Numerical Implementation of a Critical State Model for Soft Rocks

This paper details the basic tasks for the numerical implementation of a simple elasto-plastic critical state model for bonded materials (i.e. soft rocks-hard soils) into the finite element program SNAC developed at the University of Newcastle in Australia. The first task described focusses on the derivation of the incremental constitutive relationships used to represent the mechanical response of a bonded/cemented material under saturated conditions. The second task presents how these stress-strain relations can be numerically integrated using an explicit substepping scheme with automatic error control. The third task concentrates on the verification of the substepping algorithm proposed. The model used to represent the saturated mechanical response of a bonded material combines the modified Cam clay with the constitutive relationships for cemented materials proposed in Gens & Nova (1993), but incorporates some flexibility on the degradation law adopted. The role of suction and other relevant aspects of unsaturated behaviour are also discussed at the end of the paper

Porphyria cutanea tarda, dermatomyositis and non-Hodgkin lymphoma in virus C infection

Virus C infection has been associated with a broad spectrum of extrahepatic diseases such as essential mixed cryoglobulinemia, membranous glomerulonephritis, vasculitis, rheumatoid arthritis and lupus erythematosus. The etiologic role of virus C has also been observed in some neoplasms such as non-Hodgkin’s lymphoma and the monoclonal gammapathies. Many studies also support the link between this virus and porphyria cutanea tarda (PCT). Isolated cases suggest a relationship with dermatomyositis. Herein, we report the coexistence of PCT, non-Hodgkin’s lymphoma and dermatomyositis in the same patient affected with virus C infection which has never previously been described

Temperature effects on the hydraulic behaviour of an unsaturated clay

The influence of temperature on the hydraulic properties of unsaturated clays is of major concern in the design of engineered barriers in underground repositories for high-level radioactive waste disposal. This paper presents an experimental study centred on the investigation of the influence of temperature on soil hydraulic properties related to water retention and permeability. Laboratory tests were conducted on artificially prepared unsaturated fabrics obtained from a natural kaolinitic-illitic clay. Special attention is given to the testing procedures involving controlled suction and temperature oedometer cells and the application of the vapour equilibrium technique at high temperatures. Retention curves at different temperatures show that total suction tends to reduce with increasing temperatures at constant water content. Temperature influence on water permeability is more relevant at low matric suctions corresponding to bulk water preponderance (inter-aggregate zone). Below a degree of saturation of 75% no clear effect is detected. Experimental data show that temperature dependence on permeability at constant degree of saturation and constant void ratio is smaller than what could be expected from the thermal change in water viscosity. This behaviour suggests that phenomena such as porosity redistribution and thermo-chemical interactions, which alter clay fabric and pore fluid, can be relevant

On the estimation of scale of fluctuation in geostatistics

Describing how soil properties vary spatially is of particular importance in stochastic analyses of geotechnical problems, because spatial variability has a significant influence on local material and global geotechnical response. In particular, the scale of fluctuation θ is a key parameter in the correlation model used to represent the spatial variability of a site through a random field. It is, therefore, of fundamental importance to accurately estimate θ in order to best model the actual soil heterogeneity. In this paper, two methodologies are investigated to assess their abilities to estimate the vertical and horizontal scales of fluctuation of a particular site using in situ cone penetration test (CPT) data. The first method belongs to the family of more traditional approaches, which are based on best fitting a theoretical correlation model to available CPT data. The second method involves a new strategy which combines information from conditional random fields with the traditional approach. Both methods are applied to a case study involving the estimation of θ at three two-dimensional sections across a site and the results obtained show general agreement between the two methods, suggesting a similar level of accuracy between the new and traditional approaches. However, in order to further assess the relative accuracy of estimates provided by each method, a second numerical analysis is proposed. The results confirm the general consistency observed in the case study calculations, particularly in the vertical direction where a large amount of data are available. Interestingly, for the horizontal direction, where data are typically scarce, some additional improvement in terms of relative error is obtained with the new approach

