JP3751357B2 - Excavation method and excavator therefor - Google Patents

Description

【００１８】
微視的に破壊は応力σ₂ が引張強度より大きくなったとき、または剪断応力が剪断強度よりも大きくなったときに起こる現象であり、剪断強度はモール・クーロンの理論から主応力に比例する値であるから、剪断破壊は上記（２）式においてモール・クーロンの式の内部摩擦角をφとしたときのλ＝π／４−φ／２の角度で発生する。
【００１９】
一方、図１５に示されるように、半無限板上に線荷重Ｐが作用するとき、任意の点における応力状態はTimoshenkoとGoodier によって次式（３）によって与えられている。
【００２０】
【数２】

【００２１】
最大主応力の方向とλ_f の角度をなす面で破壊が起こるものとすれば、載荷点の直下 r₀ の点から出発する破壊線は載荷点を中心とする放射線と常に一定の角度λ_f をもつ対数ら線になる。すなわち、次式（５）で表される。
【００２２】
【数３】

【００２３】
また、以上の各式から破壊線に沿った剪断応力τと垂直応力σが、次式で表されるように破壊線は左右両方向にできる。
【００２４】
【数４】

【００２５】
Maurerは上記(6) 、(7) 式より破壊線に沿う２応力の比が一定になることから下式（８）を与えている。
【００２６】
【数５】

【００２７】
この関係は最大剪断破壊線（λ_f ＝π／４）で、τ。＝σに減少することになり、応力は図１６（ａ）に示すように、破壊線に沿って変化し、岩石の表面（θ＝±π／２）では０となり、θ＝±（π／２−λ_f ）のところで最大となる。また、荷重の直下に最大剪断応力が発生する。図１６（ｂ）に示されるクレータの破壊線は岩石表面では剪断応力が０となるから、破壊線に沿って破砕帯の近い部分では剪断破壊が起こり、表面近くでは曲げ荷重による引張破壊が生じていると考えることができる。
【００２８】
ところで、カッタ刃先を岩盤の表面に押し付けて貫入させるとき、クレータを発生させるのに必要な最小限の荷重をスレショルド荷重と言う。刃先の貫入圧力がこのスレショルド荷重に関係するため、刃先が摩耗して接触面積が増大するとスレショルド荷重が増大する関係にある。刃先の摩耗幅とスレショルド荷重との関係式を調べたものとしては、Maurer,M,Cによる実験結果がある（The State of Mechanics Knowledge in Drilling,8th symposium on Rock Mechanics AIME,University of Minnesota,Sept.,1966,P.355) 。スレショルド荷重に対して、刃先幅１／２inのツールをBerea sandstone に貫入させた実験から、摩耗幅とスレショルド荷重との関係について図１７に示される関係を得ている。同図は刃先の貫入力が図の直線よりも大きい領域ではクレータができるが、その下の領域では岩石の面に刃先の跡がつくだけでクレータができないということを示したもので、刃先が僅かに摩耗しただけでスレショルド荷重が大幅に増加すること、すなわち刃先が摩耗することにより破砕効率が急激に低下する理由を示している。
【００２９】
以上の説明より、岩石表面に垂直方向の荷重が加わったときの破壊メカニズムが明らかになるとともに、掘削に従い刃先に摩耗が生じるとスレショルド荷重が増加し削孔効率が低下する理由が明らかとなる。すなわち、ディスクカッタのみによる破壊の場合には、掘削面に対して垂直にかつ刃先先端から作用するディスクカッタの貫入力により擬似半楕円状の剪断破壊線に沿って破壊が発生し、また前記スレショルド荷重についての説明により、破壊能力に関しては刃先先端から岩石側に伝達される貫入力（貫入応力）の影響が大であることが判明した。
【００３０】
ところで、本発明の場合には、カッタ刃先を岩石に貫入させる直前に該貫入位置に超高圧水により切削溝または割れ目を形成するため、上記した破壊メカニズムと若干異なる破壊メカニズムを採る。すなわち、図１１に示されるように、ディスクカッタによる破砕に先立って、予め切削溝または割れ目１４が形成されるため、ディスクカッタ刃体１０ａの刃先Ｓは掘削対象の岩石等に接触しないか、或いは接触したとしても該刃先Ｓから岩石等に伝達される貫入力は支配的でない当接状態となる。ディスクカッタからの貫入力は主に、刃体１０ａの側部傾斜面と前記切削溝または割れ目１４との肩部との接触部位Ｕ，Ｕから岩石側に伝達される。このような当接態様を採る場合には、図１２に示されるように、斜方向の楔貫入力Ｐ_U により破壊線Ｋ上に垂直応力σ_N と破壊線Ｋに沿う剪断力τとが作用し、この剪断力τにより直接的にすべり破壊が行われる。つまり、基本的に掘削対象面に対して垂直方向の貫入力は作用せず、刃先面から斜め方向に楔貫入力Ｐ_U が直接作用し、両側の破壊部分１５、１５を夫々横に押し出すようにして破砕する。したがって、剪断力が直接的作用する点で効果的に破砕が行われるようになるともに、同図に示すように、刃先Ｓは岩石等に接触しないか、または接触したとしても刃先部分に作用する貫入力は小さいため刃先の摩耗が少なくなる。
【００３１】
また、本発明では刃先１０ａ先端が直接的に破壊に寄与しない。したがって、前述したような、刃先摩耗によるスレショルド荷重の増大といった現象が起きないかまたは小さいため、長期間に亘り掘削性能を維持し得るようになる。
【００３２】
他方、前記掘削方法を行うための本発明掘削機は、掘削ヘッド部に１または複数のディスクカッタを備え、少なくともこの掘削ヘッド部が掘削方向軸回りに回転することにより前記ディスクカッタを転動させ掘削面の破砕を行うようにした掘削機において、前記ディスクカッタの一部または全部を対象として、ディスクカッタによる掘削面の破砕中に、この掘削面に対してディスクカッタの通過予定線に沿う切削溝または割れ目を形成するための超高圧水噴射装置を設け、この超高圧水噴射装置の噴射ノズル部分を球体としその回動位置制御により噴射ノズルの目詰まりを防止したことを特徴とするものである。
【００３３】
この場合、前記超高圧水噴射装置において、超高圧水の噴射停止時に微細土粒子の流入による噴射ノズルの目詰まりを防止するため、噴射口に開閉自在の蓋体を設けることもできる。
【００３４】
また、ＴＢＭやシールド機などのように、複数のディスクカッタを備えた地盤当接部位が中心軸回りに回転自在とされる構造において、前記地盤当接部位の回転中心軸を基準として相対的に遠距離位置に配置されたディスクカッタ群に対してのみ前記超高圧水噴射装置を設けることもできる。回転中心軸部から相対的に遠距離位置に配置されたディスクカッタ群は、前記カッターヘッドの１回転当りの転動距離が相対的に長くなるため、中心側のディスクカッタよりも掘削負荷が大きくなり刃先摩耗の程度も大きくなる。そのため、一般にはディスクカッタの負荷がいくらかでも均等になるように、外周側に取付けるディスクカッタの数を増やすようにしているが、本発明では切削溝または割れ目の形成により掘削負荷の調整が可能であるため、上記のように掘削負荷の大きい外周側のディスクカッタ群のみに超高圧水噴射設備を設けることにより、掘削負荷の均一化を図ることが可能となる。
