, the section between the maximum drilling depth and the pull-up depth in the driving hole DH is filled with the fluidity solidifying material SM.

[0047]

As shown in a fifth process in FIG 2B, the pull-up of the vibratory hammer BH (that is, the pull-up of the steel pipe pile 1) by the crane is stopped while injecting the fluidity solidifying material SM from each of the injection nozzles 4 even after the steel pipe pile 1 reaches the pull-up depth. The steel pipe pile 1 starts settling again along the driving hole DH due to its own weight and the weight of the vibratory hammer BH. Then, as shown in a sixth process in FIG. 2B, when the steel pipe pile 1 reaches a fixing depth, a wire of the crane is fixed, and thus the position of the steel pipe pile 1 in the driving hole DH is maintained at the fixing depth.

In addition, the fixing depth is set at a position shallower than the maximum drilling depth and deeper than the pull-up depth, in the bearing stratum. Further, it is preferable that the distance between the fixing depth and the pull-up depth be longer than the length L of the dividing member 3 in the axial direction AX of the pile main body 2.

[0048]

Then, as shown in a seventh process in FIG. 2C, in a state where the position of the steel pipe pile 1 is maintained at the fixing depth, the injection nozzles 4 and the pipes 5 are pulled up to the ground while the fluidity solidifying material SM is injected from each of the injection nozzles 4 of the steel pipe pile 1. Before the injection nozzles 4 and the pipes 5 are pulled up, it is necessary to separate the injection nozzles 4 and the pipes 5 from the steel pipe pile 1 in a state where the injection of the fluidity solidifying material SM from the injection nozzles 4 is temporarily stopped. In the seventh process in FIG 2C, an example in which the injection nozzles 4 and the pipes 5 are pulled up to the ground is shown. However, an example is also possible in which the pipe 5 is separated from a joint portion between the injection nozzle 4 and the pipe 5 and only the pipe 5 is pulled up to the ground. Otherwise, an example is also possible in which at least a portion of the pipe 5 is separated from the steel pipe pile 1 in a state where the injection of the fluidity solidifying material SM from the injection nozzles 4 is temporarily stopped, and only a portion of the separated pipe is pulled up to the ground while injecting the fluidity solidifying material SM from the leading end of the separated pipe.

Then, as shown in an eighth process in FIG. 2C, after the pull-up (recovery) of the injection nozzles 4 and the pipes 5 is completed and the fluidity solidifying material SM is solidified, the vibratory hammer BH is removed from the pile main body 2, and thus the construction (driving) of the steel pipe pile 1 is completed.

[0049]

As shown in FIG. 2C, after the recovery of the injection nozzles 4 and the pipes 5 is completed, the pile main body 2 and the dividing member 3 (in FIG 2C, not shown) mounted on the inner peripheral surface 2a of the leading end portion of the pile main body 2, among the constituent elements of the steel pipe pile 1, remain in the driving hole DH, and the section between the pull-up depth and the surface of ground GS in the driving hole DH is also fdled with the fluidity solidifying material SM.

That is, a region which is included between the surface of ground GS and the fixing depth, of the outer peripheral surface 2b of the pile main body 2, is covered with the fluidity solidifying material SM, and a space between the pull-up depth and the fixing depth, of an internal space (also including spaces divided by the dividing member 3) of the pile main body 2, is filled with the fluidity solidifying material SM.

[0050]

As shown in FIG 3, when the fluidity solidifying material SM is solidified in such a state, a foot protection block FPB (soil-cement solidified body) is constructed so as to cover the leading end portion of the pile main body 2. The foot protection block FPB also penetrates the space between the pull-up depth and the fixing depth, of the internal space (also including the spaces divided by the dividing member 3) of the pile main body 2, without a gap.

