JP3885997B2

JP3885997B2 - Steel pipe pile and its construction method

Info

Publication number: JP3885997B2
Application number: JP2001375458A
Authority: JP
Inventors: 一夫堀; 義則住友; 義武大西; 順三郎山田
Original assignee: Sekisui House Ltd
Current assignee: Sekisui House Ltd
Priority date: 2001-12-10
Filing date: 2001-12-10
Publication date: 2007-02-28
Anticipated expiration: 2021-12-10
Also published as: JP2003176534A

Description

【０００１】
【発明の属する技術分野】
この発明は、軟弱地盤における住宅等の不同沈下防止等のために使用される鋼管杭及びその施工方法に関する。
【０００２】
【従来の技術】
周知のように、軟弱地盤における住宅等の不同沈下を防止する方法や上部荷重を地盤に伝達する方法としては、例えば、騒音や振動等の問題がない鋼管杭の回転貫入工法がある。
【０００３】
この回転貫入工法においては、図１３及び図１４に示すように、螺旋翼７が先端２ａ付近の外周に螺旋状に突設され、例えば三角板状の掘削片５２を一面側８ａに突設した底板８の他面側８ｂが先端２ａに固着された鋼管製の軸管２からなる鋼管杭５１を使用することが多い。施工に際しては、鋼管杭５１の頭部５１ｂを重機で押さえながら、あるいは支持しながら回転を加えて地盤に貫入するのが一般的である。回転貫入後においては、螺旋翼７を含む鋼管杭５１の先端５１ａが受ける地盤反力（先端支持力）と、鋼管杭５１と地盤との間に発生する摩擦力（周面摩擦力）とによって支持力を得る構造となっている。
【０００４】
【発明が解決しようとする課題】
しかしながら、上記のような従来の鋼管杭５１においては、地盤への回転貫入時に鋼管杭５１の１回転当りの貫入量が螺旋翼７の周回ピッチＰより小さい場合、地盤中に螺旋翼７によって乱されたまま残る部分が発生する。また、掘削片５２によって乱されたまま残る部分も発生する。そのため、鋼管杭５１に荷重が作用すれば住宅等を支持する上で有害な沈下が発生するおそれがあり、地盤に対する先端支持力はあまり大きくないという問題点がある。
【０００５】
この発明は、以上のような問題点に鑑みてなされたものであり、地盤に対する先端支持力を向上できる鋼管杭及びその施工方法を提供することを目的とする。
【０００７】
【課題を解決するための手段】
上記目的を達成するための請求項１の鋼管杭は、少なくとも１つの螺旋翼が先端付近の外周に螺旋状に突設され、少なくとも１つの切欠部又は突出部が先端に設けられた鋼管製の軸管と、この軸管の内径より外径が少し小さい鋼管製で、底板が先端に固着され、前記軸管内に前記底板を軸管の先端側に向けて挿入された内管とを備えた鋼管杭であって、前記内管の先端の内部に、面方向が前記内管の長さ方向に対して平行とされた状態で前記底板に当接する補強板を架設したものである。
【０００８】
請求項２の鋼管杭は、前記内管の先端の内部における前記補強板の上方に、面方向が前記内管の長さ方向に対して平行でかつ前記補強板の面方向に対して直角とされた状態で前記補強板に当接する他の補強板を架設したものである。
【０００９】
請求項３の鋼管杭の施工方法は、少なくとも１つの螺旋翼が先端付近の外周に螺旋状に突設され、少なくとも１つの切欠部又は突出部が先端に設けられた鋼管製の軸管と、この軸管の内径より外径が少し小さい鋼管製で、底板が先端に固着され、前記軸管内に前記底板を軸管の先端側に向けて挿入された内管とを備えた鋼管杭の施工方法であって、前記軸管の切欠部又は突出部より上方に前記内管を引き込んだ状態で鋼管杭を地盤の所定深さまで回転貫入し、鋼管杭を回転させながら上下に移動させ、鋼管杭の先端付近の地盤を砕くことによって砕土部を設け、この砕土部内の所定高さに鋼管杭の先端を位置させた状態で前記内管を圧下することによって砕土部を締め固めた後、前記内管を前記軸管に固定するものである。
【００１０】