【００３５】
【発明の実施の形態】
以下、本発明の実施の形態について図面に基づき詳述する。
図１は本発明に係るカッタ部構造を採用したＴＢＭの概略図であり、図２および図３はディスクカッタ部の拡大図である。
図１に示されるように、トンネル掘削機１はマシン本体の前面部にカッタヘッド（本発明にいう掘削ヘッド）２を備え、このカッタヘッド２面に取付けられた複数のディスクカッタ１０、１０…により地山を連続的に破砕して掘進する。前記ディスクカッタ１０は、図２および図３に示されるように、カッタサドル１０ｂの外周にリング状に形成した断面楔形状の刃体１０ａを有するカッタ構造であり、カッタヘッド２面に固設されたカッタ取付台１１に対して軸受１３を介して転動自在に取り付けられる。地盤掘削に当たっては、掘削機１内に設けられたスラストジャッキ８によりカッタヘッド２に岩盤当接方向の推進力が与えられた状態で、カッタヘッド２がカッタ駆動用モータ２４からの回転駆動力により掘削方向軸回りに回転する。そして、前記ディスクカッタ１０、１０…が円周方向に転動することにより刃体１０ａが岩盤、砂礫等の破砕を行う。
【００３６】
他方、トンネル掘削機１の胴部は前記カッタヘッド２に続く前胴部３と、後胴部４とからなり、これら前胴部３と後胴部４との接続部に屈折可能な中折れ部５が形成され曲線施工も可能となっている。前記ディスクカッタ１０、１０…により削り取られた掘削ズリはカッタチャンバ２５内に取り込まれ、送水管２０を通じて流入した水とともに、排泥管２１により地上側まで排出される。
【００３７】
また、前記前胴部３にフロントグリッパ６、６を備えるとともに、後方側にメイングリッパ７、７を備え、かつ前胴部３とメイングリッパ７部分とがスラストジャッキ８により連結されている。トンネル掘進機１の推進は、フロントグリッパ６による坑壁支持を開放し、かつメイングリッパ７を伸ばして坑壁に対して反力を取り、スラストジャッキ８を伸長させ前胴部３を前進させることにより掘削を行う。１サイクル長の掘削が完了したならば、前記フロントグリッパ６を伸ばして坑壁に反力を取るとともに、メイングリッパ７による坑壁支持を開放し、スラストジャッキ８を収縮させることにより後胴部４を前方に移動させることにより前進する。トンネル掘削機１の後方ではエレクター２２によりセグメント２３が組み立てられる。
【００３８】
本発明トンネル掘進機１においては、図２および図３に示されるように、前記ディスクカッタ１０、１０…の配設部位に近接して、前記ディスクカッタ１０により岩盤破砕が行われる直前に、このディスクカッタ１０の通過予定線上に向けて超高圧水を噴射し掘削地盤面に対して切削溝または割れ目を形成するための超高圧水噴射装置１２が設けられている。前記超高圧水噴射装置１２は、図４に示されるように、ノズルヘッド１２ｂと、このノズルヘッド１２ｂの先端に固定された噴射ノズル１２ａと、好ましくは超高圧水のオンオフ制御を行う制御バルブ１２ｃとから構成される。前記噴射ノズル１２ａのノズル径は通常０．１〜１．０mm程度であり、材質的にはダイヤモンドが使用されている。
【００３９】
また、前記超高圧水噴射装置１２はカッタヘッド２に設けられた全てのディスクカッタ１０、１０…に対して設けることもできるし、またその一部群に対してのみ配設することもできる。この一部群に対して設ける場合の例としては、たとえば各ディスクカッタ１０、１０…間での摩耗度の偏りを防止するために、カッタヘッド２の回転中心軸を基準として相対的に遠距離位置に配置されたディスクカッタ群に対してのみ設けることができる。また、ディスクカッタ１０が２つの刃体１０ａ、１０ａを有するダブルディスク構造やそれ以上の刃体を有する場合には、図５に示されるように、各刃体１０ａ、１０ａ…に対して夫々超高圧水噴射装置１２、１２…を設けるようにする。
【００４０】
なお、超高圧水噴射装置１２の他の態様としては、図示のようにカッタ取付台１１を支持台として取付ける方法の他、カッタ取付台１１に溝孔を形成して直接的に噴射ノズル１２ａを取付けることもできる。
【００４１】
さらに、前記ノズルヘッド１２ｂ部分に研磨材を供給し、研磨材を超高圧水とともに掘削面に噴射することもできる。なお、前記研磨材としては一般的に珪砂（６０メッシュ程度）、ガーネット（６０〜１００メッシュ程度）の他、アルミナ系、鋳鉄グリッド、コランダム等の研磨材が用いられる。
【００４２】
他方、本発明トンネル掘削機１の掘削済み坑道内には超高圧水ユニット９が設備される。この超高圧水発生ユニット９で製造された超高圧水が前記超高圧水噴射装置１２に送られる。前記超高圧水ユニット９は、油圧ユニット３０と給水ユニット３１とブースター（増圧機）３２とアキュムレータ３３とから構成され、油圧ユニット３０から吐出された作動油によりブースター３２内のピストンが左右に動作され、ウォーターチャンバー内にある水が圧縮され超高圧水となる。また、アキュムレータ３３を介在させることにより超高圧水の圧力が一定に保たれるようになっている。通常は、前記超高圧水ユニット９により１０００〜４０００kgf/cm² の超高圧水が発生させることができる。
【００４３】
前記ディスクカッタ１０による岩盤等の破砕は、図２に示されるように、前記ディスクカッタ１０による破砕が行われる直前に、前記ディスクカッタ１０の通過予定線上に超高圧水噴射装置１２から噴射される超高圧水を衝突させて掘削面に切削溝または割れ目１４を形成し、ディスクカッタ１０の刃先１０ａが切削溝または割れ目１４線上を通過しながら前記破砕が行われるようにする。
【００４４】
前記超高圧水噴射装置１２の取付けおよび噴射態様としては、図２に示されるようにカッタ取付台１１に取り付けた前記超高圧水噴射装置１２から掘削面に向けて垂直に超高圧水を衝突させることもできるし、また図６に示されるように、傾斜角をもって衝突させることもできる。また、カッタヘッド２の面盤に前記超高圧水噴射装置１２を取付け掘削面に対して噴射することもできる。さらに、図８に示されるように、ディスクカッタ１０の刃体１０ａ線上から側方にずらした位置に前記超高圧水噴射装置１２を取付け、該斜め位置から通過予定線に対して噴射することもできる。
【００４５】
ところで、前記超高圧水を併用した掘削方法は、基本的には岩盤、砂礫層などを対象とするものであり、掘進中に軟弱層に突入した場合には超高圧水を併用することなくディスクカッタのみで掘削を行ってもよい。超高圧水の噴射を停止した場合には、泥水や泥土中の微細土粒子が前記噴射ノズル１２ａに入り込み、目詰まりを起こす場合があるため、超高圧水の噴射停止時であっても常時少量の水を噴射し続けながら地盤の掘削を行うようにするのが望ましい。また、噴射ノズル１２ａに開閉自在の蓋体を設けることでノズル目詰まりを防止してもよい。さらに、図９に示されるように、噴射ノズル２６を球体とし、これを水圧または油圧により回動位置制御できるようにしておき（図示しない）、超高圧水噴射時には同図の回動位置に位置決めして超高圧水の噴射を行い、噴射停止時には、図１０に示されるように、球体ノズル２６を回動させることによりノズル口を内部に仕舞い込むようにしてもよい。なお、図９および図１０のノズル構造例では別途洗浄水流路２７を設け、噴射停止時に逆流水により超高圧水路の洗浄ができるようにしてある。
