JP7012584B2 - How to build cast-in-place concrete piles - Google Patents

How to build cast-in-place concrete piles Download PDF

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JP7012584B2
JP7012584B2 JP2018075063A JP2018075063A JP7012584B2 JP 7012584 B2 JP7012584 B2 JP 7012584B2 JP 2018075063 A JP2018075063 A JP 2018075063A JP 2018075063 A JP2018075063 A JP 2018075063A JP 7012584 B2 JP7012584 B2 JP 7012584B2
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英之 眞野
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Shimizu Corp
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Description

本発明は、場所打ちコンクリート杭の構築方法に関する。 The present invention relates to a method for constructing cast-in-place concrete piles.

従来、超高層ビルなど重量の大きい建物では、杭基礎として場所打ちコンクリート拡底杭が多用されている。 Conventionally, cast-in-place concrete expansion piles are often used as pile foundations in heavy buildings such as high-rise buildings.

場所打ちコンクリート拡底杭（場所打ちコンクリート杭）は、略一定の径の軸部と、軸部の先端部側を必要な支持力に合わせて拡底してなる略円錐台状の拡底部とを備えて構築され、杭先端部に拡底部を設けることで支持耐力を大幅に向上させることができる（例えば、特許文献１参照）。 The cast-in-place concrete expanded pile (cast-in-place concrete pile) is provided with a shaft portion having a substantially constant diameter and a substantially truncated cone-shaped expanded portion in which the tip end side of the shaft portion is expanded according to the required bearing capacity. By providing a bottom-expanded portion at the tip of the pile, the bearing capacity can be significantly improved (see, for example, Patent Document 1).

場所打ちコンクリート拡底杭を構築する際には、例えば、掘削機を用いて地表面から略一定の径の掘削孔を所定の深度まで安定液を充填しつつ掘削形成する。次に、ロッドの先端に接続した拡底用掘削機（拡底バケットなどの拡底機）を挿入して掘削孔の先端部に配置した段階で、拡底用掘削機を拡張させつつロッドを中心軸周りに回転させて孔壁部分の地盤を掘削し、掘削孔の先端部を拡底する。そして、拡底した掘削孔に鉄筋籠を建て込むとともにトレミー管を用いて安定液と置換するようにコンクリートを打設し、必要に応じて杭頭部側を埋め戻したり、杭頭基礎を構築するなどし、場所打ちコンクリート拡底杭の施工が完了する。 When constructing a cast-in-place concrete expansion pile, for example, an excavator is used to excavate and form an excavation hole having a diameter substantially constant from the ground surface while filling a predetermined depth with a stabilizing liquid. Next, at the stage where the bottom-expanding excavator (bottom-expanding machine such as a bottom-expanding bucket) connected to the tip of the rod is inserted and placed at the tip of the excavator, the rod is moved around the central axis while expanding the bottom-expanding excavator. The ground of the hole wall is excavated by rotating it, and the tip of the hole is expanded. Then, a reinforcing bar cage is built in the expanded drilling hole, and concrete is placed so as to replace the stabilizer using a tremie pipe, and if necessary, the pile head side is backfilled or the pile head foundation is constructed. Construction of cast-in-place concrete expansion piles is completed.

特許第２６０７９６６号公報Japanese Patent No. 2607966

ここで、上記のように構築される場所打ちコンクリート拡底杭１は、図６（ａ）に示すように、各種工法ごとにその大きさが異なるが、現状では軸径（軸部２の径）が最大約３ｍ、拡底径（拡底部３の径）が最大４．８ｍ～５．５ｍである。 Here, as shown in FIG. 6A, the cast-in-place concrete expanded pile 1 constructed as described above has a different size depending on various construction methods, but at present, the shaft diameter (diameter of the shaft portion 2). The maximum is about 3 m, and the maximum diameter of the expanded bottom (diameter of the expanded bottom portion 3) is 4.8 m to 5.5 m.

一方、超高層ビルなど非常に大きな柱軸力を受ける杭では、最大拡底径でも支持力が不足する場合があり、支持力の不足を補うために、例えば図６（ｂ）に示すように、拡底部３を複数形成するなどの対策工法が提案、実用化されている。 On the other hand, in a pile that receives a very large column axial force such as a skyscraper, the bearing capacity may be insufficient even at the maximum expansion diameter, and in order to compensate for the insufficient bearing capacity, for example, as shown in FIG. 6 (b). Countermeasure construction methods such as forming a plurality of expanded bottom portions 3 have been proposed and put into practical use.

しかしながら、拡底部３を２つ以上形成する場合には、その分硬質な支持層Ｇ１を掘削して杭長を長くする必要があり、工費、工程に与える影響が非常に大きい。このため、より効率的且つ効果的に支持耐力を向上させることを可能にする手法が強く望まれている。 However, when two or more bottom-expanded portions 3 are formed, it is necessary to excavate a hard support layer G1 to lengthen the pile length, which has a great influence on the construction cost and the process. Therefore, there is a strong demand for a method that makes it possible to improve the bearing capacity more efficiently and effectively.