[0051]

The foot protection block FPB described above is constructed, whereby the inner peripheral surface 2a of the pile main body 2 and the surface of the dividing member 3 come into contact with the foot protection block FPB, that is, the soil-cement solidified body. As a result, the contact area between the foot protection block FPB and the inside of the leading end portion of the pile main body 2 increases, and therefore, a confining force of the pile main body 2 by the foot protection block FPB is increased.

[0052]

As already described, in the related art, in a case where the outer diameter of a steel pipe pile is large, in order to obtain a sufficient leading end plugging effect (leading end bearing capacity) by increasing a confining force of the steel pipe pile by a foot protection block, it is necessary to increase the length of the foot protection block (the length of a soil-cement solidified body) on the inside of the steel pipe pile.

[0053]

However, as described above, according to this embodiment, it is possible to increase the confining force of the pile main body 2 by the foot protection block FPB by an increase in the contact area between the foot protection block FPB and the inside of the leading end portion of the pile main body 2. Therefore, according to this embodiment, in a case where the outer diameter D of the pile main body 2 is large, even if the length of the foot protection block FPB on the inside of the pile main body 2 is set to be short, it is possible to sufficiently secure the confining force of the pile main body 2 by the foot protection block FPB, and as a result, it is possible to obtain a leading end plugging effect (leading end bearing capacity) of the pile main body 2 to a maximum extent.

[0054]

In particular, in a case where the outer diameter D of the pile main body 2 exceeds 1000 mm, the confining force of the pile main body 2 by the foot protection block FPB greatly varies according to the presence or absence of the dividing member 3 in the leading end portion of the pile main body 2, and therefore, the effect of improving the leading end bearing capacity which is obtained by the mounting of the dividing member 3 is remarkable.

[0055]

Further, in this embodiment, the distance between the fixing depth and the pull-up depth is set to be longer than the length L of the dividing member 3 in the axial direction AX of the pile main body 2. For this reason, as shown in FIG. 3, the foot protection block FPB penetrates to a space above the dividing member 3, of the internal space of the pile main body 2. In this manner, according to this embodiment, an upper end of the dividing member 3 is covered with the foot protection block FPB, whereby an anchor effect by the foot protection block FPB is also obtained, and therefore, it is possible to further improve the leading end bearing capacity of the pile main body 2.

[0056]

Here, the length L of the dividing member 3 which is integrated with the foot protection block FPB will be described. As already described, in a case where a dividing member is mounted on a steel pipe pile which is driven by a pile driving by hammer, it is preferable that the length of the dividing member be set to be greater than or equal to twice the outer diameter of the steel pipe pile. However, as shown in FIG 3, in this embodiment, the dividing member 3 is integrated with the fluidity solidifying material SM, and thus the foot protection block FPB is constructed along with the leading end portion of the pile main body 2, and therefore, it is sufficient if the length L of the dividing member 3 is a length which is integrated with the fluidity solidifying material SM.

[0057]

The upper limit of the length L of the dividing member 3 depends on the state of the ground and the outer diameter D of the pile main body 2. According to the results of the tests carried out by the inventors of this application, in order to sufficiently secure the confining force by the foot protection block FPB, it is preferable that the length L of the dividing member 3 be less than twice the outer diameter D of the pile main body 2. In a case where the length L of the dividing member 3 is greater than or equal to twice the outer diameter D of the pile main body 2, since it is necessary for a worker to enter the inside of the pile main body 2 and perform work of welding the dividing member 3, working hours for the mounting of the dividing member 3 become longer, and thus the physical burden of a worker increases.

[0058]

On the other hand, if the length L of the dividing member 3 is too short, even if the dividing member 3 is integrated with the fluidity solidifying material SM, it is difficult to construct a robust foot protection block FPB, and it is difficult to secure the quality and the strength of a welded portion between the pile main body 2 and the dividing member 3. The lower limit of the length L of the dividing member 3 depends on the state of the ground, the outer diameter D of the pile main body 2, and the number of divisions by the dividing member 3. According to the results of the tests carried out by the inventors of this application, it is preferable that the lower limit of the length L of the dividing member 3 be greater than or equal to 0.5 times the outer diameter D of the pile main body 2.