【００４６】
ところで、上記実施の形態では、トンネル掘削機を例に挙げ本発明を説明したが、本発明は他に岩石、コンクリート面などのはつり作業（チッピング作業）、舗装面の剥離作業など、他のディスクカッタを用いた切削、破砕、剥離作業に対しても適用できる。
【００４７】
【発明の効果】
以上詳説のとおり、本発明によれば、ディスクカッタによる破砕に先立って、予め切削溝または割れ目を形成するようにしたため、カッタ寿命の延命化を図ることができるようになる。また、岩石等が破砕し易くなるため削孔速度が向上するとともに、従来装置と比較して掘削機能力を縮小化することも可能となる。さらに、掘削時の粉塵を抑え作業環境の悪化を防止することができるようになるなど種々の利点がもたらされる。
【図面の簡単な説明】
【図１】トンネル掘削機の概略図である。
【図２】本発明に係るディスクカッタ部構造の側面図である。
【図３】本発明に係るディスクカッタ部構造の平面図である。
【図４】超高圧水噴射装置の詳細図である。
【図５】ダブルディスク構造の場合の平面図である。
【図６】他の超高圧水噴射態様図である。
【図７】他の超高圧水噴射態様図である。
【図８】他のノズル構造例における超高圧水噴射時の縦断面図である。
【図９】他のノズル構造例における超高圧水停止時の縦断面図である。
【図１０】他の超高圧水噴射態様図である。
【図１１】本掘削方法の場合の破砕概念図である。
【図１２】破砕部分の拡大模式図である。
【図１３】ディスクカッタのみにより破砕概念図である。
【図１４】ディスクカッタのみによる破壊メカニズムの説明図である。
【図１５】ディスクカッタのみによる破壊メカニズムの説明図である。
【図１６】ディスクカッタのみによる破壊メカニズムの説明図である。
【図１７】スレショルド荷重の説明図である。
【符号の説明】
１…トンネル掘削機、２…カッタヘッド、３…前胴部、４…後胴部、５…中折れ部、６…フロントグリッパ、７…メイングリッパ、８…スラストジャッキ、９…超高圧水発生ユニット、１０…ディスクカッタ、１０ａ…刃体、１１…カッタ取付台、１２…超高圧水噴射装置、１２ａ…噴射ノズル、１２ｂ…ノズルヘッド、１２ｃ…オンオフバルブ、３０…油圧ユニット、３１…給水ユニット、３２…ブースター、３３…アキュムレータ[0001]
BACKGROUND OF THE INVENTION
In the excavator such as a tunnel excavator such as a TBM, a shield machine, a foundation pile construction excavator for a large structure, an underground excavator for an underground space, etc. The present invention relates to an excavation method and an excavator for the excavation method capable of efficiently crushing strata such as gravel and concrete.
[0002]
[Prior art]
For example, tunnel construction machines such as TBM (Tunnel Boring Machine ) and shield machines (Shield Machine ) are actively used to construct tunnels such as railways, roads, water conduits, and water and sewage systems. A tunnel excavator (hereinafter also simply referred to as an excavator) is an excavation machine that excavates while cutting and crushing earth and sand continuously with a cutter head on the front surface. The TBM is an excavator mainly used for mountain tunnels, and the cutter head has a roller cutter type cutter structure such as a two-cutter, a disc cutter, an insert cutter, etc. so that it can efficiently excavate formations such as rocks and gravel layers. Adopted. In addition, the shield machine mainly uses a cutter structure with a cutting bit fixed so that soft ground such as sandy soil and clay with high water content can be efficiently excavated, but it enters the bedrock layer and gravel layer. In consideration of such cases, there is a composite type using the roller cutter together.
[0003]
In addition, a cutter method using a roller cutter or the like is also adopted for a drilling machine for foundation excavation of a large structure, an underground excavation machine for underground space, and the like in order to cope with a bedrock layer and a gravel layer.
[0004]
