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Excess pore-water pressure development during installation of piles into saturated clays is of primary importance and strongly affects pile bearing capacity and settlements. Such a problem is well known in literature, but excess pore-water pressure magnitude prediction, and then that of the bearing capacity, is an open research topic. In addition, excess pore-water pressure may increase greatly when numerous piles are installed in a relatively small area - as in the case of a pile group foundation - thus leading to a non-negligible modification of stress conditions at the soil-pile interface and, as a consequence, to a temporary reduction of ultimate load-bearing capacity. The paper focuses on the interpretation of load-test data performed on several auger-screw piles (full displacement), part of an important soil improvement intervention in Parma (Italy). The analysis of load test showed low values of ultimate load bearing capacity of the tested piles. Hence, the need to investigate the evolution of excess pore-water pressure with time and its relationship with the ultimate pile bearing capacity. In addition, special attention is dedicated to the study of possible mechanisms standing beneath the superposition of excess pore-water pressure effects among adjacent piles. Eventually, in order to give a consistent theoretical explanation of the recorded data, a simplified model is introduced. Such a model could be applied to similar case studies.

The reliability of river embankments is essential for flood risk management. The Po River, which flows through the North of Italy, is safeguarded over half of its length by major river embankments. Performance assessment of such water-retaining structures has become a major concern following some significant flood events in the past. Among the possible initiating causes of failure, backward erosion piping turns out to be particularly threating in the middle-lower stretch of the river. In particular, the November 2014 high-water event triggered the formation or reactivation of a few important sand boils. The paper presents a preliminary 3D finite element model of the groundwater flow through a selected cross section of the Po river, located in the Province of Reggio Emilia, which experienced a reactivation of piping phenomena after the 2014 event. The numerical model, based on a detailed geotechnical characterization obtained from in situ tests, was calibrated on the basis of the 2014 high-water event measurements and verified for a subsequent event that took place in November 2016, though without any relevant sand boil reactivation. Results are discussed with the aim of providing some insight into the mechanism under study.

This paper illustrates the design issues of a pile supported wharf in a high seismicity area in Indonesia, a commonplace port structures in which the seismic response involves significant pile–slope interaction. Pile design in high-seismicity liquefiable areas involves different aspects of earthquake geotechnical engineering with important consequences both on structural and geotechnical calculation. For the structural design, non-linear soil structure interaction (pseudo-static analysis) has been considered. Moreover, in the geotechnical design, liquefaction mitigation measures and global stability assessment have been treated. The global stability assessment of the structure is deeply affected by simplified design methodology. In particular the hypothesis of simultaneous occurrence of maximum inertial forces and liquefaction during a seismic event is an assumption full of consequences in the current practice of geotechnical design in liquefiable soils; although international codes do not provide any specific recommendation. Such an example eventually shows very clearly that absence of precise recommendations may lead to an over conservative design.

L’articolo descrive uno studio riguardante i fenomeni deformativi osservati dopo il sisma dell’Emilia del maggio 2012 lungo un tratto di argine del Canale Diversivo di Burana che ricade nell’abitato di Scortichino, frazione del comune di Bondeno (FE). In questa porzione del rilevato arginale sono state edificate oltre un centinaio di abitazioni ed alcune strutture di medio-piccole dimensioni adibite ad attività produttive o a deposito, molte delle quali sono risultate pesantemente danneggiate e dichiarate inagibili proprio a causa delle deformazioni e del sistema di fratture longitudinali presenti nel terreno in seguito al terremoto. Il contributo qui presentato si prefigge di analizzare la risposta sismica dell’argine durante la sequenza sismica del 2012, comprendere le cause dei dissesti nonché individuare le necessarie azioni di mitigazione e gli eventuali interventi di messa in sicurezza nei confronti di terremoti futuri. A questo scopo è stata condotta un’ampia campagna sperimentale di indagini in sito e in laboratorio, finalizzata alla ricostruzione di un accurato modello geotecnico per la valutazione delle condizioni di stabilità dell’argine in condizioni sismiche, portando in conto anche l’eventuale insorgenza di fenomeni di liquefazione nei terreni sabbiosi superficiali costituenti la fondazione del corpo arginale. L’analisi illustrata è il risultato dell’attività di indagine svolta per più di un anno dal Gruppo di Lavoro Argini (GdLA), costituitosi nel luglio 2012 in seguito ad un accordo fra la Regione Emilia-Romagna e l’Associazione Geotecnica Italiana per la verifica delle condizioni di stabilità dei rilevati arginali nelle aree colpite dal terremoto.

The seismic sequence that in May 2012 struck a large area of the river Po Valley (Emilia-Romagna region, Northern Italy) triggered significant fractures and deformations in a number of riverbanks located close to the earthquake epicenter. Among them, one of the most severely damaged structures turned out to be the banks of an irrigation canal known as Canale Diversivo di Burana, flowing through the small village of Scortichino (Municipality of Bondeno), near the historic town of Ferrara. Large, longitudinally-oriented ground cracks were observed along a 3 km bank stretch, causing in turn severe structural damages to a large part of the approximately one hundred houses and productive activities built on the bank crown. In order to interpret the response of such soil structure during the 2012 earthquake by identifying possible damage causes as well as to suggest relevant remedial measures and seismic risk mitigation actions towards possible future earthquakes, the Emilia-Romagna regional authority launched an in-depth study carried out by a number of research groups from various Italian universities in cooperation with technical experts of the Geological, Seismic and Soil Survey Regional Department. To this purpose, a number of geotechnical investigations were performed (in situ and laboratory tests) and an accurate geotechnical model for the seismic stability analyses was thus defined. Potential liquefaction phenomena of the shallow sandy soils, in the foundation subsoil, were taken into account in the analyses. The paper describes the main features of the extensive study carried out by the working group and summarizes the most significant achievements of the analyses.