JP4216492B2

JP4216492B2 - Ground improvement device

Info

Publication number: JP4216492B2
Application number: JP2001173123A
Authority: JP
Inventors: 満生原
Original assignee: エポコラム機工株式会社
Priority date: 2001-06-07
Filing date: 2001-06-07
Publication date: 2009-01-28
Anticipated expiration: 2021-06-07
Also published as: JP2002363969A

Description

【０００１】
【発明の属する技術分野】
本発明は、地盤改良装置に関する。
【０００２】
【従来の技術】
従来、地盤改良装置の一形態として、内側軸と外側軸とを内外側二重軸に形成すると共に、両内・外側軸を相互に逆回転可能となした掘削軸体と、同掘削軸体に、内側撹拌翼と外側撹拌翼とを内外側位置にて相対的に逆回転させるべく取り付けた相対撹拌翼体とを具備したものがあり、掘削軸体は、軸線方向に複数継ぎ足し状に接続して掘削深さを変更可能となしている。
【０００３】
そして、掘削軸体は、内側軸の軸長を外側軸の軸長よりも長めに設定して、内側軸の端部を外側軸の端部から露出するようにしており、かかる掘削軸体を接続する際には、露出する上下側の内側軸の端部同士を接続ピンにより接続し、これら内側軸の端部の外周に外側軸の端部同士を接続する接続体を介設するようにしている。
【０００４】
ここで、接続体は、筒状体を軸線方向に二つ割り状態となした左右一対の半筒状片と、各半筒状片の上下端部と側縁部とにそれぞれ設けた接続用フランジ片とを具備し、内側軸の端部の外方より左右一対の半筒状片を側縁部の接続用フランジ片を介して突き合わせ状態にして接続ボルトにより接続すると共に、上下端部の接続用フランジ片を外側軸の上下端部に形成した接続用フランジ片に突き合わせ状態にして接続ボルトにより接続するようにしている。
【０００５】
【発明が解決しようとする課題】
ところが、上記した掘削軸体の接続作業では、外側軸同士を接続する際に、接続体を介して接続するようにしているために、かかる接続作業に手間を要するという不具合がある。
【０００６】
すなわち、掘削軸体の接続作業は、掘削軸体の建て込み長さによっては高所にて行わなければならないものであるが、接続体は、左右一対の半筒状片同士を突き合わせ状態にして接続ボルトにより接続し、その後に、外側軸の端部と突き合わせ状態にして接続ボルトにより接続しなければならないという煩雑さがあるために、接続作業にかなりの手間を要して、掘削作業能率を低下させている。
【０００７】
【課題を解決するための手段】
そこで、本発明では、内側軸と外側軸とを内外側二重軸に形成すると共に、両内・外側軸を相互に逆回転可能となした掘削軸体と、同掘削軸体に、内側撹拌翼と外側撹拌翼とを内外側位置にて相対的に逆回転させるべく取り付けた相対撹拌翼体とを具備し、掘削軸体は、軸線方向に複数継ぎ足し状に接続して掘削深さを変更可能となした地盤改良装置において、内・外側軸は、それぞれ一端に段付き凸状の雄側端部を形成する一方、他端に同雄側端部が嵌入する段付き凹状の雌側端部を形成して、これら雄側端部と雌側端部とを印籠嵌合可能となし、内側軸の印籠嵌合部には、外側軸に形成した接続ピン挿入孔を通して接続ピンを抜き差し自在に挿入して、複数の内側軸を接続可能となし、上記接続ピンは、同接続ピンの外周面の中途部に略直交する方向に押圧させるようにした接続ピン抜け止めボルトにより固定した地盤改良装置であって、上下の内側軸同士及び外側軸同士を印籠嵌合して形成される各印籠嵌合部には、略水平方向に貫通する接続ピン貫入孔を形成して、各接続ピン貫入孔中に接続ピンを抜き差し自在に貫入させることにより、上下の内側軸同士及び外側軸同士を接続して、それぞれ内側軸同士及び外側軸同士を同軸上にて一体回転させることができるようにし、内側軸同士を接続している接続ピンの軸線方向と符合する外側軸の部分にはそれぞれ接続ピン挿入孔を形成し、各接続ピン挿入孔を閉蓋体により開閉自在に閉蓋して、各閉蓋体を取り外して各接続ピン挿入孔を開孔させた状態にて、各接続ピン挿入孔を通して各接続ピンを抜き差し自在に挿入可能とし、各印籠嵌合部の雌側端部には、各接続ピン貫入孔中に貫入した各接続ピンの中途部と符合するボルト孔を形成して、各ボルト孔中に接続ピン抜け止めボルトを螺着すると共に、各接続ピン抜け止めボルトの先端部を接続ピンの中途部の外周面に略直交方向から押圧状態にて当接させることにより、各接続ピンを各印籠嵌合部に固定することができるようにし、内側の各接続ピン抜け止めボルトの軸線方向と符合する外側軸の部分にはそれぞれ抜け止めボルト挿入孔を形成し、同抜け止めボルト挿入孔を閉蓋体により開閉自在に閉蓋して、同閉蓋体を取り外して抜け止めボルト挿入孔を開孔させた状態にて、同抜け止めボルト挿入孔を通して接続ピン抜け止めボルトをボルト孔に取り付け・取り外し自在となしたことを特徴とする地盤改良装置を提供するものである。
【００１１】
【発明の実施の形態】
以下に、本発明の実施の形態について説明する。
【００１２】
すなわち、本発明に係る地盤改良装置は、基本的構造として、内側軸と外側軸とを内外側二重軸に形成すると共に、両内・外側軸を相互に逆回転可能となした掘削軸体と、同掘削軸体に、内側撹拌翼と外側撹拌翼とを内外側位置にて相対的に逆回転させるべく取り付けた相対撹拌翼体とを具備し、掘削軸体は、軸線方向に複数継ぎ足し状に接続して掘削深さを変更可能となしている。
【００１３】
そして、特徴的構造として、内・外側軸は、それぞれ一端に段付き凸状の雄側端部を形成する一方、他端に同雄側端部が嵌入する段付き凹状の雌側端部を形成して、これら雄側端部と雌側端部とを印籠嵌合可能となし、これら印籠嵌合部には、外側軸に形成した接続ピン挿入孔を通して接続ピンを抜き差し自在に挿入して、複数の掘削軸体を接続可能となしている。
【００１４】
しかも、接続ピンは、接続ピン抜け止めボルトを介して固定しており、同接続ピン抜け止めボルトは、接続ピンの外周面の中途部に略直交する方向に押圧させるようにしている。
【００１５】
【実施例】
