development of underground space, especially in the tunnel and in mining and procedures to bring this project

摘要

Support for underground excavations, usch as tunnels and galleries, consists of a concrete cover that is protected against water by (I) =1 impermeable sheet inserted between the rock and the cover, separated from the rock by a (II) plastic adherent layer, and coated on its side turned towards the bonding layer with (III) an elastic material capable of being wleded to the plastic material by application of heat. Good resistance to all types of forces, including the pressume of water, and the movements of the rock, without damage low cost. Long life. (I) pref. consists of 45-50 wt. % of a 50:50 thermoplastic mixt. of amolefin polymer, esp. an ethylene/(meth)acrylate copolymer, and bitumen, and ca. 40 wt. % fine anthracite powder, opt. contg. up to 30 wt. % ash, the remainder being high pressure polyethylene. (II) pref. consists of a mat of plastic, esp. polypropylene or polyester, fibres (III) is pref. based on an acrylic polymer.