JP4526018B2

JP4526018B2 - Vertical hole drilling device, vertical hole construction method using the same, and lower propelling body

Info

Publication number: JP4526018B2
Application number: JP2004185320A
Authority: JP
Inventors: 和夫柴田; 靖中村
Original assignee: Nippon Steel Engineering Co Ltd
Current assignee: Nippon Steel Engineering Co Ltd
Priority date: 2004-06-23
Filing date: 2004-06-23
Publication date: 2010-08-18
Anticipated expiration: 2024-06-23
Also published as: JP2006009313A

Description

本発明は、地盤に立孔を掘削する技術分野に係り、中空管体と、該中空管体に分離可能に連結した回転羽根を有する下部推進体からなる回転圧入式または貫入式の立孔掘削装置と、これを用いた立孔構築方法および下部推進体に関するものである。 The present invention relates to a technical field of excavating a vertical hole in the ground, and is a rotary press-fitting type or a penetrating type standing unit comprising a hollow tubular body and a lower propelling body having a rotating blade separably connected to the hollow tubular body. The present invention relates to a hole excavator, a method for constructing a vertical hole using the same, and a lower propelling body.

地盤に掘削される立孔（立坑）は種々の目的で利用される。例えば、（１）地盤を蓄熱体又は熱源として利用する場合、地中熱交換の採放熱管の挿入孔として利用する、（２）井戸構築の際の井戸ケーシング挿入孔として利用する、（３）アンカー部材の地盤定着のための鉄筋の挿入孔として利用する、（４）地盤改良のスリーブ管の挿入孔として利用する、などの例がある。 Vertical holes (shafts) excavated in the ground are used for various purposes. For example, (1) When the ground is used as a heat storage body or heat source, it is used as an insertion hole for a heat collecting and radiating pipe for underground heat exchange. (2) It is used as a well casing insertion hole when a well is constructed. (3) There are examples of using as an insertion hole of a reinforcing bar for anchoring the ground of an anchor member, and (4) using as an insertion hole of a sleeve pipe for ground improvement.

前記の各種用途のために地盤に掘削される掘削孔は、通常は、孔径が約１１０ｍｍ前後、深さが数メートルから１００メートル前後の規模であるが、従来はこの掘削孔を二重管式ドリリングシステム、一重管式ドリリングシステムなどの掘削装置を用いて掘削しおり、特に二重管式ドリリングシステムが一般に行われている。この二重管方式は同時穿孔システムで、ローテーションとパーカッションにフィード・送水を併用して穿孔するものである。 The excavation hole excavated in the ground for the various uses described above is usually about 110 mm in diameter and about several to 100 meters in depth. Conventionally, this excavation hole is a double pipe type. Drilling is performed using a drilling device such as a drilling system or a single-pipe drilling system, and a double-pipe drilling system is generally used. This double-pipe system is a simultaneous drilling system that uses both feed and water for rotation and percussion.

すなわち二重管方式による掘削に際しては、インナーロッド（内管）とケーシング（外管）は、同時回転、同時打撃で作動し、ビット先端の地盤を破砕すると共に、インナーロッド（内管）から掘削水を送水し、インナーロッド（内管）とケーシング（外管）の間隙から前記掘削水の排水を行いながら同時に掘削土砂（スライム）を排出しながら掘進するものである。なお、特開平８−２７０３５３にも、前述と同様にビット掘削した土砂を送水管（内管）から送られた水で泥水としてケーシング（外管）の後端側に設けられた泥水取出し管から排水する二重管式掘削機が開示されている。
特開平８−２７０３５３号公報 In other words, when excavating by the double pipe method, the inner rod (inner pipe) and casing (outer pipe) are operated by simultaneous rotation and impact, crushing the ground at the tip of the bit and excavating from the inner rod (inner pipe). Water is fed, and the digging water is drained from the gap between the inner rod (inner pipe) and the casing (outer pipe) while digging earth and sand (slime) is discharged while digging. JP-A-8-270353 also uses a muddy water extraction pipe provided on the rear end side of a casing (outer pipe) as muddy water using the water excavated from the water pipe (inner pipe) as in the above. A double-pipe excavator for draining is disclosed.
JP-A-8-270353

従来の掘削方法では、次の問題があった。（１）孔掘削により排土が生じるため、その排土を遠方の処理場に運ぶなど大変面倒でコストが掛る。（２）掘削水を使用するため泥水を浄化して送り込むプラント設備が必要になり施工コストアップとなる。加えて、地盤によっては掘削水が逃げてしまい、掘削できないことがある。さらに、地盤によっては、周囲の地下水を汚染する可能性がある。（３）一重ケーシング方式は、二重ケーシング方式見比べて構造が簡単であるが、掘削した地盤との間から泥水を上げる方式であるから、自立性の高い硬い地盤しかつかえない。 The conventional excavation method has the following problems. (1) Since excavation is generated by excavation, the excavation is very troublesome and expensive, such as transporting the excavation to a distant treatment plant. (2) Since drilling water is used, plant facilities for purifying and sending mud water are required, which increases construction costs. In addition, depending on the ground, the drilling water may escape and drilling may not be possible. In addition, depending on the ground, the surrounding groundwater may be contaminated. (3) The single casing method is simpler in structure than the double casing method, but is a method in which muddy water is raised from the excavated ground, so it can only use hard ground that is highly self-supporting.

（４）孔壁が自立するような硬質地盤以外では、二重ケーシング掘りが一般的であるが、ケーシングの接続延長・引き抜きには一重ケーシングの場合の２倍の手間が必要であり高コストになる。（５）掘削水を噴出する掘削歯の先端部が泥で閉塞して掘削水の流通が止まり掘削できなくなることがある。また、本発明の方法に比べて、掘削速度が劣る。さらに、ケーシングを継ぎ足す場合、二重ケーシングでは接続箇所も内管と外管の２箇所が必要であり、掘削孔を地中熱利用の設備のための採放熱管等を挿入する孔として使用する場合は、２重管を引き抜くことになるが、その場合はまず内管を抜いて、それから採放熱管等を挿入するという２倍の手間が必要であり、掘削効率が悪い。 (4) Except for hard ground where the hole wall is self-supporting, double casing digging is common, but connecting and extending the casing requires twice as much work as a single casing, resulting in high costs. Become. (5) The tip of the digging tooth that ejects the digging water may be blocked by mud and the circulation of the digging water may stop, making it impossible to dig. Also, the excavation speed is inferior compared with the method of the present invention. In addition, when connecting casings, the double casing requires two locations for the inner and outer pipes, and the excavation hole is used as a hole to insert a heat-dissipating pipe for facilities using geothermal heat. In this case, the double pipe is pulled out, but in that case, it takes twice as much work to first pull out the inner pipe and then insert a heat-dissipating pipe and the like, and the excavation efficiency is poor.

