JP5700639B2 - Pile hole construction method - Google Patents

Pile hole construction method Download PDF

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JP5700639B2
JP5700639B2 JP2010290253A JP2010290253A JP5700639B2 JP 5700639 B2 JP5700639 B2 JP 5700639B2 JP 2010290253 A JP2010290253 A JP 2010290253A JP 2010290253 A JP2010290253 A JP 2010290253A JP 5700639 B2 JP5700639 B2 JP 5700639B2
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root
pile hole
cement milk
pile
injection
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JP2012136875A (en
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木谷　好伸
好伸 木谷
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Mitani Sekisan Co Ltd
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Description

この発明は、杭穴を掘削して、杭穴内に既製杭などの構造物を埋設して、基礎杭構造を構成するための、杭穴の構築方法に関する。   The present invention relates to a method for constructing a pile hole for excavating a pile hole and burying a structure such as a ready-made pile in the pile hole to constitute a foundation pile structure.

従来、杭穴を掘削して、杭穴内にセメントミルクを注入して、杭穴内の泥土と置換して、あるいは泥土とセメントミルクとを撹混合して、その後、杭穴内に既製杭を埋設していた。そして、杭穴底部に既製杭の下端部を位置させていた。
この場合、節付き既製杭で、
既製杭：軸部径６０ｃｍ、節径７５ｃｍ
杭穴：根固め部径１１０ｃｍ 高さ２５０ｃｍ
体積２．３８ｍ３
程度となっていた。また、昨今の１本の既製杭に要求される支持力の増加に伴い、大径化が進んでおり、
既製杭：軸部径１１０ｃｍ、節径１３０ｃｍ
杭穴：根固め部径２６０ｃｍ 高さ４６５ｃｍ
体積２４．６８ｍ３
の場合も施工されている。この場合、これだけ大きな根固め部を築造する際には、セメントミルクを杭穴の周辺部まで充分に行き届かせる必要があった。従来の施工管理では、主にセメントミルクの総注入量が問題とされ、具体的な注入方法については重視されてこなかった。 Conventionally, drilling a pile hole, injecting cement milk into the pile hole, replacing it with mud in the pile hole, or mixing the mud and cement milk, and then burying the ready-made pile in the pile hole It was. And the lower end part of the ready-made pile was located in the pile hole bottom part.
In this case, it is a ready-made pile with a knot,
Ready-made pile: shaft diameter 60cm, node diameter 75cm
Pile hole: Root consolidation part diameter 110cm Height 250cm
Volume 2.38m 3
It was about. In addition, with the increase in bearing capacity required for a single ready-made pile, the diameter has been increasing,
Ready-made pile: Shaft diameter 110cm, node diameter 130cm
Pile hole: Root consolidation part diameter 260cm Height 465cm
Volume 24.68m 3
In the case of, it is constructed. In this case, when constructing such a large solidified part, it was necessary to make the cement milk sufficiently reach the periphery of the pile hole. In conventional construction management, the total injection amount of cement milk is mainly a problem, and a specific injection method has not been emphasized.

例えば、従来は、杭穴内に注入するセメントミルクは、最大で２２．６ｍ３／ｈ 程度が主流であった。これは、地上のセメントミルク製造プラントから、杭穴内への送り出し量から規定されていた。大容量の根固め部を効率よく構築するためには、大量のセメントミルクをできるだけ注入圧を高めて噴射することが必要であった。 For example, conventionally, cement milk injected into a pile hole has been mainly 22.6 m 3 / h at the maximum. This was defined by the amount of feed from the above-ground cement milk production plant into the pile hole. In order to efficiently construct a large-capacity root consolidation part, it was necessary to inject a large amount of cement milk at as high an injection pressure as possible.

なお、従来は、セメントミルクの吐出速度（圧力）着目して工夫をすることはなく、例えば、縦方向、横方向に２つの吐出口を設けて総吐出量を調節する工夫をする技術はあった（特許文献１）。   Conventionally, there is no effort to pay attention to the discharge speed (pressure) of cement milk. For example, there is a technique for adjusting the total discharge amount by providing two discharge ports in the vertical and horizontal directions. (Patent Document 1).

特開２００６−２３３７４９公報JP 2006-233749 A

しかし、大量のセメントミルクを、注入圧を高めて大量に注入する場合には、杭穴底に高圧のセメントミルクが当たった場合には、杭穴底面が乱れ、あるいは杭穴壁が崩れ、土砂が杭穴底に貯まり、杭穴根固め部の精度を損ね、支持力にも影響を与える問題点があった。また、杭穴底部の掘削泥土をセメントミルクで置換する場合には、できるだけ杭穴底（根固め部の底）付近に吐出口を位置させる必要があったので、杭穴底面が乱されるおそれが高かった。   However, when a large amount of cement milk is injected at a high injection pressure, when the high-pressure cement milk hits the bottom of the pile hole, the bottom of the pile hole is disturbed or the wall of the pile hole collapses, Accumulated at the bottom of the pile hole, impairing the accuracy of the pile hole consolidation part and affecting the bearing capacity. Also, when excavating mud at the bottom of the pile hole is replaced with cement milk, the bottom of the pile hole may be disturbed because it is necessary to position the discharge port as close as possible to the bottom of the pile hole (the bottom of the rooting portion) Was expensive.

