Reconstruction of the evolution phases of a landslide by using multi-layer back-analysis methods

Abstract Back analysis is the most common method to study landslide movements after event, and it allows us understand how a evolved along slope. This paper presents back-analysis of Pomarico (Basilicata, Italy) that occurred on January 25th, 2019, southwestern slope hill. The landslide, rotational clayey retrogressive type—planar sliding, in different phases until caused paroxysmal movement early afternoon 29th, 2019. collapse bulkhead (built at end twentieth century) some buildings village’s main road. In this paper, multi-layer presented, based limit equilibrium model (LEM), applying solution proposed by Morgenstern Price Geotechnique 15(1):79–93zh, (1965) implemented freeware software SSAP 2010. allowed reconstruction entire evolution, using geotechnical parameters obtained from both laboratory situ tests, data literature. application multilayer made possible avoid homogenisation layers, modelling event according real conditions present use curb problem related theoretical limitation shape rupture surfaces, evaluating independently friction angle locally discarding all those which, due problem, presented non-reliable factor safety (FS) value. revealed highly unstable as height water table changes. FS calculated under close ground level was less than 1 (FS = 0.98), simulating first (November 2018). subsequent reconstructed critical surface responsible for 2019 1.01). Eventually, modelled, returning an 0.83, sliding sets below bulkhead, causing its failure. Furthermore, presence adequate retaining structures demonstrated (non-) effectiveness wall system represented bulkhead. suggests further applications similar complex soil-structure interaction scenarios.