以下に、本発明の実施例を、図面を参照しながら説明する。
【００１６】
図1に示すＡは、本発明に係る地盤改良装置であり、同地盤改良装置Ａは、自走可能なベースマシン１に上下方向に伸延するリーダ２を設け、同リーダ２にモータ支持体３を昇降自在に取り付け、同モータ支持体３に駆動用モータ４を搭載し、同駆動用モータ４に二重反転歯車機構５を介して上下方向に伸延する掘削軸体６の上端部を着脱自在に取り付け、同掘削軸体６の下部周面に相対撹拌翼体７を取り付けると共に、同掘削軸体６の下端部に掘削刃体８を取り付けている。
【００１７】
なお、前記掘削軸体６には固化材供給ホース（図示せず）を介して固化材を供給し、掘削軸体６の下端部と前記相対撹拌翼体７より固化材を吐出させるようにしている。
【００１８】
掘削軸体６は、図２〜図４にも示すように、上下方向に伸延させて形成した筒状の内側軸10と、同内側軸10の外周を囲繞する状態に上下方向に伸延させて形成した筒状の外側軸11とから内外側二重軸構造に構成しており、内側軸10と外側軸11は、駆動用モータ４により二重反転歯車機構５を介して同一軸芯廻りに相互に反対方向に回転するようにしている。
【００１９】
そして、内側軸10中には上下方向に伸延させて形成した筒状体12を挿通して、同筒状体12中に内側固化材供給路13を形成する一方、同筒状体12の外周面と内側軸10の内周面との間に外側固化材供給路14を形成している。
【００２０】
しかも、内側軸10の上端部には連通路（図示せず）を形成して、同連通路を介して内側固化材供給路13と外側固化材供給路14とを連通させ、前記した固化材供給ホースを通して供給される固化材を、内側固化材供給路13と外側固化材供給路14とに分流させて供給することができるようにしている。
【００２１】
ここで、掘削軸体６は、軸線方向に複数継ぎ足し状に接続することにより、掘削深さを変更可能としている。
【００２２】
また、相対撹拌翼体７は、前記内側軸10に連設した内側撹拌翼15と、前記外側軸11に連設した外側撹拌翼16とを具備しており、これら内・外側撹拌翼15,16を内外側位置にて相対的に逆回転させるようにしている。
【００２３】
上記のような構成において、本発明の要旨は、複数の掘削軸体６の接続構造にあり、以下に図２〜図４を参照しながら説明する。
【００２４】
すなわち、内・外側軸10,11は、それぞれ一端に段付き凸状の雄側端部10a,11aを形成する一方、他端に同雄側端部10a,11aが嵌入する段付き凹状の雌側端部10b,11bを形成して、これら雄側端部10a,11aと雌側端部10b,11bとにより上下方向に印籠嵌合する印籠嵌合部20,21を形成している。
【００２５】
そして、印籠嵌合部20,21には、略水平方向に貫通する接続ピン貫入孔22,22,23,23を形成して、各接続ピン貫入孔22,22,23,23中に接続ピン24,24,25,25を抜き差し自在に貫入させることにより、上下の内側軸10,10同士及び外側軸11,11同士を接続（連結）して、それぞれ内側軸10,10同士及び外側軸11,11同士を同軸上にて一体回転させることができるようにしている。
【００２６】
ここで、接続ピン貫入孔22,22,23,23は、雄側端部10a,11aの外周面に略水平方向に伸延する断面半円弧状の凹条溝22a,23aを形成する一方、雌側端部10b,11bの内周面に略水平方向に伸延する断面半円弧状の凹条溝22b,23bを形成し、両凹条溝22a,22b,23a,23bを対向状態に符合させて形成している。
【００２７】
しかも、内側軸10,10同士を接続している各接続ピン24,24の軸線方向と符合する外側軸11の部分にはそれぞれ接続ピン挿入孔26,26,26,26を形成し、各接続ピン挿入孔26,26 ,26,26を閉蓋体27,27,27,27により開閉自在に閉蓋しており、各閉蓋体27を取り外して各接続ピン挿入孔26を開孔させた状態にて、各接続ピン挿入孔26を通して各接続ピン24,24を抜き差し自在に挿入可能としている。
【００２８】
また、各印籠嵌合部20,21の雌側端部10b,11bには、各接続ピン貫入孔22,22,23,23中に貫入した各接続ピン24,24,25,25の中途部と符合するボルト孔28,28,29,29を形成して、各ボルト孔28,28,29,29中に接続ピン抜け止めボルト30,30,31,31を螺着すると共に、各接続ピン抜け止めボルト30,30,31,31の先端部を接続ピン24,24,25,25の中途部の外周面に略直交方向から押圧状態にて当接させることにより、各接続ピン24,24,25,25を各印籠嵌合部20,21に固定（抜け止め）することができるようにしている。
【００２９】
しかも、内側の各接続ピン抜け止めボルト30,30の軸線方向と符合する外側軸11の部分にはそれぞれ抜け止めボルト挿入孔32,32を形成し、各抜け止めボルト挿入孔32,32を閉蓋体33,33により開閉自在に閉蓋しており、各閉蓋体33,33を取り外して各抜け止めボルト挿入孔32,32を開孔させた状態にて、各抜け止めボルト挿入孔32,32を通して各接続ピン抜け止めボルト30,30を各ボルト孔28,28に取り付け・取り外し自在としている。
【００３０】
また、筒状体12は、図２に示すように、一端に段付き凸状の雄側端部12aを形成する一方、他端に同雄側端部12aが嵌入する段付き凹状の雌側端部12bを形成して、これら雄側端部12aと雌側端部12bとにより上下方向に印籠嵌合する印籠嵌合部40を形成している。
【００３１】
そして、図２に示すように、相対撹拌翼体７の直上方に位置する掘削軸体６の下部にはシール部35を設けており、同シール部35は、内側軸10の外周面と外側軸11の内周面との間に上下一対のローラベアリング36,37を介設して、内・外側軸10,11を同一軸線上にて相互に反対方向に回転自在となすと共に、上側のローラベアリング36よりも上方位置において、内側軸10の外周面と外側軸11の内周面との間にシール在としてのパッキン38を介設する一方、下側のローラベアリング37よりも下方位置において、内側軸10の外周面と外側軸11の内周面との間にシール在としてのパッキン39を介設している。41はグリス注入孔である。
【００３２】
このようにして、掘削軸体６の下部にシール部35を設けることにより、相対撹拌翼体７側から掘削軸体６の下部側に泥土等が流入するのを防止している。