そこでこの発明では、杭穴底部の下部ではセメントミルクの噴射圧（噴射速度）を低くして、それ以外の位置では、セメントミルクの噴射圧を（噴射速度）を高めて施工効率を高めることで、前記問題点を解決した。   Therefore, in the present invention, by lowering the cement milk injection pressure (injection speed) at the bottom of the pile hole bottom, in other positions, the cement milk injection pressure (injection speed) is increased to increase construction efficiency. The above problems were solved.

即ちこの発明は、軸部とその下端に根固め部とを有する杭穴を掘削して、前記根固め部内で噴射装置を昇降させながら、セメントミルクを注入して、その前後に、杭穴内に既製杭を初めとした杭穴構造物を埋設して基礎杭を構築する工法において、以下のように構成することを特徴とする杭穴の構築方法である。
(1) 前記根固め部内で、前記根固め部の底から距離Ｈまでを根固め部下部とし、距離Ｈから上方を根固め部上部とする。
(2) 前記杭穴内に、前記噴射装置を挿入して、前記根固め部の底に前記噴射装置の噴射口を位置させて、該噴射口からセメントミルク注入し、第１セメントミルク注入とする。
(3) 続いて、前記根固め部上部に前記噴射装置のセメントミルクの吐出口を位置させて、該吐出口からセメントミルク注入し、第２セメントミルク注入とする。
(4) 前記第１セメントミルク注入を、第２セメントミルク注入に比して、低速度又は低圧力による注入とする。
(5) 続いて、前記杭穴内に杭穴構造物を埋設し、前記杭穴構造物の底を、前記根固め部下部内又は前記根固め部下部の直上に位置させる。 That the present invention is to drill a Kuiana having a shaft portion and root solidified portion at its lower end, while lifting the injector within the root consolidated unit, by injecting cement milk, before and after, Kuiananai In the construction method for constructing a foundation pile by burying a pile hole structure such as a ready-made pile, the construction method is as follows.
(1) Within the root consolidation part, a distance from the bottom of the root consolidation part to a distance H is a lower part of the root consolidation part, and an upper part from the distance H is an upper part of the root consolidation part .
(2) into the pile bore, wherein by inserting the injector, said the bottom of the root hardened portion to position the injection port of the injection device, the injection port or racemate placement and milk injected first cement milk injection And
(3) Subsequently, the root consolidated portion upper portion to position the discharge opening of the cement milk of the injector, the discharge port or racemate placement and milk injected, the second cement milk injection.
(4) The first cement milk injection is an injection at a lower speed or lower pressure than the second cement milk injection.
(5) Subsequently, a pile hole structure is embedded in the pile hole, and the bottom of the pile hole structure is positioned in the lower part of the root-solidified part or directly above the lower part of the root-solidified part.

また、前記において、以下のように構成することを特徴とする杭穴の構築方法である。
(1) 根固め部内で、杭穴底と前記根固め部の上縁との間で、噴射装置を昇降する。
(2) 前記噴射装置の吐出口が前記根固め部下部に位置するときは、前記根固め部上部に位置するときに較べて低速度又は低圧力で吐出する。 Moreover, in the above, it is the construction method of the pile hole characterized by being comprised as follows.
(1) within the root hardened portion, between the upper edge of the the pile hole bottom roots consolidated unit, for lifting the injector.
(2) when the discharge port of the injector is positioned at the root compaction subordinate unit discharges at a low speed or low pressure compared to when located at the root consolidated upper part.

更に、前記において、以下のように構成することを特徴とする杭穴の構築方法である。
(1) 噴射装置に斜め下方に向けて吐出口を形成し
(2) 根固め部下部で、前記噴射装置を回転させて、回転方向と反対側に向けてセメントミルクを低速度又は低圧力で吐出する。 Furthermore, in the above, it is the construction method of the pile hole characterized by being comprised as follows.
(1) A discharge port is formed in the injection device diagonally downward.
(2) at the root compaction subordinate unit, said injection device is rotated to eject the cement milk at a low speed or low pressure toward the opposite side of the rotational direction.

前記における噴射装置は、通常掘削ヘッドの下端部に設けた吐出口を指すが、掘削ヘッドとは別途に、セメントミルク吐出用のロッドを用いることもできる。   The spray device in the above refers to a discharge port provided at the lower end of the excavation head, but a cement milk discharge rod can also be used separately from the excavation head.

また、前記における噴射速度の調節は、地上のセメントミルク製造プラントのバルブとポンプの調節で行う。あるいは、掘削ロッドの吐出口に設けたバルブ等を、地上からの操作で調節して噴射速度を調節することもできる。   The injection speed is adjusted by adjusting the valves and pumps of the cement milk production plant on the ground. Alternatively, the injection speed can be adjusted by adjusting a valve or the like provided at the discharge port of the excavation rod by an operation from the ground.

この発明では、杭穴底側で低速でセメントミルクを吐出するので、根固め部で支持地盤と直結する底側が乱されることなく設計通りの精度で効率よく構築できる。従って、通常は、下部の範囲内に、基礎杭の底面が位置するので、より確実な支持力を期待できる効果がある。   In this invention, since cement milk is discharged at a low speed on the bottom side of the pile hole, the bottom side directly connected to the support ground at the rooting portion can be efficiently constructed with the accuracy as designed. Therefore, normally, since the bottom face of the foundation pile is located within the lower range, there is an effect that a more reliable support force can be expected.

