# Mechanisms of deformation and failure in colluvial slope under artificial surcharge loading

## TL;DR

This study explores how artificial surcharge loading causes landslides in colluvial slopes, using physical tests and simulations to identify failure mechanisms and key indicators for early landslide detection.

## Contribution

The study provides new insights into the progressive failure mechanisms of colluvial slopes under artificial loading and identifies critical monitoring indicators.

## Key findings

- Maximum vertical and horizontal displacements of 40 mm and 50 mm were observed under loading.
- Shear stress concentrated along the loading boundary, with vertical stress penetrating deeper than horizontal stress.
- Progressive failure stages include rear-edge tensile cracking, upper soil sliding, and front-edge bulging.

## Abstract

Large-scale artificial surcharge loading often triggers landslides in colluvial deposits, yet the mechanical response and failure mechanisms of such slopes under loading remain insufficiently understood. Using a typical colluvial slope in Tibet as a case study, this research integrates physical model tests and FLAC3D simulations to investigate loading-induced deformation and failure processes. Analogous materials composed of river sand, barite powder, calcium carbonate powder, and water were prepared, and multiple regression analysis was used to establish empirical relationships between mix ratios and the resulting cohesion and internal friction angle, yielding high similarity (Ra2=0.8732−0.9326). Under loading, the slope exhibits maximum vertical and horizontal displacements of 40 mm and 50 mm, respectively, with shear stress concentrated along the loading boundary and vertical stress penetrating deeper than horizontal stress. The slope undergoes progressive failure: loading → initial equilibrium failure → rear-edge tensile cracking → upper soil mass sliding → front-edge extrusion and bulging → sliding surface propagation → overall failure. Furthermore, the colluvial slope exhibits pronounced failure sensitivity under loading, particularly in the progressive development of rear-edge tensile cracking, toe bulging, and deep shear bands, which should be regarded as key indicators for monitoring. These findings clarify the typical loading-induced failure mechanisms of accumulation-body slopes and provide a scientific basis for early landslide identification and hazard mitigation.