Interface instability between high-density pdyethylene (HDPE) geomembrane and sand is a main reason for landfill structural failure on lining interface. A series of direct shear tests are carried out to investigate interfacial characteristics and specimen failure types of a novel geosynthetics-reinforced HDPE geomembrane and sandy soil interface. Based on the results of direct shear tests

the interaction mechanism of interface is analyzed. It is proposed that the total resistance of interface between reinforced geomembrane and sandy soil is made up of skin friction resistance

side frictional resistance and bearing resistance of reinforcement. Bearing resistance of reinforcement is given by using the theory of slip line field. Results also show that the interface shear strength is significantly enhanced by the bearing resistance of reinforcement

especially in the higher normal stress. The results show that the theoretical value and experimental value varies in the same trend. The analytic solutions can reasonably indicate the interface total resistance.