Landslide Hazard Affecting Historical Buildings: Santa Scolastica Monastery in Subiaco

Abstract

Every year landslides occur as a consequence of ground conditions, geomorphological, physical or man-made processes, often triggered by heavy rainfalls or earthquakes. They affect buildings and infrastructures, causing economic and life losses. On the Italian territory, more than 14,000 heritage sites interact with potentially unstable slopes. This work investigates the effects of a landslide, occurred on the 26th of November 2018, on the Monastry of Santa Scolastica in Subiaco (Rome), one of the most ancient and well-preserved examples of medieval architecture in Central Italy. The geometry of the slope was reconstructed based on aerial photographic survey and point-cloud processing, obtaining meshed surfaces and extracting relevant sections. The mechanical parameters and the specific hydraulic conditions triggering the failure mechanism were first recognised by traditional limit equilibrium back-analyses and then implemented in a 3D non-linear finite element (FE) model, which included both the slope and the interacting portion of the ancient structure. Elastic-perfectly plastic constitutive assumptions were adopted for the soil, while the structure was modelled by a three-dimensional anisotropic elastic-perfectly plastic constitutive model, specifically conceived for masonry, accounting for block dimensions and staggering joints effects. Finite element approach proves to be very effective in the analysis of such a coupled interaction problem, leading to a realistic representation of the interplay between the soil displacements and their deformative effects within the structure. The numerical results have been interpreted to highlight the structural response in terms of crack pattern and stress distribution as induced by the interaction with the deforming slope, leading to a quantitative evaluation of the landslide-induced damage. Several scenarios were simulated: first, the pre landslide existing crack pattern was reproduced, then the event was modelled as it occurred, evaluating its consequences on the structure.

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References

[1] Puzrin, A. M., Alonso, E. E. and Pinyol, N. M. Geomechanics of failures. Springer Science & Business Media, (2010).

[2] Canuti P., Margottini C., Fanti R. and Bromhead E.N. Cultural Heritage and Landslides: Research for Risk Prevention and Conservation. In: Sassa K., Canuti P. (eds) Landslides – Disaster Risk Reduction. Springer, Berlin, Heidelberg (2009).

[3] ISPRA. Landslides in Italy. Special Report 2008; ISPRA: Roma, Italy, 2008; ISBN 978- 88-448-0355-1.

[4] Negulescu, C., Ulrich, T., Baills, A., and Seyedi, D. M. Fragility curves for masonry structures submitted to permanent ground displacements and earthquakes. Natural hazards (2014) 74(3): 1461-1474.

[5] Palmisano, F., Vitone, C., and Cotecchia, F. Assessment of landslide damage to buildings at the urban scale. Journal of Performance of Constructed Facilities (2018) 32(4):04018055.

[6] Parisi, F., Galasso, C., and Sabella, G. Fragility of reinforced concrete framed structures to flow-type landslides. In: 12th International Conference on Applications of Statistics and Probability in Civil Engineering (ICASP12) (2015).

[7] Ferlisi, S., Nicodemo, G., Peduto, D., Negulescu, C., and Grandjean, G.Deterministic and probabilistic analyses of the 3D response of masonry buildings to imposed settlement troughs. Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards, (2019), 1-20.

[8] Fargnoli, V., Boldini, D., and Amorosi, A. Twin tunnel excavation in coarse grained soils: observations and numerical back-predictions under free field conditions and in presence of a surface structure. Tunnelling and Underground Space Technology (2015) 49: 454-469.

[9] Zienkiewicz, O.C. and Taylor, R.L. The finite element method. McGraw Hill, Vol. I., (1989), Vol. II, (1991).

[10] Griffiths, D. V. and Lane, P. A. Slope stability analysis by finite elements. Geotechnique (1999) 49(3), 387-403.

[11] Lasciarrea, W. G., Amorosi, A., Boldini, D., de Felice, G., and Malena, M. Jointed Masonry Model: A constitutive law for 3D soil-structure interaction analysis. Engineering Structures (2019), 201: 109803.

[12] Sangirardi, M., Malena, M., and de Felice, G. (2019) Settlement-induced crack pattern prediction through the jointed masonry model. In: AIMETA 2019 XXIV conference. The Italian Association of Theoretical and Applied Mechanics, Rome, Italy (2019).

[13] Castellazzi, G., D’Altri, A. M., de Miranda, S., and Ubertini, F. An innovative numerical modeling strategy for the structural analysis of historical monumental buildings. Engineering Structures (2017) 132: 229-248.

[14] Morgenstern, N.U. and Price, V.E. The analysis of the stability of general slip surfaces. Géotechnique (1965) 15(1): 79-93.

[15] NTC, 2018. Ministero Infrastrutture e Trasporti (MIT). D.M. 17.01.2018. Norme Tecniche per le Costruzioni. Rome, Italy.