Ordinance on Industrial Safety and Health
Ministry of Labour Ordinance No. 32 of September 30, 1972
Latest Amendments:
Ministry of Health, Labour and Welfare Ordinance No. 47 of March 30, 2007
In Japanese
掲載日：2008.03.28
Part II Safety Standards
Chapter VI Prevention of Dangers in Excavating Work, etc.
Section 2 Construction Work of Tunnels, etc
Subsection 2 Tunnel Shoring
Article 390 (Material)
- (1) The employer shall not use materials having marked damage, deformation or corrosions as materials for tunnel shoring.
- (2) The employer shall, as regards the wooden materials for tunnel shoring, not use unless these are of good toughness such as Japanese red pine or black pine, and free from the marked defects for strength such as cracks, worm-eaten spots, gnarls and slanted fibres.
Article 391 (Structure of Tunnel Shoring)
- (1) The employer shall make the structure of tunnel shoring sufficiently sound corresponding to the condition of nature of the soil, strata, water content, spring water, cracks and loose stones pertaining to the natural ground where the said tunnel shoring was installed and method of excavation.
Article 392 (Standard Drawing)
- (1) The employer shall, when constructing the tunnel shoring, prepare in advance a standard drawing, and construct such support by the said standard drawing.
- (2) The standard drawing prescribed in the preceding paragraph shall describe the arrangement, size and materials of the members of tunnel shoring.
Article 393 (Construction or Alteration)
- (1) The employer shall, when constructing or altering the tunnel shoring, comply with the following provisions:
- (i) To arrange a set of members composing the main members on the same plane;
- (ii) For wooden tunnel shoring, to make the degree of compression of each member of said tunnel shoring the same level.
Article 394 (Prevention of Dangers of Tunnel Shoring)
- (1) The employer shall, as regards tunnel shoring, comply with the following provisions:
- (i) To take measures such as providing sill plates at the foot portion to prevent from settling.
- (ii) For steel arch shoring, to comply with followings:
- (a) To make the distance between an interval1.5 m or less.
- (b) To take measures such as driving wedges so that the main members display arch functions sufficiently .
- (c) To couple firmly main members with one another using connecting bolts and connecting girders, bracings, etc.
- (d) To provide slant props at the entrance of tunnels, etc.
- (e) When it is liable that steel arch shoring may fall or be twisted due to longitudinal load of tunnels, etc., applied to such shoring, for example, when longitudinal length of tunnels, etc., supported by steel arch shoring is short, to provide slant props also to portions other than the portions of the entrance of such tunnels, etc., or take other measures to prevent steel arch shoring from falling or being twisted.
- (f) When it is liable to cause dangers to workers due to fall of rocks, to provide sheet piles, wooden sheets, linier plates, etc.
- (iii) For wooden prop type shoring, to comply with followings:
- (a) To fasten sleepers to the ground with nose girders, etc., to prevent displacement.
- (b) To provide slant props at both ends.
- (c) When it is liable that wooden prop type shoring may fall or be twisted due to longitudinal load of tunnels, etc., applied to such shoring, to provide slant props also to portions other than both ends or take other measures to prevent wooden prop typed shoring from falling or being twisted.
- (d) To make the connecting portions of members fit and fasten them with clamps, etc.
- (e) Not to arrange caps within the vertical plane including longitudinal bar braces or girders collar braces.
- (f) To make longitudinal bar braces and girder collar braces display arch functions sufficiently.
- (iv) For tunnel shoring other than steel arch shoring and wooden prop type shoring, to provide slant props at portion of the entrance of tunnels, etc.
Article 395 (Removal of Members)
- (1) The employer shall, when removing members of tunnel shoring to which a load is applied, not remove such members unless measures have been taken to remove the load applied to such members to tunnel concrete form shoring, etc.
Article 396 (Checkup)
- (1) The employer shall, when having installed tunnel shoring, check the following matters every day, after an earthquake of medium shock or heavier, and immediately reinforce or repair when having found any abnormalities:
- (i) Existence and condition of damage, deformation, corrosion, displacements and coming off of members.
- (ii) Degree of compression of members.
- (iii) Conditions of the connecting portions and crossing portions of members.
- (iv) Existence and condition of settling of the foot portion.
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