上記事情に鑑み、本発明は、従来と比較し、より効率的且つ効果的に支持耐力を向上させることが可能な場所打ちコンクリート杭の構築方法を提供することを目的とする。 In view of the above circumstances, it is an object of the present invention to provide a method for constructing a cast-in-place concrete pile capable of improving the bearing capacity more efficiently and effectively as compared with the conventional case.

上記の目的を達するために、この発明は以下の手段を提供している。 In order to achieve the above object, the present invention provides the following means.

本発明の場所打ちコンクリート杭の構築方法は、円柱状の軸部と、該軸部の先端部を拡張してなる略円錐台状の拡底部を備えた場所打ちコンクリート杭を構築する方法であって、杭用の掘削機を用いて地盤の所定の深度まで前記軸部の掘削孔を先行掘削して形成し、前記軸部の掘削孔よりも小径の軸部用の拡底用掘削機を前記軸部の掘削孔の先端部に挿入し、且つ、前記軸部の掘削孔の内部に配設した偏心位置決め保持手段によって前記拡底用削孔機に接続したロッド及び／又は前記拡底用掘削機のガイド部を、前記ロッド及び前記拡底用掘削機の中心軸を前記軸部の中心軸に対して所定量偏心させた状態で前記ロッド及び前記拡底用掘削機の中心軸周りに回転可能に保持させ、先行掘削して形成した前記軸部の掘削孔の先端部の孔壁を前記拡底用掘削機で拡底掘削して前記拡底部の掘削孔を形成し、前記軸部と前記拡底部の掘削孔にコンクリートを打設することを特徴とする。 The method for constructing a cast-in-place concrete pile of the present invention is a method for constructing a cast-in-place concrete pile having a columnar shaft portion and a substantially conical stand-shaped bottom expansion portion formed by expanding the tip portion of the shaft portion. Then, the excavator for the shaft portion is formed by pre-excavating the excavation hole of the shaft portion to a predetermined depth of the ground using the excavator for the pile, and the bottom expansion excavator for the shaft portion having a diameter smaller than the excavation hole of the shaft portion is described above. The rod and / or the bottom-expanding excavator inserted into the tip of the excavation hole of the shaft and connected to the bottom-expanding drilling machine by the eccentric positioning and holding means disposed inside the excavation hole of the shaft. The guide portion is rotatably held around the central axis of the rod and the bottom expansion excavator in a state where the central axis of the rod and the bottom expansion excavator is eccentric with respect to the central axis of the shaft portion by a predetermined amount. The hole wall at the tip of the excavation hole of the shaft portion formed by prior excavation is expanded and excavated by the bottom expansion excavator to form the excavation hole of the bottom expansion portion, and the excavation hole of the shaft portion and the bottom expansion portion is formed. It is characterized by pouring concrete into.

本発明の場所打ちコンクリート杭の構築方法においては、前記拡底用掘削機の先端部に、前記拡底用掘削機の中心軸と同軸で掘削刃よりも下方に突出する位置決め凸部であるスタビライザーを設け、前記スタビライザーを掘削孔の底面の地盤に突き刺すようにして拡底掘削することが望ましい。 In the method for constructing a cast-in-place concrete pile of the present invention, a stabilizer, which is a positioning convex portion that is coaxial with the central axis of the bottom-expanding excavator and protrudes downward from the excavator, is provided at the tip of the bottom-expanding excavator. It is desirable to perform bottom-expanded excavation by piercing the stabilizer at the bottom of the excavation hole.

本発明の場所打ちコンクリート杭の構築方法においては、超高層ビルなど非常に大きな柱軸力を好適に支持できる高支持耐力の場所打ちコンクリート拡底杭を、効率的且つ効果的に構築することが可能になる。 In the method for constructing a cast-in-place concrete pile of the present invention, it is possible to efficiently and effectively construct a cast-in-place concrete expanded pile with a high bearing capacity that can suitably support a very large column axial force such as a skyscraper. become.

本発明の一実施形態に係る場所打ちコンクリート杭の構築方法を示す図である。It is a figure which shows the construction method of the cast-in-place concrete pile which concerns on one Embodiment of this invention. 従来の拡底掘削機を用いて拡底部を形成した場合を示す図である。It is a figure which shows the case where the bottom-expanded portion is formed by using the conventional bottom-expanding excavator. 本発明の一実施形態に係る場所打ちコンクリート杭を示す図であり、３箇所の偏心位置で拡底掘削を行った場合の場所打ちコンクリート杭を示す図である。It is a figure which shows the cast-in-place concrete pile which concerns on one Embodiment of this invention, and is the figure which shows the cast-in-place concrete pile when the bottom expansion excavation is performed at three eccentric positions. 本発明の一実施形態に係る場所打ちコンクリート杭を示す図であり、４箇所の偏心位置で拡底掘削を行った場合の場所打ちコンクリート杭を示す図である。It is a figure which shows the cast-in-place concrete pile which concerns on one Embodiment of this invention, and is the figure which shows the cast-in-place concrete pile when the bottom expansion excavation is performed at four eccentric positions. 本発明の一実施形態に係る場所打ちコンクリート杭の構築方法の変更例を示す図である。It is a figure which shows the modification of the construction method of the cast-in-place concrete pile which concerns on one Embodiment of this invention. 従来の場所打ちコンクリート杭（拡底杭）を示す図である。It is a figure which shows the conventional cast-in-place concrete pile (expanded pile).