図１（ａ）〜（ｅ）はこの発明の実施態様の施工手順を説明する概略した縦断面図踏である。1 (a) to 1 (e) are schematic longitudinal sectional views illustrating a construction procedure according to an embodiment of the present invention. 図２はセメントミルクの吐出を説明する概略した底面図である。FIG. 2 is a schematic bottom view illustrating the discharge of cement milk. 図３は、他のセメントミルクの吐出方法を説明する図である。FIG. 3 is a diagram for explaining another method of discharging cement milk. 図４は、他のセメントミルクの吐出方法を説明する図である。FIG. 4 is a diagram for explaining another method of discharging cement milk. 図５は、他のセメントミルクの吐出方法を説明する図である。FIG. 5 is a diagram for explaining another method for discharging cement milk. 図６は、他のセメントミルクの吐出方法を説明する図である。FIG. 6 is a diagram for explaining another method of discharging cement milk.

１．掘削ヘッド１及び掘削ロッド１０の構成 1. Configuration of excavation head 1 and excavation rod 10

（１） ヘッド本体２は、下端に固定掘削刃３、３を下方に向けて突設し、上端に掘削ロッド１０との連結凸部４を有する。ヘッド本体２の上端部の両側に直径状に、水平軸１０、１０が夫々形成され、水平軸１０に、夫々掘削腕６の上端部を回動自在に取り付ける。掘削腕６は、下端部に先端掘削刃７、７が取り付けられている（図３）。 (1) The head body 2 has fixed digging blades 3 and 3 projecting downward at the lower end, and has a connecting projection 4 with the digging rod 10 at the upper end. Horizontal shafts 10 and 10 are formed on both sides of the upper end portion of the head body 2 in a diameter shape, and the upper end portions of the excavating arms 6 are rotatably attached to the horizontal shafts 10 respectively. The excavation arm 6 has tip excavation blades 7 and 7 attached to the lower end (FIG. 3).

（２） ヘッド本体２の下端の中央付近で、固定掘削刃３、３の間に、セメントミルクの吐出口５を下方に向けて形成し、地上１９のプラントからの操作で、水やセメントミルクなどを吐出できるようになっている。以上のようにして、掘削ヘッド１を構成する（図１）。掘削ヘッド１は、練付ドラム１６を有する掘削ロッド１０の下端に連結凸部４を嵌挿して連結して使用する。 (2) Near the center of the lower end of the head body 2, a cement milk discharge port 5 is formed downward between the fixed excavating blades 3 and 3, and water or cement milk is operated by operation from a plant on the ground 19 Etc. can be discharged. The excavation head 1 is configured as described above (FIG. 1). The excavation head 1 is used by inserting and connecting the connection convex portion 4 to the lower end of the excavation rod 10 having the kneading drum 16.

（３） なお、使用する掘削ヘッド１は上記構造以外であっても、同様に杭穴掘削、セメントミルクの吐出が可能であれば、使用可能である（図示していない）。また、前記では掘削とセメントミルクの吐出を兼用の掘削ヘッド１を使用したが、掘削ヘッド１とは別途の撹拌吐出用のヘッドを用意して、掘削ロッド１に取り換えて連結して使用することもできる（図示していない）。 (3) In addition, even if the excavation head 1 to be used is other than the above structure, it can be used as long as it is possible to excavate a pile hole and discharge cement milk (not shown). In the above description, the excavation head 1 is used for both excavation and discharge of cement milk. However, a head for agitation and discharge that is separate from the excavation head 1 is prepared and replaced with the excavation rod 1 for use. (Not shown).

２．杭穴１１の掘削と既製杭２０の埋設 2. Excavation of pile hole 11 and burial of ready-made pile 20

（１） 掘削ヘッド１を連結した掘削ロッド１０を正回転しながら、掘削ヘッド１の固定掘削刃３、３及び先端掘削刃７、７で、地上１９から地盤に杭穴軸部１２を形成する（図１（ａ））。この際、必要ならば吐出口５から掘削液又は水を吐出しながら掘削し、また、練付ドラム１６、１６で杭穴１１の側壁を均す。 (1) A pile hole shaft portion 12 is formed from the ground 19 to the ground by the fixed excavation blades 3 and 3 and the tip excavation blades 7 and 7 of the excavation head 1 while rotating the excavation rod 10 to which the excavation head 1 is connected in the forward direction. (FIG. 1 (a)). At this time, if necessary, excavation is performed while discharging drilling fluid or water from the discharge port 5, and the side walls of the pile holes 11 are leveled by the kneading drums 16, 16.

（２） 続いて、掘削ロッド１０を逆回転して、杭穴軸部１２の下端に続き、あるいは杭穴軸部１２の下端部を拡大掘削して、杭穴軸部１２より大径の杭穴根固め部１３を掘削する（図１（ｂ））。 (2) Subsequently, the excavation rod 10 is reversely rotated to continue to the lower end of the pile hole shaft portion 12 or the lower end portion of the pile hole shaft portion 12 is enlarged and excavated to make a pile larger in diameter than the pile hole shaft portion 12. The hole root consolidation part 13 is excavated (FIG. 1B).