【００３３】
次に、上記した掘削軸体６の接続作業手順を、図５を参照しながら順次説明する。
【００３４】
▲１▼図５（ａ）に示すように、地盤改良装置Ａを地盤改良地点に移動させる。Ｇは地盤である。
【００３５】
この際、リーダ２により支持可能な長さの掘削軸体６を駆動用モータ４に二重反転歯車機構５を介して取り付けておく。
【００３６】
▲２▼図５（ｂ）に示すように、掘削軸体６を回転させることにより、相対撹拌翼体７と掘削刃体８を回転させて、地盤Ｇを掘削すると共に固化材を吐出して土と固化材とを撹拌し、地盤Ｇを改良する。
【００３７】
▲３▼図５（ｂ）に示すように、最上段の掘削軸体６を残して、一旦、地盤改良作業を中断する。42は掘削軸体支持片であり、同掘削軸体支持片は切り離された掘削軸体６を係止片43を介して掘削孔44中に支持するものである。
【００３８】
▲４▼図５（ｃ）に示すように、最上段の掘削軸体６と、その下段の掘削軸体６とを切り離す。
【００３９】
この際、最上段の掘削軸体６とその下段の掘削軸体６との接続部である印籠嵌合部20,21において、まず、閉蓋体33,33を取り外して各抜け止めボルト挿入孔32,32を開孔し、各抜け止めボルト挿入孔32,32を通して内側の各接続ピン抜け止めボルト30,30を各ボルト孔28,28から取り外す。続いて、閉蓋体27,27を取り外して各接続ピン挿入孔26,26を開孔し、各接続ピン挿入孔26,26を通して内側軸10,10同士を接続している各接続ピン24,24を各接続ピン貫入孔22,22より抜き取る。
【００４０】
次に、外側軸11に取り付けている各抜け止めボルト31,31を各ボルト孔29,29から取り外し、続いて、外側軸11, 11同士を接続している各接続ピン25,25を各接続ピン貫入孔23,23より抜き取る。
【００４１】
このようにして、印籠嵌合部20,21の印籠嵌合を解除することができ、最上段の掘削軸体６とその下段の掘削軸体６とを切り離すことができる。
【００４２】
この際、筒状体12,12同士を印籠嵌合している印籠嵌合部40も、掘削軸体6,6の切り離しと同時に嵌合解除される。
【００４３】
▲５▼図５（ｃ）に示すように、予め地盤Ｇに建て込んでおいた継ぎ足し用の掘削軸体６の上端部に、最上段の掘削軸体６の下端部を印籠嵌合して接続する。
【００４４】
この際、まず、最上段の掘削軸体６とその下段の継ぎ足し用の掘削軸体６の中心部に配置している筒状体12,12の雄側端部12aと雌側端部12bとを印籠嵌合し、その後に、内・外側軸10,10,11,11同士を接続する。
【００４５】
すなわち、内・外側軸10,10,11,11同士の接続部である印籠嵌合部20,21において、各接続ピン25,25を各接続ピン貫入孔23,23中に貫入して外側軸11,11同士を接続し、続いて、各抜け止めボルト31,31を各ボルト孔29,29中に螺着して、各抜け止めボルト31,31により各接続ピン25,25を押圧して固定する。
【００４６】
次に、閉蓋体27,27を取り外して各接続ピン挿入孔26,26を開孔し、各接続ピン挿入孔26,26を通して各接続ピン24,24を各接続ピン貫入孔22,22中に貫入して内側軸10,10同士を接続し、続いて、閉蓋体33,33を取り外して各抜け止めボルト挿入孔32,32を開孔し、各抜け止めボルト挿入孔32,32を通して内側の各接続ピン抜け止めボルト30,30を各ボルト孔28,28に螺着して、各抜け止めボルト30,30により各接続ピン24,25を押圧して固定する。
【００４７】
その後に、各接続ピン挿入孔26,26を閉蓋体27, 27により閉蓋すると共に、各抜け止めボルト挿入孔32,32を閉蓋体33,33により閉蓋して、内側軸10と外側軸11との間に泥土等が侵入しないようにしておく。
【００４８】
▲６▼図５（ｄ）に示すように、最上段の掘削軸体６と継ぎ足し用の掘削軸体６とを接続した状態にて吊り上げて、継ぎ足し用の掘削軸体６を地盤Ｇより引き抜く。
【００４９】
▲７▼図５（ｅ）に示すように、継ぎ足し用の掘削軸体６の下端部に取り付けている捨て掘り用ヘッド45を取り外し、同掘削軸体６の下端部を、先に、地盤改良していた掘削軸体６の上端部に接続する。
【００５０】
この際、掘削軸体6, 6同士の接続は、前記した▲５▼と同様に行う。
【００５１】
このようにして、地盤改良作業を順次行い、所望の掘削深さに満たない場合には、適宜、継ぎ足し用の掘削軸体６を継ぎ足すことにより、所望の掘削深さまで地盤改良を行うことができる。
【００５２】
この際、掘削軸体６の継ぎ足し作業は、上記したように接続ピン24,24,25,25の抜き差しにより簡単かつ確実に行うことができるため、地盤改良作業能率を向上させることができる。
【００５３】
【発明の効果】
本発明によれば、次のような効果が得られる。
【００５４】
本発明では、内・外側軸は、それぞれ一端に段付き凸状の雄側端部を形成する一方、他端に同雄側端部が嵌入する段付き凹状の雌側端部を形成して、これら雄側端部と雌側端部とを印籠嵌合可能となし、内側軸の印籠嵌合部には、外側軸に形成した接続ピン挿入孔を通して接続ピンを抜き差し自在に挿入して、複数の内側軸を接続可能となしている。
【００５５】
このようにして、内・外側軸をそれぞれ印籠嵌合して位置決めすると共に、これら印籠嵌合部に外側軸に形成した接続ピン挿入孔を通して接続ピンを抜き差し自在に挿入することにより、掘削軸体同士を接続することができるため、かかる接続作業を構造簡易にして迅速かつ確実に行うことができる。
【００５６】
しかも、かかる接続ピンの抜き差し作業は、高所においても楽に行えるため、接続作業能率、さらには、掘削（地盤改良）作業能率を向上させることができる。
【００５７】
また、掘削軸体の接続解除作業も、接続ピンを引き抜くことにより簡単に行うことができて、この点からも掘削（地盤改良）作業能率を向上させることができる。
【００５８】
また、接続ピンは、同接続ピンの外周面の中途部に略直交する方向に押圧させるようにした接続ピン抜け止めボルトにより固定している。
【００５９】
このようにして、接続ピンを接続ピン抜け止めボルトを介して固定しているため、掘削作業中に接続ピンが抜けるという不具合の発生を確実に防止することができて、掘削（地盤改良）作業性能を良好に確保することができる。