以下、図１から図５を参照し、本発明の一実施形態に係る場所打ちコンクリート杭の構築方法について説明する。 Hereinafter, a method of constructing a cast-in-place concrete pile according to an embodiment of the present invention will be described with reference to FIGS. 1 to 5.

本実施形態の場所打ちコンクリート杭の構築方法では、従来と同様、アースドリルなどの掘削機を用いて地表面から所定の深度まで安定液を充填しつつ掘削し、場所打ちコンクリート杭１’の略一定の径の円柱状の軸部２の掘削孔１０を形成する（図１参照）。次に、ロッド４の下端に接続した拡底用掘削機（拡底バケットなどの拡底機）５を軸部２の掘削孔１０に挿入して先端部に配置し、拡底用掘削機５を拡張しつつ中心軸Ｏ１周りに回転させて先端部の掘削孔１０の孔壁部分を拡底掘削し、先端部に略円錐台状の拡底部３の掘削孔１１を形成する。そして、掘削孔１０、１１にトレミー管を用いて安定液と置換するようにコンクリートを打設し場所打ちコンクリート杭１’を構築する。なお、掘削孔１０、１１内に鉄筋篭を挿入したり、必要に応じて杭頭部側を埋め戻したり、杭頭基礎を構築するなどし、場所打ちコンクリート拡底杭の施工が完了する。 In the method of constructing a cast-in-place concrete pile of the present embodiment, as in the conventional case, excavation is performed while filling a stabilizing liquid from the ground surface to a predetermined depth using an excavator such as an earth drill, which is an abbreviation for cast-in-place concrete pile 1'. An excavation hole 10 of a cylindrical shaft portion 2 having a constant diameter is formed (see FIG. 1). Next, the bottom-expanding excavator (bottom-expanding machine such as a bottom-expanding bucket) 5 connected to the lower end of the rod 4 is inserted into the excavation hole 10 of the shaft portion 2 and placed at the tip portion, while expanding the bottom-expanding excavator 5. The hole wall portion of the excavation hole 10 at the tip portion is excavated by expanding the bottom by rotating it around the central axis O1, and the excavation hole 11 of the bottom expansion portion 3 having a substantially truncated cone shape is formed at the tip portion. Then, concrete is poured into the excavation holes 10 and 11 so as to replace the stabilizing liquid by using a tremie pipe, and a cast-in-place concrete pile 1'is constructed. The construction of the cast-in-place concrete expanded pile is completed by inserting a reinforcing bar cage into the excavation holes 10 and 11, backfilling the pile head side as necessary, and constructing a pile head foundation.

ここで、従来周知の通り、拡底用掘削機５は、図２に示すように、例えばφ２．１～３．０ｍなど、ある範囲の径の軸部２に対応して拡底部３（軸部２の掘削孔１０に対応して拡底部３の掘削孔１１）を形成できるようになっている。 Here, as is well known in the past, as shown in FIG. 2, the bottom-expanding excavator 5 has a bottom-expanding portion 3 (shaft portion) corresponding to a shaft portion 2 having a diameter in a certain range, for example, φ2.1 to 3.0 m. The excavation hole 11) of the bottom expansion portion 3 can be formed corresponding to the excavation hole 10 of 2.

本実施形態の場所打ちコンクリート杭の構築方法では、この拡底用掘削機５がある範囲の径の軸部２に対応して拡底部３を形成できることを利用する。 In the method of constructing the cast-in-place concrete pile of the present embodiment, it is utilized that the bottom-expanding excavator 5 can form the bottom-expanding portion 3 corresponding to the shaft portion 2 having a diameter in a certain range.

具体的に、本実施形態の場所打ちコンクリート杭の構築方法では、図１に示すように、掘削機（軸部大径用拡底機）５によって例えば３．０ｍなどの大きな軸径で軸部２の掘削孔１０を先行掘削し、次に、例えば、最大拡底径が２．１ｍなどの拡底用掘削機（軸部小径用拡底機）５を用い、軸部２の中心軸Ｏ１に対して拡底用掘削機５（ロッド４）の中心軸Ｏ２を偏心させて、先行掘削して形成した軸部２の掘削孔１０の先端部の孔壁を拡底掘削する。また、複数箇所の偏心位置に拡底用掘削機５を配置して拡底掘削を行い、拡底部３の掘削孔１１を形成する。 Specifically, in the method of constructing a cast-in-place concrete pile of the present embodiment, as shown in FIG. 1, the shaft portion 2 has a large shaft diameter such as 3.0 m by the excavator (bottom expansion machine for large diameter shaft portion) 5. The excavation hole 10 of the above is excavated in advance, and then, for example, a bottom expansion excavator (bottom expansion machine for small shaft diameter) 5 having a maximum bottom expansion diameter of 2.1 m is used to expand the bottom with respect to the central axis O1 of the shaft portion 2. The central axis O2 of the excavator 5 (rod 4) is eccentric, and the hole wall at the tip of the excavation hole 10 of the shaft portion 2 formed by the preceding excavation is expanded and excavated. Further, the bottom-expanding excavator 5 is arranged at a plurality of eccentric positions to perform bottom-expanding excavation, and the excavation hole 11 of the bottom-expanding portion 3 is formed.

