Time and temperature effects on geomembrane strain from a gravel particle subjected to sustained vertical force

Abstract

Experimental data is reported that quantifies how time (up to 10 000 h) and temperature (from 22 to 85 °C) impact tensile strains in a 1.5 mm thick high-density polyethylene geomembrane — with a compressible clay liner beneath it — that are induced by an overlying gravel particle when subjected to a sustained vertical force. At an average applied stress of 250 kPa and clay water content of 16%, tensile strains were found to increase by 1.25 times as the temperature was increased from 22 to 55 °C after 1000 h. Similarly, strains were found to increase by factors between 1.2 to 1.3 as time was increased from 10 to 1000 h. Based on the measured data, time–temperature superposition (tTS) was then used to develop an approach to predict long-term geomembrane strains from gravel indentations. The tTS approach was validated against independent experiments conducted for 10 000 h (1.14 years) as it was found that the predicted strain of 19% was very close to the measured strain of 18%. Provided that the physical properties of the geomembrane do not decrease abruptly, the results suggest that the tTS approach developed can be used to provide estimates of long-term geomembrane strains.