請求項４の鋼管杭の施工方法においては、前記内管の圧下時における前記砕土部の底面から鋼管杭の先端までの高さが前記螺旋翼の外径以上である。
【００１１】
請求項５の鋼管杭の施工方法は、前記内管を、この内管内に挿入されたモンケンの自由落下によって圧下するものである。
【００１２】
【発明の実施の形態】
以下、この発明の実施形態を図面に基づいて説明する。なお、従来技術と同じ構成については、同一符号を付している。
【００１３】
図１乃至図５に示すように、この実施形態に係る鋼管杭１の施工方法は、例えば、軸管２の切欠部３より上方に内管４を引き込んだ状態で鋼管杭１を地盤５の所定深さまで回転貫入し、鋼管杭１を回転させながら上下に移動させ、鋼管杭１の先端１ａ付近の地盤５を砕くことによって砕土部６を設け、この砕土部６内の所定高さに鋼管杭１の先端１ａを位置させた状態で内管４を圧下することによって砕土部６を締め固めた後、内管４を軸管２に固定するものである。
【００１４】
鋼管杭１は、図１乃至図７に示すように、螺旋翼７が先端２ａ付近の外周に螺旋状に突設され、例えば２つの切欠部３が先端３ａに設けられた鋼管製の軸管２と、この軸管２の内径より外径が少し小さい鋼管製で、底板８が先端４ａに固着され、軸管２内に底板８を軸管２の先端２ａ側に向けて挿入された内管４とを備えている。
【００１５】
軸管２は、例えば、外径が約１０〜数十ｃｍ、肉厚が数ｍｍの円管状の鋼管製で、数ｍ〜十数ｍの長尺に形成されている。
【００１６】
螺旋翼７は、例えば鋼板製で、軸管２の先端２ａ付近の外周に溶接等により螺旋状に突設されている。なお、この実施形態においては、１周しか周回させていないが、これに限定されるものではなく、それ以上周回させてもよい。また、螺旋翼７の数も１つに限定されるものではなく、軸管２の長さ方向に沿って複数個突設してもよい。
【００１７】
切欠部３は、例えば、幅及び深さがそれぞれ数ｃｍの凹状に形成されており、軸管２の先端２ａに相対向するように２つ形成されている。なお、切欠部３の形状、サイズ、数等は特に限定されるものではなく、適宜変更可能である。また、図８及び図９に示すように、切欠部３を設ける代わりに軸管２の先端２ａに突出部９を設けてもよい。図８及び図９に示す例では、幅及び突出長さがそれぞれ数ｃｍの凸状の突出部９を相対向するように軸管２と一体的に２つ設けているが、これに限定されるものではなく、突出部９の形状、サイズ、数等も適宜変更可能である。
【００１８】
内管４は、図１乃至図９に示すように、軸管２と同様の円管状の鋼管製であるが、軸管２の内径より外径が少し小さく形成されており、軸管２内に底板８を軸管２の先端２ａ側に向けて出し入れ自在に挿入されている。なお、内管４の長さは、この実施形態のように軸管２より少し短くしておけばよいが、これに限定されるものではなく、地盤５への回転貫入時に切欠部３又は突出部９より上方に内管４を引き込んだ状態で内管４と軸管２とを重機等により同時に回転可能な長さであればよい。
【００１９】
底板８は、例えば円板状の鋼板製で、内管４の先端４ａに溶接等により固着されている。
【００２０】
鋼管杭１の施工に際しては、まず、図１に示すように、切欠部３の上方に内管４を引き込んだ状態で鋼管杭１を地盤５の所定深さまで回転貫入する。この場合、重機等により軸管２と内管４とを同時に同じ方向に回転させればよい。あるいは、従来公知の固定手段により軸管２と内管４とを固定した状態で回転させてもよい。なお、回転貫入時においては、軸管２の先端２ａに切欠部３を設けることにより形成された回転方向の後方側の角部１０が掘削片としての役割を果たす。このように、従来のような掘削片５２を別途固着する必要がないので、その分、製造時の手間を省けるという利点がある。既述の突出部９を軸管２と一体的に設ける場合も同様である。
【００２１】
そして、図２に示すように、鋼管杭１を重機等により回転させながら上下に移動させ、鋼管杭１の先端１ａ付近の地盤５を砕くことによって砕土部６を設ける。この場合、鋼管杭１の回転や移動は適宜の方向に行えばよく、螺旋翼７で地盤５の所定範囲を砕いて砕土部６とすればよい。
【００２２】
次いで、図３及び図４に示すように、砕土部６内の所定高さに鋼管杭１の先端１ａを位置させた後、軸管２内にワイヤーロープ１１等を介して自由落下及び引き上げ自在に挿入されたモンケン１２等により内管４を圧下する。なお、内管４の圧下方法は特に限定されるものではなく、従来公知の適宜の方法を使用できるが、この実施形態のようなモンケン１２の自由落下によれば、簡単にかつ大荷重で圧下できるという利点がある。
