Stability of two landfills against sliding along interfaces of geosynthetics in base lining systems

This paper describes the results of two separate case studies conducted to assess the stabil-ity of hazardous waste landfills against sliding along interfaces of geosynthetics in the base liner systems and highlights the influence of various parameters on the factor of safety. In case study A, the base was horizontal and the height of landfill was increased from 14.0 m to 31.8 m. As a consequence, sliding along the base became the critical failure surface for temporary waste slopes. In case study B, the base profile was governed by the bedrock level which was at a shallow depth below the ground surface. Dur-ing the excavation, it became evident that the bedrock level exhibited significant elevation difference from one end to the other resulting in variable inclination of the base. The stability of the landfill against sliding along the interfaces of geosynthetics in the liner system was analysed for different conditions.
The studies highlight the influence of the following factors on the base sliding stability along soil–geosynthetic and geosynthetic-geosynthetic interfaces: (a) smooth versus textured geomembrane; (b) height of waste, (c) base inclination, (d) pore water pressures in wet waste, (e) leachate head, (f) seismic forces and (g) berm at the toe.
It is found that factors of safety are high when textured geomembranes are used, and when leachate head and pore water pressures are low and stabilizing berms are provided.