Operation, maintenance, drainage, water proofing, rehabilitation, renovation and repair of underground structures New waterproof structure for New Austrian Tunneling Method

Tunnels in mountainous areas are waterproofed to reduce the restrain from the back of the lining and control cracks usually by nailing waterproofing sheets on sprayed concrete surface. However, this method is prone to excessive and insufficient allowance of waterproofing sheets, which causes entrainment of the sheets in lining concrete, blockage of grouting, insufficiency of lining thickness, and voids behind the sheets. A practical method should be developed to apply sheets tightly to sprayed concrete so that the sheets do not block injection of grout.