Geotechnical net of large surface area and high tensile strength, method of and apparatus for manufacturing same as well as application thereof in drainage, concrete reinforcing and fencing as well

The rods used are molecularly-orientated and of high tensile strength. They are laid in a single layer. Welding takes place cyclically, at successive adjacent crossing locations, using vibro-welding technology (friction welding). An Independent claim is included for the grid or mesh so produced. The vibro-welding system is also claimed Preferred features: 500-8000 intersections are welded simultaneously. Vibro-welders are operated simultaneously, applying uniform mechanical pressure, with the same amplitude (0.5-2.5 mm, preferably 1-2 mm) and oscillation frequency (60-300 Hz, preferably 150-180 Hz). Mutually-parallel rods run across the direction of feed (transverse rods). Others run parallel to each other and the feed (longitudinal rods). Their intersections are at 45 degrees to 90 degrees . Spacings side to side, are 10-100 mm, preferably 20-80 mm. Rods are located in numbers suitable to make grid or mesh 3-6 m wide, preferably 5 m wide. Total length is 25-500 m, preferably 50-100 m. Tensile strength is 300-800 N/mm<2>. Dimensions are quoted for square or rectangular rod cross sections, their sides ranging from 1 mm up to as much as 40 mm. Rods employed have embossments (to 0.5%-30% of their thickness) on top and/or underneath, for keying. Longitudinal rods are wider and/or thicker than transverse rods. In addition, fleece, fabric, knit or sheet is welded to one or both sides, using a hot iron, hot air or adhesive.