[0059]

The present invention is not limited to the above-described embodiment and the following modified examples can be given. (1) In the above-described embodiment, an example that the injection nozzles 4 are mounted on only the outer peripheral surface 2b of the leading end portion of the pile main body 2 is explained. However, it is enough if the injection nozzles 4 are mounted on at least one of the outer peripheral surface 2b of the leading end portion of the pile main body 2 and the inner peripheral surface 2a of the leading end portion of the pile main body 2.

[0060] FIG. 4 is a diagram showing an example in which the injection nozzles 4 are mounted on both the outer peripheral surface 2b and the inner peripheral surface 2a of the leading end portion of the pile main body 2. In the example shown in FIG. 4, three injection nozzles 4 are mounted along the circumferential direction of the pile main body 2 on the outer peripheral surface 2b of the leading end portion of the pile main body 2, and three injection nozzles 4 are mounted along the circumferential direction of the pile main body 2 on the inner peripheral surface 2a of the leading end portion of the pile main body 2.

[0061]

By injecting high-pressure water from the injection nozzles 4 mounted on the inner peripheral surface 2a of the pile main body 2, it is possible to efficiently dig the ground which is present in the driving direction of the steel pipe pile 1. Further, since the inner peripheral surface 2a of the pile main body 2 is cleaned, adhesion between the fluidity solidifying material SM and the inner peripheral surface 2a of the pile main body 2 increases.

[0062]

In addition, in a case of preferentially blocking the leading end portion of the steel pipe pile 1 (that is, the leading end portion of the pile main body 2), the crosssectional area of the lead ing end portion of the pile main body 2 is divided into small areas by the dividing member 3. Therefore, by injecting the fluidity solidifying material SM from the injection nozzles 4 while pulling up the injection nozzles 4 disposed on the inner peripheral surface 2a of the pile main body 2, it becomes possible to construct the foot protection block FPB which integrates the inner peripheral surface 2a of the pile main body 2, the surface of the dividing member 3, and the fluidity solidifying material SM with each other.

[0063] (2) In the above-described embodiment, an example that the number of injection nozzles 4 is six is explained. However, it is favorable if the number, the positions, the disposition interval, and the like of the injection nozzles 4 are appropriately set according to the state of the ground, the outer diameter D of the pile main body 2, and the like.

[0064] (3) As shown in FIG. 5, a plurality of through-holes 3a may be provided in the dividing member 3. The through-holes 3 a are provided in the dividing member 3 (a steel plate), whereby the fluidity solidifying material SM solidified on the inside of the pile main body 2 is integrated with the dividing member 3 through the through-holes 3 a, and therefore, a confining force on the dividing member 3 is further improved and the bearing capacity of the pile main body 2 is also improved. It is enough if at least one through-hole 3 a is provided in the dividing member 3. There is no limit to the number of through-holes 3 a. However, it is preferable to appropriately set the number of through-holes 3 a in consideration of the strength of the dividing member 3 and a confining force of the solidified fluidity solidifying material SM on the dividing member 3.

[0065] (4) In the above-described embodiment, an example that the cross section of the pile main body 2 is divided into two sections by using a single flat steel plate as the dividing member 3 is explained. However, it is favorable if the number of divisions of the cross section of the pile main body 1 and the disposition of the divid ing member 3 are appropriately set according to the state of the ground or the outer diameter D of the pile main body 2.

[0066] FIG. 6A shows an example in which the injection nozzles 4 are disposed on the outer peripheral surface 2b of the pile main body 2 and the cross section of the pile main body 2 is divided into three sections by three dividing members 6 (flat steel plates) joined to each other at the center of the pile main body 2. FIG 6B shows an example in which the injection nozzles 4 are disposed on the outer peripheral surface 2b of the pile main body 2 and the cross section of the pile main body 2 is divided into three sections by two arc-shaped dividing members 7.

