Proprietà petrofisiche e comportamento dei materiali coesivi di copertura di discariche RSU alle sollecitazioni termiche

The present work allowed the thermal characterization of the materials of the temporary covering of a MSW landfill (Torretta landfill), and devoted particular attention to investigating the conduct of cohesive materials in response to thermal stress caused by the change in air temperature and from endogenous heat produced by the biodegradation of waste. The research activity was divided into a first phase of bibliographical survey, and then continued with several laboratory tests and numerical finite element modeling with Feflow software, the most popular software for the modeling of the thermal transport in the porous means. The laboratory analysis was conducted on material from the Torretta landfill (Legnaro, VR). The material of the impermeable barrier was classified through grain size tests, aerometry, X-ray diffraction, Atterberg limits, determination of organic content and specific weight of the grains. The distribution grain size curve of the coarse material was also created. 3 Direct measurements of thermal conductivity were made with different types of tools in order to ensure perfect contact between the probe and the samples. The fine material was tested in different conditions of temperature, even at temperatures below 0°C, using ISOMET 2114. The gravel material was tested with a specific instrument composed of a hot plate and a containment ring at the IUAV laboratory (Mestre, VE). The sample was first tested in dry condition and later in wet conditions. The thermal parameters obtained from experimental measurements at different temperature have allowed to obtain the law that describes the variation of a function of temperature. These values were used to characterize different materials in a FEM model, realized through the Feflow code. In four simulations, it was discovered that the impermeable barrier was influenced both by high temperatures from the waste mass below and by seasonal air fluctuations (Arpav data, Castelnovo Bariano Station). From this knowledge, permeability analysis can be made to determinate the variation of permeability of the barrier subject to thermal stress.