Centrifuge modeling of municipal solid waste landfill failures induced by rising water levels

New types of synthetic municipal solid wastes (MSWs) were developed, exhibiting engineering characteristics similar to those of real MSWs at different states of degradation in terms of total unit weight, void ratio, water content, compressibility, permeability, stress-strain relationship, and shear strength. Using these synthetic MSWs, several centrifuge model tests on the stability of geosynthetics-lined landfills with rising water levels were performed. The test results revealed the developing processes of MSW landfill failures induced by rising water levels. In most tests, a continuous slide occurred once a critical water level was attained. The ratio of critical water level and landfill height was 0.75-0.92 for present model tests using fresh or partly degraded synthetic MSWs with landfill slope ratio of 1: 1-1: 3, increasing with the increases of MSW degradation states and decreases of the slope ratio. An engineered berm increased the critical water level by 1.3%-9.5%. The landfills without an engineered berm tended to slide along the bottom liner; however, for normal landfills with an engineered berm and a slope ratio of 1: 3, penetrating cracks developed when the failures occurred. These results provide a good reference for water level and stability control of the landfill, and the construction of an engineered berm is suggested to improve the stability of these landfills.