また、本実施形態の場所打ちコンクリート杭の構築方法では、このとき、偏心位置決め保持手段の偏心拡底掘削用ガイド８を使用する。 Further, in the method of constructing the cast-in-place concrete pile of the present embodiment, at this time, the eccentric expansion bottom excavation guide 8 of the eccentric positioning and holding means is used.

図１に示すように、偏心拡底掘削用ガイド８は、鋼製であり、軸部２の掘削孔１０の径よりもわずかに小さな直径を有し、側面が軸部２の掘削孔１０の孔壁面に当接あるいは近接して沿うように円環状に形成された外環保持部８ａと、外環保持部８ａの中心軸Ｏ３に対して所定の量ずれた偏心位置に上下方向に貫通形成され、拡底用掘削機５に接続されたロッド４を挿通するとともにロッド４及び拡底用掘削機５を中心軸Ｏ２周りに回転可能に保持するロッド保持部８ｂとを備えて形成されている。 As shown in FIG. 1, the eccentric expansion excavation guide 8 is made of steel, has a diameter slightly smaller than the diameter of the excavation hole 10 of the shaft portion 2, and has a side surface of the excavation hole 10 of the shaft portion 2. The outer ring holding portion 8a formed in an annular shape so as to abut on or close to the wall surface and the outer ring holding portion 8a are formed to penetrate in the vertical direction at an eccentric position deviated by a predetermined amount from the central axis O3. The rod 4 connected to the bottom expansion excavator 5 is inserted, and the rod 4 and the bottom expansion excavator 5 are provided with a rod holding portion 8b for rotatably holding the rod 4 and the bottom expansion excavator 5 around the central axis O2.

そして、軸部２の掘削孔１０を形成した段階で、ロッド保持部８ｂにロッド４を挿通し、ロッド４に接続した拡底用掘削機５を軸部２の掘削孔１０の先端部に配置するとともに、偏心拡底掘削用ガイド８を軸部２の掘削孔１０の所定位置に挿入配置する。 Then, at the stage where the excavation hole 10 of the shaft portion 2 is formed, the rod 4 is inserted into the rod holding portion 8b, and the bottom expansion excavator 5 connected to the rod 4 is arranged at the tip of the excavation hole 10 of the shaft portion 2. At the same time, the eccentric expansion excavation guide 8 is inserted and arranged at a predetermined position of the excavation hole 10 of the shaft portion 2.

この状態で、拡底用掘削機５を拡張しつつ中心軸Ｏ２周りに回転させて先端部の掘削孔１０の孔壁を拡底掘削すると、拡底用掘削機５が偏心拡底掘削用ガイド８によってその偏心位置で保持され、好適に拡底掘削を行うことができる。 In this state, when the bottom-expanding excavator 5 is expanded and rotated around the central axis O2 to expand the hole wall of the excavation hole 10 at the tip, the bottom-expanding excavator 5 is eccentric by the eccentric bottom-expanding excavation guide 8. It is held in position and can be suitably used for bottom expansion excavation.

また、図１（ａ）に示すように一箇所の偏心位置で拡底掘削を行った後、図１（ｂ）に示すように偏心拡底掘削用ガイド８を軸部２の中心軸Ｏ１周りに所定量回動させて設置し、他の偏心位置で拡底用掘削機５を保持して拡底掘削を行う。 Further, after the bottom expansion excavation is performed at one eccentric position as shown in FIG. 1 (a), the eccentric bottom expansion excavation guide 8 is placed around the central axis O1 of the shaft portion 2 as shown in FIG. 1 (b). It is installed by rotating it a fixed amount, and the bottom-expanding excavator 5 is held at another eccentric position to perform bottom-expanding excavation.

これにより、本実施形態の場所打ちコンクリート杭の構築方法によれば、図３や図４に示すように、拡底用掘削機５の最大拡底径を超えた場所打ちコンクリート杭（拡底杭）１’、すなわち、高支持耐力の場所打ちコンクリート杭１’を構築することが可能になる。例えば、軸部大径用拡底機５を用いて従来通りに拡底部３を形成した場合の杭底面積に対し、本実施形態の場所打ちコンクリート杭の構築方法においては１．３倍以上の杭底面積の拡底部３を形成、構築することが可能である。 As a result, according to the method for constructing the cast-in-place concrete pile of the present embodiment, as shown in FIGS. 3 and 4, the cast-in-place concrete pile (expanded pile) 1'exceeds the maximum bottom expansion diameter of the bottom expansion excavator 5. That is, it becomes possible to construct a cast-in-place concrete pile 1'with a high bearing capacity. For example, in the method of constructing a cast-in-place concrete pile of the present embodiment, the pile is 1.3 times or more the pile bottom area when the bottom expansion portion 3 is formed as before by using the bottom expansion machine 5 for a large diameter shaft portion. It is possible to form and construct an expanded bottom portion 3 having a bottom area.