[0067]

If the number of divisions of the cross section of the pile main body 2 increases, the surface areas of the dividing members 6 (or 7) increase, and therefore, the confining force of the pile main body 2 by the foot protection block FPB increases. However, work of mounting the dividing members 6 (or 7) becomes complicated, and therefore, it is preferable to appropriately set the number of divisions of the cross section of the pile main body 2 so as not to inhibit the workability of construction of the steel pipe pile 1, after the consideration of the outer diameter D of the pile main body 2.

[0068]

Further, if the number of divisions of the cross section of the pile main body 2 increases, the surface areas of the dividing members 6 (or 7) increase, and therefore, the confining force of the pile main body 2 by the foot protection block FPB increases. For this reason, the length of each of the dividing members 6 (or 7) in the axial direction AX of the pile main body 2 may be shorter than the length L of the dividing member 3.

[0069] FIG. 7 A shows an example in which the injection nozzles 4 are disposed on the outer peripheral surface 2b and the inner peripheral surface 2a of the pile main body 2 and the cross section of the pile main body 2 is divided into three sections by the three dividing members 6 (flat steel plates) joined to each other at the center of the pile main body 2. FIG 7B shows an example in which the injection nozzles 4 are disposed on the outer peripheral surface 2b and the inner peripheral surface 2a of the pile main body 2 and the cross section of the pile main body 2 is divided into three sections by the two arc-shaped dividing members 7.

[0070]

In the examples shown in FIGS. 7A and 713. the injection nozzles 4 are disposed on the outer peripheral surface 2b and the inner peripheral surface 2a of the pile main body 2, and therefore, it is possible to reliably inject the fluidity solidifying material SM to divided portions in the leading end portion of the pile main body 2 by the injection nozzles 4 disposed on the inner peripheral surface 2a, and thus the leading end plugging effect is significantly improved.

[0071] (5) As described above, it is enough if the injection nozzles 4 are mounted on at least one of the outer peripheral surface 2b and the inner peripheral surface 2a of the pile main body 2. However, in order to quicken a driving speed of the steel pipe pile 1 and improve the leading end plugging effect, the injection nozzles 4 may be mounted on the dividing member 3 (or, 6 or 7) as well.

[0072] FIG. 8 shows an example in which two injection nozzles 4 are also disposed on both sides of the dividing member 3 which is a single flat steel plate as shown in FIG. IB. FIG. 9A shows an example in which one injection nozzle 4 is disposed on one side of each of the three dividing members 6 as shown in FIG. 6A. FIG. 9B shows an example in which one injection nozzle 4 is disposed on one side of each of the two arc-shaped dividing members 7 as shown in FIG. 6B.

[0073]

The disposition of the injection nozzles 4 is not limited to the examples shown in FIGS. 8, 9A, and 9B. For example, in the example shown in FIG. 8, two injection nozzles 4 may be disposed on one side of the dividing member 3. In the example shown in FIG. 9A, for example, a total of two or more injection nozzles 4 may be disposed on both sides of one dividing member 6. In the example shown in FIG. 9B, at least one injection nozzle 4 may be disposed on the inside of one arc-shaped dividing member 7.

[0074] (6) In the above-described embodiment, an example that the injection direction JD of each of the injection nozzles 4 is a direction parallel to the axial direction AX of the pile main body 2 and outward in the axial direction AX is explained. However, the injection directions JD of the injection nozzles 4 may be directions parallel to the axial direction AX of the pile main body 2 and toward the inside of the inner peripheral surface 2a of the pile main body 2. It is preferable that the injection directions JD of the injection nozzles 4 be set in consideration of the state of the ground, the drilling efficiency, and the like. In addition, the injection directions JD of each of the injection nozzles 4 may be different from each other.