本発明は、従来の掘削工法（ボーリング工法）における前記（１）〜（５）の問題を解決したものである。すなわち、鋼管からなる中空管体の先端に螺旋状の回転羽根または非螺旋状の回転羽根を備えた下部推進体を着脱自在に連結し、中空管体を地中に回転圧入または貫入した後、下部推進体を地中に残して中空管体を地上に引き上げ、その後にできる内部空洞（立孔）を所要の用途に利用することを目的とするもので、従来のように掘削水を使用せず、排土も生じず、かつ効率的な削孔ができる立孔掘削装置とこれを用いた立孔掘削方法を提供することを目的とする。 The present invention solves the problems (1) to (5) in the conventional excavation method (boring method). That is, a lower propulsion body having a spiral rotating blade or a non-helical rotating blade is detachably connected to the tip of a hollow tube body made of a steel tube, and the hollow tube body is rotationally press-fitted or penetrated into the ground. After that, the lower propellant is left in the ground and the hollow tube is lifted to the ground, and then the internal cavity (standing hole) is used for the required application. It is an object of the present invention to provide a borehole excavating apparatus that can efficiently drill holes without using any earth, and that does not generate soil, and a borehole excavation method using the same.

前記の課題を解決するため、本発明は、次のように構成する。 In order to solve the above-described problems, the present invention is configured as follows.

第１の発明は、回転羽根を有する下部推進体と、下部推進体に連結機構を介して着脱自在に連結される中空管体とからなり、前記連結機構は、中空管体を地中に回転貫入した後、貫入時とは逆回転すると共に引上げ力を加えることで下部推進体から離脱可能に構成され、下部推進体は、高さ方向の中間部を境として中空管体に嵌合できる上側小径部および、中空管体の下端面が係止する上端面を有する下側大径部からなる筒状本体と、下側大径部に設けられる前記回転羽根からなり、前記連結機構は、中空管体の下端面と筒状本体の下側大径部の上端面にそれぞれ設けた凹凸部を互いに嵌合すると共に周方向に若干回動可能に設けられ、かつ、中空管体と下部推進体の一方の部材の凹部に配置された係合ピンが、中空管体の正逆回転により他方の部材の凹部に設けた係合溝に係脱可能に構成され、筒状本体に設けられる回転羽根は、中心部に下側大径部より縮径され、掘削土砂を内部へ通過させるための開口を有する開端羽根であり、かつ前記筒状本体の上部は、閉塞されていること
を特徴とする。 1st invention consists of the lower propulsion body which has a rotary blade, and the hollow tube body connected to a lower propulsion body through a connection mechanism so that attachment or detachment is possible, and the said connection mechanism is underground in a hollow tube body. It is configured so that it can be detached from the lower propulsion body by applying a pulling force while rotating in reverse, and the lower propulsion body is fitted into the hollow tube with the middle part in the height direction as a boundary. The upper small-diameter portion that can be joined together, a cylindrical main body composed of a lower large-diameter portion having an upper end surface to which the lower end surface of the hollow tubular body is locked, and the rotating blade provided in the lower large-diameter portion, and the connection The mechanism is provided so that the concave and convex portions provided on the lower end surface of the hollow tubular body and the upper end surface of the lower large-diameter portion of the cylindrical main body are fitted to each other and can be slightly rotated in the circumferential direction. The engagement pin arranged in the recess of one member of the tube body and the lower propulsion body is moved by the forward / reverse rotation of the hollow tube body. The rotating blade provided in the cylindrical body is reduced in diameter from the lower large-diameter portion at the center, and allows the excavated sediment to pass inside. An open-ended blade having an opening, and an upper portion of the cylindrical main body is closed .

第２の発明は、第１の発明において、既製の鋼管からなる中空管体の端部に短管状の連結部材がネジ結合され、前記連結機構における中空管体の凹凸部は、該連結部材に設けられていることを特徴とする。 According to a second invention, in the first invention, a short tubular connecting member is screwed to an end portion of a hollow tube body made of a ready-made steel pipe, and the uneven portion of the hollow tube body in the connection mechanism is It is provided in the member.

第３発明は、第１又は第２の発明に係る立孔掘削装置により地中の所定深度まで中空管体を回転貫入した後、該中空管体を逆回転して下部推進体との係合を解除し地上に引き抜き抜くことで、中空管体を引き抜いた後にできる立孔を、蓄熱、地中熱利用、井戸構築、地盤改良などに用いる管その他の各種機具、またはアースアンカーなどの挿入孔とすることを特徴とする。 According to a third aspect of the present invention, after the hollow tube body is rotated and penetrated to a predetermined depth in the ground by the vertical hole excavation device according to the first or second aspect of the invention, the hollow tube body is reversely rotated to By releasing the engagement and pulling it out to the ground, the vertical hole created after pulling out the hollow tube can be used for heat storage, underground heat utilization, well construction, ground improvement etc. It is characterized by using an insertion hole.

第４発明は、第１又は第２の発明に係る立孔掘削装置により地中の所定深度まで中空管体を回転貫入した後、該中空管体を逆回転して下部推進体との係合を解除し、該中空管体の内部に蓄熱、地中熱利用、井戸構築、地盤改良などに用いる管その他の各種機具、またはアースアンカーを挿入し、つづいて中空管体に充填材を充填した後、該中空管体を地上に引き抜き抜くことを特徴とする。 According to a fourth aspect of the present invention, after the hollow tube body is rotated and penetrated to a predetermined depth in the ground by the vertical hole excavation device according to the first or second aspect of the invention, the hollow tube body is reversely rotated to Release the engagement, insert pipes and other equipment used for heat storage, underground heat utilization, well construction, ground improvement, etc., or earth anchors inside the hollow tube body, and then fill the hollow tube body After filling the material, the hollow tube body is drawn out to the ground.

第５発明は、第１又は第２の発明に係る立孔掘削装置により地中の所定深度まで中空管体を回転貫入した後、該中空管体を逆回転して下部推進体との係合を解除して地上に引き抜くことで立孔を構築し、その後、該立孔の内部に蓄熱、地中熱利用、井戸構築、地盤改良などに用いる管その他の各種機具、またはアースアンカーを挿入し、つづいて充填材を充填する。 According to a fifth aspect of the present invention, after the hollow tube body is rotated and penetrated to a predetermined depth in the ground by the vertical excavation device according to the first or second invention, the hollow tube body is reversely rotated to A vertical hole is constructed by releasing the engagement and pulling it out to the ground. After that, pipes and other equipment or earth anchors used for heat storage, underground heat utilization, well construction, ground improvement, etc. are installed inside the vertical hole. Insert and then fill with filler.

