Performance of Plastic Canal Linings

摘要

A study was conducted to determine the performance of buried plastic membrane linings, primarily 10-mil PVC, used for seepage control in Bureau irrigation canals. Samples from 10 canal installations ranging in service life from 1 to 19 years were evaluated. Results of this study indicate that buried plastic membrane linings are providing satisfactory service for seepage control. These linings are viable alternatives in areas not suitable for concrete or compacted earth linings. Laboratory studies and field observations indicate that some stiffening of the PVC lining has occurred with time. This stiffening or aging is caused by the loss of plasticizer, the agent used in the manufacturing of the lining to impart flexibility. With aging, there is generally a reduction in elongation, an increase in modulus at 100 percent elongation, and a decrease in resistance to impact damage at low temperatures. The rate of this aging is primarily dependent on three factors: (1) The linings originally manufactured with a high plasticizer content exhibited less aging, (2) Samples obtained from within the water prism exhibited less aging than those obtained outside the prism, and (3) Samples obtained from areas where the lining had been placed over a fairly smooth subgrade exhibited less aging than those installed over a coarser base. This report also presents design criteria, construction procedures, and updated construction and material specifications for PVC linings.