The Pretare-Piedilama rock block deposit: evidence of a further case of quaternary rock avalanche in Central Apennines, Italy

<p>In the last two decades large clastic deposits in Central Apennines with specific morphological and sedimentological features have been interpreted as the result of Quaternary rock avalanche events (e.g., Di Luzio et al., 2004; Bianchi Fasani et al., 2014; Schilirò et al., 2019; Antonielli et al., 2020). The analysis of such deposits, that are located within intermontane basins and narrow valleys bounded by high mountain ridges, have improved the knowledge about this kind of massive rock slope failures, also clarifying their relationship with Deep-seated Gravitational Slope Deformations.</p><p>The present study then describes a multidisciplinary analysis carried out on a huge rock block deposit which crops out within the Pretare-Piedilama Valley, in the piedmont junction area of the Sibillini Mountain range (Central Italy), where Mesozoic basinal carbonates overthrust Miocene foredeep deposits.</p><p>Specifically, we performed sedimentological, stratigraphical and morphometric analyses on the clastic deposit; results support the interpretation of the event as a rock avalanche body. The accumulation area shows a T-like shape with a wide, E-W-oriented, proximal part and a N-S channelization in the central and lower sectors. The evidence suggests erosional events and tectonics as controlling factors on rock flow deposition. In this respect, the area was involved in the 2016 central Italy seismic sequence and was tectonically active during Quaternary times<strong> </strong>(Tortorici et al., 2009).</p><p>As regards on the deposit genesis, considering the geometric characteristics of a sub-rectangular detachment area located on the southern edge of the Sibillini Range, an original mechanism of rockslide failure involving about 8·10<sup>6</sup>m<sup>3</sup> of Early Jurassic limestone was inferred. Here, the post-failure geomorphic features behind the main scarp are considered for the evaluation of hazard conditions.</p><p>Finally, well-log analysis of the clastic sequence filling the Pretare-Piedilama Valley evidenced additional Quaternary landslide events occurred before the rock avalanche, thus testifying to a long history of large slope instabilities in the area controlling the landscape development.</p><p> </p><p><strong>REFERENCES</strong></p><p> </p><ul><li>Antonielli B., Della Seta M., Esposito C., Scarascia-Mugnozza G., Schilirò L., Spadi M., Tallini M. (2020). Quaternary rock avalanches in the Apennines: New data and interpretation of the huge clastic deposit of the L'Aquila Basin (central Italy). Geomorphology, 361, 107-194. doi:10.1016/j.geomorph.2020.107194.</li> <li>Bianchi Fasani G., Di Luzio E., Esposito C., Evans S.G., Scarascia-Mugnozza G. (2014). Quaternary, catastrophic rock avalanches in the Central Apennines (Italy): relationships with inherited tectonic features, gravity-driven deformations and the geodynamic frame. Geomorphology, 21, 22–42. doi:10.1016/j.geomorph.2013.12.027.</li> <li>Di Luzio E., Bianchi-Fasani G., Saroli M., Esposito C., Cavinato G.P., Scarascia-Mugnozza G. (2004). Massive rock slope failure in the central Apennines (Italy): the case of the Campo di Giove rock avalanche. Bullettin of Engineering Geology and the Environment 63, 1-12. doi:10.1007/s10064-003-0212-7.</li> <li>Schilirò L., Esposito C., De Blasio F.V., Scarascia-Mugnozza G. (2019). <strong>Sediment texture in rock avalanche deposits: insights from field and experimental observations. </strong>Landslides, 16, 1629-1643. doi: 10.1007/s10346-019-01210-x.</li> <li>Tortorici G., Romagnoli G., Grassi S. et al. (2019). Quaternary negative tectonic inversion along the Sibillini Mts. thrust zone: the Arquata del Tronto case history (Central Italy). Environ Earth Sci 78:<strong> </strong>37. doi:10.1007/s12665-018-8021-2.</li> </ul>

REASSEMBLY OF ROCK SEGMENTS, THE CASE OF AREOPAGUS HILL

<p><strong>Abstract.</strong> There are no specifications and/or standards for the restoration of collapsed masses of rocks, as in most cases the rocks bear no historical/archaeological value and their restoration would require significant budget and resources. But plenty of colossal statues, ancient temples, tombs and whole cities are carved on the surface or even expand in the interior of solid natural rocks. These so-called rock-cut monuments are located all around the globe and, in most cases, are made on a grand scale. Earthquakes, rock’s faults, erosion and karst can lead to massive rock collapses.The purpose of this paper is to establish an integrated methodology for the relocation of detached rock segments to their original positions. Specifically, the proposed methodology is based on the case of the Areopagus Hill and involves the generation of 3d models of the rock segments, their virtual reassembly and their utilization for the reconstruction of a part of the peak of the hill.</p>

Mechanical analysis and interpretation of excavation damage zone formation around deep tunnels within massive rock masses using hybrid finite–discrete element approach: case of Atomic Energy of Canada Limited (AECL) Underground Research Laboratory (URL) test tunnel

The construction of an underground opening leads to changes in the in situ stress regime surrounding the excavation. The opening influences the rock mass owing to the redistribution of the stresses and results in the disturbance of the surrounding ground. At great depths, massive to slightly or moderately fractured rock masses are usually encountered, and under high stresses, they are more likely to behave in a brittle manner during an excavation. While constitutive models have been developed and proposed for the numerical simulation of such excavations using continuum mechanics, this brittle response cannot be simulated accurately enough, since the material behaviour is governed by fracture initiation and propagation. On the contrary, discontinuum approaches are more suitable in such cases. For the purposes of this paper, the brittle behaviour of hard, massive rock masses and the associated spalling failure mechanisms were simulated by employing a finite–discrete element method (FDEM) approach using Irazu software. The generated numerical model was utilized to replicate field conditions based on the observations at the Atomic Energy of Canada Limited (AECL) Underground Research Laboratory (URL) test tunnel located in Pinawa, Manitoba, Canada. The model results are compared with field observation data to explicitly demonstrate the suitability of the method.

PROPOSAL FOR SECURING A ROCK MASSIF NEAR BEROUN RAILWAY STATION

The proposal concerns the securing of a 100 m long section of the rock slope along the lead track at Beroun railway station, where a relatively massive rock block collapsed in June 2016. The rock slope is about 30 m high and its character is mainly determined by the orientation of several discontinuity systems. It was proposed for the most dangerous discontinuities that monitoring elements be used for measuring deformations at least for half a year. Dynamic barriers and protective fences were proposed for the most endangered parts of the slope.