しかも、接続ピン抜け止めボルトを進出方向に締め付けることにより、接続ピンを簡単かつ確実に固定することができて、この点からも掘削（地盤改良）作業性能を良好に確保することができる。
【００６０】
また、上下の内側軸同士及び外側軸同士を印籠嵌合して形成される各印籠嵌合部には、略水平方向に貫通する接続ピン貫入孔を形成して、各接続ピン貫入孔中に接続ピンを抜き差し自在に貫入させることにより、上下の内側軸同士及び外側軸同士を接続（連結）して、それぞれ内側軸同士及び外側軸同士を同軸上にて一体回転させることができるようにし、内側軸同士を接続している接続ピンの軸線方向と符合する外側軸の部分にはそれぞれ接続ピン挿入孔を形成し、各接続ピン挿入孔を閉蓋体により開閉自在に閉蓋して、各閉蓋体を取り外して各接続ピン挿入孔を開孔させた状態にて、各接続ピン挿入孔を通して各接続ピンを抜き差し自在に挿入可能とし、各印籠嵌合部の雌側端部には、各接続ピン貫入孔中に貫入した各接続ピンの中途部と符合するボルト孔を形成して、各ボルト孔中に接続ピン抜け止めボルトを螺着すると共に、各接続ピン抜け止めボルトの先端部を接続ピンの中途部の外周面に略直交方向から押圧状態にて当接させることにより、各接続ピンを各印籠嵌合部に固定（抜け止め）することができるようにし、内側の各接続ピン抜け止めボルトの軸線方向と符合する外側軸の部分にはそれぞれ抜け止めボルト挿入孔を形成し、同抜け止めボルト挿入孔を閉蓋体により開閉自在に閉蓋して、同閉蓋体を取り外して抜け止めボルト挿入孔を開孔させた状態にて、同抜け止めボルト挿入孔を通して接続ピン抜け止めボルトをボルト孔に取り付け・取り外し自在となしている。
【００６１】
このようにして、上段の掘削軸体と、その下段の掘削軸体とを切り離す際には、上段の掘削軸体とその下段の掘削軸体との接続部である印籠嵌合部において、まず、閉蓋体を取り外して各抜け止めボルト挿入孔を開孔し、各抜け止めボルト挿入孔を通して内側の各接続ピン抜け止めボルトを各ボルト孔から取り外す。続いて、閉蓋体を取り外して各接続ピン挿入孔を開孔し、各接続ピン挿入孔を通して内側軸同士を接続している各接続ピンを各接続ピン貫入孔より抜き取る。
次に、外側軸に取り付けている各抜け止めボルトを各ボルト孔から取り外し、続いて、外側軸同士を接続している各接続ピンを各接続ピン貫入孔より抜き取る。このようにして、印籠嵌合部の印籠嵌合を解除することができ、上段の掘削軸体とその下段の掘削軸体とを切り離すことができる。
また、上段の掘削軸体と、その下段の掘削軸体とを接続する際には、内・外側軸同士の接続部である印籠嵌合部において、各接続ピンを各接続ピン貫入孔中に貫入して外側軸同士を接続し、続いて、各抜け止めボルトを各ボルト孔中に螺着して、各抜け止めボルトにより各接続ピンを押圧して固定する。
次に、閉蓋体を取り外して接続ピン挿入孔を開孔し、接続ピン挿入孔を通して接続ピンを接続ピン貫入孔中に貫入して内側軸同士を接続し、続いて、閉蓋体を取り外して抜け止めボルト挿入孔を開孔し、抜け止めボルト挿入孔を通して内側の接続ピン抜け止めボルトをボルト孔に螺着して、抜け止めボルトにより接続ピンを押圧して固定する。
その後に、接続ピン挿入孔を閉蓋体により閉蓋すると共に、抜け止めボルト挿入孔を閉蓋体により閉蓋することにより、内側軸と外側軸との間に泥土等が侵入しないようにすることができる。
【図面の簡単な説明】
【図１】本発明にかかる地盤改良装置の側面図。
【図２】同地盤改良装置の掘削軸体の断面側面図。
【図３】図２のI-I線断面図。
【図４】図２のII-II線断面図。
【図５】掘削軸体の接続作業の説明図。
【符号の説明】
Ａ地盤改良装置
１ベースマシン
２リーダ
３モータ支持体
４駆動用モータ
５二重反転歯車機構
６掘削軸体
７相対撹拌翼体
８掘削刃体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ground improvement device.
[0002]
[Prior art]
Conventionally, as one form of the ground improvement device, an inner shaft and an outer shaft are formed as an inner and outer double shaft, and both the inner and outer shafts can be rotated in reverse to each other. In addition, there is provided a relative stirring blade body that is attached so as to relatively reversely rotate the inner stirring blade and the outer stirring blade at the inner and outer positions, and a plurality of excavation shaft bodies are connected in an axial direction. The drilling depth can be changed.
[0003]
The excavation shaft body is set such that the axial length of the inner shaft is longer than the axial length of the outer shaft so that the end portion of the inner shaft is exposed from the end portion of the outer shaft. When connecting, the ends of the exposed inner shafts on the upper and lower sides are connected by connecting pins, and a connecting body for connecting the ends of the outer shafts to the outer periphery of these inner shaft ends is provided. ing.