Among these roller cutter type cutter structures, the present invention is particularly intended for a disk cutter having a wedge-shaped blade body in a ring shape on the outer periphery of the cutter saddle, and the excavating head (cutter head) of the excavator A plurality of disk cutters are arranged on the part based on the design calculation so as to realize the most efficient excavation. Then, by rotating the excavation head while pressing the disk cutter against the rock with a constant thrust, the disk cutter rolls in the circumferential direction to cut and crush the rock.
[0005]
In this case, as the excavation progresses, the cutting edge of the disk cutter is worn, and the drilling speed gradually decreases. If the worn cutter continues to be used as it is, the drilling speed will decrease even if the cutter life can be extended, so the operating costs of the drilling machine equipment etc. will increase and the drilling unit price will increase overall. To do. Therefore, the drilling unit price is expressed as a function of the drilling speed and cutter life. Therefore, the drilling speed is defined by geological conditions such as rock type and strength, operating conditions such as thrust and rotational speed, cutter type, and cleaning. The cost is calculated from the formula of the drilling speed considering the above, and the economical operating conditions are determined by calculating the cutter life from the formula of the cutter blade edge and the bearing wear rate using factors such as cutter penetration and rotational speed as factors. The disk cutter is being replaced.
[0006]
When crushing rocks or gravel with a disc cutter, investigate the rock and soil in advance, and add the coefficient due to the cracks in the ground to the amount of intrusion of the cutter determined from the condition that there is no fracture. The optimum amount of cutter penetration is determined.
[0007]
[Problems to be solved by the invention]
However, a large error is likely to occur due to variations in actual natural ground properties, which seriously affects the cutter life and the excavation speed. That is, when construction is actually started, the wear of the cutter may proceed in a very short time or the excavation speed may decrease, resulting in an increase in cutter cost and a significant delay in the process. is there.
[0008]
In addition, since the ratio of the cutter cost to the total drilling cost is large, the drilling cost will inevitably increase as the number of cutter replacement increases. There are permanent issues such as extending the cutter life without reducing the efficiency, or improving the drilling efficiency.
[0009]
In excavator design, there is a margin in mechanical capacity in consideration of unexpected entry into a rocky layer or encountering a rocky layer that is stronger than designed. The ability to improve the rockability (which is an index of the ease with which the rock can be excavated) has the advantage of reducing mechanical capabilities such as the excavator propulsion force and disc cutter drive torque.