ここで、図３は３箇所か所の偏心位置で拡底掘削を行った場合の場所打ちコンクリート杭１’、図４は４箇所の偏心位置で拡底掘削を行った場合の場所打ちコンクリート杭１’の形状をそれぞれ示している。 Here, FIG. 3 shows cast-in-place concrete piles 1'when bottom-expanded excavation is performed at three eccentric positions, and FIG. 4 shows cast-in-place concrete piles 1'when bottom-expanded excavation is performed at four eccentric positions. The shape of each is shown.

図３、図４に示すように、上記のように構築した本実施形態の場所打ちコンクリート杭１’は、その拡底部（杭底面１ａ）が平断面視で軸部２の中心軸Ｏ１を中心とした円形外面から径方向外側に突出する凸円弧部（凸円弧面）６を備えた形で構築される。これにより、拡底部３が円弧凹凸状の外面によって従来の円錐台形状の拡底部３よりも鉛直部分の面の摩擦耐力を向上させることができ、この点からも、高支持耐力の拡底杭を実現することが可能になる。 As shown in FIGS. 3 and 4, in the cast-in-place concrete pile 1'of the present embodiment constructed as described above, the expanded bottom portion (pile bottom surface 1a) is centered on the central axis O1 of the shaft portion 2 in a plan sectional view. It is constructed in a form provided with a convex arc portion (convex arc surface) 6 protruding outward in the radial direction from the circular outer surface. As a result, the bottom-expanded portion 3 can improve the frictional strength of the vertical portion surface as compared with the conventional truncated cone-shaped bottom-expanded portion 3 due to the arc-shaped uneven outer surface. It will be possible to realize.

一方、従来、アースドリルなどの掘削機によって形成した杭の底面は、中心軸Ｏ１から径方向外側に向かうに従い漸次上方に傾斜するすり鉢状になる。このため、例えば、支持層Ｇ１が砂礫などの場合には、拡底用掘削機（軸部小径用拡底機）５の中心軸Ｏ２を偏心させた状態で後行掘削する際に杭の底面に当接する掘削機５の底部が安定せず、底面地盤が崩壊したり、拡底用掘削機５が軸部２の中心軸Ｏ１側に滑って芯ずれが生じ、小口径の拡底用掘削機５で拡底部３の掘削孔１１を拡張形成できなくなることも考えられる。 On the other hand, conventionally, the bottom surface of a pile formed by an excavator such as an earth drill becomes a mortar shape that gradually inclines upward from the central axis O1 toward the outside in the radial direction. Therefore, for example, when the support layer G1 is gravel or the like, it hits the bottom surface of the pile when excavating in a state where the central axis O2 of the bottom-expanding excavator (bottom-diameter excavator for small shaft portion) 5 is eccentric. The bottom of the excavator 5 in contact with the excavator 5 is not stable, the bottom ground collapses, or the excavator 5 for expanding the bottom slips toward the central axis O1 of the shaft portion 2 and causes misalignment. It is also conceivable that the excavation hole 11 of the portion 3 cannot be expanded and formed.

これに対し、本実施形態では、図１に示すように、拡底用掘削機５の底部に、中心軸Ｏ１と同軸で底面から下方に突出し、掘削孔１０の底面に突き当たって突き刺さるなどし拡底用掘削機５を安定させるための位置決め凸部であるスタビライザー７を設ける。また、スタビライザー７は、拡底用掘削機５の底部の掘削刃よりも下方に突出するように形成されている。なお、本実施形態のスタビライザー７はその突出方向先端部がテーパー状、尖った形で形成されている。また、ドリルやオーガー状にして下方地盤に突き刺さりやすくしても良い。 On the other hand, in the present embodiment, as shown in FIG. 1, the bottom of the bottom-expanding excavator 5 projects downward from the bottom surface coaxially with the central axis O1 and abuts against the bottom surface of the excavation hole 10 for bottom-expanding. A stabilizer 7 which is a positioning convex portion for stabilizing the excavator 5 is provided. Further, the stabilizer 7 is formed so as to project downward from the excavator blade at the bottom of the bottom expansion excavator 5. The stabilizer 7 of the present embodiment is formed with a tapered or pointed tip portion in the protruding direction. In addition, it may be shaped like a drill or an auger so that it can be easily pierced into the lower ground.

