Tensile properties of geosynthetics after installation damage

In this paper, data from field installation trials of geosynthetics and laboratory tests are presented and analysed. The influence of several factors was assessed, namely nominal strength and type of geosynthetic, soil, compaction energy and method used to induce installation damage. Visual observations using a scanning electron microscope were performed. From the data collected, reduction factors for installation damage were derived using tensile strength values (traditional approach) and stiffness modulus (for 2% strain). Relative to the stiffness approach, the results obtained indicate that the traditional approach can be conservative. The reduction factors, determined using the traditional approach, were also compared with interval estimates from the literature. To contribute to supporting a shift from a factor of safety approach to a limit state design, bias statistics to correct the deterministic predictions were determined from the results. Different correlations were also established to enable using these results to interpolate reduction factors for similar installation conditions and/or geosynthetics from the same family of products. Installation damage reduction factors should be used in limit state design (ultimate and serviceability). Nevertheless, the stiffness approach can only be used for limit states where tensile failure of the geosynthetics will not occur

Synergy between mechanical damage and abrasion of a composite geosynthetic and its variability

In this paper results of tests to assess the effect of mechanical damage (generally associated with installation processes) and abrasion are presented. Laboratory tests were carried out. The material tested is a composite consisting of two overlapped geosynthetics: a nonwoven geotextile and a woven geogrid. The composite was submitted to each referred agent (mechanical damage and abrasion damage) in isolation and sequentially, in order to assess an eventual synergetic effect. The effect of the damage induced in the short-term mechanical properties of the geosynthetic was assessed. The variability of these properties was assessed by using either 1 or 3 tests per sample. Abrasion damage (either isolated or combined with mechanical damage) was the most critical mechanism, leading to higher reductions of tensile strength. Increasing the number of tests used to characterise the samples from 1 to 3, has reduced the variability of the properties assessed, although the tensile strength values decreased and the peak strain and secant stiffness modulus for 2% strain increased. The number of characterisation tests carried out per sample didn’t affect the trends observed associated with the damage induced. Some synergisms were observed for mechanical and abrasion damag

Tensile and hydraulic properties of geosynthetics after mechanical damage and abrasion laboratory tests

Installation damage of geosynthetics occurs during their handling, positioning on the ground and the placing and compacting of fill material. Abrasion is a common damage mechanism where there is cyclic relative motion (friction) between a geosynthetic and contact soil. This paper presents the laboratory test results of mechanical damage and abrasion performed on six geosynthetics. The in isolation and combined effects on mechanical, hydraulic and physical properties of the geosynthetics were assessed. Results show that the effects of induced mechanical and abrasion damage essentially depend on the geosynthetic structure. For the most affected materials, strength losses after abrasion (in isolation and combined with mechanical damage) are higher than after the induced mechanical damage. Therefore, for most geosynthetics studied, abrasion is the conditioning mechanism which most affects their tensile strength. An increase of the characteristic opening size of the geosynthetics was observed, while their permittivity did not increase. This may be caused by differences in the test set-ups

Flume tests on fine soil reinforced with geosynthetics – walls of the salt pans (Aveiro lagoon, Portugal)

This paper presents exploratory work on the use of geosynthetics for reinforcing fine soils, particularly for applications in the Aveiro lagoon, Portugal. The behaviour of local fine soil reinforced with geosynthetics under hydraulic actions was studied using flume tests. The case study was a typical cross section of the walls of the salt pans of the Aveiro lagoon. A preliminary design of a structure was done, for different reinforcements (geogrid, geocomposite, association of geogrid and geotextile). Local soil was collected and characterised using laboratory tests. The flume tests included performing permeability, erosion and overtopping tests, for actions typical of the lagoon environment. The models reinforced with geogrid GGR exhibited the highest global permeability, due to the difficulty of soil lumps to penetrate the geogrid openings. Although this type of reinforcement provides low resistance to erosion, promoting vegetation growth or including other elements can reduce surface erosion. The other reinforcements (sheets) enabled containing the soil. Non-uniformity of the soil compaction caused local differences of permeability. Thus, ensuring uniform compaction on site is necessary; however it can be challenging, particularly for fine soils. The results indicate that seepage is likely to induce some clogging of the reinforcements. The reinforced soil models tested exhibited higher permeability and lower resistance to erosion and overtopping than the traditional solution (soil matrix with vegetation). The results indicate that a possible alternative solution for the walls could use fibre reinforcement. Further work is necessary to ensure adequate (low) permeability of new solutions for these wall

Effect of geosynthetic reinforcement inclusion on the strength parameters and bearing ratio of a fine soil

This paper reports an investigation on the beneficial effects of reinforcing a fine soil with a geosynthetic (reinforcement geocomposite) and their behaviour under loading. The effectiveness of the reinforcement was investigated through triaxial and California Bearing Ratio, CBR, tests. The triaxial tests showed that including the reinforcement provided additional confinement to the reinforced soil samples, causing an increase in the corresponding strength parameters. However, the reinforcement decreased the secant stiffness modulus of the composite material, particularly for low strains. The CBR tests were performed on soaked samples, compacted for different initial water content values. The influence of increasing the number of reinforcement layers was also analysed. The results showed that the reinforced samples had a maximum bearing capacity larger than the unreinforced material. The reinforcing mechanisms observed in the CBR tests were membrane tension support and bearing capacity increase. Increasing the number of reinforcement layers induced an improved response of the soil-geosynthetic composite material, particularly for a water content lower than the optimum. An increase in the initial water content induced reductions of the bearing capacity of the soil, with different values, depending on position of the initial value relative to the optimum water content