[0004]
Here, the connection body includes a pair of left and right semi-cylindrical pieces in which the cylindrical body is divided into two in the axial direction, and connecting flange pieces provided on the upper and lower ends and the side edges of each semi-cylindrical piece. A pair of left and right semi-cylindrical pieces from the outside of the end portion of the inner shaft are connected to each other through a connecting flange piece on the side edge portion, and connected to the upper and lower end portions. The flange pieces are brought into contact with the connecting flange pieces formed on the upper and lower ends of the outer shaft and connected by connecting bolts.
[0005]
[Problems to be solved by the invention]
However, in the connection work of the excavation shaft body described above, when connecting the outer shafts, since the connection is made via the connection body, there is a problem that this connection work takes time.
[0006]
That is, the connecting operation of the excavation shaft body must be performed at a high place depending on the built-in length of the excavation shaft body, but the connection body is in a state where the pair of left and right semi-cylindrical pieces are brought into contact with each other. Since there is the complexity of connecting with the connecting bolt and then connecting with the connecting bolt in a state of being in contact with the end of the outer shaft, it takes a considerable amount of time for connecting work, and the excavation work efficiency is increased. It is decreasing.
[0007]
[Means for Solving the Problems]
Therefore, in the present invention, an inner shaft and an outer shaft are formed as inner and outer double shafts, and both the inner and outer shafts can be rotated in reverse to each other. Relative stirrer blades attached to rotate the blades and outer stirrer blades relatively in reverse at the inner and outer positions, and the excavation shaft body is connected in the form of multiple splices in the axial direction to change the excavation depth In the ground improvement device that has become possible, the inner and outer shafts each form a stepped convex male end at one end, and the stepped concave female end at which the male end is fitted at the other end. parts to form, without the these male end and a female end capable faucet fitting, the spigot fitting portion of the inner shaft, telescopically connecting pins through the connecting pin insertion hole formed in the outer shaft and inserted into, without connectable plurality of inner shaft, the connecting pin is approximately in the middle portion of the outer peripheral surface of the connecting pin It is a ground improvement device fixed by connecting pin retaining bolts that are pressed in the intersecting direction, and each stamping joint part formed by stamping and fitting the upper and lower inner shafts and outer shafts, By forming connection pin penetration holes penetrating in a substantially horizontal direction and inserting the connection pins into the connection pin penetration holes so as to be freely inserted and removed, the upper and lower inner shafts and the outer shafts are connected to each other. The outer shafts and the outer shafts can be rotated integrally on the same axis, and the connection pin insertion holes are formed in the portions of the outer shafts that coincide with the axial direction of the connection pins connecting the inner shafts. Each connection pin insertion hole is opened and closed freely with a lid, and each connection pin is inserted and removed through each connection pin insertion hole with each lid removed and each connection pin insertion hole opened. It can be inserted freely In addition, a bolt hole that matches the middle part of each connection pin that has penetrated into each connection pin penetration hole is formed at the female side end of each indicia fitting part, and a connection pin retaining bolt is provided in each bolt hole. Each connection pin is fixed to each seal fitting portion by screwing and bringing the tip of each connection pin retaining bolt into contact with the outer peripheral surface of the intermediate portion of the connection pin in a pressed state from a substantially orthogonal direction. A retaining bolt insertion hole is formed in each outer shaft portion that coincides with the axial direction of each inner connecting pin retaining bolt, and the retaining bolt insertion hole can be freely opened and closed by a lid. With the lid closed and the lid removed and the retaining bolt insertion hole opened, the connection pin retaining bolt can be attached to and removed from the bolt hole through the retaining bolt insertion hole. Ground improvement equipment characterized by It provides a place.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0012]
That is, the ground improvement device according to the present invention has, as a basic structure, an excavation shaft body in which an inner shaft and an outer shaft are formed as inner and outer double shafts, and both the inner and outer shafts can be rotated in reverse to each other. And a relative stirring blade body attached to the excavation shaft body so as to relatively reversely rotate the inner stirring blade and the outer stirring blade at the inner and outer positions, and a plurality of the drilling shaft bodies are added in the axial direction. The drilling depth can be changed by connecting to the shape.
[0013]
As a characteristic structure, the inner and outer shafts each have a stepped convex male end at one end and a stepped concave female end at which the male end is fitted at the other end. The male end and the female end can be fitted with an indicia, and the connecting pins can be inserted and removed through the connecting pin insertion holes formed in the outer shaft. A plurality of drilling shaft bodies can be connected.
[0014]
In addition, the connection pin is fixed via a connection pin retaining bolt, and the connection pin retaining bolt is pressed in a direction substantially orthogonal to a midway portion of the outer peripheral surface of the connection pin.
[0015]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0016]
A shown in FIG. 1 is a ground improvement device according to the present invention. The ground improvement device A includes a self-propelled base machine 1 provided with a leader 2 extending in the vertical direction, and the leader 2 has a motor support 3. The motor support 3 is mounted on the motor support 3, and the upper end of the excavation shaft body 6 extending in the vertical direction via the counter rotating gear mechanism 5 is detachably attached to the motor support 3. The relative stirring blade body 7 is attached to the lower peripheral surface of the excavation shaft body 6, and the excavation blade body 8 is attached to the lower end portion of the excavation shaft body 6.
[0017]
The excavation shaft body 6 is supplied with a solidification material via a solidification material supply hose (not shown), and the solidification material is discharged from the lower end portion of the excavation shaft body 6 and the relative stirring blade body 7. Yes.
[0018]
As shown in FIGS. 2 to 4, the excavation shaft body 6 is extended in the vertical direction so as to surround the outer periphery of the cylindrical inner shaft 10 formed in the vertical direction and the inner shaft 10. The cylindrical outer shaft 11 is formed into an inner / outer double shaft structure, and the inner shaft 10 and the outer shaft 11 are rotated about the same axis via a counter rotating gear mechanism 5 by a drive motor 4. They are designed to rotate in opposite directions.
[0019]
A cylindrical body 12 formed by extending in the vertical direction is inserted into the inner shaft 10 to form an inner solidified material supply path 13 in the cylindrical body 12, while the outer periphery of the cylindrical body 12 is An outer solidified material supply path 14 is formed between the surface and the inner peripheral surface of the inner shaft 10.
[0020]
In addition, a communication path (not shown) is formed at the upper end of the inner shaft 10, and the inner solidification material supply path 13 and the outer solidification material supply path 14 are communicated with each other via the communication path. The solidified material supplied through the supply hose can be divided and supplied to the inner solidified material supply path 13 and the outer solidified material supply path 14.