（３） 杭穴軸部１２、根固め部１３を掘削して杭穴１１の掘削が完了したならば、根固め部１３の底１４（杭穴の底）に掘削ヘッド１を位置させ、掘削ロッド１０を回転しながら、吐出口５から２０ｍ３／ｈでセメントミルクを注入しながら、掘削ロッド１０を根固め部１３の底１４から距離Ｈまで上昇する（図１（ｃ））。根固め部１３の底１４から距離Ｈの根固め部１３の下部１３Ａで、セメントミルクは低速度で根固め部１７内に注入されるので、根固め部１３の底１４を乱さないと共に、根固め部１３の底１４から距離Ｈまでの間で確実に杭穴残存物（掘削泥土）をセメントミルクに置換できる。ここで、距離Ｈは５０ｃｍ程度とする。 (3) When excavation of the pile hole shaft portion 12 and root consolidation portion 13 and excavation of the pile hole 11 is completed, the excavation head 1 is positioned on the bottom 14 (bottom of the pile hole) of the root consolidation portion 13 and excavation is performed. While rotating the rod 10 and injecting cement milk from the discharge port 5 at 20 m 3 / h, the excavating rod 10 is lifted from the bottom 14 of the rooting portion 13 to a distance H (FIG. 1 (c)). Since the cement milk is injected into the root consolidation part 17 at a low speed in the lower part 13A of the root consolidation part 13 at a distance H from the bottom 14 of the root consolidation part 13, the bottom 14 of the root consolidation part 13 is not disturbed and the root The pile hole residue (excavated mud) can be reliably replaced with cement milk between the bottom 14 of the consolidated portion 13 and the distance H. Here, the distance H is about 50 cm.

（４） 続いて、距離Ｈから上方で、速度４５ｍ３／ｈ に切り換えて、同様に吐出口５からセメントミルクを吐出しながら、かつ掘削ロッド１０を回転しながら上昇して、根固め部１３の上縁１５まで掘削ロッド１０を上昇させる（図１（ｄ））。これにより、セメントミルクは撹拌され掘削泥土が残留していた場合にも良質のソイルセメントを形成できる。
また、前記におけるセメントミルクの吐出速度の調節は、地上１９のセメントミルク製造プラントの吐出ポンプの調節あるいはバルブ等を調節することにより行う（図示していない）。 (4) Subsequently, the distance H is switched to a speed of 45 m 3 / h upward from the distance H, and similarly, the cement milk is discharged from the discharge port 5 and the excavating rod 10 is rotated to rise, and the root-solidifying portion 13 The excavation rod 10 is raised to the upper edge 15 (FIG. 1 (d)). Thereby, even when cement milk is stirred and excavated mud remains, a high-quality soil cement can be formed.
Further, the adjustment of the discharge rate of the cement milk is performed by adjusting a discharge pump or a valve or the like of the cement milk production plant on the ground 19 (not shown).

（５） 続いて、杭穴１１の軸部１２にもセメントミルクを注入して、掘削ヘッド１を掘削ロッド１０と共に地上１９に引き上げて、杭穴１１内に既製杭２０を埋設して基礎杭２５を構築する（図１（ｅ））。この際、既製杭２０の底２１は、根固め部１３の底１４から上方の下部１３Ａ内又は１３Ａの直上付近に位置する。 (5) Subsequently, cement milk is also injected into the shaft portion 12 of the pile hole 11, the excavation head 1 is pulled up to the ground 19 together with the excavation rod 10, and the ready-made pile 20 is buried in the pile hole 11 to form a foundation pile. 25 is constructed (FIG. 1 (e)). Under the present circumstances, the bottom 21 of the ready-made pile 20 is located in the lower part 13A above the bottom 14 of the root hardening part 13, or just above 13A.

（６） 前記において、杭穴１１を掘削した後に既製杭２０を埋設する、いわゆる先掘り工法に適用したが、杭穴１１を掘削しつつ既製杭２０を埋設する中掘工法に採用することもできる（図示していない）。さらに、既製杭２０に代わり鉄筋篭などの杭穴構造物を採用して、セメントミルクの濃度を増して骨材を入れてコンクリートとして、いわゆる現場造成杭に適用することもできる（図示していない）。
また、何らかの芯材となる杭穴構造物を埋設すれば、各種の地盤改良工法の底部の構築にも適用することもできる（図示していない）。 (6) In the above description, the present invention is applied to the so-called pre-digging method in which the ready-made pile 20 is buried after the pile hole 11 is excavated, but it is also possible to adopt the intermediate-digging method in which the ready-made pile 20 is buried while the pile hole 11 is excavated. Yes (not shown). Furthermore, a pile hole structure such as a reinforcing bar can be used instead of the ready-made pile 20, and the concentration of cement milk can be increased to put aggregate into concrete, so that it can be applied to a so-called field-built pile (not shown). ).
In addition, if a pile hole structure to be some kind of core material is embedded, it can also be applied to the construction of the bottom of various ground improvement methods (not shown).

