Evaluation of Different Protection Systems to Control the Geomembrane Deformations in Liner Applications

In landfill backfill systems and mining tailings piles, it is required to use a protective layer above the geomembrane to prevent physical damage from the overlying granular drainage layer. In this work, an experimental study was carried out to evaluate the deformed surface of a 2-mm-thick HDPE geomembrane from a coarse drainage gravel overlying when placed above a clayed underliner subjected to loads of 600 kPa and 1800 kPa over 100 h. Four nonwoven PP-type geotextiles with a mass per unit area ranging from 550 to 1300 g/m² and a layer of 100 mm of clay placed above the geomembrane were tested as protection layers. A machine of reading by coordinates with a grid of 1 mm was used to develop a contour map and the strains were calculated for the whole geomembrane deformed surface in percentage. The results showed that the geomembrane presented puncture and large tensile strain values without protection. The clayed soil was the only protection limiting the tensile strains below the proposed limits. It was verified that at high pressure, the geotextile protection could not avoid a puncture, and although the double nonwoven geotextile reduced the strain values, the GMB area exhibiting strain above the proposed limit was too high and could lead to long-term failure. Even with a lower applied load, the single geotextile protection had 30% of the geomembrane area exceeding the 3% strain threshold. On the other hand, the double geotextile showed a performance improvement presenting 14% of the area exceeding the proposed limit.