Behavior of Domestic Waste Landfill Foundation.

Recently, demand for the reuse of terminated domestic waste landfills is growing due to its economical benefit. For the reuse of the terminated domestic waste landfills, ground improvement techniques on the landfills are necessary because its foundations typically have high settlement and low strength. In this study, we examined two domestic waste landfills that are terminated more than 10 years ago. For the ground improvement of the landfills, we applied three popular ground improvement techniques (Dynamic Compaction, Chemical Grouting, and Cement Grouting methods) on the each site for the comparison of the effectiveness of ground improvement among the methods. Both long-term and immediate (elastic) settlements of the foundations of landfills were examined. The soils from the landfills have a little organic content and high permeability. This reveals that the settlements by organic decomposition and consolidation are negligible. However, elastic settlements are expected to occur. Based on the equation from Yen and Scanlon, we concluded that the long-term settlements of these two landfills due to organic decomposition are completed. For the estimation of immediate settlement, we compared the calculated elastic settlements before ground improvement to those after ground improvement using the equations from Osterberg, Burland and Burbidge, Stamatopoulos and Kotzias, and Bowles methods. There was much difference among the elastic settlements calculated using these equations. By performing numerical analysis (finite element analysis) based on the inputs resulting from different types of field and laboratory tests such as field density tests, plate bearing tests, sieve analyses, and Atterberg limits tests, we found that the elastic settlement calculated using Osterberg formula was the best fit to that calculated using the numerical analysis.