３．他の実施態様 3. Other embodiments

（１） 前記実施態様において、根固め部１３でのセメンミルクの吐出は、根固め部１３の底１４から根固め部１３の上縁１５まで、掘削ヘッド１を上昇させながらセメントミルクの全量を吐出したが、吐出方法は任意であり、例えば、以下の４つの方法の何れかを採用することもできる（図３〜図６）。いずれの吐出方法でも、杭穴１１の根固め部１３の底１４から距離Ｈまでの下部１３Ａの範囲では、吐出口５から低速度でセメントミルクを吐出して、上部１３Ｂでは、高速度でセメントミルクを突出する。また、吐出口５から水を吐出する際にも、下部１３Ａでは低速度、上部１３Ｂでは高速度で吐出することが望ましい。 (1) In the said embodiment, discharge of the cement milk in the root consolidation part 13 discharges the whole quantity of cement milk, raising the excavation head 1 from the bottom 14 of the root consolidation part 13 to the upper edge 15 of the root consolidation part 13. However, the discharge method is arbitrary, and for example, any of the following four methods can be adopted (FIGS. 3 to 6). In any of the discharge methods, cement milk is discharged from the discharge port 5 at a low speed in the range of the lower portion 13A from the bottom 14 of the rooted portion 13 of the pile hole 11 to the distance H, and the upper portion 13B is cemented at a high speed. Protruding milk. Also, when water is discharged from the discharge port 5, it is desirable to discharge at a low speed at the lower portion 13A and at a high speed at the upper portion 13B.

（ａ） 第１の方法（図３）では、杭穴１１の根固め部１３の底１４付近で掘削ヘッド１を回転させて、吐出すべき全セメント量の３分の１量をそのまま吐出する。続いて、掘削ヘッド１を根固め部１３の底１４から根固め部１３の上縁１５まで、掘削ヘッド１を回転させながら上昇させる。この作動中に、吐出口５からセメントミルク（吐出すべき全セメント量の３分の１量）を根固め部１３内に注入する。
続いて、根固め部１３の上縁１５に位置する掘削ヘッド１を、根固め部１３の底１４まで２回反復上下動させ、再度、根固め部１３の上縁１５に位置させる。この間で、掘削ヘッド１を回転して撹拌し、かつ吐出口５からセメントミルク（吐出すべき全セメント量の３分の１量）を根固め部１３内に注入する。以上で、全部のセメントミルクの注入が完了する（図３）。 (A) In the first method (FIG. 3), the excavation head 1 is rotated in the vicinity of the bottom 14 of the consolidation part 13 of the pile hole 11, and one third of the total cement amount to be discharged is discharged as it is. . Subsequently, the excavation head 1 is raised while rotating the excavation head 1 from the bottom 14 of the root consolidation part 13 to the upper edge 15 of the root consolidation part 13. During this operation, cement milk (one third of the total amount of cement to be discharged) is injected into the rooting portion 13 from the discharge port 5.
Subsequently, the excavation head 1 located at the upper edge 15 of the root consolidation part 13 is repeatedly moved up and down twice to the bottom 14 of the root consolidation part 13 and is again positioned at the upper edge 15 of the root consolidation part 13. During this time, the excavation head 1 is rotated and agitated, and cement milk (a third of the total cement amount to be discharged) is injected into the rooting portion 13 from the discharge port 5. This completes the injection of the entire cement milk (FIG. 3).

（ｂ） 第２の方法（図４）では、第一の方法と同様に、杭穴１１の拡底部１３の底１４に掘削ヘッド１を位置させ、掘削ヘッド１の吐出口５から掘削水を放出しながら、かつ掘削ロッド１０を回転しながら掘削残存物（掘削泥土など）を撹拌しながら、杭穴根固め部１３の上縁１５付近まで掘削ヘッド１を上昇させ、引き続き掘削ヘッド１を杭穴１１の根固め部１３の底１４まで下げる。以上の反復工程動作をもう１回、繰り返し、掘削ヘッド１を杭穴１１の根固め部１３の底１４に位置させる。続いて、根固め部１３付近で掘削ヘッド１を回転させて、吐出すべき全セメント量の３０％量を、杭穴拡底部１３の底１４付近から吐出する。続いて、掘削ヘッド１を根固め部１３の底１４から根固め部１３の上縁１５まで、回転して上昇させる。この作動中に、吐出口５からセメントミルク（吐出すべき全セメント量の６０％の量）を根固め部１３内に注入する。続いて、根固め部１３の上縁１５に位置する掘削ヘッド１を、根固め部１３の底１４まで２回反復上下動させ、再度、根固め部１３の上縁１５に位置させる。この間で、掘削ヘッド１を回転して撹拌し、かつ吐出口５からセメントミルク（吐出すべき全セメント量の１０％の量）を根固め部１３内に注入する。以上で、全部のセメントミルクの注入が完了する（図４）。         (B) In the second method (FIG. 4), similarly to the first method, the excavation head 1 is positioned on the bottom 14 of the bottom expanded portion 13 of the pile hole 11 and the excavation water is discharged from the discharge port 5 of the excavation head 1. While discharging and stirring the excavation residue (excavation mud, etc.) while rotating the excavation rod 10, the excavation head 1 is raised to the vicinity of the upper edge 15 of the pile hole root consolidation part 13 and the excavation head 1 is subsequently piled. The bottom 11 of the hole 11 is lowered to the bottom 14. The above iterative process operation is repeated once more, and the excavation head 1 is positioned at the bottom 14 of the rooting portion 13 of the pile hole 11. Subsequently, the excavation head 1 is rotated in the vicinity of the root hardening portion 13, and 30% of the total cement amount to be discharged is discharged from the vicinity of the bottom 14 of the pile hole widening portion 13. Subsequently, the excavation head 1 is rotated and raised from the bottom 14 of the root consolidation part 13 to the upper edge 15 of the root consolidation part 13. During this operation, cement milk (60% of the total amount of cement to be discharged) is injected into the rooting portion 13 from the discharge port 5. Subsequently, the excavation head 1 located at the upper edge 15 of the root consolidation part 13 is repeatedly moved up and down twice to the bottom 14 of the root consolidation part 13 and is again positioned at the upper edge 15 of the root consolidation part 13. During this time, the excavation head 1 is rotated and agitated, and cement milk (an amount of 10% of the total cement amount to be discharged) is injected into the rooting portion 13 from the discharge port 5. This completes the injection of the entire cement milk (FIG. 4).