【００２３】
モンケン１２を自由落下させる場合、モンケン１２が内管４の底板８に衝突することによって内管４が砕土部６に圧入されるので、図１０乃至図１２に示すように、底板８を補強板１３等により補強しておけば、底板８に大荷重が作用しても外れるおそれがないという利点がある。この場合、２つの補強板１３，１４を使用した方がより効果的である。補強板１３は、内管４の先端４ａの内部に、面方向が内管４の長さ方向に対して平行とされた状態で底板８に当接するように溶接等により架設しておけばよい。他の補強板１４は、内管４の先端４ａの内部における補強板１３の上方に、面方向が内管４の長さ方向に対して平行でかつ補強板１３の面方向に対して直角とされた状態で補強板１３に当接するように溶接等により架設しておけばよい。補強板１３，１４同士も溶接等により固定してもよい。
【００２４】
図４に示すように、上記のようにして内管４を圧下すれば、砕土部６が締め固められる。内管４は、図５に示すように、必要に応じて軸管２と共に所定高さで切断した後、軸管２に溶接等により固定すればよい。また、切断後の鋼管杭１の頭部１ｂには、必要に応じて円板状の鋼板製等の上板１５を溶接等により固着すればよい。布基礎等の基礎は、従来公知の方法により鋼管杭１の上方に施工すればよい。
【００２５】
このようにして軸管２の先端２ａに砕土部６を設けると共に、内管４の圧下により砕土部６を締め固めれば、地盤５に対する先端支持力が大きくなるので、鋼管杭１に荷重が作用しても沈下量を小さく抑えることができるという利点がある。ここで、内管４の圧下時における砕土部６の底面６ｄから軸管２の先端２ａまでの高さが螺旋翼７の外径以上であれば、内管４の圧下ストロークを十分に確保できるので、砕土部６を十分に締め固めることができるという利点がある。
【００２７】
【発明の効果】
以上のように、請求項１の発明によれば、内管の先端の内部に前記補強板を架設しているので、底板に大荷重が作用しても外れるおそれがない。
【００２８】
請求項２の発明によれば、内管の先端の内部における補強板の上方に前記他の補強板を架設しているので、請求項１の効果がより大きい。
【００２９】
請求項３の発明によれば、軸管の先端に砕土部を設けると共に、内管の圧下により砕土部を締め固めるので、地盤に対する先端支持力が大きくなり、そのため鋼管杭に荷重が作用しても沈下量を小さく抑えることができる。
【００３０】
請求項４の発明によれば、内管の圧下時における砕土部の底面から軸管の先端までの高さが螺旋翼の外径以上であるので、内管の圧下ストロークを十分に確保でき、そのため砕土部を十分に締め固めることができる。
【００３１】
請求項５の発明によれば、内管をモンケンの自由落下によって圧下するので、簡単にかつ大荷重で圧下できる。
【図面の簡単な説明】
【図１】実施形態に係る鋼管杭の施工方法において、鋼管杭を地盤の所定深さまで回転貫入した後の状態を示す一部省略断面図。
【図２】砕土部を設けた後の状態を示す一部省略断面図。
【図３】鋼管杭の先端を砕土部内の所定高さに位置させた状態を示す一部省略断面図。
【図４】砕土部を締め固めた後の状態を示す一部省略断面図。
【図５】鋼管杭を所定高さで切断した後の状態を示す一部省略断面図。
【図６】図１の鋼管杭の底面図。
【図７】図１の内管の一部省略正面図。
【図８】鋼管杭の他例を示す一部省略正面図。
【図９】図８の鋼管杭の底面図。
【図１０】鋼管杭の他例を示す一部省略正面図。
【図１１】図１０の鋼管杭の底面図。
【図１２】図１０の内管の一部省略正面図。
【図１３】従来例の一部省略正面図。
【図１４】従来例の底面図。
【符号の説明】
１鋼管杭
１ａ先端
２軸管
２ａ先端
３切欠部
４内管
４ａ先端
５地盤
６砕土部
６ｄ底面
７螺旋翼
８底板
９突出部
１２モンケン
１３補強板
１４他の補強板[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steel pipe pile used for preventing uneven settlement of a house or the like in soft ground and a construction method thereof.
