Geomembrane tubes are sometimes stacked in layers to form higher flood-control dykes or other types of geotechnical structures. In this study, an analytical solution for two-layer stacked geomembrane tubes is proposed and evaluated using large-scale laboratory model tests. The geometries of the three geomembrane tube models are 1.0, 1.5 or 2.0 m in width, and 2.0, 3.0 or 4.0 m in length, respectively. The cross-sections of the two-layer geomembrane tubes obtained from the analytical solutions agree well with those obtained from model tests. The tensile forces measured from the model tests are scattered but show a trend similar to that indicated by the analytical solutions. Parametric studies are also carried out to investigate the major factors that influence the design of geomembrane tubes. Several charts are also produced for the design of two-layer impermeable geomembrane tubes resting on a rigid foundation.