Two-tier framework for landslide risk assessment of construction solid waste landfills

Frequent landslides in construction solid waste (CSW) landfills pose significant safety risks. To address this, an integrated and practical two-tier framework is proposed for landslide risk assessment of CSW landfills, consisting of qualitative and quantitative assessments. In Tier 1, a multi-scale hazard and vulnerability assessment index system incorporating mitigation measures is established. This enables the rapid screening of multiple landfills to identify sites requiring prioritized attention, while also allowing for a comparative evaluation of risk levels both before and after the implementation of such measures. In Tier 2, a refined quantitative risk assessment is performed for the higher risk landfills identified in Tier 1, focusing on the spatial variability of CSW strength parameters. The application of F-N curves to quantify risk acceptability provides a quantitative basis for proposing targeted risk mitigation measures. Guangxi, China, with significant CSW disposal pressure, was chosen as the case study. Empirical findings include: (1) Among 131 CSW landfills, 12 sites were identified at a higher risk level through the initial screening, primarily located in Lingshan County; (2) Quantitative risk assessment of the high-risk Landfill No. 34 revealed that its societal risk fell within the unacceptable region under saturated conditions; (3) To address the unacceptable risk, comprehensive risk mitigation measures were proposed, with their effectiveness validated through comparative analysis. Overall, this two-tier framework optimizes the balance between regional screening efficiency and site-specific assessment accuracy, providing a reference for landslide risk management in CSW landfills.