Mine timbering

Japanese: 坑内支保 - こうないしほ（英語表記）mine timbering

Supports installed in tunnels, mining faces, etc. to maintain space or to prevent rockfalls and other damage and to protect personnel and machinery. Also the task of installing them. There are many types, depending on location, material, function, etc. (1) Location (a) Face support Usually installed temporarily. (b) Tunnel support Installed for a long period of time. (2) Material Pit timber support, steel support, concrete support, etc. (3) Function (a) Rigid support Support that has absolute strength up to a certain level of rock pressure and is not affected by cross-sectional area or shape. (b) Shrinkable support Support that shrinks while supporting rock pressure when the rock pressure exceeds a certain level, preventing damage inside the mine. (c) Flexible support Support that supports the rock pressure by deforming the entire framework. The frames (pillars) used for the supports also come in many types depending on their shape, including (1) multi-frames, which are the most common type of pillar made of three pieces arranged in a torii gate shape, (2) polygonal frames, which are pillars made of four or five relatively short pieces arranged in a polygonal shape, such as the gassho frame, which are stronger than multi-frames and have better flexibility, and (3) arch frames, which are arch-shaped pillars made of special steel shapes, and other types such as irregular frames. Support work has traditionally required technical skill, and mechanization has not progressed very quickly, but in recent years, mobile supports (self-propelled supports) using hydraulic steel pillars have been developed and are used mainly at longwall-type coal faces in coal mines, streamlining support work.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

坑道，採掘切羽などにおいて，その空間を維持し，あるいは落盤，落石などの発生を防止して人員，機械などを保護する目的で設けられる支保。またそれを設ける作業。場所，材料，機能などにより多くの種類がある。 (1) 場所 (a) 切羽支保　通常一時的に設置される。 (b) 坑道支保　長期にわたり設置される。 (2) 材料　坑木支保，鋼材支保，コンクリート支保など。 (3) 機能 (a) 剛性支保　一定盤圧までは絶対強度があり，断面積や形状などに影響を受けない支保工。 (b) 可縮支保　一定盤圧以上になると，盤圧を支持しながら縮んで坑内破損を防ぐ支保工。 (c) 可屈支保　盤圧により組枠全体が変形して支持する支保工。また，支持部に使用される枠 (支柱) も形状により多くの種類があり，(1) 諸枠　3個の部材を鳥居状に組合わせた支柱で最も一般的なもの，(2) 多角形枠　合掌枠に代表される4～5本の比較的短い部材を多角形状に組合わせた支柱で，諸枠よりも強度で支柱自体の可縮性がよいもの，(3) アーチ枠　特殊な形鋼のアーチ形状の支柱，そのほか，異形枠などがある。支保は従来，技術的に熟練を要す作業であったため機械化がなかなか進展しなかったが，近年，水圧鉄柱を利用した移動式の支保 (自走支保) が開発され，おもに炭鉱での長壁式の採炭切羽で利用されており，支保作業の合理化が進んでいる。

出典　ブリタニカ国際大百科事典小項目事典ブリタニカ国際大百科事典小項目事典について　情報

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