第６発明は、中空管体に対して着脱自在に設けられ、回転羽根を具備した下部推進体であって、該下部推進体は、中空管体の正回転と逆回転により係合・離脱可能な連結機構を介して該中空管体に設けられ、前記下部推進体は、高さ方向の中間部を境として中空管体に嵌合できる上側小径部および、中空管体の下端面が係止する上端面を有する下側大径部からなる筒状本体と、下側大径部に設けられる前記回転羽根からなり、前記連結機構は、中空管体の下端面と筒状本体の下側大径部の上端面にそれぞれ設けた凹凸部を互いに嵌合すると共に周方向に若干回動可能に設けられ、かつ、中空管体と下部推進体の一方の部材の凹部に配置された係合ピンが、中空管体の正逆回転により他方の部材の凹部に設けた係合溝に係脱可能に構成され、筒状本体に設けられる回転羽根は、中心部に下側大径部より縮径され、掘削土砂を内部へ通過させるための開口を有する開端羽根であり、かつ前記筒状本体の上部は、閉塞されていること
を特徴とする。 A sixth aspect of the present invention is a lower propulsion body that is provided detachably with respect to the hollow tube body, and is provided with a rotating blade, and the lower propulsion body is engaged / removed by forward rotation and reverse rotation of the hollow tube body. The lower propulsion body is provided on the hollow tube body through a detachable connecting mechanism, and the lower propulsion body is fitted with the upper small diameter portion that can be fitted to the hollow tube body with an intermediate portion in the height direction as a boundary. A cylindrical main body having a lower large-diameter portion having an upper end surface which is engaged with the lower end surface, and the rotating blade provided in the lower large-diameter portion, and the connecting mechanism includes a lower end surface of the hollow tube and a cylinder The concave and convex portions provided on the upper end surface of the lower large-diameter portion of the main body are fitted with each other and are slightly rotatable in the circumferential direction, and the concave portion of one member of the hollow tube body and the lower propulsion body The engagement pin disposed in the tube is configured to be detachable from the engagement groove provided in the recess of the other member by forward and reverse rotation of the hollow tube body. The rotating blade provided in the main body is an open-ended blade having an opening for allowing the excavated earth and sand to pass inside, and the upper portion of the cylindrical main body is closed. Being
It is characterized by.

本発明によると、次の効果がある。（１）無排土で立孔を掘削できるので、手間の掛る排土処理が不要であり、経済的である。（２）掘削水を使用しないため、プラント設備が不要であり、掘削水の逃げによる掘削不能や地下水汚染の可能性がない。（３）回転羽根を具備した下部推進体を捨てビットとして地中に残して、一重管（中空管体）の引き抜きだけとなるので、掘削時間の短縮化を図れる。（４）回転羽根は開端羽根であるので下部推進体の内部に土砂を取り込みながら効率的に圧入または貫入できて掘削不能がない。（５）中空管体の内部空洞を利用して採放熱管などのU字パイプ、井戸ケーシング、地盤改良の薬剤注入用のスリーブ管、アースアンカー材の鋼棒など各種の機具の地中への挿入および、内部空洞を埋める充填材を充填でき、中空管体を引き上げることで前記の必要な作業を容易、迅速に完了できる。（５）以上により立孔の掘削工事その他の施工コストの大幅なコストダウンと速度アップが実現される。 The present invention has the following effects. (1) Since the vertical hole can be excavated without soil removal, laborious soil removal treatment is unnecessary and economical. (2) Since no drilling water is used, no plant equipment is required, and there is no possibility of excavation or groundwater contamination due to excavation of the drilling water. (3) Since the lower propulsion body provided with the rotary blade is discarded as a bit and left in the ground, only the single pipe (hollow pipe body) is pulled out, so that the excavation time can be shortened. (4) Since the rotating blades are open-ended blades, they can be efficiently press-fitted or penetrated while taking earth and sand into the lower propulsion body, and there is no inability to excavate. (5) Utilizing the internal cavity of the hollow tube to the ground of various equipment such as U-shaped pipes such as heat collection and discharge pipes, well casings, sleeve pipes for injecting chemicals for ground improvement, and steel bars for earth anchor materials And the filling material filling the internal cavity can be filled, and the necessary work can be completed easily and quickly by pulling up the hollow tube body. (5) By the above, a drastic cost reduction and speed increase of the excavation work of the vertical hole and other construction costs are realized.

以下、本発明の実施形態を図を参照して説明する。 Embodiments of the present invention will be described below with reference to the drawings.

図１〜図３は、本発明の立孔掘削装置を用いた基本的実施形態の第１工程〜第３工程を示す全体の概要図である。回転貫入式の立孔掘削装置１は、先端部に螺旋状の回転羽根２を有する下部推進体（ドリルビット）３と、下部推進体３に連結機構５を介して着脱自在に連結される上部の中空管体４とから構成される。連結機構５は、回転駆動側である中空管体４を立孔掘削時に一方向に回転するときは該中空管体４と下部推進体３は連結されて一体回転し、立孔掘削時と逆回転させることで中空管体４と下部推進体３の連結一体化を解除できる回転式の連結・分離機構を採用する。 1 to 3 are overall schematic diagrams showing first to third steps of a basic embodiment using the vertical excavation device of the present invention. A rotary penetrating hole drilling device 1 includes a lower propulsion body (drill bit) 3 having a spiral rotary blade 2 at a tip portion, and an upper portion that is detachably connected to the lower propulsion body 3 via a coupling mechanism 5. The hollow tube body 4 is configured. When the hollow tube 4 on the rotational drive side is rotated in one direction when excavating a hole, the connecting mechanism 5 is connected to the hollow propellant 4 and the lower propelling body 3 to rotate integrally. And a rotating connection / separation mechanism that can release the connection and integration of the hollow tube body 4 and the lower propelling body 3 by rotating in reverse.

