Paleosols are recurrent features in alluvial successions and provide information about past sedimentary dynamics and climate change. Through sedimentological analysis on six sediment cores, the mud-dominated succession beneath the medieval 'Two Towers' of Bologna was investigated down to 100 m depth. A succession of weakly developed paleosols (Inceptisols) was identified. Four paleosols (P1, P2, P3 and PH) were radiocarbon-dated to 40-10 cal ka BP. Organic matter and CaCO 3 determinations indicate low groundwater levels during soil development, which spanned periods < 5 ka. The development and burial of soils, which occurred synchronously in the Bologna region and in other sectors of the Po Plain, are interpreted to reflect climatic and eustatic variations. Climatic oscillations, at the scale of the Bond cycles, controlled soil development and burial during Marine Isotope Stage (MIS) 3 (P1 and P2). Rapid sea-level oscillations probably induced soil development at the MIS 3/2 transition (P3) and favored burial of PH after 10 ka BP. Weakly developed paleosols in alluvial successions can provide clues to millennial-scale climatic and environmental variations. In particular, the paleosol-bearing succession of the Po Plain represents an unprecedent record of environmental changes across the Late Pleistocene (MIS 3 and 2) in the Mediterranean region.

Time-dependent boundary conditions, uncertainties and variability of soil suction and water content of the filling material together with the use of proper retention and strength soil models are crucial aspects to be included for reliable analyses of the actual stability of river embankments. However, due to a typical lack of information in many practical cases, the use of simplistic assumptions on both hydraulic and mechanical response of earth infrastructures to hydrometric water level fluctuation and atmospheric loading is largely diffused, thus providing erroneous conclusions on the effective safety margins towards possible slope instability and collapse. Within this context, site measurements down to relevant depths, combined to an accurate soil characterization under partially saturated conditions, can be extremely useful to evaluate unsaturated variables (i.e. soil water content and suction) under transient flow conditions and hence carry out realistic stability analyses. A comprehensive monitoring system has been therefore designed and installed on a relevant representative section along river Secchia, a right-hand tributary of river Po (Northern Italy). The paper aims at presenting a methodological approach for a sustainable performance assessment of such geotechnical infrastructures, based on the complementary use of laboratory tests, field measurements and numerical analyses.

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The Garisenda Tower and the Asinelli Tower, also widely known as the Two Towers, are the best preserved and famous medieval towers in the city of Bologna (Northern Italy). Standing one close to the other, right in the heart of the city centre, the Two Towers are delicate remains of the old towered city, which counted more than 75 towers in the 12 th century.The foundations of historic towers and the surrounding soil often hide major hazards for the long-term preservation of these heritage structures. The initial fundamental step is indeed a deep understanding of their original conception, including their foundations and subsoil. However, the idea that also such elements are an integral part of the overall structure, and thus subjected to the same conservation rules, is relatively new. The present paper outlines the investigation criteria applied to the soil-foundation systems of the Two Towers of Bologna and describes the authenticity of their characteristics, through the interpretation of new experimental data and the analysis of historical documents. A geotechnical perspective on this type of monuments turns out to be crucial in order to effectively understand the soil-structure interaction mechanisms, which govern their safety conditions over time. This study also aims to better understand the reasons why the Two Towers of Bologna, despite their numerous similarities, have reached completely different structural configurations.The methodology described to investigate this case study, which required the integration of several aspects, can be usefully applied to any historic tower.

The stability of slopes is greatly influenced by seasonal variations in pore water pressures (pwp) induced by rainfall infiltration and evapotranspiration processes. Despite that, the prediction of the hydrological effects of long-stem planting is often simplified or neglected because it is challenging to address. Its computation requires a proper definition of the plant root water uptake spatial distribution, which depends, in turn, on geometry and spatial root density. A well-suited case study in this field of application has been provided by a soil-filled embankment, close to an important traffic artery in Newcastle (Australia), which experienced shallow instability. The implementation of long-stem planting has been suggested as a remediation intervention. Based on this, an experimental study focusing on the effects of plant roots on the distribution of pwp in the site soil has been performed by means of a large-scale laboratory experiment on a 2-year-old native plant. Suction measurements were recorded within the vegetated soil mass under controlled boundary conditions and used to calibrate two different root spatial distributions in a seepage simulation. One is based on a flexible RWU spatial distribution function, and the other, specific for the plant RWU pattern, is simpler in its formulation and requires the definition of a lower number of parameters. A comparison between their performances in reproducing pwp distribution suggests that the second one is a better alternative. The methodological approach adopted has proven to be suitable for representing the hydraulic behaviour of a vegetated hillslope, to be eventually implemented in a proper stability assessment problem.