Landfill Settlement and Instability

This chapter focuses on the application of the degradation‒consolidation theory in the context of MSW landfill settlement, capacity, and stability. Typically, the degradation of organic matter within landfills increases leachate levels and gas pressures, significantly impacting effective stress and consequently influencing MSW compressibility and shear strength. These changes ultimately influence landfill settlement and stability. Beginning with an examination of long-term degradation compression tests, this chapter subsequently introduces compression models for MSW, along with methods for landfill settlement and capacity calculations. The discussion then focuses on landfill stability analysis, emphasizing factors such as the shear strength of MSW, instability modes, critical water levels, and critical LFG pressures. Furthermore, centrifugal hypergravity modeling of MSW landfill failures triggered by rising water levels and LFG pressures is presented, proposing critical water level and critical gas pressure values for landfill stability assessments. Strategies for expanding landfill capacity based on stability control are also discussed, including techniques such as dewatering and gas venting for landfill slopes and geogrid reinforcements, along with landfill capacity expansion rate calculations.