各図によって工程の概要を説明すると、図１のように、地上に設置した回転圧入駆動装置（図示せず）によって中空管体４に回転力を加えることにより、下部推進体３は回転羽根２により中空管体４と一体に地中６に深く推進する。次に図２に示すように、中空管体４が地中所定の深さまで掘進した後、地上に設置の回転貫入駆動装置により中空管体４に逆回転力を加えることで連結機構５の係合が外れるので、この状態で中空管体４に引上げ力を加えることで、中空管体４は下部推進体３と離脱する。さらに、図３に示すように下部推進体４を地底に残して中空管体４にみを徐々に引き上げることにより、中空管体４を引き抜いた後に立孔７が形成される。 The outline of the process will be described with reference to the drawings. As shown in FIG. 1, the lower propulsion body 3 is rotated by applying a rotational force to the hollow tube body 4 by a rotary press-fitting drive device (not shown) installed on the ground. 2 is deeply propelled into the underground 6 integrally with the hollow tube 4. Next, as shown in FIG. 2, after the hollow tube body 4 is dug to a predetermined depth in the ground, a connection mechanism 5 is applied by applying a reverse rotational force to the hollow tube body 4 by a rotary penetration drive device installed on the ground. Therefore, the hollow tube 4 is detached from the lower propelling body 3 by applying a pulling force to the hollow tube 4 in this state. Furthermore, as shown in FIG. 3, the lower propellant 4 is left on the ground, and the hollow tube 4 is gradually lifted to form the standing hole 7 after the hollow tube 4 is pulled out.

本発明の特徴は、図１〜図３の工程で立孔７を掘削する際、従来のように掘削水を使用せず、それに伴い排土（スライム）を生じず、しかも効率的に立孔７を掘削できる点にある。さらに、立孔７は種々の適用形態で使用される。すなわち図２に示すように、中空管体４を所定深さ貫入し、下部推進体３から離脱した後、中空管体４を引き上げる前に、該中空管体４内に地中熱や地下水を利用するために必要な器具、地盤改良のための薬剤注入用のスリーブ管、地盤にアンカーを取る場合のアンカー鉄筋などを挿入し、これらの器具の周囲に伝熱用または定着用の各種充填材を充填して中空管体の内部の空洞を埋め戻し、その後に中空管体４を引き上げることにより、充填材を介して立孔７に挿入した各種部材と地中とが効率的な導通状態となり、または地中に確実に定着でき迅速に所期の施工を完了できる。なお、地盤が硬質土の場合などには、前記中空管体４を引き上げることで立孔を構築し、その後この立孔に地中熱や地下水を利用するために必要な器具等を挿入し、立孔を埋め戻す工程を実施しても良い。 The feature of the present invention is that when excavating the vertical hole 7 in the steps of FIGS. 1 to 3, no excavated water is used as in the prior art, so that no soil (slime) is generated, and the vertical hole is efficiently formed. The point is that 7 can be excavated. Furthermore, the vertical holes 7 are used in various applications. That is, as shown in FIG. 2, after the hollow tube body 4 has penetrated to a predetermined depth and separated from the lower propelling body 3, before the hollow tube body 4 is pulled up, And equipment necessary for using groundwater, sleeve pipes for injecting drugs to improve the ground, anchor rebars for anchoring the ground, etc., are inserted around these devices for heat transfer or fixation By filling various fillers to refill the cavity inside the hollow tube body and then pulling up the hollow tube body 4, various members inserted into the vertical holes 7 through the filler material and the ground are efficient. It is possible to establish a proper continuity, or to settle firmly in the ground and complete the intended construction quickly. In addition, when the ground is hard soil, a vertical hole is constructed by pulling up the hollow tube body 4, and thereafter, necessary tools for using underground heat and groundwater are inserted into the vertical hole. The step of refilling the vertical holes may be performed.

図４〜図６によって、中空管体４と、その下端に設ける短管状の連結部材８と、この連結部材８に着脱自在に連結される下部推進体の構成を順に説明する。 The structure of the hollow tube body 4, the short tubular connecting member 8 provided at the lower end thereof, and the lower propulsion body detachably connected to the connecting member 8 will be described in order with reference to FIGS.

下部推進体３は、図６に示すように上端部が天蓋１０で閉じられた所定の長さ（Ｌ）の筒状本体１１の下端に回転羽根２を設けて構成され、回転羽根２の中心部には開端口１２を有する構成とされる。回転羽根２は、筒状本体１１に対して同心状に固定され該筒状本体１１の下端１３から離れながら螺旋状に上昇し、終端面１４までほぼ１周程度周回するように形成されている。回転羽根２の周回数や開き角度等は筒状本体１１に連結する中空管体４の地中への回転圧入に適した設計とするのが良い。なお、螺旋状の回転羽根３に代えて非螺旋状の回転羽根を下部推進体３に設けても構わない。 As shown in FIG. 6, the lower propulsion body 3 is configured by providing a rotating blade 2 at the lower end of a cylindrical body 11 having a predetermined length (L) whose upper end is closed by a canopy 10. The part has an open end 12. The rotary blade 2 is fixed concentrically with respect to the cylindrical main body 11, rises in a spiral shape while being separated from the lower end 13 of the cylindrical main body 11, and is formed so as to circulate about one turn to the end surface 14. . The number of rotations, the opening angle, and the like of the rotary blade 2 are preferably designed to be suitable for rotational press-fitting into the ground of the hollow tube body 4 connected to the cylindrical main body 11. Note that a non-spiral rotating blade may be provided in the lower propelling body 3 instead of the spiral rotating blade 3.

筒状本体１１は、高さ方向の中間部に形成される段部を境として下側大径部１５と上側小径部１６とから構成され、かつ下側大径部１５の上端面には、周方向に所定の範囲にわたり凹部１７と凸部１８が対称的に２組形成されている。さらに、凹部１７の垂直一側面１７ａの近傍において、筒状本体１１の中心から半径方向に向けて設けられた係合ピン１９が配置されている。筒状本体１１の構成は、下側大径部１５を構成する下部筒体１５ａの内側に、上側径小部１６を構成する上部筒体１６ａを所定深さ差込み、各筒体の内外径差は殆どなく、上部筒体１６ａの下端縁を下部筒体１５ａの内面に開先溶接２０にて溶接接合して構成される。したがって、上部筒体１６ａの上部に天蓋１０が設けられ、また下部筒体１５ａの上端面に前記の凹部１７と凸部１８が対称的に形成される。また、上部筒体１６ａに基端部を螺合した係合ピン１９の先端が半径方向に突出して凹部１７の垂直一側面１７ａの近傍に位置する構成とされている。 The cylindrical main body 11 is composed of a lower large-diameter portion 15 and an upper small-diameter portion 16 with a step portion formed at an intermediate portion in the height direction as a boundary, and an upper end surface of the lower large-diameter portion 15 is Two sets of concave portions 17 and convex portions 18 are formed symmetrically over a predetermined range in the circumferential direction. Furthermore, in the vicinity of the vertical one side surface 17a of the recess 17, an engagement pin 19 provided in the radial direction from the center of the cylindrical main body 11 is disposed. The configuration of the cylindrical main body 11 is such that the upper cylinder 16a constituting the upper small diameter portion 16 is inserted into the inside of the lower cylinder 15a constituting the lower large diameter portion 15 by a predetermined depth, and the inner and outer diameter differences between the respective cylinders. There is almost no, and the lower end edge of the upper cylinder 16a is welded and joined to the inner surface of the lower cylinder 15a by groove welding 20. Therefore, the canopy 10 is provided on the upper part of the upper cylinder 16a, and the concave part 17 and the convex part 18 are formed symmetrically on the upper end surface of the lower cylinder 15a. In addition, the distal end of the engaging pin 19 screwed into the upper cylindrical body 16 a is projected in the radial direction and is positioned in the vicinity of the vertical one side surface 17 a of the recess 17.