[0010]
In addition, in the case of the conventional open type TBM, dust is generated when the rock is crushed, which causes a problem in the sanitary environment such as causing deterioration of the working environment.
[0011]
Therefore, the main problems of the present invention are as follows. First, the cutter life is prolonged, the drilling speed is improved, and secondly, the improvement of ripperability is artificially made. Therefore, it is possible to reduce the excavating function force and to suppress the dust during excavation to prevent the working environment from deteriorating.
[0012]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides an irradiation device for injecting ultra-high pressure water for each blade of a disk cutter, and during the crushing of the excavation surface by the disc cutter, A cutting groove or a crack is formed in advance by ultra-high pressure water along the planned passage line, and the crushing is performed while the cutting edge of the disk cutter rolls on the cutting groove or the crack line thus formed. To do.
[0013]
In this case, 1000 to 3500 kgf / cm ² is preferable as the range of the injection pressure of the ultrahigh pressure water. Further, in the injection nozzle for injecting the ultra-high pressure water, in order to prevent clogging of the injection nozzle due to the inflow of fine soil particles when the injection of the ultra-high pressure water is stopped, it is always possible even when the injection of the ultra high pressure water is stopped It is better to dig while continuing to spray a small amount of water. Furthermore, the formation efficiency of the said cutting groove or a crack can also be improved by mixing a fine-grain abrasive | polishing material in the said ultrahigh pressure water.
[0014]
As described above, in the case of the present invention, before crushing by a disk cutter, a cutting groove or a crack is formed in advance by ultra-high pressure water along a planned passage line of the disk cutter. Accordingly, the ground such as the bedrock or the gravel layer is easily crushed and the wear of the disk cutter edge is reduced, so that the cutter life is extended. Naturally, the excavation speed is also improved because the rock to be excavated is easily crushed. Further, since the ripperability is improved by the artificially formed cutting grooves and cracks, the driving force of the excavator and the driving torque of the disk cutter can be reduced.
[0015]
Further, in the open TBM, dust is captured by the ultrahigh pressure water sprayed toward the excavation surface, so that the working environment is greatly improved.
[0016]
Hereinafter, in order to clarify the operational effects of the ground excavation method according to the present invention, the destruction mechanism of the excavation method using ultra-high pressure water will be described in detail in comparison with the destruction mechanism using only the disk cutter.
First, as shown in FIG. 13, the crushing mechanism when the cutting edge 10a of the disc cutter 10 is inserted into the rock will be described in detail ("Study on drilling performance of large-diameter drilling machine" See the Ministry of Construction Public Works Research Institute).
As shown in FIG. 14, when two stresses σ ₁ and σ ₂ are generally applied to a minute two-dimensional cross section, the normal stress σ and shear stress acting on an arbitrary inclined surface are expressed by the following equations (1) and (2 ).
[0017]
[Expression 1]

[0018]
Microscopic failure is a phenomenon that occurs when the stress σ ₂ is greater than the tensile strength, or when the shear stress is greater than the shear strength, and the shear strength is proportional to the principal stress from the theory of Morse-Coulomb. Therefore, the shear fracture occurs at an angle of λ = π / 4−φ / 2 where φ is the internal friction angle of the Mole-Coulomb equation in the above equation (2).
[0019]
On the other hand, as shown in FIG. 15, when a line load P acts on a semi-infinite plate, the stress state at an arbitrary point is given by Timoshenko and Goodier by the following equation (3).
[0020]
[Expression 2]

[0021]
If fracture occurs at a plane that forms an angle of λ _f with the direction of the maximum principal stress, the fracture line starting from the point r ₀ immediately below the loading point is always at a constant angle λ _f with the radiation centered on the loading point. Logarithmic lines with That is, it is represented by the following formula (5).
[0022]
[Equation 3]

[0023]
Further, from the above equations, the shear line τ and the vertical stress σ along the fracture line can be expressed in the left and right directions as represented by the following formula.
[0024]
[Expression 4]

[0025]
Maurer gives the following equation (8) because the ratio of two stresses along the fracture line is constant from the above equations (6) and (7).
[0026]
[Equation 5]

[0027]
This relationship is the maximum shear fracture line (λ _f = π / 4), τ. As shown in FIG. 16A, the stress changes along the fracture line and becomes 0 at the rock surface (θ = ± π / 2), and θ = ± (π / It becomes maximum at 2-λ _f ). In addition, a maximum shear stress is generated immediately below the load. The fracture line of the crater shown in FIG. 16 (b) has a shear stress of 0 on the rock surface. Therefore, a shear fracture occurs near the fracture zone along the fracture line, and a tensile fracture due to bending load occurs near the surface. Can be considered.