[0021]
Here, the excavation shaft body 6 can change the excavation depth by connecting a plurality of excavation shaft bodies 6 in the axial direction.
[0022]
The relative stirring blade body 7 includes an inner stirring blade 15 connected to the inner shaft 10 and an outer stirring blade 16 connected to the outer shaft 11, and the inner and outer stirring blades 15, 16 is rotated in the reverse direction relatively at the inner and outer positions.
[0023]
In the configuration as described above, the gist of the present invention resides in the connection structure of the plurality of excavation shaft bodies 6, and will be described below with reference to FIGS.
[0024]
That is, the inner and outer shafts 10, 11 each have a stepped convex male end 10a, 11a at one end, while the other end has a stepped concave female fitting with the male end 10a, 11a. The side end portions 10b and 11b are formed, and the male side end portions 10a and 11a and the female side end portions 10b and 11b form stamping fitting portions 20 and 21 that fit in the vertical direction.
[0025]
In addition, the seal fitting portions 20, 21 are formed with connection pin penetration holes 22, 22, 23, 23 penetrating in a substantially horizontal direction, and the connection pins are inserted into the connection pin penetration holes 22, 22, 23, 23. By connecting 24, 24, 25, 25 so that it can be inserted and removed freely, the upper and lower inner shafts 10, 10 and the outer shafts 11, 11 are connected (linked) to each other, and the inner shafts 10, 10 and the outer shafts 11, respectively. , 11 can be rotated together on the same axis.
[0026]
Here, the connection pin penetration holes 22, 22, 23, 23 form the groove grooves 22a, 23a having a semicircular arc cross section extending in the substantially horizontal direction on the outer peripheral surface of the male end 10a, 11a, while the female Formed in the inner peripheral surfaces of the side end portions 10b, 11b are groove grooves 22b, 23b having a semicircular cross section extending in a substantially horizontal direction, and the groove grooves 22a, 22b, 23a, 23b are matched to each other. Forming.
[0027]
In addition, connection pin insertion holes 26, 26, 26, 26 are formed in the portions of the outer shaft 11 that coincide with the axial direction of the connection pins 24, 24 that connect the inner shafts 10, 10, respectively. The pin insertion holes 26, 26, 26, 26 are closed by the closure bodies 27, 27, 27, 27 so that they can be opened and closed, and each connection body 27 is removed to open each connection pin insertion hole 26. In this state, the connection pins 24 and 24 can be inserted and removed freely through the connection pin insertion holes 26.
[0028]
Further, the female-side end portions 10b, 11b of the respective seal fitting portions 20, 21 have intermediate portions of the respective connection pins 24, 24, 25, 25 that are inserted into the respective connection pin insertion holes 22, 22, 23, 23. Bolt holes 28, 28, 29, and 29 are formed, and connection pin retaining bolts 30, 30, 31, and 31 are screwed into the respective bolt holes 28, 28, 29, and 29, and each connection pin is By bringing the tip of the retaining bolts 30, 30, 31, 31 into contact with the outer peripheral surface of the middle part of the connection pins 24, 24, 25, 25 in a pressed state from a substantially orthogonal direction, each connection pin 24, 24 , 25, 25 can be fixed (prevented from coming off) to the respective stamp fitting portions 20, 21.
[0029]
In addition, retaining bolt insertion holes 32, 32 are formed in the portions of the outer shaft 11 that coincide with the axial direction of the inner connecting pin retaining bolts 30, 30, respectively, and the retaining bolt insertion holes 32, 32 are closed. The lids 33, 33 are closed so that they can be opened and closed. With the lids 33, 33 removed and the retaining bolt insertion holes 32, 32 opened, the retaining bolt insertion holes 32 , 32, the connecting pin retaining bolts 30, 30 can be freely attached to and detached from the bolt holes 28, 28.
[0030]
Further, as shown in FIG. 2, the cylindrical body 12 has a stepped convex male side end portion 12a at one end and a stepped concave female side into which the male side end portion 12a is fitted at the other end. The end portion 12b is formed, and the male side end portion 12a and the female side end portion 12b form a stamp fitting portion 40 that fits in the vertical direction.
[0031]
As shown in FIG. 2, a seal portion 35 is provided at the lower portion of the excavation shaft body 6 located immediately above the relative stirring blade body 7, and the seal portion 35 is formed on the outer peripheral surface and the outer side of the inner shaft 10. A pair of upper and lower roller bearings 36 and 37 are interposed between the inner peripheral surface of the shaft 11 so that the inner and outer shafts 10 and 11 can rotate in opposite directions on the same axis, At a position above the roller bearing 36, a packing 38 is provided as a seal between the outer peripheral surface of the inner shaft 10 and the inner peripheral surface of the outer shaft 11, while at a position lower than the lower roller bearing 37. A packing 39 serving as a seal is interposed between the outer peripheral surface of the inner shaft 10 and the inner peripheral surface of the outer shaft 11. 41 is a grease injection hole.
[0032]
Thus, by providing the seal portion 35 at the lower part of the excavation shaft body 6, mud or the like is prevented from flowing from the relative stirring blade body 7 side to the lower side of the excavation shaft body 6.
[0033]
Next, the procedure for connecting the excavation shaft body 6 will be described sequentially with reference to FIG.
[0034]
(1) As shown in FIG. 5 (a), the ground improvement device A is moved to the ground improvement point. G is the ground.
[0035]
At this time, the excavation shaft 6 having a length that can be supported by the reader 2 is attached to the drive motor 4 via the counter rotating gear mechanism 5.
[0036]
(2) As shown in FIG. 5 (b), by rotating the excavation shaft body 6, the relative stirring blade body 7 and the excavation blade body 8 are rotated to excavate the ground G and discharge the solidified material. The soil and the solidified material are agitated to improve the ground G.
[0037]
(3) As shown in FIG. 5 (b), the ground improvement work is temporarily suspended, leaving the uppermost excavated shaft body 6. 42 is an excavation shaft body support piece, and the excavation shaft body support piece supports the cut excavation shaft body 6 in the excavation hole 44 through the locking piece 43.
[0038]
(4) As shown in FIG. 5 (c), the uppermost excavation shaft 6 and the lower excavation shaft 6 are separated.
