Deformation mechanism and early warning of an accumulation-layer landslide: integrated analysis of multi-source monitoring and numerical simulation

Abstract

Researching the deformation mechanisms and early warning of landslides holds significant engineering importance. A typical accumulation-structured landslide in southern China was selected as the case study to investigate the intrinsic failure mechanisms of slopes, with adjacent tunnel construction and rainfall considered as external boundary conditions. By combining geological surveys, borehole exploration, and multi-source monitoring data, including GNSS-based surface displacement and deep inclinometer measurements, the spatial-temporal evolution of slope deformation was systematically investigated. Numerical simulations were performed in FLAC3D using the Strength Reduction Method (SRM) to assess slope stability and determine the potential critical slip surface. Subsequently, an early warning criterion was established using a refined displacement tangent angle method. The results indicate that intense tectonic activity, prolonged weathering, and rainfall infiltration are the primary predisposing factors. Deformation manifests as progressive tensile cracking that propagates from the landslide toe to the crest. The critical displacements at the toe and crest are determined to be 1035 mm and 145 mm, respectively, with a corresponding critical displacement rate of 25 mm/d at the toe. This study proposes a robust framework for predicting accumulation - layer landslides, providing valuable guidance for similar geotechnical engineering projects irrespective of specific triggering factors.