The settlement characteristics of solid waste landfill site must be considered in the design of sanitary landfill site as well as in the course of the rehabilitation of the landfill site. Thus a number of investigators have studied on the subject for several decades. Yen et al. have studied settlement properties of landfill sites by analyzing in-situ data, but they couldn't derived any prediction method applicable to an actual refuse landfill site. Sowers have divided the total settlement into two parts ; primary settlement, and secondary settlement. He proposed a range of Cc and Cα for refuse landfill sites based wholly on the initial void ratio of the site. Thus the values of Cc and Cα is very much dependent on the engineering judgment.
A variety of prediction methods for settlement of landfill site have been proposed. Among those, Morris theory, Zimmerman theory, Gibson and Lo model and Power Creep Law are the most widely applied methods. Especially Gibson and Lo model and Power Creep Law have been successfully applied to the landfill site where the amount of settlement was large and the secondary settlement was obvious. However in their models, the influence of the organic content due to decomposition can't be taken into account.
When the refuse is decomposed both the total volume and the void ratio are decreased, and settlement characteristics will be accordingly changed. Thus in this study, a settlement prediction method practically applicable to the landfill site is proposed. The effects of organic content on the model parameter values utilized in both Gibson and Lo model and Power Creep Law are studied by using a large consolidation testing apparatus. A representative municipal refuse sample was selected for the test and was decomposed to have the required organic contents.
The results obtained were analyzed to investigate the effects of variation in organic content on the model parameters. If some more data are available, a reasonable settlement prediction method could be developed for applying to the actual landfill site.
