Failure and deformation behavior of underground geo-structures: advances in geomechanics.

Underground geo-structures play a crucial role in various aspects of modern society for several reasons [...

Preliminary experimental investigation into the use of recycled fibres from textile waste for the improvement of embankments

Failures that occurred in the last few decades highlighted the need to raise awareness about the emergent risk related to the impact localised degradation phenomena have on embankments. Common interventions aimed to improve embankments, such as the reconstruction of the damaged area or the injection of low-pressure grouts to fill fractures and burrows, may cause the weakening of the structure due to discontinuities between natural and treated zones. Moreover, since such repair techniques require huge volumes of materials, more sustainable solutions are encouraged. At the same time, the textile and fashion industries are looking for sustainable waste management and disposal strategies to face environmental problems concerned with the voluminous textile waste dispatched to landfills or incinerators. The use of soil mixed with textile waste in embankment improvement has been investigated to identify an effective engineering practice and to provide a strategy for the circular economy of textiles. Preliminary laboratory tests have been conducted on soil specimens collected from the Secchia River embankment, Northern Italy, to define the appropriate mixture proportions and to compare physical properties and hydro-mechanical behaviour of natural and treated soils. The results show that an appropriate fibre content offers manageable and relatively homogeneous mixtures. The indluence on soil consistency is mainly due to the textile fibre hydrophilic nature. The addition of fibres reduces the maximum dry density and increases the optimum water content. At low stress levels, the compressibility and hydraulic conductivity appear higher, however macro voids produced during sample preparation may alter the findings

Systematic and statistical errors in homodyne measurements of the density matrix

We study both systematic and statistical errors in radiation density matrix measurements. First we estimate the minimum number of scanning phases needed to reduce systematic errors below a fixed threshold. Then, we calculate the statistical errors, intrinsic in the procedure that gives the density matrix. We present a detailed study of such errors versus the detectors quantum efficiency $\eta$ and the matrix indexes in the number representation, for different radiation states. For unit quantum efficiency, and for both coherent and squeezed states, the statistical errors of the diagonal matrix elements saturate for large n. On the contrary, off-diagonal errors increase with the distance from the diagonal. For non unit quantum efficiency the statistical errors along the diagonal do not saturate, and increase dramatically versus both $1-\eta$ and the matrix indexes

Robot-aided neurorehabilitation in sub-acute and chronic stroke: Does spontaneous recovery have a limited impact on outcome?

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Compressibilità e resistenza di un terreno arginale rinforzato con fibre da scarti tessili

L'articolo propone un'indagine sperimentale sul miglioramento e il rinforzo di terreni arginali tramite l'utilizzo di fibre da scarti tessili. Attraverso prove di laboratorio su terreni a cui sono state aggiunte fibre di lino e viscosa, sono stati valutati gli effetti della presenza delle fibre sulla compattazione e sulla resistenza del terreno. I risultati mostrano che l’aggiunta di fibre modifica la risposta del terreno in termini di compattazione riducendo la massima densità secca e aumentando il contenuto d’acqua ottimo. Inoltre, la presenza delle fibre può aumentare significativamente la resistenza al taglio del terreno, in funzione della loro geometria (i.e. diametro e lunghezza) e della quantità considerata. Ulteriori analisi su campioni di dimensioni maggiori sono raccomandate per studiare il comportamento dei terreni rinforzati con fibre tessili, a diverse scale

Internal Erosion in Earthdams, Dikes and Levees

The volume contains the contributions to the 26th Annual Meeting of the European Working Group on Internal Erosion in Embankment Dams, Levees and Dikes, and their Foundations (EWG-IE), held at Politecnico di Milano, in Milano, Italy, from September 10 to 13, 2018. The European Working Group was set up in 1993 to focus on the vulnerability of dams to internal erosion. After an inaugural workshop on definitions and needs, the Group has regularly organized Annual Meetings to share knowledge and address emerging issues on soil internal erosion in water retaining structures. Over the years, the Meetings have seen the participation of university researchers, scientists and engineers from agencies, industries, and public bodies, from Europe and overseas. Following the last successful event in Delft in September 2017, the objective of the meeting in Milano was to serve as a fertile discussion platform, strengthening sound knowledge as well as introducing novel ideas, in the thematic areas in line with the traditional aims of EWG-IE. More than 100 authors, coming from academic institutions, private and public bodies, in European and overseas countries, contributed to the peer-reviewed papers included in the volume. These are grouped into four sections, namely • Laboratory techniques and findings; • From modeling to design criteria; • Prevention measures and field assessment; • Open issues for discussion and contribution. We gratefully acknowledge the careful reviewing work by the members of the Scientific Committee, the technical and administrative support by Federica Aggio and Silvia Spada of the Department of Civil and Environmental Engineering, the skills, patience and care of Marco Caruso who took charge of the editing process, and the support of Politecnico di Milano in providing the facilities for the organization of the meeting. Finally, we are very glad to have hosted the contributors in Milano, a city that was able to evolve and expand its horizons, from the Celtic origin to the twenty-first century, to become a center where dynamism and creativity still coexist with the quietness of old hidden corners. Cristina Jommi, Donatella Sterpi Chairpersons of 26th Annual Meetin