Suction effects on a compacted clay under non-isothermal conditions

The paper presents the results of an experimental study on the effects of suction and temperature on the volumetric behaviour of an unsaturated soil. Statically compacted Boom clay samples have been used in the testing programme, which has been performed using an oedometer apparatus with simultaneous control of suction and temperature. Suctions up to 0·45 MPa and temperatures up to 80°C have been applied. Special measures have been taken to control and minimise the problems associated with phase changes and vapour migration at high temperatures. A comprehensive experimental programme has been carried out, including isothermal tests with control of vertical stress, suction and temperature, non-isothermal tests under constant suction, and isothermal swelling pressure tests. Testing samples at two compacted soil densities provides observations concerning a wide scope of behaviour ranging from collapse to swelling behaviour on wetting. Test results obtained at 80°C have been compared with those of tests performed at room temperature (22°C). Based on these comparisons, thermal effects on a variety of features of behaviour such as swelling potential, swelling pressure, collapsibility, shrinkage strains, compressibility, stress path dependence and degree of strain reversibility are presented and discussed. Although the basic behaviour is similar at high and low temperatures, various significant differences are identified concerning mainly swelling strains developed during wetting and compressibility with respect to loading. Swelling pressure test results indicate that the high-temperature samples yield at a lower stress than that observed in room-temperature samples, suggesting that the stress domain bounded by the main yield surface reduces as temperature increases—a behaviour feature shared with saturated soils

Cultural heritage and environmental ethical values in governance models : Conflicts between recreational fisheries and other maritime activities in Mediterranean marine protected areas

Altres ajuts: Acord transformatiu CRUE-CSICWe would like to thank the collaboration of all the Pharos4MPAs project members, especially Catherine Piante, Pierre-Yves Hardy, Evan Jeffries, Alessandro Mullazzani, Elvira S?nchez and Esther Mart?nez. We thank the anonymous reviewers for their accurate and constructive comments, which helped to improve the manuscript Interreg Mediterranean 3MED17-3.2-M3-066. The authors declare no conflicts of interest.The seas as the next economic frontier have led to conflicts at the intersection of resource conservation and exploitation; a space where cultural values and social practices overlap. Underpinned by a literature review, surveys and personal interviews, this study identifies the main policy, socio-economic, environmental and cultural drivers of conflicts arising from the coexistence of recreational fishing -a major maritime activity in Mediterranean marine protected areas- and other maritime users. Results show that the constant paradoxes arising from the conflict stem from different concepts of heritage, appropriation of resources and preservation. Recreational fishing lacks a common definition and governance institution, but nevertheless regards itself as a fishing community and has behavioural traits which challenge other maritime activities, particularly small-scale fishing. This study highlights the importance of fostering socio-ecological relational values, which must necessarily be evaluated through the lens of environmental ethics, and contends that this is almost as relevant as the governance system. Given the divergent values of the different stakeholders and the high degree of scientific uncertainty found, we conclude that the main challenge in attaining a solid governance of multiple recreational and professional activities in marine reserves is to adopt a "middle ground" approach that combines top-down and bottom-up governance approaches

Saving the pharmacy of the sea : how does global change affect species with bioactive potential in the Mediterranean?

Several marine species in the Mediterranean produce molecules with bioactive potential that could be used to develop new drugs (antibiotics, antifungals, antivirals, and antitumourals). Different human activities such as pollution, marine recreation, and fishing, as well as climate change, threaten and even endanger some of these species. These vulnerable species with bioactive potential must be protected, especially in marine reserves, not only because they are valuable components of marine ecosystems, but also because they are a potential source of molecules with pharmacological properties that are currently being researched for the creation of new drugs

Local flexibility market design for aggregators providing multiple flexibility services at distribution network level

This paper presents a general description of local flexibility markets as a market-based management mechanism for aggregators. The high penetration of distributed energy resources introduces new flexibility services like prosumer or community self-balancing, congestion management and time-of-use optimization. This work is focused on the flexibility framework to enable multiple participants to compete for selling or buying flexibility. In this framework, the aggregator acts as a local market operator and supervises flexibility transactions of the local energy community. Local market participation is voluntary. Potential flexibility stakeholders are the distribution system operator, the balance responsible party and end-users themselves. Flexibility is sold by means of loads, generators, storage units and electric vehicles. Finally, this paper presents needed interactions between all local market stakeholders, the corresponding inputs and outputs of local market operation algorithms from participants and a case study to highlight the application of the local flexibility market in three scenarios. The local market framework could postpone grid upgrades, reduce energy costs and increase distribution grids’ hosting capacity.Postprint (published version