（ｃ） 第３の方法（図５）では、前記第１の方法では、セメントミルクを注入する前の反復工程を２回繰り返したが、４回繰り返す。         (C) In the third method (FIG. 5), in the first method, the repetition process before injecting cement milk is repeated twice, but is repeated four times.

（ｄ） 第４の方法（図６）では、前記第２の方法の２回の反復工程の後に、根固め部１３の穴底１４付近で、掘削水からセメントミルクに切り換えて、反復工程と同様に、掘削ヘッド１を根固め部１３の底１４から根固め部１３の上縁１５まで往復する前処理工程動作を２回繰り返す。前処理工程動作では、反復工程と異なり、掘削水に代えてセメントミルクを吐出しながら、掘削ヘッド１を回転して撹拌する。続いて、根固め部１３の底１４付近で、掘削ヘッド１を回転させて、吐出すべき全セメント量の３０％量を吐出する。続いて、掘削ヘッド１を根固め部１３の底１４から根固め部１３の上縁１５まで、回転させて上昇させる。この作動中に、吐出口５からセメントミルク（吐出すべき全セメント量の６０％量）を根固め部１３内に注入する。続いて、根固め部１３の上縁１５に位置する掘削ヘッド１を、根固め部１３の底１４まで２回反復上下動させ、再度根固め部１３の上縁１５に位置させる。この間で、掘削ヘッド１を回転して撹拌し、かつ吐出口５からセメントミルク（吐出すべき全セメント量の１０％量）を根固め部１３内に注入する。以上で、全部のセメントミルクの注入が完了する（図６）。         (D) In the fourth method (FIG. 6), after two iterations of the second method, the drilling water is switched to cement milk in the vicinity of the hole bottom 14 of the root consolidation portion 13 to repeat the iterations. Similarly, the pretreatment process operation of reciprocating the excavation head 1 from the bottom 14 of the root consolidation part 13 to the upper edge 15 of the root consolidation part 13 is repeated twice. In the pretreatment process operation, unlike the repetitive process, the excavation head 1 is rotated and agitated while discharging the cement milk instead of the excavation water. Subsequently, the excavation head 1 is rotated in the vicinity of the bottom 14 of the root hardening portion 13 to discharge 30% of the total cement amount to be discharged. Subsequently, the excavation head 1 is rotated and raised from the bottom 14 of the root consolidation part 13 to the upper edge 15 of the root consolidation part 13. During this operation, cement milk (60% of the total amount of cement to be discharged) is injected into the rooting portion 13 from the discharge port 5. Subsequently, the excavation head 1 located at the upper edge 15 of the root consolidation part 13 is repeatedly moved up and down twice to the bottom 14 of the root consolidation part 13, and is again positioned at the upper edge 15 of the root consolidation part 13. During this time, the excavation head 1 is rotated and agitated, and cement milk (10% of the total amount of cement to be discharged) is injected into the rooting portion 13 from the discharge port 5. This completes the injection of the entire cement milk (FIG. 6).

（２） また、前記実施態様において、根固め部１３の底１４から距離Ｈの高さまでを下部１３Ａとして、Ｈを５０ｃｍ程度としたが、距離Ｈを３０ｃｍ〜７０ｃｍとすることもできる。
施工効率からするとできるだけ高速度（高圧力）で大量のセメントミルクを注入することが好ましいが、この発明ではこれを制限して、底面１４近辺の下部１３Ａに限って低速度（低圧力）としたものである。従って、３０ｃｍ未満では根固め部１３の底１４に対する影響力が極めて強いので、３０ｃｍ未満は考えられず、また７０ｃｍを超えると施工効率上好ましくない。
また、距離Ｈを３０ｃｍ〜７０ｃｍ としたが、他の基準とすることもできる。例えば、根固め部１３の底１４から既製杭２０の底２１に間隙を設けて埋設する場合には、距離Ｈをその間隙に一致させることもできる。この間隙は、通常、１ｍや杭径と同等などの基準で設定される。 (2) Moreover, in the said embodiment, although H was made into about 50 cm from the bottom 14 of the root hardening part 13 to the height of the distance H as the lower part 13A, the distance H can also be made into 30 cm-70 cm.
From the viewpoint of construction efficiency, it is preferable to inject a large amount of cement milk at as high a speed as possible (high pressure). However, in the present invention, this is limited to a lower speed (low pressure) only in the lower portion 13A near the bottom surface 14. Is. Therefore, if it is less than 30 cm, the influence on the bottom 14 of the root hardening part 13 is very strong, so that less than 30 cm cannot be considered, and if it exceeds 70 cm, it is not preferable in terms of construction efficiency.
Further, although the distance H is set to 30 cm to 70 cm 2, other standards can be used. For example, in the case where a gap is provided from the bottom 14 of the root hardening portion 13 to the bottom 21 of the ready-made pile 20, the distance H can be made to coincide with the gap. This gap is usually set based on a standard such as 1 m or a pile diameter.