[0028]
By the way, when the cutter blade edge is pressed against the surface of the rock and penetrated, the minimum load necessary for generating a crater is called a threshold load. Since the penetration pressure of the cutting edge is related to this threshold load, the threshold load increases as the cutting edge wears and the contact area increases. There is an experimental result by Maurer, M, C to investigate the relational expression between the wear width of the cutting edge and the threshold load (The State of Mechanics Knowledge in Drilling, 8th symposium on Rock Mechanics AIME, University of Minnesota, Sept. , 1966, P.355). FIG. 17 shows the relationship between the wear width and the threshold load from an experiment in which a tool having a cutting edge width of 1/2 inch is inserted into the Berea sandstone with respect to the threshold load. The figure shows that the crater is created in the area where the penetration of the cutting edge is larger than the straight line in the figure, but in the area below it, the crater cannot be formed just by marking the cutting edge on the rock surface. This shows the reason why the threshold load greatly increases with only slight wear, that is, the crushing efficiency rapidly decreases due to wear of the cutting edge.
[0029]
From the above explanation, the fracture mechanism when a vertical load is applied to the rock surface is clarified, and the reason why the threshold load increases and the drilling efficiency decreases when wear occurs on the cutting edge as excavation occurs. That is, in the case of the failure only by the disc cutter, the fracture occurs along the quasi-semi-elliptical shear fracture line due to the penetration of the disc cutter acting from the tip of the blade perpendicular to the excavation surface, and the threshold From the explanation of the load, it was found that the influence of penetration input (penetration stress) transmitted from the tip of the cutting edge to the rock side is large in terms of fracture capability.
[0030]
By the way, in the case of this invention, in order to form a cutting groove or a crack with ultra-high pressure water at the penetration position immediately before the cutter blade edge penetrates into the rock, a fracture mechanism slightly different from the above fracture mechanism is adopted. That is, as shown in FIG. 11, since the cutting groove or crack 14 is formed in advance prior to crushing by the disc cutter, the cutting edge S of the disc cutter blade 10a does not contact the rock to be excavated, or Even if they come into contact, the penetration force transmitted from the cutting edge S to the rock or the like becomes a non-dominant contact state. The penetration input from the disc cutter is mainly transmitted to the rock side from the contact portions U, U between the side inclined surface of the blade body 10a and the shoulder portion of the cutting groove or crack 14. In the case of adopting such a contact mode, as shown in FIG. 12, a vertical stress σ _N and a shearing force τ along the fracture line K act on the fracture line K by the wedge penetration input P _U in the oblique direction. However, the slip failure is directly performed by the shearing force τ. That is, basically, the penetrating input in the vertical direction does not act on the surface to be excavated, but the wedge penetrating input P _U acts directly in an oblique direction from the blade surface, so that the fracture portions 15 and 15 on both sides are pushed out sideways. Crush. Accordingly, the crushing is effectively performed at the point where the shearing force directly acts, and as shown in the figure, the cutting edge S does not contact the rock or the like, or even if it contacts, it acts on the cutting edge portion. Since the penetration force is small, wear of the cutting edge is reduced.
[0031]
In the present invention, the tip of the blade edge 10a does not directly contribute to destruction. Therefore, since the phenomenon such as the increase in the threshold load due to the wear of the blade edge as described above does not occur or is small, the excavation performance can be maintained for a long period of time.
[0032]
On the other hand, the excavator of the present invention for performing the excavation method includes one or more disc cutters in the excavation head portion, and at least the excavation head portion rotates about the excavation direction axis to roll the disc cutter. In an excavator adapted to crush the excavation surface, cutting along the planned cutting line of the disc cutter with respect to the excavation surface during crushing of the excavation surface by the disc cutter for a part or all of the disc cutter An ultra-high pressure water injection device for forming a groove or a crack is provided , and the injection nozzle portion of the ultra-high pressure water injection device is a sphere, and its injection position is prevented by clogging the injection nozzle. It is.
[0033]
In this case, the in the ultra-high pressure water injection system, in order to prevent clogging of the injection nozzle due to the inflow of the fine soil particles during injection stop ultrahigh pressure water, Ru can also be provided a cover member openably to the injection port.
[0034]
In addition, in a structure in which a ground contact portion having a plurality of disc cutters is rotatable about a central axis, such as a TBM or a shield machine, the relative position with respect to the rotation center axis of the ground contact portion is relatively It is also possible to provide the ultrahigh pressure water jetting device only for the disk cutter group disposed at a long distance position. The disk cutter group disposed at a relatively far position from the rotation center shaft portion has a relatively long rolling distance per rotation of the cutter head, and therefore has a larger excavation load than the disk cutter on the center side. As a result, the degree of edge wear increases. Therefore, in general, the number of disk cutters attached to the outer peripheral side is increased so that the load of the disk cutter is evenly distributed. However, in the present invention, the excavation load can be adjusted by forming a cutting groove or a crack. Therefore, as described above, it is possible to make the excavation load uniform by providing the ultrahigh pressure water injection equipment only on the outer peripheral disk cutter group having a large excavation load.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic view of a TBM employing a cutter structure according to the present invention, and FIGS. 2 and 3 are enlarged views of a disk cutter part.
As shown in FIG. 1, a tunnel excavator 1 includes a cutter head (excavation head according to the present invention) 2 on the front surface of a machine body, and a plurality of disc cutters 10, 10... Attached to the surface of the cutter head 2. The ground is crushed continuously by excavation. As shown in FIGS. 2 and 3, the disk cutter 10 has a cutter structure having a blade body 10a having a wedge-shaped cross section formed in a ring shape on the outer periphery of the cutter saddle 10b, and is fixed to the surface of the cutter head 2. It is attached to the cutter mount 11 via a bearing 13 so as to be freely rollable. When excavating the ground, the cutter head 2 is driven by the rotational driving force from the cutter driving motor 24 in a state in which thrust force in the rock contact direction is given to the cutter head 2 by the thrust jack 8 provided in the excavator 1. Rotate around the excavation direction axis. Then, the disc cutters 10, 10... Roll in the circumferential direction, whereby the blade body 10a crushes the rock mass, gravel, and the like.
