Further study of geomembrane/cohesive soil interface shear behavior

The results presented in this paper contribute to an existing data base on the shear strength of geomembrane/cohesive soil interfaces. Three different clay materials are studied, and the interfaces include both smooth and textured HDPE geomembranes. Consolidated drained and consolidated undrained direct shear tests were performed on samples compacted wet of optimum under both partially saturated and saturated conditions. The effect of rate of shear is studied through a range from 12·7 mm/min to 0·005 mm/min (0·5 in/min to 0·0002 in/min). The shear strength of textured geomembrane interfaces during drained shear loading was equal to or less than that of the clay alone, and the consolidated undrained shear strength was higher than for the clay alone. Deformations during shear were studied and used to explain the variation in shear strength due to the rate of shear loading for textured geomembrane/clay interfaces.