Deep-seated landslide triggered by tunnel excavation

Ruggeri, Paolo; Fruzzetti, Viviene M. E.; Vita, Alessandro De; Paternesi, Alessandra; Scarpelli, Giuseppe; Segato, David

doi:10.1201/9781315375007-208

Cited by 5 publications

(4 citation statements)

References 4 publications

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“…This last hypothesis was confirmed by the presence of slickensided discontinuities on the soil coring close to the failure surface. Slickensided discontinuities in clays are typical evidence of the shear zone when experiencing large displacements, and have been observed in other studies on deep-seated landslides in complex clayey formations (Scarpelli et al, 2013 [29]; Segato et al, 2015 [30]; Ruggeri et al, 2016 [31]; Ruggeri et al, 2020 [32]; Ruggeri et al, 2020 [33]). It is interesting to observe that, in several case studies, even the presence of a significant granular fraction could not avoid the reaching of residual conditions along the sliding surface when matrix sustained conditions hold, as documented in Ruggeri et al, 2016 [34].…”

Section: Case History Descriptionsupporting

confidence: 62%

Seismic and Rainfall Induced Displacements of an Existing Landslide: Findings from the Continuous Monitoring

et al. 2020

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“La Sorbella” is a deep-seated existing landslide in a Miocene clayey formation located in central Italy. Given the interaction with a national road, this landslide has been monitored for a long time with inclinometers and hydraulic piezometers. Recently, the monitoring system was implemented by adding pressure transducers in the Casagrande cells and by equipping the old inclinometers with in-place probes, to allow a remote reading of the instruments and data recording. This system allowed to identify that the very small average rate of movement observed over one year (1.0–1.5 cm/year) is the sum of small single sliding processes, strictly linked to the sequence of rainfall events. Moreover, data recorded by in-place inclinometer probes detected the response of the landslide to the seismic sequence of 2016 occurring in central Italy. Such in situ measurements during earthquakes, indeed rarely available in the scientific literature, allowed an assessment of the critical acceleration of the sliding mass by means of a back-analysis. The possibility to distinguish the difference between seismic and rainfall induced displacements of the slope underlines the potential of continuous monitoring in the diagnosis of landslide mechanisms.

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Section: Case History Descriptionsupporting

confidence: 62%

Seismic and Rainfall Induced Displacements of an Existing Landslide: Findings from the Continuous Monitoring

et al. 2020

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“…2015 [31]; Ruggeri et at. 2016 [32]; Ruggeri et al 2020 [33]), in the analysis of tunnels along the road (Paternesi et al 2017 [34]), and with more general studies of structurally complex formations (Scarpelli et al 2003 [35]; Ruggeri et al 2016 [36]; Ferretti et al 2019 [37]), aims at addressing possible design strategies to reduce the risk of inducing slope instabilities, dangerous releases of soil masses, and excessive stresses in the retaining structures. Because of the main structural features of the Blue Clay formation, the most effective design strategies could be found only on the basis of a detailed geological model, on the top of which geotechnical models could be implemented with due consideration of the pattern of existing discontinuities; in most cases, design solutions were sought with the aim of reducing stress release in the zone of influence of excavations.…”

Section: The Dg21 and Dg22 Maxi Lotsmentioning

confidence: 99%

Design Strategies to Mitigate Slope Instabilities in Structurally Complex Formations

2020

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Stiff jointed clays (SJC) belong to so-called structurally complex formations in which the macroscale features of the deposit, that is the pattern of discontinuities affecting the soil mass, influence its response at the scale of engineering works. Such peculiar response was largely recognized during the excavation works carried out for the construction of two new road segments in southern Italy, where several structurally conditioned instability processes were triggered during excavation works. These phenomena mainly involved the Plio-Pleistocene marine clayey formation outcropping along the East coast of the Calabria region, where it constitutes most of the hills interested by construction works. Under a geotechnical perspective, the SJC-formation exhibits good mechanical characteristics at the scale of samples but, if considered as a whole, its behaviour is governed by the presence of discontinuities along which strength is typically at residual. Building on the author’s experience of some exemplary failure events, this paper aims at defining possible design strategies to minimize the risk of adverse and unexpected instability phenomena during construction in structurally complex formations. Design strategies oriented at reducing and possibly avoiding stress releases in the zone of influence were found to be most effective at preventing failures or restoring safety after the occurrence of a failure event.

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“…The construction of a robust structure covering the final tunnel that allows the filling of the slope toe before any new excavation (in a way conceptually similar to the topdown construction) allowed a safe completion of the work. In Segato et al (2015) and Ruggeri et al (2016) details about similar instabilities occurred during the construction of the two maxi-lots have been described.…”

Section: The Deep Slide At the South Portal Of Baldaia I Tunnelmentioning

confidence: 99%

Lessons Learnt from the SS 106 Jonica Highway Construction Works

Ruggeri

Fruzzetti

Scarpelli

2019

Lecture Notes in Civil Engineering

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During the construction of a new highway segment in the hilly territory of the Calabria region, in South Italy, several instability processes have been activated so delaying the works and causing a cost increase of the infrastructure. Building an infrastructure in structurally complex clayey formations, so widely spread over the entire construction area, is certainly cumbersome; the highly tectonized clayey formations can hardly be characterized and their discontinuity patterns, often masked by the complexities of the geological features, make the instability phenomena difficult to foresee through standard practice investigations. Nevertheless, the risk of instability may be minimized if design strategies that resulted successful in similar conditions are implemented. In this paper such design strategies, to be adopted for excavations and earthworks in geologically complex soil formations, will be presented and analysed in the light of their economic and environmental sustainability, through the discussion of few case studies.

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Deep-seated landslide triggered by tunnel excavation

Cited by 5 publications

References 4 publications

Seismic and Rainfall Induced Displacements of an Existing Landslide: Findings from the Continuous Monitoring

Seismic and Rainfall Induced Displacements of an Existing Landslide: Findings from the Continuous Monitoring

Design Strategies to Mitigate Slope Instabilities in Structurally Complex Formations

Lessons Learnt from the SS 106 Jonica Highway Construction Works

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