これにより、先行掘削した掘削孔１０の底面がすり鉢状に形成されていたり、砂礫などの崩れやすい地盤Ｇであっても、後行掘削によって拡底部３の掘削を行う際に、軸部２の掘削孔１０の中心軸Ｏ１から偏心した位置の底面にスタビライザー７が突き刺さるなどして拡底用掘削機５が安定し、この状態で拡底用掘削機５が中心軸Ｏ２周りに回転して掘削孔１０の孔壁を拡底掘削することができる。すなわち、偏心位置に配置した拡底用掘削機５が芯ずれすることなく拡底掘削を行うことができ、確実で好適に拡底用掘削機５の最大拡底径を超えた場所打ちコンクリート杭（拡底杭）１’を構築することが可能になる。 As a result, even if the bottom surface of the excavation hole 10 excavated in advance is formed in a mortar shape or the ground G is liable to collapse such as gravel, when excavating the bottom expansion portion 3 by subsequent excavation, the shaft portion 2 The bottom-expanding excavator 5 is stabilized by the stabilizer 7 sticking into the bottom surface at a position eccentric from the central axis O1 of the excavation hole 10, and in this state, the bottom-expanding excavator 5 rotates around the central axis O2 to excavate the hole 10. It is possible to excavate the bottom of the hole wall. That is, the bottom-expanding excavator 5 arranged at the eccentric position can perform the bottom-expanding excavation without misalignment, and the cast-in-place concrete pile (bottom-expanding pile) that exceeds the maximum bottom-expanding diameter of the bottom-expanding excavator 5 reliably and suitably. It becomes possible to build 1'.

ここで、本実施形態では、偏心位置決め保持手段の偏心拡底掘削用ガイド８が掘削ロッド４を偏心位置で回転可能に保持するものとして説明を行ったが、偏心位置決め保持手段の偏心拡底掘削用ガイド９が拡底用掘削機５を偏心位置で回転可能に保持するように構成されていてもよい。 Here, in the present embodiment, the eccentric bottom-expanding excavation guide 8 of the eccentric positioning holding means has been described as holding the excavation rod 4 rotatably at the eccentric position. 9 may be configured to rotatably hold the bottom expansion excavator 5 at an eccentric position.

例えば、図５に示すように、偏心拡底掘削用ガイド９を構成してもよい。
この偏心拡底掘削用ガイド９は、鋼管（外環保持部）や、鋼管（外環保持部）９ａと鉄筋９ｂを用いるなどして軸部２の掘削孔１０に挿入可能で且つ掘削孔１０内で保持可能な略円筒状、略円筒籠状に形成されている。そして、掘削孔１０の地表開口部から軸部２の掘削孔１０の所定深度まで挿入した状態で保持されるとともに、拡底用掘削機５のガイド部５ａを挿通して鉛直方向に進退自在に且つ横方向に略変位不能に保持するガイド保持部９ｃが鋼管９ａによって中心軸Ｏ１に対して所定量偏心した偏心位置に設けられている。なお、重量に支障がなければ鋼管（外部保持部）９ａで偏心拡底掘削用ガイド９を構成してもよい。 For example, as shown in FIG. 5, a guide 9 for eccentric bottom expansion excavation may be configured.
This eccentric bottom expansion excavation guide 9 can be inserted into the excavation hole 10 of the shaft portion 2 by using a steel pipe (outer ring holding portion), a steel pipe (outer ring holding portion) 9a and a reinforcing bar 9b, and is inside the excavation hole 10. It is formed in a substantially cylindrical shape and a substantially cylindrical cage shape that can be held by. Then, it is held in a state of being inserted from the ground surface opening of the excavation hole 10 to a predetermined depth of the excavation hole 10 of the shaft portion 2, and is freely advanced and retracted in the vertical direction by inserting the guide portion 5a of the bottom expansion excavator 5. A guide holding portion 9c for holding the guide holding portion 9c so as to be substantially non-displaceable in the lateral direction is provided at an eccentric position eccentric with respect to the central axis O1 by a steel pipe 9a. If the weight is not hindered, the steel pipe (external holding portion) 9a may be used to form the eccentric bottom expansion excavation guide 9.

この場合には、杭用の掘削機で軸部２の掘削孔１０を先行掘削した後に、軸部２の掘削孔１０に偏心拡底掘削用ガイド９を挿入設置し、偏心拡底掘削用ガイド９のガイド保持部９ｃを通して拡底用掘削機５を軸部２の掘削孔１０の先端部に配置する。このように配置することにより、偏心拡底掘削用ガイド９のガイド保持部９ｃに拡底用掘削機５のガイド部５ａが保持されるようにする。 In this case, after excavating the excavation hole 10 of the shaft portion 2 in advance with the excavator for piles, the eccentric bottom expansion excavation guide 9 is inserted and installed in the excavation hole 10 of the shaft portion 2, and the eccentric bottom expansion excavation guide 9 is used. The bottom expansion excavator 5 is arranged at the tip of the excavation hole 10 of the shaft portion 2 through the guide holding portion 9c. By arranging in this way, the guide portion 5a of the bottom expansion excavator 5 is held by the guide holding portion 9c of the eccentric bottom expansion excavation guide 9.