[0075]

In particular, in a case of driving the steel pipe pile 1 into hard ground, there is also a possibility that the ground of a central portion of the steel pipe pile 1 cannot be dug. Therefore, in a case where the plurality of injection nozzles 4 are mounted on at least one of the outer peripheral surface 2b and the inner peripheral surface 2a of the lead ing end portion of the pile main body 2 in order to easily dig the ground, it is preferable that the injection directions JD of the plurality of injection nozzles 4 intersect the axial direction AX of the pile main body 2.

[0076] FIG. 10 shows an example in which the injection directions of the two injection nozzles 4 intersect the axial direction AX of the pile main body 2. In the example shown in FIG. 10, the injection direction JD of an injection nozzle 4b disposed at the dividing member 3 which is a sheet of steel plate is parallel to the axial direction AX of the pile main body 2 and is directed to a point X on the line of the axial direction AX of the pile main body 2. On the other hand, the injection directions JD of two injection nozzles 4c and 4d facing each other, which are disposed on the outer peripheral surface 2b of the pile main body 2, intersect each other at the point X on the line of the axial direction AX of the pile main body 2.

[0077] (7) At least one projection may be provided on the outer peripheral surface 2b of the leading end portion of the pile main body 2. In a case where a projection is provided on the outer peripheral surface 2b of the leading end portion of the pile main body 2, the contact area between the foot protection block FPB which covers the leading end portion of the pile main body 2 and the surface of the pile main body 2 is enlarged, and therefore, the bearing capacity of the pile main body 2 from the ground increases. Further, at least one projection may also be provided on the inner peripheral surface 2a of the leading end portion of the pile main body 2 and the dividing member 3 (or, 6 or 7).

[0078] FIG. 11A shows a schematic diagram when the pile main body 2 with four projections 11 (steel plates) provided on the outer peripheral surface 2b is viewed from the axial direction AX. FIG. 11B shows a schematic diagram when the pile main body 2 with the four projections (steel plates) provided on the outer peripheral surface 2b is viewed from a direction orthogonal to the axial direction AX. In FIGS. 11A and 11B, the four projections 11 which are steel plates are welded to the outer peripheral surface 2b of the leading end portion of the pile main body 2 which is buried in the foot protection block FPB, along the axial direction AX.

[0079]

In addition, it is favorable if the number of projections is appropriately set in consideration of the state of the ground, the drilling efficiency, and the like. Further, the shape of the projection is not limited to a plate shape. However, it is preferable that the shape of the projection be a plate shape.

[0080] FIG. 12 shows an example in which a projection 12 (a reinforcing bar) is provided at the dividing member 3 which is a single flat steel plate. As shown in FIG. 12, a plurality of the projections 12 which are reinforcing bars are welded to the surface of the dividing member 3 at regular intervals along the axial direction AX and so as to extend in a direction orthogonal to the axial direction AX.

[0081]

In addition, it is favorable if the number of projections which are provided at the dividing member 3 (or, 6 or 7) is appropriately set in consideration of the state of the ground, the drilling efficiency, and the like. Further, as the projection which is provided at the dividing member 3 (or, 6 or 7), instead of the reinforcing bar, a rib steel plate may be provided . Further, the projection may be formed with a bolt joint or the like without being limited to welding.

[0082] (8) In the above-described embodiment, an example that the injection nozzles 4 and the pipes 5 are detachably mounted on the pile main body 2 is explained. In this case, as described in the above-described embodiment, a method of constructing the steel pipe pile 1 includes: a process of driving the steel pipe pile 1 to the maximum drilling depth in the bearing stratum while injecting the high-pressure water WJ from the injection nozzles 4; a process of pulling up the steel pipe pile 1 to a predetermined pull-up depth while injecting the fluidity solidifying material SM from the injection nozzles 4; a process of driving the steel pipe pile 1 to the fixing depth in the bearing stratum while continuing to inject the fluidity solidifying material SM from the injection nozzles 4; a process of separating the injection nozzles 4 and the pipes 5 from the steel pipe pile 1 in a state where the injection of the fluidity solidifying material SM from the injection nozzles 4 is temporarily stopped; a process of pulling up the injection nozzles 4 and the pipes 5 to the ground while injecting the fluidity solidifying material SM from the injection nozzles 4; and a process of constmcting a foot protection block of the steel pipe pile (that is, the pile main body 2 remaining in the ground) by solidification of the fluidity solidifying material SM.