中空管体４の下端部に設けられる連結部材８は、図５に示すように所定の長さ（Ｌ１）を有する短管で構成され上端部に雄ネジ２１を有し、この雄ネジ２１を中空管体４の下端部に形成した雌ネジ２２（図４）にねじ込むことで両部材を着脱自在に連結できる。連結部材８の下端部に所定の角度範囲にわたり凸部２３と凹部２４が形成されている。この凸部２３と凹部２４は、筒状本体１１の凹部１７と凸部１８に周方向に若干の回動間隙を介して嵌合できるように設けられる。また、連結部材８の凹部２４の底（図では上端）で周方向の一側には、筒状本体１１の係合ピン１９が周方向に若干回動することで係合・離脱できる係合溝２５が形成されている。 As shown in FIG. 5, the connecting member 8 provided at the lower end portion of the hollow tube body 4 is constituted by a short tube having a predetermined length (L1) and has a male screw 21 at the upper end portion. Can be detachably connected by screwing into a female screw 22 (FIG. 4) formed at the lower end of the hollow tube body 4. A convex portion 23 and a concave portion 24 are formed at a lower end portion of the connecting member 8 over a predetermined angle range. The convex portion 23 and the concave portion 24 are provided so as to be fitted to the concave portion 17 and the convex portion 18 of the cylindrical main body 11 via a slight rotation gap in the circumferential direction. Further, the engagement pin 19 of the cylindrical main body 11 can be engaged and disengaged by slightly rotating in the circumferential direction on one side in the circumferential direction at the bottom (upper end in the drawing) of the recess 24 of the connecting member 8. A groove 25 is formed.

したがって、図４に示すように中空管体４の下端に連結した連結部材８と下部推進体３を、各軸線が揃うように配置して、連結部材８と下部推進体３の各々の凸部２３と凹部１７、凹部２４と凸部１８を嵌合させたうえ、中空管体４を掘削時の方向に回転させることで係合ピン１９と係合溝２５が互いに係合し連結部材８と下部推進体３が連結される。この状態で中空管体４を掘削時の方向に回転させることでその回転力を下部推進体３に伝達できかつ、中空管体４と下部推進体３は離脱することがない。また、中空管体４を掘削時と反対に若干角度回転させることで係合ピン１９と係合溝２５の係合が外れ、中空管体４と下部推進体３を分離できる。 Therefore, as shown in FIG. 4, the connecting member 8 and the lower propelling body 3 connected to the lower end of the hollow tubular body 4 are arranged so that the respective axes are aligned, and the convex portions of the connecting member 8 and the lower propelling body 3 are arranged. The engagement pin 19 and the engagement groove 25 are engaged with each other by rotating the hollow tube body 4 in the direction of excavation after fitting the portion 23 and the recess 17 and the recess 24 and the projection 18. 8 and the lower propulsion body 3 are connected. In this state, by rotating the hollow tube body 4 in the direction of excavation, the rotational force can be transmitted to the lower propulsion body 3, and the hollow tube body 4 and the lower propulsion body 3 are not separated. Further, by rotating the hollow tube body 4 at a slight angle opposite to that during excavation, the engagement pin 19 and the engagement groove 25 are disengaged, and the hollow tube body 4 and the lower propulsion body 3 can be separated.

前記のように中空管体４の下端に下部推進体３が連結された状態で、該中空管体４を垂直に立て回転力を加えることで、連結部材８を介して中空管体４の回転力が下部推進体３に伝わり、回転羽根２によって中空管体４を地中に円滑に貫入できる（図１）。 In the state where the lower propulsion body 3 is connected to the lower end of the hollow tube body 4 as described above, the hollow tube body 4 is vertically raised and a rotational force is applied to the hollow tube body via the connecting member 8. The rotational force 4 is transmitted to the lower propelling body 3, and the hollow blade 4 can be smoothly penetrated into the ground by the rotating blade 2 (FIG. 1).

中空管体４が地中の所定深度まで貫入された後、中空管体４を回転圧入時と逆回転させることで、係合ピン１９が周方向に若干移動して係合溝２５から脱出しする。この状態で中空管体４を上方向に引き上げることで該中空管体４を下部推進体３から離脱させることができる（図２）。なお、図に示す連結機構５の構成は一例であって、その他の正逆回転式の係合・離脱機構を適用することは構わない。 After the hollow tube body 4 is penetrated to a predetermined depth in the ground, the engagement pin 19 is slightly moved in the circumferential direction by rotating the hollow tube body 4 in the reverse direction to the rotational press-fitting, so that Escape. In this state, the hollow tube body 4 can be detached from the lower propelling body 3 by pulling the hollow tube body 4 upward (FIG. 2). Note that the configuration of the coupling mechanism 5 shown in the drawing is merely an example, and other forward / reverse rotating engagement / disengagement mechanisms may be applied.

また、下部推進体３は回転羽根２の中心部に開端口１２を有するので、中空管体４の回転圧入に際し、掘削土砂は開端口１２を通って筒状本体１１の内部に入り天蓋１０の位置で止まるまで充填されるので、この充填土砂がクッションとなって円滑な掘削が可能になる。 Further, since the lower propulsion body 3 has the open end 12 at the center of the rotary blade 2, when the hollow tube body 4 is rotationally press-fitted, the excavated earth and sand passes through the open end 12 and enters the cylindrical main body 11 and the canopy 10. Since it is filled until it stops at this position, this filled earth and sand becomes a cushion and smooth excavation becomes possible.

