Some geomembranes are connected with adhesive tape, while others require heat-welding by a professional in order to connect their seams. The goal of connecting geomembranes is to restructure the polymeric makeup of the material itself. This creates an incredibly strong material, without points of particular weakness or stress.
This can be done by melting the seams, and restructuring the individual atoms through thermal means. Alternatively, there also chemical processes that can create new seams in or on your geomembrane.