[0002]
[Prior art]
As is well known, as a method for preventing the uneven settlement of a house or the like in soft ground and a method for transmitting an upper load to the ground, there is, for example, a rotary penetration method of a steel pipe pile that is free from problems such as noise and vibration.
[0003]
In this rotary penetration method, as shown in FIG. 13 and FIG. 14, the bottom plate in which the spiral blade 7 is spirally provided on the outer periphery in the vicinity of the tip 2 a, for example, a triangular plate-like excavation piece 52 is provided on the one side 8 a. In many cases, a steel pipe pile 51 composed of a steel pipe shaft pipe 2 having the other surface side 8b fixed to the tip 2a is used. At the time of construction, it is common to rotate the steel pipe pile 51 while pressing or supporting the head 51b of the steel pipe pile 51 into the ground. After the rotation penetration, the ground reaction force (tip support force) received by the tip 51a of the steel pipe pile 51 including the spiral blade 7 and the friction force (circumferential friction force) generated between the steel pipe pile 51 and the ground It has a structure that provides support.
[0004]
[Problems to be solved by the invention]
However, in the conventional steel pipe pile 51 as described above, when the penetration amount per rotation of the steel pipe pile 51 is smaller than the circulation pitch P of the spiral blade 7 during the rotation penetration into the ground, the spiral blade 7 disturbs the ground. The part that remains is generated. Further, a portion that remains disturbed by the excavation piece 52 also occurs. Therefore, if a load acts on the steel pipe pile 51, there is a possibility that harmful settlement occurs when supporting a house or the like, and there is a problem that the tip supporting force with respect to the ground is not so large.
[0005]
This invention is made | formed in view of the above problems, and it aims at providing the steel pipe pile which can improve the front-end | tip support force with respect to the ground, and its construction method.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a steel pipe pile according to claim 1 is made of a steel pipe in which at least one spiral wing is provided in a spiral manner on the outer periphery near the tip, and at least one notch or protrusion is provided at the tip. A shaft tube and an inner tube made of a steel tube having an outer diameter slightly smaller than the inner diameter of the shaft tube, with a bottom plate fixed to the tip, and inserted into the shaft tube with the bottom plate facing the tip side of the shaft tube. In the steel pipe pile, a reinforcing plate that abuts against the bottom plate in a state where the surface direction is parallel to the length direction of the inner pipe is installed inside the tip of the inner pipe.
[0008]
The steel pipe pile according to claim 2 , wherein the surface direction is parallel to the length direction of the inner pipe and perpendicular to the surface direction of the reinforcing plate above the reinforcing plate inside the tip of the inner pipe. In this state, another reinforcing plate that contacts the reinforcing plate is installed.
[0009]
The steel pipe pile construction method according to claim 3 , wherein at least one spiral blade is spirally provided on the outer periphery in the vicinity of the tip, and at least one notch or protrusion is provided at the tip. Construction of a steel pipe pile made of a steel pipe whose outer diameter is slightly smaller than the inner diameter of the shaft pipe, with a bottom plate fixed to the tip, and an inner pipe inserted into the shaft pipe with the bottom plate facing the tip side of the shaft pipe The steel pipe pile is rotated and penetrated to a predetermined depth of the ground in a state where the inner pipe is retracted above the notch portion or the protruding portion of the shaft pipe, and the steel pipe pile is moved up and down while rotating. After crushing the ground in the vicinity of the tip of the slab, the crushed part is provided, and after crushing the inner pipe by pressing the inner pipe with the tip of the steel pipe pile positioned at a predetermined height in the crushed part, The tube is fixed to the shaft tube.
