Hyunku Park

Long-term settlement behaviour of MSW landfills with various fill ages

MSW landfill settlement characteristics are peculiar because a considerable amount of settlement occurs due to the decomposition of waste organic solids for very long duration. The total amount of settlement that occurs due to this decomposition in a MSW landfill is mainly dependent upon the amount of biodegradable solid waste and hence the fill age of the MSW landfill. The settlement stabilisation period is also dependent upon the decomposition condition. In order to investigate the settlement characteristics of MSW landfills, a mathematical model was proposed and applied to settlement data of MSW landfills which have various fill ages. A data bank of model parameters were obtained and the trends were analysed. The long-term settlement behaviour of MSW landfills can be fairly well estimated by the proposed model. It is supposed that the total remaining amount of settlement might be predicted on the basis of the fill age with two appropriate design parameters.

Cover Placement on Dredged Marine Clay Reclaimed Deposit

This paper presents a case history of geotextile-reinforced dry cover placement on a reclaimed clay deposit treated by progressive trenching method. In order to investigate the effects of the cover materials characteristic of ensuring trafficability with respect to bearing failure and ground deformation, two types of covers were considered in pilot tests: a layer of weathered granite soil cover and a layer of weathered granite soil over stiff crushed stone. A number of in-situ plate load tests were conducted for various cover conditions to assess the bearing capacity of the reclaimed deposit and to determine the thickness and material compositions that satisfy the bearing capacity requirement. In full-scale pilot tests for cover placement, field monitoring was carried out for the surface settlement and pore pressure that developed in the reclaimed clay layer. The results of plate-loading tests and monitoring during staged cover placements are discussed and compared using numerical predictions obtained from both finite element analyses and undrained stability analyses. The comparison results showed that the drainage condition of the ground surface facing the dry cover is strongly related to the ground response and stability.