中空管体４の下端に直接に連結機構を設けないで、連結機構５を備えた連結部材８を中空管体４にネジ連結するように構成したのは、立孔掘削装置１の製作の容易性とコストの低減化のためである。すなわち、中空管体４には市販の汎用製品である鋼管を使用し、該中空管体４に簡単な雌ネジ２２加工のみを施し、他方、単品部材として別工程で必要な加工を施した連結部材８を雄ネジ２１を介して中空管体４に結合することで、中空管体４に直接に連結機構５を設ける場合に比べて製造工程の効率化とコストダウンが図れるためである。なお、中空管体４の下端部に直に連結機構５を設け、下部推進体３を中空管体４の下端部に直接に着脱自在に構成することは構わない。 The construction of the borehole excavator 1 is such that the connecting member 8 provided with the connecting mechanism 5 is screw-connected to the hollow tube 4 without providing a connecting mechanism directly at the lower end of the hollow tube 4. This is for ease of use and cost reduction. That is, a commercially available general-purpose steel pipe is used for the hollow tube 4 and only the simple female screw 22 is processed on the hollow tube 4, and on the other hand, necessary processing is performed in a separate process as a single member. By connecting the connecting member 8 to the hollow tube body 4 via the male screw 21, the manufacturing process can be made more efficient and the cost can be reduced compared to the case where the connecting mechanism 5 is provided directly on the hollow tube body 4. It is. It should be noted that the connecting mechanism 5 may be provided directly at the lower end portion of the hollow tube body 4 and the lower propelling body 3 may be configured to be directly detachable from the lower end portion of the hollow tube body 4.

本発明では、硬い地盤や軟らかい地盤の何れの地盤への立孔７の掘削を想定しており、硬い地盤の場合は、螺旋状または非螺旋状の何れの回転羽根にあっても、回転力と下向きの力、又は回転力と打撃力を併用して下部推進体３の推進力で中空管体４を所期深度まで圧入または貫入して行くものである。すなわち、中空管体４の回転圧入に際して、回転羽根２が図のような螺旋状の羽根の場合は、地盤によっては回転のみで圧入でき、回転羽根が非螺旋状の場合は、押圧力を加えながら中空管体４を回転貫入していく。さらに、硬い地盤や礫層では、螺旋状や非螺旋状の何れの回転羽根の場合も、バイブロハンマによる打撃力を加えて貫入していく場合がある。また、掘削する立孔７の掘削孔の深度が深い場合は、例えば、長さ３ｍなどの中空管体４を必要本数だけ継ぎ足していくもので、その連結手段はネジ等を用いる。 In the present invention, excavation of the vertical hole 7 to any of the hard ground and the soft ground is assumed, and in the case of the hard ground, the rotational force can be applied to any spiral or non-spiral rotating blade. The hollow tube 4 is pressed into or penetrates to a desired depth by the propulsive force of the lower propelling body 3 using both the downward force and the rotational force and the striking force. That is, when the rotary blade 2 is a spiral blade as shown in the figure, the hollow tube body 4 can be press-fitted only by rotation depending on the ground, and when the rotary blade is non-spiral, the pressing force is applied. While adding, the hollow tube 4 is rotated and penetrated. Furthermore, in the case of a hard ground or gravel layer, there is a case where a spiral blade or a non-spiral rotating blade is applied with a striking force by a vibro hammer. Moreover, when the depth of the excavation hole of the vertical hole 7 to excavate is deep, for example, a required number of hollow tubes 4 having a length of 3 m or the like are added, and the connecting means uses screws or the like.

また、バイブロハンマにより打撃力を加えて中空管体４を回転貫入する場合は、中空管体４と連結部材８とのネジ結合部や中空管体４同士のをネジ結合部には、前記バイブロハンマによる打撃力に耐えるいわゆる打撃対応型のネジ構造を採用するもが良い。 Further, when the hollow tube 4 is rotated and penetrated by applying a striking force with a vibro hammer, the screw connection portion between the hollow tube body 4 and the connecting member 8 or the hollow tube bodies 4 is connected to the screw connection portion. A so-called hitting type screw structure that can withstand the hitting force of the vibratory hammer may be employed.

図７（ａ）〜（ｅ）は実施例の工程図を示し、図（ａ）は、先端に下部推進体３を連結した中空管体４を地中の所定深度まで回転圧入した工程を示す。図（ｂ）は、中空管体４を逆回転して下部推進体３を離脱した工程を示す。図（ｃ）は、下部推進体３から離脱した中空管体４の内部空洞に地中熱利用のためのU字状の採放熱管２６を挿入した工程を示す。図（ｄ）は、中空管体４の内部空洞を埋め戻すように、U字状の採放熱管２６と中空管体４の隙間に土砂、水、グラウト材等の熱伝達用の充填材２７を充填した工程を示す。これは、中空管体４である鋼管内部は空洞なので、採放熱管２６を挿入し終わったところで空洞部を埋め戻さないと熱を伝えないので充填材２７を充填（注入）して空洞を埋め戻すものである。図（ｅ）は、中空管体４を地上まで引き抜く工程を示し、これにより充填材２７と地中６とが直接接触する。 FIGS. 7A to 7E show process diagrams of the embodiment, and FIG. 7A shows a process in which a hollow tube body 4 having a lower propellant 3 connected to the tip is rotationally press-fitted to a predetermined depth in the ground. Show. FIG. 2B shows a process in which the hollow propellant 4 is rotated in the reverse direction and the lower propellant 3 is detached. FIG. (C) shows a process in which a U-shaped heat collecting and radiating tube 26 for use of underground heat is inserted into the internal cavity of the hollow tube body 4 detached from the lower propelling body 3. The figure (d) is the filling for heat transfer, such as earth and sand, water, and grout material, in the gap between the U-shaped heat collecting and radiating tube 26 and the hollow tube 4 so as to refill the internal cavity of the hollow tube 4. The process of filling the material 27 is shown. This is because the inside of the steel pipe, which is the hollow tube body 4, is hollow, so that heat cannot be transmitted unless the cavity is refilled after the heat-dissipating tube 26 has been inserted, so the filler 27 is filled (injected) to fill the cavity. It will be backfilled. FIG. (E) shows the process of pulling out the hollow tube 4 to the ground, whereby the filler 27 and the underground 6 are in direct contact.

前記の（ａ）〜（ｅ）の工程によると、下部推進体３を地中に残置した状態で、泥水や排土を生じることなく迅速かつ効率的に立孔７を削孔でき、立孔７内に充填された充填材２７の中に採放熱管２６が埋った状態で迅速かつ効率的に施工が完了する。 According to the steps (a) to (e), the vertical hole 7 can be drilled quickly and efficiently without causing muddy water or soil discharge with the lower propelling body 3 left in the ground. The construction is completed quickly and efficiently in a state in which the heat-dissipating tube 26 is buried in the filler 27 filled in the inside 7.