この状態で、拡底用掘削機５を拡張しつつ中心軸Ｏ２周りに回転させて先端部の掘削孔１０の孔壁を掘削すると、拡底用掘削機５が偏心拡底掘削用ガイド９によってその偏心位置で保持され、好適に拡底掘削を行うことができる。 In this state, when the bottom expansion excavator 5 is expanded and rotated around the central axis O2 to excavate the hole wall of the excavation hole 10 at the tip portion, the bottom expansion excavator 5 is eccentric by the eccentric bottom expansion excavation guide 9. It can be held at the bottom and can be suitably used for bottom expansion excavation.

また、一箇所の偏心位置で拡底掘削を行った後、偏心拡底掘削用ガイド９を軸部２の中心軸Ｏ１周りに所定量回動させれば、他の偏心位置で拡底用掘削機５を確実に保持して拡底掘削を行うことができる。 Further, if the bottom expansion excavation is performed at one eccentric position and then the eccentric bottom expansion excavation guide 9 is rotated by a predetermined amount around the central axis O1 of the shaft portion 2, the bottom expansion excavator 5 can be operated at another eccentric position. It can be held securely for bottom expansion excavation.

これにより、順次複数箇所の偏心位置にガイド保持部９ｃを位置合わせしながら拡底掘削を行うことによって、所定形状の大きな拡底部３を備えた場所打ちコンクリート杭１’を形成することが可能になる。 As a result, it becomes possible to form a cast-in-place concrete pile 1'with a large bottom-expanded portion 3 having a predetermined shape by performing bottom-expanded excavation while sequentially aligning guide holding portions 9c at a plurality of eccentric positions. ..

よって、拡底用掘削機５を偏心位置で保持する偏心拡底掘削用ガイド９を用いる場合であっても、上記のロッド４を保持する偏心拡底掘削用ガイド８と同様に、機械の最大拡底径よりも大きく、高支持耐力の拡底杭１’を構築、実現することが可能になる。 Therefore, even when the eccentric bottom expansion excavation guide 9 that holds the bottom expansion excavator 5 at the eccentric position is used, the maximum bottom diameter of the machine is increased as in the case of the eccentric bottom expansion excavation guide 8 that holds the rod 4. It is possible to construct and realize a bottom expansion pile 1'with a high bearing capacity.

以上、本発明に係る場所打ちコンクリート杭の構築方法の一実施形態について説明したが、本発明は上記の一実施形態に限定されるものではなく、その趣旨を逸脱しない範囲で適宜変更可能である。 Although one embodiment of the method for constructing a cast-in-place concrete pile according to the present invention has been described above, the present invention is not limited to the above-mentioned one embodiment and can be appropriately changed without departing from the spirit of the present invention. ..

例えば、予め、杭底部直下の地盤全体やスタビライザーが突き当たる部分の地盤（偏心位置の杭底部直下の地盤）を、深層地盤改良工法などを用いて地盤改良しておいてもよい。この場合には、後行掘削によって拡底部の掘削を行う際に、さらに拡底用掘削機を安定した状態にして掘削孔の孔壁を拡底掘削することができ、より確実で好適に拡底用掘削機の最大拡底径を超えた拡底杭を構築することが可能になる。なお、この地盤改良部は、例えば、杭支持力の３倍以上の一軸圧縮強度となるように形成する。 For example, the entire ground directly below the pile bottom or the ground where the stabilizer abuts (the ground directly below the pile bottom at the eccentric position) may be improved in advance by using a deep ground improvement method or the like. In this case, when excavating the bottom-expanding portion by subsequent excavation, the bottom-expanding excavator can be further stabilized and the hole wall of the excavation hole can be expanded and excavated. It will be possible to construct an expansion pile that exceeds the maximum expansion diameter of the machine. The ground improvement portion is formed so as to have a uniaxial compressive strength of, for example, three times or more the pile bearing capacity.

１ 従来の場所打ちコンクリート杭（拡底杭）
１’ 場所打ちコンクリート杭（拡底杭）
２ 軸部
３ 拡底部
４ ロッド
５ 拡底用掘削機
６ 凸円弧部
７ スタビライザー（位置決め凸部）
８ 偏心拡底掘削用ガイド
８ａ 外環保持部
８ｂ ロッド保持部
９ 偏心拡底掘削用ガイド
９ａ 鋼管（外環保持部）
９ｂ 鉄筋
９ｃ ガイド保持部
１０ 軸部の掘削孔
１１ 拡底部の掘削孔
Ｇ 地盤
Ｇ１ 支持層 1 Conventional cast-in-place concrete pile (expanded pile)
1'cast-in-place concrete pile (expanded pile)
2 Shaft part 3 Bottom expansion part 4 Rod 5 Bottom expansion excavator 6 Convex arc part 7 Stabilizer (positioning convex part)
8 Eccentric bottom expansion excavation guide 8a Outer ring holding part 8b Rod holding part 9 Eccentric bottom expansion excavation guide 9a Steel pipe (outer ring holding part)
9b Reinforcing bar 9c Guide holding part 10 Excavation hole in the shaft part 11 Excavation hole in the bottom expansion part G Ground G1 Support layer