[0010]
In the steel pipe pile construction method according to claim 4 , the height from the bottom of the crushed portion to the tip of the steel pipe pile when the inner pipe is being reduced is equal to or greater than the outer diameter of the spiral blade.
[0011]
The construction method of the steel pipe pile according to claim 5 is to reduce the inner pipe by free fall of monken inserted in the inner pipe.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected about the same structure as a prior art.
[0013]
As shown in FIG. 1 to FIG. 5, the construction method of the steel pipe pile 1 according to this embodiment is, for example, the steel pipe pile 1 of the ground 5 in a state where the inner pipe 4 is drawn above the notch 3 of the shaft pipe 2. By rotating and penetrating to a predetermined depth, the steel pipe pile 1 is moved up and down while rotating, and the ground 5 near the tip 1a of the steel pipe pile 1 is crushed to provide a crushed portion 6, and the steel pipe is set at a predetermined height in the crushed portion 6. The inner tube 4 is fixed to the shaft tube 2 after the crushed soil portion 6 is compacted by reducing the inner tube 4 with the tip 1a of the pile 1 positioned.
[0014]
As shown in FIGS. 1 to 7, the steel pipe pile 1 is a steel pipe shaft pipe in which a spiral blade 7 is provided in a spiral shape on the outer periphery in the vicinity of the tip 2 a and, for example, two notches 3 are provided on the tip 3 a. 2 and made of a steel pipe whose outer diameter is slightly smaller than the inner diameter of the shaft tube 2, the bottom plate 8 is fixed to the tip 4 a, and the bottom plate 8 is inserted into the shaft tube 2 toward the tip 2 a side of the shaft tube 2. Tube 4.
[0015]
The shaft tube 2 is made of, for example, a tubular steel tube having an outer diameter of about 10 to several tens of centimeters and a thickness of several millimeters, and is formed in a length of several meters to several tens of meters.
[0016]
The spiral blade 7 is made of, for example, a steel plate, and is projected in a spiral shape by welding or the like on the outer periphery in the vicinity of the tip 2 a of the shaft tube 2. In this embodiment, the circuit circulates only once, but the present invention is not limited to this. Further, the number of spiral blades 7 is not limited to one, and a plurality of spiral blades 7 may be provided along the length direction of the shaft tube 2.
[0017]
For example, the notch 3 is formed in a concave shape having a width and a depth of several centimeters, and two notches are formed so as to oppose the tip 2 a of the axial tube 2. In addition, the shape, size, number, etc. of the notch part 3 are not specifically limited, It can change suitably. Further, as shown in FIGS. 8 and 9, a protruding portion 9 may be provided at the tip 2 a of the shaft tube 2 instead of providing the notch portion 3. In the example shown in FIG. 8 and FIG. 9, two projecting projections 9 each having a width and a projection length of several centimeters are provided integrally with the shaft tube 2 so as to face each other, but the present invention is not limited to this. However, the shape, size, number, and the like of the protrusions 9 can be changed as appropriate.
[0018]
As shown in FIGS. 1 to 9, the inner tube 4 is made of a circular steel pipe similar to the shaft tube 2, but has an outer diameter slightly smaller than the inner diameter of the shaft tube 2. The bottom plate 8 is inserted into the shaft tube 2 so as to be able to be taken in and out. The length of the inner tube 4 may be slightly shorter than that of the shaft tube 2 as in this embodiment, but is not limited to this, and the notch 3 or the protruding portion is not limited to this when rotating into the ground 5. Any length may be used as long as the inner tube 4 and the shaft tube 2 can be simultaneously rotated by a heavy machine or the like in a state where the inner tube 4 is drawn above the portion 9.
[0019]
The bottom plate 8 is made of, for example, a disk-shaped steel plate, and is fixed to the distal end 4a of the inner tube 4 by welding or the like.
[0020]
When constructing the steel pipe pile 1, first, as shown in FIG. 1, the steel pipe pile 1 is rotated and penetrated to a predetermined depth of the ground 5 in a state where the inner pipe 4 is drawn above the notch 3. In this case, the shaft tube 2 and the inner tube 4 may be simultaneously rotated in the same direction by a heavy machine or the like. Alternatively, the shaft tube 2 and the inner tube 4 may be rotated while being fixed by a conventionally known fixing means. In addition, at the time of rotation penetration, the corner 10 on the rear side in the rotation direction formed by providing the notch 3 at the tip 2a of the shaft tube 2 serves as an excavation piece. In this way, there is no need to separately fix the excavation piece 52 as in the prior art, so that there is an advantage that the labor for manufacturing can be saved correspondingly. The same applies to the case where the protrusion 9 described above is provided integrally with the shaft tube 2.