（３） また、前記実施態様において、吐出速度の調節は、地上１９のセメントミルク製造プラントから掘削ロッド１０への供給側で行ったが、掘削ヘッド１のヘッド本体２内で吐出口５に至る間で、バルブなどの速度（即ち圧力）調節機構を設けることもできる（図示していない）。この場合、調節機構の操作は地上１９で行う。
また、この場合、地上１９のセメントミルク製造プラント側での吐出速度（供給配管径が同一であれば圧力の調節と同じ）を一定にした場合、例えば、掘削ヘッド１に２つの吐出口５、５を形成して、高速の場合には、１方の吐出口５を閉じて、１つの吐出口５からのみ吐出する。また、低速の場合には、両方の吐出口５、５を開いて断面積を２倍にすれば、吐出速度を２分の１に下げることができる（図示していない）。 (3) In the above embodiment, the discharge speed is adjusted on the supply side from the cement milk production plant on the ground 19 to the excavation rod 10, but reaches the discharge port 5 in the head body 2 of the excavation head 1. A speed (ie, pressure) adjusting mechanism such as a valve may be provided between them (not shown). In this case, the adjustment mechanism is operated on the ground 19.
Moreover, in this case, when the discharge speed on the cement milk production plant side of the ground 19 is the same (the same as the pressure adjustment if the supply pipe diameter is the same), for example, two discharge ports 5 are provided in the excavation head 1. In the case of high speed, one of the discharge ports 5 is closed and discharged from only one discharge port 5. In the case of a low speed, the discharge speed can be reduced to half (not shown) by opening both the discharge ports 5 and 5 and doubling the cross-sectional area.

（４） また、前記実施態様において、吐出口５は、ヘッド本体２の下端で固定掘削刃３，３の間に形成したが、掘削ロッド１０のセメントミルク配送パイプ（図示していない）に連通できる位置であれば、ヘッド本体２、掘削腕６の任意の位置に吐出口５を配置することができる（図示していない）。 (4) Moreover, in the said embodiment, although the discharge outlet 5 was formed between the fixed excavation blades 3 and 3 in the lower end of the head main body 2, it communicates with the cement milk delivery pipe (not shown) of the excavation rod 10. If possible, the discharge port 5 can be arranged at any position of the head body 2 and the excavating arm 6 (not shown).

（５） また、前記実施態様において、吐出口５を下方に向けて形成したので、下方に向けて円錐状にセメントミルクは広がるが、下方から傾斜させて吐出方向を向けることもできる（図示していない）。この場合、掘削ロッド１０（掘削ヘッド１）の回転方向（杭穴底付近での）に対して、反対側に傾斜させると相対的に吐出速度が遅くなり、吐出量を維持して根固め部１３の底１４への影響を軽減できる。
また、吐出口５、５を複数形成することもでき、この場合には、回転方向Ａの場合には、回転方向Aと反対向きに配置した吐出口５Ａ、５Ａからセメントミルクを吐出し、回転方向Ｂ（回転方向Ａと逆方向）の場合には、回転方向Bと反対向きに配置した吐出口５B、５Bからセメントミルクを吐出する（図２）。 (5) Moreover, in the said embodiment, since the discharge outlet 5 was formed facing down, cement milk spreads conically toward the downward direction, but it is also possible to incline the discharge direction by inclining from below (illustration). Not) In this case, when the drilling rod 10 (the drilling head 1) is tilted in the opposite direction with respect to the rotation direction (near the bottom of the pile hole), the discharge speed is relatively slow, and the discharge amount is maintained and the solidified portion is maintained. The influence on the bottom 14 of 13 can be reduced.
Also, a plurality of discharge ports 5 and 5 can be formed. In this case, in the case of the rotation direction A, the cement milk is discharged from the discharge ports 5A and 5A arranged in the direction opposite to the rotation direction A and rotated. In the case of the direction B (the direction opposite to the rotation direction A), the cement milk is discharged from the discharge ports 5B and 5B arranged in the direction opposite to the rotation direction B (FIG. 2).

（６） また、前記実施態様において、根固め部１３の下部１３Ａを低速度、上部１３Ｂを高速度としたが、圧力を基準として、根固め部１３の下部１３Ａを低圧力、上部１３Ｂを高圧力とすることもできる。この場合、低圧１０ＭＰａ以下、高圧１５ＭＰａ以上、とすることが望ましい。例えば、下部１３Ａ（底面１７〜距離Ｈ）を吐出圧力１．９ＭＰａ、上部１３Ｂ（距離Ｈの上方）を高圧２８．４ＭＰａで設定する。 (6) In the above embodiment, the lower portion 13A of the root consolidation portion 13 is set to a low speed and the upper portion 13B is set to a high speed. However, based on the pressure, the lower portion 13A of the root consolidation portion 13 is set to a low pressure and the upper portion 13B is set to a high speed. It can also be a pressure. In this case, it is desirable that the low pressure is 10 MPa or less and the high pressure is 15 MPa or more. For example, the lower pressure 13A (bottom 17 to distance H) is set at a discharge pressure of 1.9 MPa, and the upper pressure 13B (above distance H) is set at a high pressure of 28.4 MPa.