Claims (2)

円柱状の軸部と、該軸部の先端部を拡張してなる略円錐台状の拡底部を備えた場所打ちコンクリート杭を構築する方法であって、
杭用の掘削機を用いて地盤の所定の深度まで前記軸部の掘削孔を先行掘削して形成し、
前記軸部の掘削孔よりも小径の軸部用の拡底用掘削機を前記軸部の掘削孔の先端部に挿入し、且つ、前記軸部の掘削孔の内部に配設した偏心位置決め保持手段によって前記拡底用削孔機に接続したロッド及び／又は前記拡底用掘削機のガイド部を、前記ロッド及び前記拡底用掘削機の中心軸を前記軸部の中心軸に対して所定量偏心させた状態で前記ロッド及び前記拡底用掘削機の中心軸周りに回転可能に保持させ、
先行掘削して形成した前記軸部の掘削孔の先端部の孔壁を前記拡底用掘削機で拡底掘削して前記拡底部の掘削孔を形成し、
前記軸部と前記拡底部の掘削孔にコンクリートを打設することを特徴とする場所打ちコンクリート杭の構築方法。 It is a method of constructing a cast-in-place concrete pile having a columnar shaft portion and a substantially truncated cone-shaped bottom expansion portion formed by expanding the tip portion of the shaft portion.
Using an excavator for piles, excavation holes in the shaft portion are drilled in advance to a predetermined depth in the ground to form the excavator.
An eccentric positioning holding means for inserting a bottom-expanding excavator for a shaft portion having a diameter smaller than that of the excavation hole of the shaft portion into the tip portion of the excavation hole of the shaft portion and disposing it inside the excavation hole of the shaft portion. The rod connected to the bottom-expanding drilling machine and / or the guide portion of the bottom-expanding excavator was decentered by a predetermined amount with respect to the central axis of the rod and the bottom-expanding excavator. In this state, it is rotatably held around the central axis of the rod and the bottom-expanding excavator.
The hole wall at the tip of the excavation hole of the shaft portion formed by prior excavation is expanded and excavated by the bottom expansion excavator to form the excavation hole of the bottom expansion portion.
A method for constructing a cast-in-place concrete pile, which comprises placing concrete in the excavation holes of the shaft portion and the bottom expansion portion. 請求項１記載の場所打ちコンクリート杭の構築方法において、
前記拡底用掘削機の先端部に、前記拡底用掘削機の中心軸と同軸で掘削刃よりも下方に突出する位置決め凸部であるスタビライザーを設け、
前記スタビライザーを掘削孔の底面の地盤に突き刺すようにして拡底掘削することを特徴とする場所打ちコンクリート杭の構築方法。 In the method for constructing cast-in-place concrete piles according to claim 1,
A stabilizer, which is a positioning convex portion that is coaxial with the central axis of the bottom-expanding excavator and protrudes below the excavator blade, is provided at the tip of the bottom-expanding excavator.
A method for constructing a cast-in-place concrete pile, characterized in that the stabilizer is pierced into the ground at the bottom of the excavation hole for expansion excavation.
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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004211492A (en) 2003-01-08 2004-07-29 Mitsubishi Materials Corp Excavating tool
JP2006307593A (en) 2005-05-02 2006-11-09 Taisei Corp Grout pipe and grouting in cast-in-place concrete pile
JP4228797B2 (en) 2003-06-25 2009-02-25 株式会社デンソー Exhaust gas purification system for internal combustion engine
JP2010255212A (en) 2009-04-22 2010-11-11 System Keisoku Kk Bell bucket, casing, and method for constructing bell pipe
JP2014141844A (en) 2013-01-25 2014-08-07 System Keisoku Kk Bottom enlarged bucket
JP2017218810A (en) 2016-06-08 2017-12-14 株式会社大林組 Construction method for cast-in-place concrete pile

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63156288U (en) * 1987-03-30 1988-10-13
JPH04228797A (en) * 1991-05-28 1992-08-18 Hitachi Constr Mach Co Ltd Method for executing widened bottom pile by earth drill process
JP3246371B2 (en) * 1996-12-26 2002-01-15 三菱マテリアル株式会社 Drilling tools

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004211492A (en) 2003-01-08 2004-07-29 Mitsubishi Materials Corp Excavating tool
JP4228797B2 (en) 2003-06-25 2009-02-25 株式会社デンソー Exhaust gas purification system for internal combustion engine
JP2006307593A (en) 2005-05-02 2006-11-09 Taisei Corp Grout pipe and grouting in cast-in-place concrete pile
JP2010255212A (en) 2009-04-22 2010-11-11 System Keisoku Kk Bell bucket, casing, and method for constructing bell pipe
JP2014141844A (en) 2013-01-25 2014-08-07 System Keisoku Kk Bottom enlarged bucket
JP2017218810A (en) 2016-06-08 2017-12-14 株式会社大林組 Construction method for cast-in-place concrete pile

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