With respect to the above-described embodiment, a configuration of separating the pipe 5 at a joint portion between the injection nozzle 4 and the pipe 5 and pulling up only the pipe 5 to the ground, rather than pulling up the injection nozzles 4 and the pipes 5, is also acceptable. Otherwise, a configuration of separating at least a portion of the pipe 5 from the steel pipe pile 1 in a state where the injection of the fluidity solidifying material SM from the injection nozzle 4 is temporarily stopped and pulling up only a portion of the separated pipe 5 to the ground while injecting the fluidity solidifying material SM from the leading end of the separated pipe is also acceptable.

Further, after the process of driving the steel pipe pile 1 to the maximum drilling depth in the bearing stratum while injecting water from the injection nozzles 4 and before the process of pulling up the steel pipe pile 1 to a predetermined pull-up depth while injecting the fluidity solidifying material SM from the injection nozzles 4, a process of pulling up the steel pipe pile 1 while injecting the fluidity solidifying material SM or the water from the injection nozzles 4, and then driving the steel pipe pile 1, may be performed at least once. In the case of hard ground, it is possible to sufficiently secure a construction area of the foot protection block FPB by stirring the ground by repeating this process. In this process, from the viewpoint of delaying solidification, it is preferable to use water, rather than the fluidity solidifying material SM.

[0083]

In addition, with respect to the above-described embodiment, the injection nozzles 4 and the pipes 5 may be fixed to the pile main body 2. In a method of constructing the steel pipe pile 1 in this modified example, the injection nozzles 4 and the pipes 5 are buried in the ground along with the pile main body 2 without being pulled up to the ground.

Specifically, the method of constructing the steel pipe pile 1 in this modified example includes: a process of driving the steel pipe pile 1 to the maximum drilling depth in the bearing stratum while injecting the high-pressure water WJ from the injection nozzles 4; a process of pulling up the steel pipe pile 1 to a predetermined pull-up depth while injecting the fluidity solidifying material SM from the injection nozzles 4; a process of driving the steel pipe pile 1 to the fixing depth in the bearing stratum while injecting the fluidity solidifying material SM from the injection nozzles 4; and a process of constructing a foot protection block of the steel pipe pile 1 by solidification of the fluidity solidifying material SM.

[0084]

That is, in the method of constructing the steel pipe pile 1 in this modified example, the first to sixth processes shown in FIGS. 2A and 2B are the same as those in the construction method of the above-described embodiment. However, the seventh process shown in FIG. 2C is omitted, and the foot protection block is constructed in a state where all the constituent elements of the steel pipe pile 1 remain in the ground.

[Examples] [0085]

Next, an example of the present invention will be described. However, the conditions in the example are one example case adopted in order to verify the feasibility and the effects of the present invention, and the present invention is not limited to the one example case. The present invention can adopt various conditions without departing from the gist of the present invention, as long as they achieve the object of the present invention.

[0086] (Example 1) A pile main body (a steel pipe) having an outer diameter D of 1300 mm was prepared and a steel plate dividing the cross section of the pile main body into two sections was welded to a leading end portion of the pile main body as a dividing member. A length L of the dividing member in an axial direction of the pile main body was set to be 0.5 times the outer diameter D of the pile main body (that is, to be 650 mm).

