Effects of Slope Movements on Soil Structure and Hydrological Response

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TECHNICAL NOTE

Effects of Slope Movements on Soil Structure and Hydrological Response Luca Comegna

. Luciano Picarelli

. Gianfranco Urciuoli

Received: 20 September 2019 / Accepted: 2 May 2020 Ó Springer Nature Switzerland AG 2020

Abstract Active slope movements can lead to continuous changes in soil macro-fabric, micro-structure and properties. In fact, depending on landslide mechanisms, the internal deformations which are induced by movement can deeply remould the mass, favouring formation of cracks and fissures; in addition, sliding leads to formation of an anisotropic shear zone just at the interface with the underlying stable formation. The result of movements and associated deformation phenomena is then a continuous change of soil properties thus of the hydrological and mechanical slope response. This is the focus of the paper, which discusses the key role of the shear zone on the groundwater regime, based on data collected during

Luciano Picarelli is the ‘‘chair’’ of JTC1 (www.issmge.org/ fedigs). L. Comegna (&) Department of Engineering, Universita` degli Studi della Campania ‘‘Luigi Vanvitelli’’, Via Roma 29, 81031 Aversa, Italy e-mail: [email protected] L. Picarelli JTC1 ‘‘Natural Slopes and Landslides’’, Federation of International Geo-Engineering Societies (FedIGS), 80131 Naples, Italy G. Urciuoli Department of Civil, Architectural and Environmental Engineering, Universita` degli Studi di Napoli ‘‘Federico II’’, Via Claudio 21, 80125 Napoli, Italy

long-lasting investigations on some slow active earthflows in the Basento valley, Southern Italy. The results of simple calculations highlight some significant effects, which are generally neglected in conventional analyses of rainwater infiltration. Keywords Tectonized clay shales  Earthflow  Shear zone  Groundwater regime  Infiltration analysis 1 Foreword The analysis of the slope behavior is a challenging problem, which is often governed by weak zones or by slow and silent mechanical or environmental soil deterioration processes (Hutchinson 1988; Picarelli and Di Maio 2010). Major effects may also include high local pore pressures due to thin pervious layers or to open persistent discontinuities present in the mass. Therefore, the past geological history, which has a key role on soil macro-fabric and micro-structure, can directly or indirectly govern the slope behaviour. Similar effects may be induced by active slope movements (thus by the recent geological history); as a consequence, the hydrological and mechanical response of unstable slopes may experience a continuous evolution due to the effects of ongoing deformations, a process which is generally disregarded in the analysis of the slope behaviour. Similar considerations may be read in a paper by Misfeldt et al. (1991) who state: ‘‘Mechanisms of

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Geotech Geol Eng

active landslides are continuous processes involving the dynamics of slope failure interacting with the groundwater regime. As failure progresses changes take place in s