１ 掘削ヘッド
２ ヘッド本体
３ 固定掘削刃
４ 連結凸部
５ 吐出口
６ 掘削腕
７ 先端掘削刃
１０ 掘削ロッド
１１ 杭穴
１２ 杭穴軸部
１３ 杭穴根固め部
１３Ａ 根固め部の下部
１３Ｂ 根固め部の上部
１４ 杭穴根固め部の底
１５ 杭穴根固め部の上縁
１６ 練付ドラム
１９ 地上
２０ 既製杭
２１ 既製杭の底
２５ 基礎杭 DESCRIPTION OF SYMBOLS 1 Excavation head 2 Head main body 3 Fixed excavation blade 4 Connection convex part 5 Discharge port 6 Excavation arm 7 Tip excavation blade 10 Excavation rod 11 Pile hole 12 Pile hole axial part 13 Pile hole root consolidation part 13A Root consolidation part lower part 13B Upper part 14 Bottom of pile hole consolidation part 15 Upper edge 16 of pile hole consolidation part Kneading drum 19 Above ground 20 Ready-made pile 21 Bottom of ready-made pile 25 Foundation pile

Claims (3)

軸部とその下端に根固め部とを有する杭穴を掘削して、前記根固め部内で噴射装置を昇降させながら、セメントミルクを注入して、その前後に、杭穴内に既製杭を初めとした杭穴構造物を埋設して基礎杭を構築する工法において、以下のように構成することを特徴とする杭穴の構築方法。
(1) 前記根固め部内で、前記根固め部の底から距離Ｈまでを根固め部下部とし、距離Ｈから上方を根固め部上部とする。
(2) 前記杭穴内に、前記噴射装置を挿入して、前記根固め部の底に前記噴射装置の噴射口を位置させて、該噴射口からセメントミルク注入し、第１セメントミルク注入とする。
(3) 続いて、前記根固め部上部に前記噴射装置のセメントミルクの吐出口を位置させて、該吐出口からセメントミルク注入し、第２セメントミルク注入とする。
(4) 前記第１セメントミルク注入を、第２セメントミルク注入に比して、低速度又は低圧力による注入とする。
(5) 続いて、前記杭穴内に杭穴構造物を埋設し、前記杭穴構造物の底を、前記根固め部下部内又は前記根固め部下部の直上に位置させる。 By drilling Kuiana that and its lower end shaft portion and a root hardened portion, said while lifting the root consolidated portion in the injection device to inject the cement milk, the back and forth, first prefabricated pile into the pile hole In the construction method which constructs a foundation pile by burying the pile hole structure which was made, it is comprised as follows, The construction method of the pile hole characterized by the above-mentioned.
(1) Within the root consolidation part, a distance from the bottom of the root consolidation part to a distance H is a lower part of the root consolidation part, and an upper part from the distance H is an upper part of the root consolidation part .
(2) into the pile bore, wherein by inserting the injector, said the bottom of the root hardened portion to position the injection port of the injection device, the injection port or racemate placement and milk injected first cement milk injection And
(3) Subsequently, the root consolidated portion upper portion to position the discharge opening of the cement milk of the injector, the discharge port or racemate placement and milk injected, the second cement milk injection.
(4) The first cement milk injection is an injection at a lower speed or lower pressure than the second cement milk injection.
(5) Subsequently, a pile hole structure is embedded in the pile hole, and the bottom of the pile hole structure is positioned in the lower part of the root-solidified part or directly above the lower part of the root-solidified part. 以下のように構成することを特徴とする請求項１記載の杭穴の構築方法。
(1) 根固め部内で、杭穴底と前記根固め部の上縁との間で、噴射装置を昇降する。
(2) 前記噴射装置の吐出口が前記根固め部下部に位置するときは、前記根固め部上部に位置するときに較べて低速度又は低圧力で吐出する。 The method for constructing a pile hole according to claim 1, wherein the method is constructed as follows.
(1) within the root hardened portion, between the upper edge of the the pile hole bottom roots consolidated unit, for lifting the injector.
(2) when the discharge port of the injector is positioned at the root compaction subordinate unit discharges at a low speed or low pressure compared to when located at the root consolidated upper part. 以下のように構成することを特徴とする請求項１記載の杭穴の構築方法。
(1) 噴射装置に斜め下方に向けて吐出口を形成し
(2) 根固め部下部で、前記噴射装置を回転させて、回転方向と反対側に向けてセメントミルクを低速度又は低圧力で吐出する。 The method for constructing a pile hole according to claim 1, wherein the method is constructed as follows.
(1) A discharge port is formed in the injection device diagonally downward.
(2) at the root compaction subordinate unit, said injection device is rotated to eject the cement milk at a low speed or low pressure toward the opposite side of the rotational direction.
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