Out-of-sync heat and gas generation in landfill and its effect on slope stability

Heat and gas generation from the degradation of municipal solid waste affects landfill slope stability. Currently, the differences between heat and gas generation are understood and landfill slope stability analyses considering these differences are required. In this study, the conducted laboratory and field monitoring tests indicated that heat generation peaked earlier than gas generation. The relationship between the heat and gas generation was then considered in a landfill slope stability analysis. The earlier the temperature and gas generation peaked, the lower the safety factor and the earlier the minimum safety factor appeared. The minimum safety factor generally occurred when gas generation peaked. The minimum safety factors obtained with consideration of the out-of-sync heat and gas generation were up to 1.25% greater than those obtained when the temperature or gas generation rate was maintained at a peak value. A later peak in the temperature peaked, earlier peak in the gas generation rate peaked, and higher leachate level resulted in a larger difference between the minimum safety factors obtained with and without consideration of the out-of-sync heat and gas generation. Landfill slope instability is more likely to occur in the initial stage of landfilling.