Mine - Gallery

A road built underground for mines, civil engineering works, etc. Those for railways, automobiles, and water are called tunnels or tunnels, those for pedestrians in urban areas are called underground passages, and those for power lines are called tunnels. When building mines to develop underground mineral deposits or underground power plants, tunnels must be excavated from an appropriate location on the surface to the mineral deposit to be developed or the location of the underground power plant. A tunnel dug vertically is called a vertical shaft, a tunnel dug at an angle is called an inclined shaft, and a tunnel dug almost horizontally is called an adit or horizontal tunnel. In metal mines, the main horizontal tunnel that leads directly from the outside of the mine to the mineral deposit is called a passageway, and is used for transportation, ventilation, and drainage. In general, the term tunnel often simply means a horizontal tunnel.

Special terms are often used in relation to tunnels. The width of the tunnel cross section is called the kase, and is expressed in terms of height and width. For example, a kase of "8.7" indicates a height of 8 shaku and a width of 7 shaku. The ceiling of the tunnel is called the kanmuri, the floor is called the fumae, and the very front of the excavation face is called the hittate, nobisaki, or tsume.

Digging a tunnel is called tunnel excavation, and when two tunnels are excavated in parallel with a certain distance between them, the main tunnel is called the honbi, and the tunnels that are excavated while connecting to the honbi at regular intervals are called tsurenobi, and these connecting tunnels are called menuki. When excavating two tunnels in parallel, air is sent in from one and exhausted from the other through the menuki. A tunnel that lets in fresh air is called an inlet air tunnel, and a tunnel that lets in dirty air that flows through the work area is called an exhaust tunnel. A tunnel that is excavated with only one tunnel is sometimes called a teppo-nobi. In this case, an air pipe is installed in the tunnel to send in the inlet air, and dirty exhaust air that flows past the excavation destination is often ventilated through the tunnel section.

Tunnels are given various names depending on how they are constructed, their purpose, and their location. In terms of construction, tunnels that are dug toward and through the ore body or coal seam are called "entrance tunnels" or "crosscuts," horizontal tunnels that are dug along the strike of the ore body are called "push tunnels," horizontal tunnels that are dug parallel to the strike of the coal seam are called "single-pane tunnels," main transport tunnels with rails laid on one pan are called "kanekata," and tunnels dug into the coal seam are called "side-layer tunnels." Depending on the purpose, there are exploration tunnels and coal exploration tunnels that are dug to explore the ore deposit or geological structure, transport tunnels for transporting mined ore and coal, gas vent tunnels that are installed to vent methane gas in the upper plate of the coal seam, and ventilation tunnels whose main purpose is ventilation - there are air inlet tunnels and exhaust tunnels, and air inlet tunnels are generally used as transport tunnels, while exhaust tunnels are sometimes used only for exhaust or as personnel passage tunnels. A tunnel that collects and drains water that springs up in the area above the horizontal tunnel that leads to the outside of the mine is called a drainage tunnel or hydrophobic tunnel. In addition, various names are given to tunnels depending on their location, place name, depth from the entrance, direction, etc.

In the development of mines and coal mines, it is necessary to establish the skeletal structure of the tunnel centered on the main tunnel according to the condition of the ore body and coal seam, excavate the preparatory tunnel before mining, and proceed with the preparation of the face one after another. Efficient tunnel excavation is as important as ore and coal production.

Tunnel excavation is generally done by blasting using a rock drill and explosives, but there is also a mechanical method using a full-face excavator. If the bedrock is very solid, there is no danger in leaving the tunnel as it is, but generally, timber, steel or concrete are used for support. In civil engineering, this is called lining. For large tunnels, a small tunnel called a pilot tunnel is first excavated, and then this is driven to the desired cross section. When tunnels are built in collapsible ground, they are excavated using the pilot method, in which a plate with a shaved tip called a sashiya is driven forward from above the supporting beam, and the support is advanced in sequence. Also, when a tunnel shrinks or deforms over time due to pressure from the surrounding bedrock (rock pressure), the process of enlarging and repairing it is called shikuri.

