A water retention model accounting for void ratio changes in double porosity clays     

De la Morena  Gema  Navarro  Vicente  Asensio  Laura  Gallipoli  Domenico 《Acta Geotechnica》2021,16(9):2775-2790

This paper presents a constitutive model that predicts the water retention behaviour of compacted clays with evolving bimodal pore size distributions. In line with previous research, the model differentiates between the water present inside the saturated pores of the clay aggregates (the microstructure) and the water present inside the pores between clay aggregates (the macrostructure). A new formulation is then introduced to account for the effect of the macrostructural porosity changes on the retention behaviour of the soil, which results in a consistent evolution of the air-entry value of suction with volumetric deformations. Data from wetting tests on three different active clays (i.e. MX-80 bentonite, FEBEX bentonite, and Boom clay), subjected to distinct mechanical restraints, were used to formulate, calibrate, and validate the proposed model. Results from free swelling tests were also modelled by using both the proposed double porosity model and a published single porosity model, which confirmed the improvement in the predictions of degree of saturation by the present approach. The proposed retention model might be applied, for example, to the simulation of the hydromechanical behaviour of engineered bentonite barriers in underground nuclear waste repositories, where compacted active clays are subjected to changes of both suction and porosity structure under restrained volume conditions.

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Effects of air temperature on the cyclic behavior of elastomeric seismic isolators     

Donatello Cardone  Giuseppe Gesualdi  Domenico Nigro 《Bulletin of Earthquake Engineering》2011,9(4):1227-1255

The mechanical properties of elastomers can change significantly due to air temperature variations. In particular, prolonged exposure to subzero temperatures can result in rubber crystallization, with a considerable increase in the shear stiffness of the material. As a result, the seismic response of structures with elastomeric isolators can be strongly influenced by air temperature. Current seismic codes, indeed, require an upper and lower bound analysis, using suitable modification factors, to account for the changes in the cyclic behavior of elastomeric isolators due to air temperature variations. In this study, the sensitivity of the cyclic behavior of elastomeric isolators to air temperature variations is investigated based on the experimental results of an extensive test program on six different elastomeric compounds for seismic isolators, characterized by a shear modulus ranging from 0.5 to 1.2 MPa at 100% shear strain and 20°C. The cyclic tests have been performed on small-size specimens, subjected to shear strain amplitudes and frequency of loading typical for elastomeric seismic isolators, at seven different air temperatures, ranging from 40 to −20°C. The effects of rubber crystallization due to prolonged exposure to low-temperatures have been also investigated. A finite element model for the evaluation of the temperature contour map inside a full-size elastomeric isolator exposed to low air temperatures has been also developed. In the paper, the experimental outcomes are compared with the modification factors provided by the current seismic codes to account for the temperature effects on the mechanical properties of elastomeric isolators.  相似文献   

The 2014 Earthquake Model of the Middle East: seismogenic sources     

Laurentiu Danciu  Karin Şeşetyan  Mine Demircioglu  Levent Gülen  Mehdi Zare  Roberto Basili  Ata Elias  Shota Adamia  Nino Tsereteli  Hilal Yalçın  Murat Utkucu  Muhammad Asif Khan  Mohammad Sayab  Khaled Hessami  Andrea N. Rovida  Massimiliano Stucchi  Jean-Pierre Burg  Arkady Karakhanian  Hektor Babayan  Mher Avanesyan  Tahir Mammadli  Mahmood Al-Qaryouti  Doğan Kalafat  Otar Varazanashvili  Mustafa Erdik  Domenico Giardini 《Bulletin of Earthquake Engineering》2018,16(8):3465-3496

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Exhumation patterns along shallow low‐angle normal faults: an example from the Altotiberina active fault system (Northern Apennines,Italy)          下载免费PDF全文

Chiara Caricchi  Luca Aldega  Massimiliano R. Barchi  Sveva Corrado  Domenico Grigo  Francesco Mirabella  Massimiliano Zattin 《地学学报》2015,27(4):312-321

A multi‐method approach (palaeothermal and thermochronological analyses; thermal modelling) is applied to reconstruct the exhumation history of the Altotiberina Fault (ATF), a representative example of crustal‐scale active low‐angle normal faulting in the Northern Apennines (Italy). Thermal maturity and thermochronological data yield similar burial histories but different exhumation patterns for the sedimentary successions in the hangingwall and the footwall of the ATF. Since 3.8 Ma, the ATF footwall has exhumed at rates of 0.90 mm a^?1. Exhumation led to bending and deactivation of the ATF uppermost portion as a result of tectonic unloading and isostatic adjustment, followed by migration of extension and the development of a set of domino‐like, east‐dipping normal faults, rooting on the buried portion of the ATF. ATF activity and isostatic rebound exhumed Triassic rock units from depths of about 4 km. We suggest that isostatic instability is accommodated at shallow crustal levels, in a similar way to what is observed on larger structures at mid‐low crustal levels.  相似文献   

Hydraulic modeling of flood pulses in the Middle Bussento Karst System (MBSKS), UNESCO Cilento Global Geopark,southern Italy          下载免费PDF全文