[0021]
And as shown in FIG. 2, the steel pipe pile 1 is moved up and down, rotating with a heavy machine etc., and the ground part 6 near the front-end | tip 1a of the steel pipe pile 1 is crushed, and the crushed part 6 is provided. In this case, the rotation and movement of the steel pipe pile 1 may be performed in an appropriate direction, and the predetermined range of the ground 5 may be crushed by the spiral blade 7 to form the crushed portion 6.
[0022]
Next, as shown in FIGS. 3 and 4, after the tip 1a of the steel pipe pile 1 is positioned at a predetermined height in the crushed portion 6, it can be freely dropped and pulled up into the shaft pipe 2 via a wire rope 11 or the like. The inner tube 4 is pressed down by the monken 12 or the like inserted into the tube. The method of reducing the inner tube 4 is not particularly limited, and any conventionally known appropriate method can be used. However, according to the free fall of the monken 12 as in this embodiment, the reduction is easily performed with a large load. There is an advantage that you can.
[0023]
When the monken 12 is freely dropped, the inner pipe 4 is press-fitted into the crushed portion 6 when the monken 12 collides with the bottom plate 8 of the inner pipe 4, so that the bottom plate 8 is reinforced as shown in FIGS. 10 to 12. If reinforced by 13 or the like, there is an advantage that even if a large load is applied to the bottom plate 8, there is no possibility of detachment. In this case, it is more effective to use the two reinforcing plates 13 and 14. The reinforcing plate 13 may be installed inside the tip 4a of the inner tube 4 by welding or the like so as to contact the bottom plate 8 in a state where the surface direction is parallel to the length direction of the inner tube 4. . The other reinforcing plate 14 has a surface direction parallel to the length direction of the inner tube 4 and perpendicular to the surface direction of the reinforcing plate 13 above the reinforcing plate 13 inside the tip 4 a of the inner tube 4. What is necessary is just to construct by welding etc. so that it may contact | abut to the reinforcement board 13 in the state made. The reinforcing plates 13 and 14 may also be fixed by welding or the like.
[0024]
As shown in FIG. 4, when the inner tube 4 is squeezed down as described above, the crushed soil portion 6 is compacted. As shown in FIG. 5, the inner tube 4 may be fixed to the shaft tube 2 by welding or the like after being cut at a predetermined height together with the shaft tube 2 as necessary. Moreover, what is necessary is just to adhere to the head 1b of the steel pipe pile 1 after a cutting | disconnection by welding etc., if necessary. A foundation such as a cloth foundation may be constructed above the steel pipe pile 1 by a conventionally known method.
[0025]
In this way, when the crushed portion 6 is provided at the tip 2 a of the shaft tube 2 and the crushed portion 6 is compacted by the pressure of the inner tube 4, the tip supporting force with respect to the ground 5 is increased, so that a load is applied to the steel pipe pile 1. Even if it acts, there exists an advantage that the amount of settlement can be suppressed small. Here, if the height from the bottom surface 6d of the crushed portion 6 to the tip 2a of the axial tube 2 is equal to or greater than the outer diameter of the spiral blade 7 when the inner tube 4 is being reduced, a sufficient reduction stroke of the inner tube 4 can be secured. Therefore, there is an advantage that the crushed soil part 6 can be sufficiently compacted.
[0027]
【The invention's effect】
As described above , according to the first aspect of the present invention, since the reinforcing plate is installed inside the tip of the inner tube, there is no possibility that it will come off even if a large load acts on the bottom plate.
[0028]
According to the second aspect of the invention, since the other reinforcing plate is installed above the reinforcing plate inside the tip of the inner tube, the effect of the first aspect is greater.
[0029]
According to the invention of claim 3 , since the crushed portion is provided at the tip of the shaft tube and the crushed portion is compacted by the pressure of the inner tube, the tip supporting force with respect to the ground is increased, so that a load acts on the steel pipe pile. Can also reduce the amount of settlement.