[Nobuo Fusamura]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

鉱山や土木工事などのために地下に設けた道。鉄道・自動車・用水用のものはトンネルまたは隧道(ずいどう)、市街地などの人道用は地下道、送電線用は洞道(どうどう)とよばれる。地下に存在する鉱床を開発する鉱山や地下発電所の建設などでは、地表の適当な位置から、開発すべき鉱床あるいは地下発電所の建設位置まで坑道を掘らなければならない。垂直に掘った坑道を立坑(たてこう)、斜めに掘った坑道を斜坑、ほぼ水平に掘った坑道を横坑または水平坑道という。金属鉱山では坑外から直接鉱床に達する主要水平坑道を通洞とよび、運搬、通気、排水に使っている。一般に単に坑道といえば水平坑道を意味している場合が多い。

　坑道に関しては特殊な用語がよく使われている。坑道断面の広さを加背(かせ)といい、高さと幅をもって表す。たとえば「八・七」の加背といえば高さ8尺、幅7尺の大きさを示している。坑道の天井部を冠(かんむり)、床面を踏前(ふまえ)、掘進切羽(きりは)の最先端の面を引立(ひったて)、延先(のびさき)、詰めなどとよぶ。

　坑道を掘ることを坑道掘進といい、2本の坑道をある間隔を置いて平行に掘進するとき、主要のほうを本延(ほんのび)、一定距離ごとに本延と連絡しながら掘進するものを連延(つれのび)、この連絡坑道を目抜(めぬき)という。2本平行に掘進するときは、一方から空気を送り、目抜を通して他方から排出する。新鮮な空気を通す坑道を入気坑道、作業場を流れて汚れた空気を通す坑道を排気坑道という。1本だけで掘進する坑道を鉄砲延とよぶことがある。この場合は坑道に風管を設けて入気を送り、掘進先を流れて汚れた排気は坑道部を通して通気を行うことが多い。

　坑道は設け方、目的、位置などによって種々の名称がつけられている。設け方では、鉱体または炭層などに向かってこれを貫くように掘進する坑道を立入(たていれ)坑道またはクロスカットcrosscut、鉱体に沿ってその走向方向に掘進する水平坑道をひ押(ひおし)坑道、炭層の走向に平行に掘進した水平坑道を片盤坑道、片盤にレールを敷設した主要運搬坑道を曲片(かねかた)、炭層中に掘った坑道を沿層坑道という。目的により、鉱床または地質構造を探査するために掘進する探鉱坑道・探炭坑道、採掘した鉱石・石炭を運搬する運搬坑道、炭層の上盤中でメタンのガス抜きのために設けるガス抜き坑道、通気を主目的とした通気坑道――これには入気坑道と排気坑道があり、一般に入気坑道は運搬坑道として用いられ、排気坑道は排気専用または人員の通行坑道として用いられることもある。坑外へつながる水平坑道より上部の区域で湧(わ)き出た水を集めて排水する坑道を排水坑道または疎水坑道という。そのほか位置、地名、坑口からの深さ、方向などによって各種の名称がつけられている。

　鉱山、炭鉱の開発には、鉱体や炭層の状況に応じて主要坑道を中心とした坑内の骨格構造を確立し、採掘に先だって採掘準備坑道を掘進し、次々と切羽準備を進めていなければならない。坑道掘進を能率よく進めることは鉱石や石炭を生産するのと同等以上にたいせつである。

　坑道掘進は一般に削岩機と爆薬による発破掘進によるが、全断面掘削機による機械的方法もある。岩盤が非常に堅固な場合は掘削したままの裸坑道でも危険はないが、一般には坑木、鋼材またはコンクリートを用いて支保を行う。土木関係ではこれを覆工という。大断面の坑道ではまず導坑という小断面の坑道を掘進し、ついでこれを追い切りして目的の断面とすることがある。崩壊性の地中に坑道を設けるときは、差矢(さしや)という先端をそいだ板材を支保の梁(はり)の上から前方に打ち込み、順次支保を進める差矢法で掘進する。また、坑道が時間の経過とともに周囲の岩盤の圧力（盤圧）などによって縮小、変形を生じたとき、これを拡大修復することを仕繰(しくり)という。

［房村信雄］

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