Vittorio Bovolin  Albina Cuomo  Domenico Guida 《水文研究》2017,31(3):639-653

Karst systems provide water for domestic and industrial uses and for generating hydropower, but they can also create fluvial hazards, such as upstream back‐flooding and downstream karst flash‐flood events. However, these hazards are difficult to foresee due to the complex recharge‐discharge processes as well as the lack of information on the inside of the system, which has often not been completely surveyed by speleologists or explored by boreholes. To overcome these difficulties, hydro‐chemical data from the monitoring system in the Middle Bussento Karst System (MBSKS), one of the first Experimental Karst Systems in southern Italy, were recorded and previously discussed. Based on shared background in flood karst hydraulic modeling, this paper describes the conceptual premises and rationale of a general‐purpose hydraulic model that is suitable both for the MBSKS and for other Mediterranean, multi‐recharge, mature, conduit‐dominated karst systems. To test the reliability of the model, simulations of time–space behavior and response are performed using natural and artificial flood pulses “as tracers”, considering a “pulse” as a significant variation in water quantity and/or quality. The results of the model explain the interactions between allogenic, autogenic, and anthropogenic recharges from differentiated sources and phreatic conduit systems. These results also clarify the overall response of karst springs at typical time scales of flood pulses. Table acronym name  相似文献   

Regularized tomographic inversion with geological constraints          下载免费PDF全文

Vincenzo Lipari  Domenico Urbano  Emmanuel Spadavecchia  Jacopo Panizzardi  Nicola Bienati 《Geophysical Prospecting》2017,65(1):305-315

Reflection tomography is the industry standard tool for velocity model building, but it is also an ill‐posed inverse problem as its solution is not unique. The usual way to obtain an acceptable result is to regularize tomography by feeding the inversion with some a priori information. The simplest regularization forces the solution to be smooth, implicitly assuming that seismic velocity exhibits some degree of spatial correlation. However, velocity is a rock property; thus, the geometry and structure of rock formations should drive correlation in velocity depth models. This observation calls for constraints driven by geological models. In this work, we present a set of structural constraints that feed reflection tomography with geometrical information. These constraints impose the desired characteristics (flatness, shape, position, etc.) on imaged reflectors but act on the velocity update. Failure to respect the constraints indicates either velocity inaccuracies or wrong assumptions concerning the constraints. Reflection tomography with structural constraints is a flexible framework that can be specialized in order to achieve different goals: among others, to flatten the base of salt bodies or detachment surfaces, to recover the horizontalness of oil–water contacts, or to impose the co‐location of the same imaged horizon between PP and PS images. The straightforward application of structural constraints is that of regularizing tomography through geological information, particularly at the latest stages of the depth imaging workflow, when the depth migration structural setting reached a consistent geological interpretation. Structural constraints are also useful in minimizing the well‐to‐seismic mis‐ties. Moreover, they can be used as a tool to check the consistency of interpreters' hypothesis with seismic data. Indeed, inversion with structural constraints will preserve image focusing only if the interpreters' insights are consistent with the data. Results from synthetic and real data demonstrate the effectiveness of reflection tomography with structural constraints.  相似文献   

Palaeoenvironments of the Mediterranean Basin at the Messinian hypersaline/hyposaline transition: evidence from natural radioactivity and microfacies of post‐evaporitic successions of the Adriatic sub‐basin     

Gianluca Sampalmieri  Annalisa Iadanza  Paola Cipollari  Domenico Cosentino  Sergio Lo Mastro 《地学学报》2010,22(4):239-250

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Magma chambers and localization of deformation during thrusting     

Domenico Montanari  Giacomo Corti  Alexander Simakin 《地学学报》2010,22(5):390-395

Terra Nova, 22, 390–395, 2010 Abstract We present the results of coupled analogue and numerical models that provide new insights into the relationships between volcanoes and thrusts. The effects of both upper‐crustal magma chambers and the load of volcanoes on the geometry of thrust systems were investigated. Analogue modelling points to a strong influence exerted by a magma chamber on thrust geometry, which, as suggested by the numerical models used to rationalize these results, is related to the stress redistribution around the weak heterogeneity. The low‐viscosity body below a volcanic edifice localizes compressional deformation and causes a curvature of the thrusts towards the magma chamber, opposite to the direction of tectonic transport. In these conditions, the volcanic load has a negligible effect on the structural geometry. These results are in contrast with those of previous studies, where intrusions or the load of major volcanoes generated a curvature of the thrusts away from volcanic edifices in the direction of tectonic transport.  相似文献   

Systematic conservation planning in the Mediterranean: a flexible tool for the identification of no-take marine protected areas     

Maiorano  Luigi; Bartolino  Valerio; Colloca  Francesco; Abella  Alvaro; Belluscio  Andrea; Carpentieri  Paolo; Criscoli  Alessandro; Jona Lasinio  Giovanna; Mannini  Alessandro; Pranovi  Fabio; Reale  Bruno; Relini  Giulio; Viva  Claudio; Ardizzone  Gian Domenico 《ICES Journal of Marine Science》2009,66(1):137-146

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Vertical variations of the chlorophyll maximum during a red tide in a shallow lagoon     

Domenico Voltolina  Leslie N. Brown  Maurice G. Robinson 《Estuarine, Coastal and Shelf Science》1985,21(6):817-822

The results of eight sets of repeated observations on the vertical variations of the chlorophyll maximum layer in a shallow lagoon during a red tide show that these were more frequently hydrologically induced, rather than due to active vertical migrations of the red tide-forming organism. These results are discussed and compared to those existing in the literature, with special regard to the role of light and nitrogen in conditioning vertical migrations in red tide-forming dinoflagellates.  相似文献