[0030]
According to the invention of claim 4 , since the height from the bottom of the crushed portion to the tip of the axial tube at the time of the reduction of the inner tube is equal to or greater than the outer diameter of the spiral blade, the reduction stroke of the inner tube can be sufficiently secured, Therefore, the crushed portion can be sufficiently compacted.
[0031]
According to the invention of claim 5 , since the inner tube is crushed by free fall of monken, it can be crushed easily and with a large load.
[Brief description of the drawings]
FIG. 1 is a partially omitted cross-sectional view showing a state after a steel pipe pile has been rotated and penetrated to a predetermined depth of the ground in a steel pipe pile construction method according to an embodiment.
FIG. 2 is a partially omitted cross-sectional view showing a state after a crushed portion is provided.
FIG. 3 is a partially omitted cross-sectional view showing a state in which the tip of the steel pipe pile is positioned at a predetermined height in the crushed portion.
FIG. 4 is a partially omitted cross-sectional view showing a state after the crushed soil portion is compacted.
FIG. 5 is a partially omitted cross-sectional view showing a state after a steel pipe pile is cut at a predetermined height.
6 is a bottom view of the steel pipe pile of FIG. 1. FIG.
7 is a partially omitted front view of the inner tube of FIG. 1. FIG.
FIG. 8 is a partially omitted front view showing another example of the steel pipe pile.
9 is a bottom view of the steel pipe pile of FIG. 8. FIG.
FIG. 10 is a partially omitted front view showing another example of the steel pipe pile.
11 is a bottom view of the steel pipe pile of FIG.
12 is a partially omitted front view of the inner tube of FIG.
FIG. 13 is a partially omitted front view of a conventional example.
FIG. 14 is a bottom view of a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Steel pipe pile 1a Tip 2 Shaft tube 2a Tip 3 Notch part 4 Inner pipe 4a Tip 5 Ground 6 Crushed part 6d Bottom face 7 Spiral wing 8 Bottom plate 9 Protrusion part 12 MONKEN 13 Reinforcement plate 14 Other reinforcement plates

Claims

At least one spiral wing projecting spirally on the outer periphery near the tip, and at least one notch or protrusion is provided at the tip of the steel tube shaft tube, and the outer diameter is slightly smaller than the inner diameter of the shaft tube It is a steel pipe pile made of steel pipe, with a bottom plate fixed to the tip, and an inner pipe inserted into the shaft pipe with the bottom plate facing the tip side of the shaft pipe ,
A steel pipe pile characterized in that a reinforcing plate that abuts against the bottom plate in a state in which a surface direction is parallel to a length direction of the inner pipe is installed inside the tip of the inner pipe.

Above the reinforcing plate inside the tip of the inner tube, the reinforcing plate is in a state in which the surface direction is parallel to the length direction of the inner tube and perpendicular to the surface direction of the reinforcing plate. The steel pipe pile according to claim 1, wherein another reinforcing plate that abuts is installed .

At least one spiral wing projecting spirally on the outer periphery near the tip, and at least one notch or protrusion is provided at the tip of the steel tube shaft tube, and the outer diameter is slightly smaller than the inner diameter of the shaft tube A steel pipe pile construction method comprising a steel pipe, a bottom plate fixed to the tip, and an inner pipe inserted into the shaft pipe with the bottom plate facing the tip side of the shaft pipe,
The steel pipe pile is rotated and penetrated to a predetermined depth of the ground with the inner pipe pulled in above the notch or protrusion of the shaft pipe, and the ground near the tip of the steel pipe pile is moved up and down while rotating the steel pipe pile. After crushing the inner pipe by pressing the inner pipe with the tip of the steel pipe pile positioned at a predetermined height in the crushed part, the inner pipe is fixed to the shaft pipe. Steel pipe pile construction method characterized by being fixed to

The construction method of the steel pipe pile of Claim 3 whose height from the bottom face of the said crushing part at the time of the said inner pipe reduction to the front-end | tip of a steel pipe pile is more than the outer diameter of the said spiral blade .

The construction method of the steel pipe pile of Claim 3 or 4 which reduces the said inner pipe by the free fall of the monken inserted in this inner pipe .