The invention provides large surface area geogrids with a high tensile strength, a method and apparatus for producing them, and their use as drain and reinforcement grids and as fences. The method for the continuous production of geogrids which have a large surface area and comprise thermoplastic bars which cross one another and are joined together by welding at the areas where they cross one another is characterized in that single-layer, homogeneous, molecular-oriented plastic bars with a high tensile strength are used and a multiplicity of crossing areas arranged behind one another and next to one another are intermittently welded simultaneously using the vibration-welding technique. In this method, a newly developed vibration-welding apparatus is used, which is characterized in that it has at least one vibration device which can be used to weld at least 100 crossing areas, preferably up to 500 crossing areas, simultaneously.