Landslide triggered by small excavation – numerical simulations

: The main objective of this work is to present the results of numerical simulations of the landslide triggered by small excavation. In south-eastern Poland in 2019, during excavation for a gas pipeline (relatively small – maximal depth 2.7 m), a landslide was observed. Length of the landslide was about 80 m, width about 50 m, maximal depth 6.5 m. Excavation was partially buried. Observed cracks of the terrain surface were wide, up to 0.8 m. Stability of the landslide was analyzed using the proportionalreductionofthesoilstrengthparameters(c-fireduction)algorithmwiththeuseofZSoil.PC Finite Element Method (FEM) system. Stability analysis of the slope before and after excavation was performed, together with analysis of the tendency of the landslide to propagate upwards. The obtained stability loss modes were compared with the results of the field observations and a good correlation was noticed. Hypothesis that a landslide was triggered by small excavation was proved (although reasonable margin of safety was obtained for state before excavation, stability factor SF = 1 . 60). Use of residual soil strength parameters (instead of peak ones) and activation of cut-off (no tension) condition are advised. Presented methodology is open and can be used in engineering practice.