[0039]
At this time, at the seal fitting portions 20 and 21 which are connecting portions between the uppermost excavation shaft body 6 and the lower excavation shaft body 6, first, the closure bodies 33 and 33 are removed, and the retaining bolt insertion holes are removed. The holes 32 and 32 are opened, and the inner connection pin retaining bolts 30 and 30 are removed from the bolt holes 28 and 28 through the retaining bolt insertion holes 32 and 32, respectively. Subsequently, the closure bodies 27, 27 are removed to open the connection pin insertion holes 26, 26, and the connection pins 24, 26 connecting the inner shafts 10, 10 through the connection pin insertion holes 26, 26, 24 is extracted from each connection pin penetration hole 22,22.
[0040]
Next, remove the retaining bolts 31 and 31 attached to the outer shaft 11 from the bolt holes 29 and 29, and then connect the connection pins 25 and 25 connecting the outer shafts 11 and 11 to each other. Pull out from the pin penetration holes 23,23.
[0041]
In this way, the stamping fitting of the stamping fitting parts 20 and 21 can be released, and the uppermost excavation shaft body 6 and the lower excavation shaft body 6 can be separated.
[0042]
At this time, the stamping fitting part 40 that stamps and fits the cylindrical bodies 12 and 12 is also released from the fitting at the same time as the excavation shafts 6 and 6 are separated.
[0043]
(5) As shown in FIG. 5 (c), the lower end of the uppermost excavation shaft 6 is stamped and fitted to the upper end of the excavation shaft 6 for extension that has been built in the ground G in advance. Connecting.
[0044]
At this time, first, the male end portion 12a and the female end portion 12b of the cylindrical bodies 12 and 12 arranged at the center of the uppermost excavation shaft body 6 and the excavation shaft body 6 for the lower addition. After that, the inner and outer shafts 10, 10, 11, 11 are connected to each other.
[0045]
That is, in the seal fitting portion 20, 21 which is a connecting portion between the inner and outer shafts 10, 10, 11, 11, the respective connection pins 25, 25 are inserted into the respective connection pin penetration holes 23, 23 so that the outer shaft 11, 11 are connected to each other, and then each retaining bolt 31, 31 is screwed into each bolt hole 29, 29, and each connecting pin 25, 25 is pressed by each retaining bolt 31, 31. Fix it.
[0046]
Next, the lid bodies 27, 27 are removed to open the connection pin insertion holes 26, 26, and the connection pins 24, 24 are inserted into the connection pin insertion holes 22, 22 through the connection pin insertion holes 26, 26. The inner shafts 10 and 10 are connected to each other, and then the lid bodies 33 and 33 are removed to open the retaining bolt insertion holes 32 and 32, and through the retaining bolt insertion holes 32 and 32. The inner connecting pin retaining bolts 30 and 30 are screwed into the bolt holes 28 and 28, and the connecting pins 24 and 25 are pressed and fixed by the retaining bolts 30 and 30, respectively.
[0047]
Thereafter, the connection pin insertion holes 26, 26 are closed by the closing bodies 27, 27, and the retaining bolt insertion holes 32, 32 are closed by the closing bodies 33, 33, so that the inner shaft 10 and Make sure that mud or the like does not enter between the outer shaft 11.
[0048]
(6) As shown in FIG. 5 (d), the uppermost excavation shaft body 6 and the excavation shaft body 6 for extension are lifted in a connected state, and the excavation shaft body 6 for extension is pulled out from the ground G. .
[0049]
(7) As shown in FIG. 5 (e), the abandoned digging head 45 attached to the lower end portion of the excavation shaft body 6 for addition is removed, and the lower end portion of the excavation shaft body 6 is first improved in the ground. It connects with the upper end part of the excavation shaft body 6 which has been.
[0050]
At this time, the excavation shafts 6 and 6 are connected in the same manner as in the above (5).
[0051]
In this way, the ground improvement work is sequentially performed, and when the desired excavation depth is not reached, the ground improvement can be performed to the desired excavation depth by adding an additional excavation shaft body 6 as appropriate. it can.
[0052]
At this time, the work of adding the excavation shaft body 6 can be easily and reliably performed by inserting / removing the connection pins 24, 24, 25, 25 as described above, so that the ground improvement work efficiency can be improved.
[0053]
【The invention's effect】
According to the present invention, the following effects can be obtained.
[0054]
In the present invention, each of the inner and outer shafts has a stepped convex male end at one end, and a stepped concave female end at which the male end is fitted at the other end. The male side end and the female side end can be inlayed and fitted, and the connecting pin of the inner shaft can be inserted and removed through the connecting pin insertion hole formed in the outer shaft. Multiple inner shafts can be connected.
[0055]
In this way, the inner and outer shafts are individually fitted and positioned, and the connecting pins are inserted into these stamped fittings through the connecting pin insertion holes formed in the outer shaft, so that the excavation shaft body can be inserted and removed. Since they can be connected to each other, the connection work can be performed quickly and reliably with a simple structure.
[0056]
In addition, since the connecting / disconnecting operation of the connecting pins can be performed easily even at a high place, it is possible to improve the connecting work efficiency and further the excavation (ground improvement) work efficiency.
[0057]
Further, the excavation shaft body can be easily disconnected by pulling out the connection pins. From this point, excavation (ground improvement) work efficiency can be improved.
[0058]
Further, the connection pin is fixed by a connection pin retaining bolt that is pressed in a direction substantially orthogonal to a middle portion of the outer peripheral surface of the connection pin.
[0059]
In this way, since the connection pin is fixed via the connection pin retaining bolt, it is possible to reliably prevent the occurrence of a problem that the connection pin comes off during excavation work, and excavation (ground improvement) work. Good performance can be ensured.
Moreover, by tightening the connection pin retaining bolt in the advance direction, the connection pin can be easily and reliably fixed, and from this point, excavation (ground improvement) work performance can be secured well.
