In this paper, the seismic behavior of embedded cantilevered retaining walls in a coarse-grained soil is studied with a number of numerical analyses, using a nonlinear hysteretic model coupled with a Mohr-Coulomb failure criterion. Two different seismic inputs are used, consisting of acceleration time histories recorded at rock outcrops in Italy. The numerical analyses are aimed to investigate the dynamic behavior of this class of retaining walls, and to interpret this behavior with a pseudostatic approach, in order to provide guidance for design. The role of the wall stiffness on the dynamic response of the system is investigated first. Then, the seismic performance of the retaining walls under severe seismic loading is investigated, exploring the possibility of designing the system in such a way that during the earthquake the strengths of both the soil and the retaining walls are mobilized. In this way, an economic design criterion may be developed, that relies on the ductility of the system, as it is customary in the seismic design of structures

We present a detailed survey on the ongoing destabilization process of the Mosul dam. The dam is located on the Tigris river and is the biggest hydraulic structure in Iraq. From a geological point of view the dam foundation is unstable due to the underlying geology that is formed by alternate and variable strata of highly soluble materials such as gypsum, anhydrite, marl and limestone. Here we present the first comprehensive multi-sensor cumulative deformation map for the dam generated from space-based synthetic aperture radar (SAR) measurements from the Italian constellation COSMO-SkyMed and the European Sentinel-1a satellite. We compared 2014-2016 data to an historic dataset spanning 2004-2010 acquired with the Envisat ASAR sensor. We found that deformation was rapid during 2004-2010, slowed down in 2012-2014, and restarted in August 2014 when grouting operations stopped due to the temporary capture of the dam by the self proclaimed Islamic State in Iraq and Syria (ISIS). We took advantage of the availability of data from multiple SAR satellites to infer the deformation at the dam in great spatial and temporal detail and shed new light on the processes of the ongoing destabilization. This study highlights how new constellations of SAR sensors together with the availability of historical datasets are leading to important advances in deformation monitoring of small scale geologic and manmade features. SECTION 1.

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This paper describes the main findings of a laboratory study on the mechanical behaviour of cemented geologically normally consolidated lacustrine clayey soils from two sites, Bacinetto (BA) and Avezzano (AZ), in the Fucino basin (Italy). One-dimensional and triaxial compression tests were carried out in order to investigate the effects of the presence and of the progressive degradation of the interparticle cementation bonds. The two tested soils showed quite different physical and mechanical properties, the more apparent ones being plasticity and yield stress values. The experimental results allowed the gross yield curves and the critical state conditions to be identified for both soils (BA clay and AZ silt). A number of typical features generally exhibited by cemented soils were clearly apparent: yield stresses greater than the in situ stress states, both soils being geologically normally consolidated; high values of compressibility index after yielding, which gradually reduce with increasingly applied stresses; strength reductions associated with a globally contractive behaviour. A convenient normalisation of the experimental results, in which the critical state conditions are assumed as a reference state, allowed the effects of cementation bonds and of their progressive degradation to be highlighted. In particular, BA samples were found to be characterised by different structures related to different degrees of cementation. Furthermore, despite the larger values of the yielding stresses exhibited by AZ silt, stronger effects of cementation are apparent in BA soil. Experimental results seem to indicate that at high values of the applied stress and strain paths, when bonds are largely damaged, the structures of the natural and parent reconstituted BA soil continue to be different. © 2010 Springer Science+Business Media B.V