چكيده به لاتين
It is well known that landfill temperature increases due to biological activity due to the decomposition processes of organic components. Therefore, the effects of temperature variations on the landfill's hydro-mechanical behavior must be addressed. The present study reveals the thermal impacts on the compressibility and permeability of municipal solid waste samples with different plastic contents. The samples were collected from Kahrizak landfill located in Tehran, Iran. Municipal Solid Waste (MSW) compressibility is normally a challenging task to study as it is affected by several parameters which are not easy to simulate in the laboratory. A large-scale oedometer was developed to evaluate the compressibility of MSW, which can apply different levels of temperature to the specimens (25, 45, and 65℃). In real MSW landfills, the anaerobic decomposition reactions act as a thermal source, raising MSW temperatures. Due to the non-standard height to diameter ratio, the mobilized inner wall friction was investigated and stress distribution in the MSW specimen was corrected. In this study, fresh MSW samples in loose (LDM) and dense (HDM) states, and also, zero plastic waste (ZPW), fresh waste containing a moderate amount of plastic (MPW), and high plastic waste (HPW) have been investigated. Also, at-rest lateral earth pressure coefficient (K0), interface friction angle (δ), and the effective-stress proportionality coefficient (β) were determined. Then a series of compressibility tests on LDM are performed at 25, 45, and 65oC and the horizontal and vertical permeability of MSW, at each loading stage were measured. It can be concluded that the developed large Thermo-Hydro-Mechanic (THM) oedometer can determine the coefficients related to the compressibility of geo-materials well. The results showed K0, δ, and β values are almost independent of density although a slight difference might be observed. Also, the results showed that the average values of C_α^' coefficients are in the range of [0.011;0.021]. C_c^' values varied in the range [0.25;0.46] whereas values of C_r^' fall in the [0.04;0.07] interval. Also, the values of horizontal to vertical permeability coefficient (kx/ky) are in the range of [3.2;9.5] for 25, 45, and 65℃ temperatures in all samples. Furthermore, the parameters of K0, ν, E, and G were calculated. Overall, the samples compressibility increases with loading steps and temperature and decreases with plastic content. Also, the horizontal and vertical permeability coefficients decreased with temperature and plastic content.
