Slope instability occurs in landfills owing to increased internal temperatures. However, strength characteristic tests for solid waste (SW) and landfill slope stability (SS) calculations that consider temperature variations are scarce in the literature. In this study, we conducted triaxial tests on SW under a range of temperature conditions and proposed the circular slide method (CSM) for calculating SS in consideration of temperature effects. SW cohesion decreased linearly with increasing temperature, whereas the internal friction angle remained essentially unchanged. Our results showed that higher temperatures reduced the SW shear strength, changing the most dangerous sliding arc away from the slope toe. The landfill slope safety factor decreased by more than 20% with an increase of the maximum temperature from 20°C to 50°C. Reduction of the leachate level (LL) led to a decrease in the landfill high-temperature zone and the safety factor increased according to LL and temperature distribution. If cooling pipes are used to control the SW temperature, we recommend arranging the cooling pipes on the landfill liner. The proposed CSM can be used to analyse landfill SS.

Slope failure in municipal solid waste (MSW) landfills is a common environmental disaster that poses serious ecological and health risks. Landfill slope stability (SS) is sensitive to leachate levels and gas pressure (GP) caused by the degradation of organic material, but the extent of these combined effects remains poorly understood. In this study, a simplified landfill GP calculation method is presented and a circular slide method that considers the combined effects of leachate and GP is established. The results show that the landfill GP is mainly affected by the gas production rate, gas conductivity of the solid waste (SW), and landfill depth. The safety factor of landfill SS is also significantly lower when GP is considered. The distribution of GP is affected by the depth of the failure circle and SW. Landfill slope instability can be explained by localized damage caused by GP breakthrough of the filled SW. This study probably provides important guidance for the design, operation, and management of MSW landfills.

The increase in landfill temperature often results in shear strength reduction of both the solid waste and the liner, which leads to slope instability. However, very few landfill slope analysis methods can simultaneously consider the effect of temperature on the shear strength of the waste solid and the liner. In this study, based on the strength parameters of the liner and waste with temperature, a wedge method for translational failure analysis of landfills considering temperature increase was established. The results showed that rising temperatures caused by biochemical degradation at the bottom and middle of the landfill reduced the anti-slide force of back slope more than that of bottom slope. With the leachate level increasing, the effect of temperature rise on landfill stability became obvious. The feasibility of the proposed wedge method was verified by the engineering case study of Xiaping Landfill, Shenzhen, China. This study probably provides important guidance for the design, operation and management of municipal solid waste landfills.