[0036]
On the other hand, the trunk part of the tunnel excavator 1 is composed of a front trunk part 3 following the cutter head 2 and a rear trunk part 4, which can be bent at the connecting part between the front trunk part 3 and the rear trunk part 4. The part 5 is formed and curve construction is also possible. The excavation sludge scraped off by the disc cutters 10, 10... Is taken into the cutter chamber 25, and is discharged to the ground side through the drainage pipe 21 together with the water flowing in through the water supply pipe 20.
[0037]
Further, the front body portion 3 is provided with front grippers 6 and 6, the rear body is provided with main grippers 7 and 7, and the front body portion 3 and the main gripper 7 portion are connected by a thrust jack 8. The tunneling machine 1 is propelled by releasing the support of the pit wall by the front gripper 6 and extending the main gripper 7 to take a reaction force against the pit wall, extending the thrust jack 8 and moving the front trunk 3 forward. Excavation. When the excavation of one cycle length is completed, the front gripper 6 is extended to take a reaction force against the pit wall, the pit wall support by the main gripper 7 is released, and the thrust jack 8 is contracted so that the rear trunk 4 Move forward by moving forward. A segment 23 is assembled by an erector 22 behind the tunnel excavator 1.
[0038]
In the tunnel excavator 1 of the present invention, as shown in FIG. 2 and FIG. 3, immediately before the rock crushing is performed by the disc cutter 10 in the vicinity of the location where the disc cutters 10, 10. An ultra-high pressure water injection device 12 is provided for injecting ultra-high pressure water onto a planned passage line of the disk cutter 10 to form a cutting groove or a crack on the excavated ground surface. As shown in FIG. 4, the ultra high pressure water injection device 12 includes a nozzle head 12b, an injection nozzle 12a fixed to the tip of the nozzle head 12b, and a control valve 12c that preferably controls on / off of ultra high pressure water. It consists of. The nozzle diameter of the spray nozzle 12a is usually about 0.1 to 1.0 mm, and diamond is used as the material.
[0039]
Further, the super high pressure water injection device 12 can be provided for all the disk cutters 10, 10... Provided in the cutter head 2, or can be provided only for a partial group thereof. As an example in the case of providing for this partial group, for example, in order to prevent the unevenness of the wear degree between the respective disk cutters 10, 10... It can be provided only for the disk cutter group arranged at the position. Further, when the disc cutter 10 has a double disc structure having two blades 10a and 10a or a blade having more than that, as shown in FIG. High pressure water injection devices 12, 12... Are provided.
[0040]
In addition, as another aspect of the ultra-high pressure water injection device 12, in addition to a method of attaching the cutter mounting base 11 as a support base as shown in the drawing, a groove hole is formed in the cutter mounting base 11 to directly set the injection nozzle 12a. It can also be installed.
[0041]
Further, an abrasive can be supplied to the nozzle head 12b portion, and the abrasive can be sprayed onto the excavation surface together with ultra high pressure water. In addition, as said abrasive | polishing material, abrasive materials, such as an alumina type | system | group, a cast iron grid, a corundum other than quartz sand (about 60 mesh) and a garnet (about 60-100 mesh) are generally used.
[0042]
On the other hand, an ultra-high pressure water unit 9 is installed in the excavated tunnel of the tunnel excavator 1 of the present invention. The ultrahigh pressure water produced by the ultrahigh pressure water generation unit 9 is sent to the ultrahigh pressure water injection device 12. The ultra-high pressure water unit 9 is composed of a hydraulic unit 30, a water supply unit 31, a booster (intensifier) 32, and an accumulator 33, and the piston in the booster 32 is operated to the left and right by the hydraulic oil discharged from the hydraulic unit 30. The water in the water chamber is compressed into ultra-high pressure water. Further, the pressure of the ultrahigh pressure water is kept constant by interposing the accumulator 33. Usually, the ultrahigh pressure water unit 9 can generate 1000 to 4000 kgf / cm ² of ultrahigh pressure water.
[0043]
As shown in FIG. 2, the crushing of the rock or the like by the disc cutter 10 is injected from the ultra-high pressure water injection device 12 onto the planned passage line of the disc cutter 10 immediately before the crushing by the disc cutter 10 is performed. Ultra high pressure water is collided to form a cutting groove or crack 14 on the excavation surface, and the crushing is performed while the cutting edge 10a of the disk cutter 10 passes over the cutting groove or crack 14 line.
[0044]
As the attachment and injection mode of the ultrahigh pressure water injection device 12, as shown in FIG. 2, the ultrahigh pressure water collides vertically from the ultrahigh pressure water injection device 12 attached to the cutter mount 11 toward the excavation surface. It is also possible to collide with an inclination angle as shown in FIG. Further, the super high pressure water injection device 12 can be attached to the face plate of the cutter head 2 and sprayed onto the excavation surface. Further, as shown in FIG. 8, the super high pressure water injection device 12 is mounted at a position shifted laterally from the blade body 10a line of the disc cutter 10, and it is possible to inject from the oblique position to the planned passage line. it can.
