Experimental Study on the Influence of Welding Parameters on the Mechanical Properties of Geomembrane Welds

In a seepage control system composed of geomembranes, the mechanical properties of the geomembrane welds directly determine the overall safety and durability of the system. To clarify the influence of welding parameters on the mechanical properties of the welds, this paper prepares weld specimens using different welding processes and systematically investigates the effects of welding temperature, welding pressure, and welding speed on the mechanical properties of double wedge welds in HDPE geomembranes through peel tests, shear tests, and DIC deformation measurement technology. The results indicate that the peel strength of HDPE welds has no linear correlation with welding pressure but there exists a threshold effect. The peel strength exhibits an exponential relationship with welding temperature and a Gaussian relationship with welding speed. The shear strength of the welds can be fitted by an exponential function for all three welding parameters. The coefficient of determination (R2) for each of the above fitting equations is higher than 0.9. Under different welding parameters, the yield strength of the double welds is slightly lower than that of the base material (approximately 89–94% of the base material), while the yield strain decreases more significantly (to 62–81% of the base material). Observations of the weld deformation distribution using DIC show that when the specimen elongation is below 11%, strain is concentrated near the weld; after reaching the yield strain, necking occurs; and the strain concentration shifts to the necking region. As the elongation further increases, significant plastic yield deformation occurs in the necking region, with a maximum strain of 500%.