Field trial of a reinforced landfill cover system: performance and failure

The geotechnical stability of an inclined multilayer capping depends on the shear strength available along the various interfaces. If the slope is very steep an additional reinforcing geosynthetic may be used to obtain a safer condition. Full-scale field trials can provide better resolution data on the reinforcement behaviour than conventional calculation methods based only on laboratory tests. The paper deals with a field trial carried out on multilayer capping, reinforced with a geogrid, in an Italian landfill. The geogrid behaviour was monitored for a month using displacement sensors and pressure cells located along the slope and in the anchor trench. Subsequently, the cover system was led to collapse by cutting the reinforcement and an analysis of the reinforcement behaviour and its relevance in the system stability were studied. This paper discusses in detail the setup of the field trial and the experimental data recorded during installation, monitoring, and failure phases of the system. The deformation behaviour of the geogrid during the entire test was recorded and analysed. The resulting data highlight the effects of the construction process on the geogrid behaviour including the contribution of geogrid creep characteristics until the failure.