[0087]

Six injection nozzles were mounted on the outer peripheral surface of the pile main body and four injection nozzles were mounted on the dividing member. Ten pipes which selectively supply water and a fluidity solidifying material to these ten injection nozzles were also mounted on the pile main body. The pipes for the injection nozzles mounted on the outer peripheral surface were extended along the outer peripheral surface of the pile main body and connected to the injection nozzles. The pipes for the injection nozzles mounted on the dividing member were extended along the inner peripheral surface of the pile main body and the dividing member, bent at a joint portion between the pile main body and the dividing member, and connected to the injection nozzles. In this manner, the steel pipe pile in this example was configured with the pile main body having the outer diameter D of 1300 mm, the dividing member mounted on the inside of the leading end portion of the pile main body, the ten injection nozzles, and the ten pipes.

[0088]

The steel pipe pile in this example was driven while digging the ground by injecting water from the ten injection nozzles. After the steel pipe pile had reached the bearing stratum, a foot protection block was constructed by switching a fluid which was injected from the injection nozzles from the water to a fluidity solidifying material (cement milk).

[0089]

The inventors of this application confirmed that the leading end bearing capacity of the steel pipe pile in this example was about 11000 kN. Further, when the inside of the steel pipe pile was dug by boring and the construction shape of the foot protection block was investigated, it could be confirmed that the foot protection block having a length greater than or equal to twice the outer diameter D of the pile main body, which could be integrated with a required maximum length (less than twice the outer diameter D of the pile main body) of the dividing member, was constructed.

[0090]

When a core was collected from the foot protection block and the strength of soil cement of the foot protection block expressing the leading end bearing capacity (11000 kN) was measured with an uniaxial compression test, the strength of the soil cement was in a range of 15 MPa to 40 MPa.

[0091]

Here, if the leading end bearing capacity (11000 kN) is divided by the crosssectional area (1.3 m2=(1.3 ηι/2)2χπ) of the pile main body, 8.3 MPa is obtained as a required strength of the soil cement.

Since the strength of the foot protection block in this example is in a range of 15 MPa to 40 MPa, it significantly exceeds the required strength of 8.3 MPa.

[0092]

Therefore, it was possible to confirm that a foot protection block more robust than that in the related art could be constructed by adopting the steel pipe pile in this example in which the dividing member and the injection nozzles were mounted on the leading end portion of the pile main body.

[Industrial Applicability] [0093]

As described above, according to the present invention, a confining force of the leading end plugging effect of the steel pipe pile is improved by the fluidity solidifying material (for example, cement milk) and the dividing member, and thus the bearing capacity of the steel pipe pile from the bearing stratum increases. In particular, in the case of a steel pipe pile having the outer diameter D exceeding 1000 mm, the confining force greatly varies according to the presence or absence of the dividing member in a leading end portion of a pile main body, and therefore, an increase in the bearing capacity of the bearing stratum due to the present invention is remarkable.

[0094]

Therefore, according to the present invention, the number of piles which are driven can be reduced by improvement in bearing capacity per single pile, and thus it is possible to obtain economical effects such as a reduction in material cost, shortening of a construction period, and a reduction in construction costs. In addition, in a case of driving a steel pipe pile by using an injection nozzle, a driving speed is fast compared to a drilling rod, and therefore, construction costs can be further reduced, and this contributes to improvement in an economical effect. Accordingly, the present invention is highly applicable in the civil engineering industry and the building industry.

[Brief Description of the Reference Symbols] [0095] 1: steel pipe pile 2: pile main body 3, 6, 7: dividing member 4: injection nozzle 5: pipe 3 a: through-hole 4a: drilling range 11, 12: projection WJ: high-pressure water SM: fluidity solidifying material FPB: foot protection block D: outer diameter of pile main body AX: axial direction of pile main body JD: injection direction of injection nozzle L: length of dividing member DH: driving hole BH: vibratory hammer

Claims

1. A steel pipe pile comprising: a pile main body configured with a steel pipe; a dividing member which is joined to the inside of a leading end portion of the pile main body, thereby dividing a cross section of the pile main body into a plurality of sections; an injection nozzle which is mounted on at least one of an outer peripheral surface of the leading end portion of the pile main body and an inner peripheral surface of the leading end portion of the pile main body and selectively injects water and a fluidity solidifying material; and a pipe which selectively supplies the water and the fluidity solidifying material to the injection nozzle, wherein the dividing member is a member for constructing a foot protection block by solidification of the fluidity solidifying material, wherein the dividing member is a steel plate joined to the inside of the leading end portion of the pile main body so as to be parallel to an axial direction of the pile main body, and wherein another injection nozzle is mounted on the dividing member.