なお、図７（ａ）〜（ｅ）の工程を若干変更して実施することもできる。すなわち、地盤が硬質土の場合などには、中空管体４を所定の深度貫入した後、下部推進体３を地中に残して中空管体４を引き上げることで立孔を構築し、その後この立孔に地中熱や地下水を利用するために必要な器具等を挿入し、充填材２７を充填（注入）して立孔を埋め戻す工程を実施しても良い。 It should be noted that the steps shown in FIGS. 7A to 7E may be slightly modified. That is, when the ground is hard soil or the like, after penetrating the hollow tube 4 to a predetermined depth, a vertical hole is constructed by pulling up the hollow tube 4 while leaving the lower propellant 3 in the ground, Thereafter, a tool necessary for using underground heat or groundwater may be inserted into the vertical hole, and a step of filling (injecting) the filler 27 to refill the vertical hole may be performed.

中空管体４内に挿入する採放熱管２６は一例である。また、井戸構築の場合は、中空管体４の底に砂利などを配置した後、下端部にメッシュ状のストレーナーを有する井戸ケーシングが挿入され、周りに砕石、砂利等を充填し、中空管体４を引き抜いた後、井戸ケーシングと立孔７の間には前記砕石、砂利等が充填された状態となる。 The heat-dissipating tube 26 inserted into the hollow tube 4 is an example. In the case of well construction, after placing gravel on the bottom of the hollow tube 4, a well casing having a mesh-like strainer is inserted at the lower end and filled with crushed stone, gravel, etc. After the tubular body 4 is pulled out, the crushed stone, gravel and the like are filled between the well casing and the vertical hole 7.

さらに本発明は、改良したい地盤の所定の深度までスリーブ管を入れてスリーブ管の回りに薬剤を注入する地盤改良工法に適用できる。この場合は、所定深度まで圧入した中空管体４にスリーブ管を挿入し、中空管体４を上方に引き抜いた後、前記スリーブ管から地盤改良材を注入して周辺の地盤を改良していくものである。その他に、地面にアースアンカーを取りたいときは、所定深度貫入した中空管体４にアースアンカーの心棒となる鉄筋を挿入し、グラウト材等の経時硬化性材料を充填し、中空管体４を上方に引き抜いた後、経時硬化性材料の硬化を待ってアースアンカーの地中への定着施工が簡単にできる。
Further, the present invention can be applied to a ground improvement method in which a sleeve tube is inserted to a predetermined depth of the ground to be improved and a medicine is injected around the sleeve tube. In this case, the sleeve tube is inserted into the hollow tube body 4 that has been press-fitted to a predetermined depth, the hollow tube body 4 is pulled upward, and then the ground improvement material is injected from the sleeve tube to improve the surrounding ground. It will be. In addition, when it is desired to take an earth anchor on the ground, a reinforcing tube serving as a mandrel of the earth anchor is inserted into the hollow tube 4 penetrating a predetermined depth, and a time-curable material such as a grout material is filled. After pulling 4 upward, the earth anchor can be easily fixed to the ground after the time-curable material is cured.

本発明の基本的実施形態の第１工程を示す全体の概要図である。It is the whole outline figure showing the 1st process of basic embodiment of the present invention. 本発明の基本的実施形態の第２工程を示す全体の概要図である。It is the whole outline figure showing the 2nd process of basic embodiment of the present invention. 本発明の基本的実施形態の第３工程を示す全体の概要図である。It is the whole outline figure showing the 3rd process of basic embodiment of the present invention. （ａ）は、中空管体と、その下端に設ける短管状の連結部材と、これに着脱自在に連結された下部推進体の一部破断して示す側面図、（ｂ）は、（ａ）のＡ−Ａ断面図である。(A) is a partially cutaway side view of a hollow tube, a short tubular connecting member provided at the lower end thereof, and a lower propulsion member detachably connected to the hollow tube, and (b) is (a) It is AA sectional drawing of). （ａ）は、中空管体の側面図、（ｂ）は、（ａ）の底面図である。(A) is a side view of a hollow tubular body, (b) is a bottom view of (a). （ａ）、（ｂ）、（ｃ）は、下部推進体の平面図と正面図と一部縦断正面図である。(A), (b), (c) is the top view and front view of a lower propulsion body, and a partially longitudinal front view. （ａ）〜（ｅ）は実施例の工程図である。(A)-(e) is process drawing of an Example.

符号の説明Explanation of symbols

１立孔掘削装置
２螺旋状の回転羽根
３下部推進体
４中空管体
５連結機構
６地中
７立孔
８連結部材
１０天蓋
１１筒状本体
１２開端口
１３下端
１４終端面
１５下側大径部
１５ａ下部筒体
１６上側小径部
１６ａ上部筒体
１７凹部
１８凸部
１９係合ピン
２０開先溶接部
２１雄ネジ
２２雌ネジ
２３凸部
２４凹部
２５係合溝
２６ U字状の採放熱管
２７充填材 1 Vertical drilling device
DESCRIPTION OF SYMBOLS 2 Spiral rotary blade 3 Lower propulsion body 4 Hollow tube body 5 Connection mechanism 6 Underground 7 Standing hole 8 Connection member 10 Canopy 11 Cylindrical main body 12 Open end port 13 Lower end 14 Termination surface 15 Lower large diameter part 15a Lower cylinder Body 16 Upper small-diameter portion 16a Upper cylindrical body 17 Concave portion 18 Convex portion 19 Engagement pin 20 Groove welded portion 21 Male screw 22 Female screw 23 Convex portion 24 Concavity 25 Engagement groove 26 U-shaped heat collection tube 27 Filler