[0060]
Further, in each stamping pin fitting portion formed by stamping and fitting the upper and lower inner shafts and outer shafts, a connection pin penetration hole penetrating in a substantially horizontal direction is formed, and each of the connection pin penetration holes is formed. By allowing the connecting pins to be inserted and removed freely, the upper and lower inner shafts and the outer shafts are connected (coupled), and the inner shafts and the outer shafts can be integrally rotated on the same axis, respectively. Each of the outer shaft portions that coincide with the axial direction of the connecting pins connecting the inner shafts is formed with a connecting pin insertion hole, and each connecting pin insertion hole is opened and closed freely by a closing body. With the lid removed and each connection pin insertion hole opened, each connection pin can be removably inserted through each connection pin insertion hole. The middle part of each connection pin that penetrates into each connection pin penetration hole Form matching bolt holes, screw connection pin retaining bolts into each bolt hole, and press the tip of each connection pin retaining bolt to the outer peripheral surface of the middle part of the connection pin from a substantially orthogonal direction The contact pins can be fixed (retained) to the respective indicia fitting parts, and the outer shaft portion coinciding with the axial direction of the inner connection pin retaining bolts With each retaining bolt insertion hole formed, the retaining bolt insertion hole is opened and closed freely by a lid, and the retaining bolt insertion hole is opened by removing the lid. The connecting pin retaining bolt can be attached to and removed from the bolt hole through the retaining bolt insertion hole.
[0061]
Thus, when the upper excavation shaft body and the lower excavation shaft body are separated from each other, first, in the stamping joint portion that is a connection portion between the upper excavation shaft body and the lower excavation shaft body, Then, the lid is removed to open each retaining bolt insertion hole, and each inner connection pin retaining bolt is removed from each bolt hole through each retaining bolt insertion hole. Subsequently, the lid is removed to open each connection pin insertion hole, and each connection pin connecting the inner shafts through each connection pin insertion hole is extracted from each connection pin penetration hole.
Next, each retaining bolt attached to the outer shaft is removed from each bolt hole, and then each connection pin connecting the outer shafts is extracted from each connection pin penetration hole. In this way, the stamp fitting of the stamp fitting portion can be released, and the upper excavation shaft body and the lower excavation shaft body can be separated.
Also, when connecting the upper excavation shaft body and the lower excavation shaft body, each connection pin is inserted into each connection pin penetration hole at the seal fitting portion which is a connection portion between the inner and outer shafts. The outer shafts are penetrated to connect the outer shafts, and then each retaining bolt is screwed into each bolt hole, and each connecting pin is pressed and fixed by each retaining bolt.
Next, the lid is removed to open the connection pin insertion hole, the connection pin is inserted into the connection pin penetration hole through the connection pin insertion hole, the inner shafts are connected to each other, and then the closure body is removed. Then, the retaining bolt insertion hole is opened, the inner connection pin retaining bolt is screwed into the bolt hole through the retaining bolt insertion hole, and the connecting pin is pressed and fixed by the retaining bolt.
After that, the connection pin insertion hole is closed with the lid, and the retaining bolt insertion hole is closed with the lid so that mud or the like does not enter between the inner shaft and the outer shaft. be able to.
[Brief description of the drawings]
FIG. 1 is a side view of a ground improvement device according to the present invention.
FIG. 2 is a cross-sectional side view of an excavation shaft body of the ground improvement device.
3 is a cross-sectional view taken along the line II in FIG.
4 is a cross-sectional view taken along line II-II in FIG.
FIG. 5 is an explanatory diagram of excavation shaft body connection work.
[Explanation of symbols]
A Ground improvement device 1 Base machine 2 Reader 3 Motor support 4 Driving motor 5 Counter-rotating gear mechanism 6 Drilling shaft body 7 Relative stirring blade body 8 Drilling blade body

Claims

An excavation shaft (6) in which the inner shaft (10) and the outer shaft (11) are formed as inner and outer double shafts, and both the inner and outer shafts (10, 11) can be rotated in reverse to each other. The excavation shaft body (6) includes a relative stirring blade body (7) attached so as to relatively reversely rotate the inner stirring blade (15) and the outer stirring blade (16) at the inner and outer positions, Excavation shaft body (6) is a ground improvement device that can change the excavation depth by connecting in the form of multiple additions in the axial direction,
The inner and outer shafts (10, 11) each have a stepped convex male end (10a, 11a) at one end, while the other male end (10a, 11a) is inserted into the other end. A concave female side end (10b , 11b) is formed, and the male side end (10a, 11a) and the female side end (10b , 11b) can be fitted with an indicia, and the inner shaft (10 ) In the seal fitting part (20, 21) , the connection pin (24) is removably inserted through the connection pin insertion hole (26, 26) formed in the outer shaft (11) , and a plurality of inner shafts ( 10) Connectable and none ,
The connection pin (24) is a ground improvement device fixed by a connection pin retaining bolt (30) that is pressed in a direction substantially orthogonal to a middle portion of the outer peripheral surface of the connection pin (24) ,
A connecting pin penetrating in a substantially horizontal direction is inserted into each of the seal fitting portions (20, 21) formed by stamping the upper and lower inner shafts (10, 10) and outer shafts (11, 11). forming a hole (22, 23), freely by penetrating or disconnect the connection pins (24, 25) during each connection pin penetration holes (22, 23), the upper and lower inner shaft (10, 10) with each other and The outer shafts (11, 11) are connected to each other so that the inner shafts (10, 10) and the outer shafts (11, 11) can be rotated integrally on the same axis ,
Connection pin insertion holes (26, 26) are formed in the portions of the outer shaft (11) that coincide with the axial direction of the connection pins (24) that connect the inner shafts (10, 10) to each other. The insertion holes (26, 26) are opened and closed freely by the closure bodies (27, 27) , the respective closure bodies (27, 27) are removed, and the connection pin insertion holes (26, 26) are opened. In this state, each connection pin (24, 24) can be inserted and removed freely through each connection pin insertion hole (26, 26) .
The female end (10b, 11b) of each indicia fitting part (20, 21) matches the middle part of each connection pin (24, 25) that penetrates into each connection pin penetration hole (22, 23). Bolt holes (28, 29) to be formed, screwing connection pin retaining bolts (30, 31) into the respective bolt holes (28, 29) , and connecting pin retaining bolts (30 , 31) middle portion of by contact with the pressing state from the substantially perpendicular direction to the outer peripheral surface, each spigot fitting portions each connecting pin (24, 25) of the tip portion of the connection pin (24, 25) (20, 21 to be able to be secured to),
A retaining bolt insertion hole (32) is formed in each of the outer shaft (11) that coincides with the axial direction of the inner connection pin retaining bolt (30) , and the retaining bolt insertion hole (32) is closed. The lid (33) is opened and closed freely by the body (33) , and the retaining body (33) is removed and the retaining bolt insertion hole (32) is opened , through the retaining bolt insertion hole (32) . Ground improvement device characterized in that a connecting pin retaining bolt (30) can be attached to and removed from the bolt hole (28) .