Numerical and Experimental Study on Seismic in-Soil Isolation of MSW Landfill by Geosynthetic Liners: Case Study of Kahrizak Landfill, Tehran, Iran

Seismic loads may damage municipal solid waste landfills (MSWLF) through the relative movements within the waste, bottom lining system, cover system, foundation, and interfaces. The smooth synthetic materials might be placed beneath the structures to provide seismic protection by absorbing the imparted energy of earthquakes through the sliding mechanism. In the present study, experimental investigations were conducted in order to evaluate role of in-soil base isolation on seismic response of the Kahrizak MSW landfill. Shaking table tests were conducted on the MSW embankment isolated by semi-elliptic shaped liners and subjected to harmonic sinusoidal base excitations. Furthermore, the shaking table model was simulated by numerical analysis. The results of the isolated and non-isolated cases are compared in terms of permanent displacement and seismic response. Subsequently, the behavior of the numerical model was evaluated for different parameters. A reasonable agreement was found between the results of the physical model and the numerical model in prototype scale. The efficiency of in-soil isolation increases with increasing the amplitude of input motion. The results show that increasing the shear modulus reduces the amount of spectral amplification and relative displacement. It was also observed that as the age of the MSW increases, base isolation increases the displacement and crack width. Moreover, employing flat liner facilitates the movement of the ridge to the sides; and the concave liner prevents the wedge to move and, hence the quantity of settlement is reduced.