Claims

回転羽根を有する下部推進体と、下部推進体に連結機構を介して着脱自在に連結される中空管体とからなり、前記連結機構は、中空管体を地中に回転貫入した後、貫入時とは逆回転すると共に引上げ力を加えることで下部推進体から離脱可能に構成され、
下部推進体は、高さ方向の中間部を境として中空管体に嵌合できる上側小径部および、中空管体の下端面が係止する上端面を有する下側大径部からなる筒状本体と、下側大径部に設けられる前記回転羽根からなり、前記連結機構は、中空管体の下端面と筒状本体の下側大径部の上端面にそれぞれ設けた凹凸部を互いに嵌合すると共に周方向に若干回動可能に設けられ、かつ、中空管体と下部推進体の一方の部材の凹部に配置された係合ピンが、中空管体の正逆回転により他方の部材の凹部に設けた係合溝に係脱可能に構成され、
筒状本体に設けられる回転羽根は、中心部に下側大径部より縮径され、掘削土砂を内部へ通過させるための開口を有する開端羽根であり、かつ前記筒状本体の上部は、閉塞されていること
を特徴とする立孔掘削装置。 It consists of a lower propulsion body having rotating blades and a hollow tube body that is detachably connected to the lower propulsion body via a coupling mechanism, and the coupling mechanism rotates and penetrates the hollow tube body into the ground, It is configured to be disengaged from the lower propulsion body by applying a pulling force while rotating in reverse from the time of penetration,
The lower propulsion body is a cylinder composed of an upper small-diameter portion that can be fitted to the hollow tube with an intermediate portion in the height direction as a boundary, and a lower large-diameter portion having an upper end surface that is engaged with the lower end surface of the hollow tube. And the rotating blades provided on the lower large-diameter portion, and the coupling mechanism includes uneven portions provided on the lower end surface of the hollow tube body and the upper end surface of the lower large-diameter portion of the cylindrical main body, respectively. Engagement pins that are fitted to each other and are provided so as to be slightly rotatable in the circumferential direction and disposed in the recess of one member of the hollow tube body and the lower propulsion body are rotated by forward and reverse rotation of the hollow tube body. It is configured to be engageable with and disengageable from the engaging groove provided in the recess of the other member,
The rotating blade provided in the cylindrical main body is an open end blade having a diameter reduced from the lower large diameter portion at the center, and an opening for allowing the excavated earth and sand to pass inside, and the upper portion of the cylindrical main body is closed Tatsuana drilling device according to claim <br/> that it is.

既製の鋼管からなる中空管体の端部に短管状の連結部材がネジ結合され、前記連結機構における中空管体の凹凸部は、該連結部材に設けられていることを特徴とする請求項１記載の立孔掘削装置。 Short tubular coupling member to an end of the hollow tube body made of ready-made steel pipes are screwed, uneven portions of the hollow tube in the coupling mechanism, characterized in that provided on the connecting member according Item 2. The hole excavator according to item 1 .

請求項１又は２記載の立孔掘削装置により地中の所定深度まで中空管体を回転貫入した後、該中空管体を逆回転して下部推進体との係合を解除し地上に引き抜き抜くことで、中空管体を引き抜いた後にできる立孔を、蓄熱、地中熱利用、井戸構築、地盤改良などに用いる管その他の各種機具、またはアースアンカーなどの挿入孔とすることを特徴とする立孔掘削方法。 After the hollow tube body is rotated and penetrated to a predetermined depth in the ground by the vertical hole excavator according to claim 1 or 2 , the hollow tube body is reversely rotated to disengage the lower propulsion body and By pulling out, the vertical hole created after pulling out the hollow tube shall be used as an insertion hole for pipes and other equipment used for heat storage, underground heat utilization, well construction, ground improvement, etc., or earth anchors, etc. A vertical hole drilling method.

請求項１又は２記載の立孔掘削装置により地中の所定深度まで中空管体を回転貫入した後、該中空管体を逆回転して下部推進体との係合を解除し、該中空管体の内部に蓄熱、地中熱利用、井戸構築、地盤改良などに用いる管その他の各種機具、またはアースアンカーを挿入し、つづいて中空管体に充填材を充填した後、該中空管体を地上に引き抜き抜くことを特徴とする立孔掘削方法。 After rotating and penetrating the hollow tube body to a predetermined depth in the ground by the vertical hole excavation device according to claim 1 or 2 , the hollow tube body is reversely rotated to disengage the lower propulsion body, After inserting a pipe or other equipment used for heat storage, underground heat utilization, well construction, ground improvement, etc., or an earth anchor inside the hollow tube body, and then filling the hollow tube body with a filler, A hole excavation method, wherein the hollow tube body is pulled out to the ground.

請求項１又は２記載の立孔掘削装置により地中の所定深度まで中空管体を回転貫入した後、該中空管体を逆回転して下部推進体との係合を解除して地上に引き抜くことで立孔を構築し、その後、該立孔の内部に蓄熱、地中熱利用、井戸構築、地盤改良などに用いる管その他の各種機具、またはアースアンカーを挿入し、つづいて充填材を充填する立孔掘削方法。 After the hollow tube body is rotated and penetrated to a predetermined depth in the ground by the vertical hole excavation device according to claim 1 or 2 , the hollow tube body is reversely rotated to release the engagement with the lower propulsion body and A vertical hole is constructed by pulling it out, and after that, pipes and other equipment used for heat storage, underground heat utilization, well construction, ground improvement, etc., or earth anchors are inserted into the vertical hole, followed by a filler. The hole drilling method to fill.

中空管体に対して着脱自在に設けられ、回転羽根を具備した下部推進体であって、該下部推進体は、中空管体の正回転と逆回転により係合・離脱可能な連結機構を介して該中空管体に設けられ、
前記下部推進体は、高さ方向の中間部を境として中空管体に嵌合できる上側小径部および、中空管体の下端面が係止する上端面を有する下側大径部からなる筒状本体と、下側大径部に設けられる前記回転羽根からなり、前記連結機構は、中空管体の下端面と筒状本体の下側大径部の上端面にそれぞれ設けた凹凸部を互いに嵌合すると共に周方向に若干回動可能に設けられ、かつ、中空管体と下部推進体の一方の部材の凹部に配置された係合ピンが、中空管体の正逆回転により他方の部材の凹部に設けた係合溝に係脱可能に構成され、
筒状本体に設けられる回転羽根は、中心部に下側大径部より縮径され、掘削土砂を内部へ通過させるための開口を有する開端羽根であり、かつ前記筒状本体の上部は、閉塞されていること
を特徴とする下部推進体。 A lower propulsion body provided detachably with respect to the hollow tube body, the lower propulsion body being engaged and disengaged by forward rotation and reverse rotation of the hollow tube body Via the hollow tube body,
The lower propulsion body includes an upper small-diameter portion that can be fitted into the hollow tube with a middle portion in the height direction as a boundary, and a lower large-diameter portion having an upper end surface that is engaged with the lower end surface of the hollow tube. Consists of a cylindrical main body and the rotating blades provided on the lower large-diameter portion, and the coupling mechanism is provided on the lower end surface of the hollow tube and the upper and lower surface of the lower large-diameter portion of the cylindrical main body. Are engaged with each other and are provided so as to be slightly rotatable in the circumferential direction, and an engagement pin disposed in a concave portion of one member of the hollow tube body and the lower propulsion body rotates forward and reverse of the hollow tube body. Is configured to be engageable with and disengageable from the engaging groove provided in the recess of the other member,
The rotating blade provided in the cylindrical main body is an open end blade having a diameter reduced from the lower large diameter portion at the center, and an opening for allowing the excavated earth and sand to pass inside, and the upper portion of the cylindrical main body is closed Lower propulsion body characterized by being made .