2. The steel pipe pile according to Claim 1, wherein a length of the dividing member in the axial direction of the pile main body is greater than or equal to 0.5 times and less than twice an outer diameter of the pile main body.

3. The steel pipe pile according to Claim 1 or 2, wherein a plurality of the injection nozzles are mounted on at least one of the outer peripheral surface and the inner peripheral surface of the leading end portion of the pile main body, and each injection direction of the plurality of injection nozzles intersects an axial direction of the pile main body.

4. The steel pipe pile according to any one of Claims 1 to 3, wherein the dividing member is provided on the pile main body having the outer diameter exceeding 1000 mm

5. The steel pipe pile according to any one of Claims 1 to 4, wherein the dividing member is provided with a through-hole.

6. The steel pipe pile according to any one of Claims 1 to 5, wherein the injection nozzle and the pipe are detachably mounted on the pile main body.

7. A steel pipe pile construction method comprising: a process of driving the steel pipe pile according to any one of Claims 1 to 6 to a maximum drilling depth in a bearing stratum while injecting the water from the injection nozzle; a process of pulling up the steel pipe pile to a predetermined pull-up depth while injecting the fluidity solidifying material from the injection nozzle; a process of driving the steel pipe pile to a fixing depth in the bearing stratum while continuing to inject the fluidity solidifying material from the injection nozzle; and a process of constructing a foot protection block of the steel pipe pile by solidification of the fluidity solidifying material.

8. A steel pipe pile construction method comprising: a process of driving the steel pipe pile according to Claim 6 to a maximum drilling depth in a bearing stratum while injecting the water from the injection nozzle; a process of pulling up the steel pipe pile to a predetermined pull-up depth while injecting the fluidity solidifying material from the injection nozzle; a process of driving the steel pipe pile to a fixing depth in the bearing stratum while continuing to inject the fluidity solidifying material from the injection nozzle; a process of separating the injection nozzle and the pipe from the steel pipe pile in a state where injection of the fluidity solidifying material from the injection nozzle is temporarily stopped; a process of pulling up the injection nozzle and the pipe to the ground while injecting the fluidity solidifying material from the injection nozzle; and a process of constructing a foot protection block of the steel pipe pile by solidification of the fluidity solidifying material.

9. A steel pipe pile construction method comprising: a process of driving the steel pipe pile according to Claim 6 to a maximum drilling depth in a bearing stratum while injecting the water from the injection nozzle; a process of pulling up the steel pipe pile to a predetermined pull-up depth while injecting the fluidity solidifying material from the injection nozzle; a process of driving the steel pipe pile to a fixing depth in the bearing stratum while continuing to inject the fluidity solidifying material from the injection nozzle; a process of separating at least a portion of the pipe from the steel pipe pile in a state where injection of the fluidity solidifying material from the injection nozzle is temporarily stopped; a process of pulling up a portion of the separated pipe to the ground while injecting the fluidity solidifying material from a leading end of the separated pipe; and a process of constructing a foot protection block of the steel pipe pile by solidification of the fluidity solidifying material.

10. The steel pipe pile construction method according to any one of Claims 7 to 9, wherein after the process of driving the steel pipe pile to the maximum drilling depth and before the process of pulling up the steel pipe pile to the pull-up depth, a process of pulling up the steel pipe pile while injecting the fluidity solidifying material or the water from the injection nozzle, and then driving the steel pipe pile, is performed at least once.