evaluation of upper limb sense of position in healthy individuals and patients after stroke

The aims of this study were to develop and evaluate reliability of a quantitative assessment tool for upper limb sense of position on the horizontal plane. We evaluated 15 healthy individuals (controls) and 9 stroke patients. A robotic device passively moved one arm of the blindfolded participant who had to actively move his/her opposite hand to the mirror location in the workspace. Upper-limb's position was evaluated by a digital camera. The position of the passive hand was compared with the active hand's 'mirror' position. Performance metrics were then computed to measure the mean absolute errors, error variability, spatial contraction/expansion, and systematic shifts. No significant differences were observed between dominant and non-dominant active arms of controls. All performance parameters of the post-stroke group differed significantly from those of controls. This tool can provide a quantitative measure of upper limb sense of position, therefore allowing detection of changes due to rehabilitation

Numerical prediction of the drying-wetting process in a river levee and floodplain

One third of the economic losses due to natural disasters in the last century has been caused by floods. Today the flood hazard is increasing due to more frequent extreme hydrological events, caused by climate change, and to the land use change and urbanization, that reduce the water storage capacity of the subsoil and the floodplain areas. An appropriate planning of river levees and floodplains is required to protect inhabited areas and infrastructures. At the same time, an efficient management, assisted by effective monitoring and prediction tools, ensures the performance of the defence systems. In this context, a land reprofiling was designed for river Secchia in Northern Italy, to widen the natural floodplain. In the paper the response of the new system to flood events is assessed by finite element analyses able to describe the soil-water-atmosphere interaction. The reliability of the numerical prediction relies on a proper description of both the hydraulic behaviour of the unsaturated soil, i.e. the water retention curve and the permeability function, and the external load history, established from the hydraulic and atmospheric boundary conditions. Indirect methods for the estimation of the Soil Water Retention Curve may involve significant limits if not combined with a laboratory information on the soil nature and state. Moreover, the numerical results show that the drying-wetting process is highly dependent on the initial saturation conditions of the subsoil, thus making it essential to simulate a sufficiently long load history

Editorial for the Special Issue: Innovative numerical methods for soil internal erosion processes

In today’s society, with environmental loads acting with unexpected great magnitude and increasingly populated areas, earth structures for water containment and water defence must be designed and monitored with utmost care, to reduce the risk where the exposure increases [Jongman et al., 2012]. Soil internal erosion is regarded to as one of the major causes of earth embankment and dam failures, leading in the past to high death toll and economic losses [Foster et al., 2000; Richards and Reddy, 2007]. Moreover, internal erosion poses a threat of broader impact to the natural and built environment, as it may lead to slope failure, soil subsidence and structure damages, and it is of concern also in industrial engineering problems such as the sand production in oil wells [Climent et al., 2014; Fox and Wilson, 2010; Gao et al., 2022; Sterpi, 2003; Vardoulakis et al., 1996; Zhang et al., 2020]. Since its establishment in 1993, the European Working Group on Internal Erosion of Dams, Dikes and Levees, and their Foundations (EWG-IE) represents a community committed to share their interest and knowledge in soil internal erosion related matters. The Group organizes Annual Meetings, the last three being held in 2018 in Milano, Italy [Bonelli et al, 2018], in 2019 in Vancouver, Canada [Fannin, 2019], and in 2022 in Sheffield, UK [Bowman, 2022]. To maintain a link among the EWG-IE members during the Covid-19 pandemic, between 2020 and 2021 online workshops on diverse topics were organized by local groups. Given the interest raised at the workshop on “Innovative numerical methods for soil internal erosion processes”, the local organizers decided to open a call to the entire scientific community and to serve as guest editors of a themed issue on the journal Geomechanics for Energy and The Environment. The valuable contents of the submissions, that bring up a well-balanced mix of topics involving the soil internal erosion, reflect that the call reached a broadly interested and lively community of researchers. This editorial aims at outlining the relevant key points of these contributions and placing them in the context of the state of the art