[0045]
By the way, the excavation method using the ultra-high pressure water is basically intended for the bedrock, the gravel layer, etc., and the disk without using the ultra-high pressure water when entering the soft layer during excavation. Excavation may be performed only with a cutter. When the injection of ultra-high pressure water is stopped, fine soil particles in the muddy water or mud may enter the injection nozzle 12a and cause clogging. It is desirable to excavate the ground while continuously spraying water. In addition, nozzle clogging may be prevented by providing an openable / closable lid on the injection nozzle 12a. Further, as shown in FIG. 9, the injection nozzle 26 is a sphere, and the rotation position of the injection nozzle 26 can be controlled by water pressure or hydraulic pressure (not shown). Then, the ultra-high pressure water is jetted, and when the jetting is stopped, as shown in FIG. 10, the spherical nozzle 26 may be rotated to bring the nozzle port into the inside. In the nozzle structure examples of FIGS. 9 and 10, a separate washing water channel 27 is provided so that the ultrahigh pressure channel can be washed with backflow water when the injection is stopped.
[0046]
By the way, in the above embodiment, the present invention has been described by taking a tunnel excavator as an example. However, the present invention is not limited to other discs such as a rocking work (chipping work) such as a rock or a concrete surface, and a pavement peeling work. It can also be applied to cutting, crushing, and peeling operations using a cutter.
[0047]
【The invention's effect】
As described above in detail, according to the present invention, since the cutting grooves or cracks are formed in advance prior to crushing by the disc cutter, the life of the cutter can be extended. Further, since rocks and the like are easily crushed, the drilling speed is improved and the excavation function force can be reduced as compared with the conventional apparatus. Furthermore, various advantages are brought about such as being able to suppress dust during excavation and prevent deterioration of the working environment.
[Brief description of the drawings]
FIG. 1 is a schematic view of a tunnel excavator.
FIG. 2 is a side view of the disc cutter structure according to the present invention.
FIG. 3 is a plan view of a disc cutter structure according to the present invention.
FIG. 4 is a detailed view of an ultrahigh pressure water injection device.
FIG. 5 is a plan view of a double disc structure.
FIG. 6 is another super high pressure water injection mode diagram.
FIG. 7 is another super high pressure water jet mode diagram.
FIG. 8 is a longitudinal sectional view at the time of super-high pressure water injection in another nozzle structure example.
FIG. 9 is a vertical cross-sectional view when stopping ultra-high pressure water in another nozzle structure example.
FIG. 10 is another super high pressure water jet mode diagram.
FIG. 11 is a conceptual diagram of crushing in the case of this excavation method.
FIG. 12 is an enlarged schematic view of a crushing portion.
FIG. 13 is a conceptual diagram of crushing only with a disk cutter.
FIG. 14 is an explanatory diagram of a destruction mechanism using only a disc cutter.
FIG. 15 is an explanatory diagram of a destruction mechanism using only a disk cutter.
FIG. 16 is an explanatory diagram of a destruction mechanism using only a disk cutter.
FIG. 17 is an explanatory diagram of a threshold load.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Tunnel excavator, 2 ... Cutter head, 3 ... Front trunk | drum, 4 ... Rear trunk | drum, 5 ... Folding part, 6 ... Front gripper, 7 ... Main gripper, 8 ... Thrust jack, 9 ... Super-high pressure water generation Unit: 10: Disc cutter, 10a: Blade, 11: Cutter mounting base, 12: Ultra-high pressure water injection device, 12a: Injection nozzle, 12b: Nozzle head, 12c: On / off valve, 30: Hydraulic unit, 31: Water supply unit 32 ... Booster 33 ... Accumulator

Claims (4)

An injection device for injecting ultra-high pressure water is provided for each disc cutter blade body, and during the crushing of the excavation surface by the disc cutter, cutting with the ultra-high pressure water in advance along the planned line of passage of the disc cutter with respect to the excavation surface A groove or a crack is formed, and the crushing is performed while the cutting edge of the disk cutter rolls on the cutting groove or the crack line formed in this way, and the injection by the inflow of fine soil particles when the injection of the ultra-high pressure water is stopped In order to prevent clogging of the nozzle, the excavation method is characterized in that excavation is performed while continuously injecting a small amount of water even when the injection of ultra-high pressure water is stopped . In the excavator provided with one or a plurality of disc cutters in the excavation head portion, and at least the excavation head portion rotates around the excavation direction axis to roll the disc cutter to crush the excavation surface.
An ultra-high pressure water jet device for forming a cutting groove or a crack along a planned line of passage of the disc cutter on the excavation surface during crushing of the excavation surface by the disc cutter for a part or all of the disc cutter The excavator is characterized in that the injection nozzle portion of the ultra-high pressure water injection device is a sphere, and clogging of the injection nozzle when the injection is stopped is prevented by controlling its rotational position. The excavator according to claim 2, wherein in the ultra-high pressure water injection device, an openable / closable lid is provided at the ultra-high pressure water injection port to prevent clogging of the injection nozzle when the injection is stopped. In drilling head having a plurality of disk cutters, only the claim 2 or 3, wherein providing the ultra-high pressure water injection system with respect to a relatively long distance it is disposed at a position a disk cutter group the rotational center axis as a reference Excavator.

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