Effect of soil grain size distribution on the mechanical damage of nonwoven geotextiles under repeated loading

Installation processes (which induce mechanical damage) may cause undesirable changes on the properties of geosynthetics, affecting their performance. This work evaluates the effect of mechanical damage on the short-term tensile behaviour of two nonwoven geotextiles (with different masses per unit area). The geotextiles were damaged in laboratory using a standardised procedure and an artificial aggregate (corundum) and eight other soils. The damage induced was characterized using wide-width tensile tests. Results showed reductions of the tensile strength of both geotextiles, which depended on the grain size distribution and uniformity of the soils and on the mass per unit area of the geotextiles. The reduction in tensile strength provoked by corundum was higher than the decreases caused by most of the other soils. The mechanical damage tests also led to a reduction of elongation at maximum load and an increase of stiffness

Three years incidence of dermatophytes in a hospital in Porto (Portugal)

Rev Iberoam Micol. 2002 Dec;19(4):201-3. [Three years incidence of dermatophytes in a hospital in Porto (Portugal)]. [Article in Spanish] Lopes V, Velho G, Amorim ML, Cardoso ML, Massa A, Amorim JM. SourceServiço de Microbiologia, Hospital Geral Santo António, Largo Prof. Abel Salazar, 4099-001 Porto, Portugal. Abstract We evaluated the incidence of dermatophytes isolated at our hospital in the years of 1997 to 2000 and correlated it with anatomical site and age. Trichophyton rubrum was the predominant species in all anatomical sites, excluding scalp, followed by Microsporum canis, the leading agent of tinea capitis. All dermatophytosis, except tinea capitis by M. canis and Trichophyton schoenleinnii appeared mainly in adult patients. Our results revealed no substantial differences to other portuguese studies regarding the major agents. We found a relatively high incidence of T. schoenleinnii as second tinea capitis agent

Estratégias de raciocínio clínico dos enfermeiros que cuidam de clientes em situação crítica: revisão sistemática da literatura

Identificar estratégias de raciocínio clínico dos enfermeiros que cuidam de clientes, em situação crítica. Foi realizada uma revisão sistemática da literatura com recurso ao método PI[C]O na EBSCO (CINAHL (Plus with Full Text), MEDLINE (Plus with Full Text)) com limitador temporal entre 2009-2015, dos quais foram selecionados 8 artigos. As estratégias de raciocínio clínico de enfermagem que emergiram foram: a relação de confiança com o cliente e envolvimento da família, aplicação de competências de negociação e compromisso, de competências crítico-reflexivas, a intuição, o reconhecimento de situações similares e teste de hipóteses. E, como critérios de raciocínio clínico, o enfermeiro avalia o risco-benefício para o cliente, avalia as necessidades organizacionais e pesquisa informação em fontes complementares(11). Esta revisão permitiu conhecer algumas estratégias e critérios de raciocínio clínico do enfermeiro que cuida de clientes em situação crítica. No entanto, são necessários mais estudos para aprofundar conhecimento sobre o processo de raciocínio clínico que promove resultados positivos para o cliente decorrentes da intervenção autónoma e capacidade de decisão da enfermagem. Descritores: Raciocínio Clínico; tomada de decisão; cuidados de enfermagem

Estudo da Sensibilização aos Aeroalergenos Phl p 1, Phl p 5, Ole e 1 e Ole e 2 em Doentes com Patologia Alérgica Sazonal

Introdução: A sensibilização aos pólenes depende de vários factores nomeadamente do tipo de vegetação local e sabe-se que a sintomatologia não está apenas associada à exposição aos pólens mas também a partículas, algumas das quais resultantes da rotura dos grãos de pólen sendo posteriormente aerossolizadas. Objectivos: Relacionar a sensibilização de doentes com a concentração polínica atmosférica e a concentração de alguns dos respectivos aerolergenos. Métodos: Das consultas externas de Imunoalergologia dos hospitais de Évora e Elvas seleccionaram-se doentes que apresentavam queixas sazonais de rinite alérgica e asma brônquica, aos quais foram realizados testes cutâneos em Prick, standardizados, aos pólenes identificados na região. A 55 doentes foram realizados testes ao extracto de Phleum, aos seus alergénios Phl p 1 e Phl p 5, bem como aos extractos das restantes gramíneas e a 47 doentes foram realizados testes ao extracto de Olea, aos seus alergénios Ole e 1 e Ole e 2. Monitorizaram-se diariamente as partículas polínicas e os aeroalergenos mediante 2 colectores específicos para cada tipo. Resultados: A percentagem de doentes que é sensível aos 3 extractos de Phleum (Phleum total, Phl p 1 e Phl p 5) é de 51% , a dos que são sensíveis aos extractos de Phleum total e Phl p 1 é de 16 % e a dos que são sensíveis a Phleum total e Phl p5 é de 2%. A percentagem de doentes que é sensível a somente um dos extractos é de 20% e os que não têm qualquer sensibilidade são 11%. A percentagem de doentes que é sensível aos 3 extractos de Olea (Olea total, Ole e 1 e Ole e 2) é de 23%, a dos que são sensíveis à Olea total e Ole e 1 é de 21 % e a dos que são sensíveis à Olea total e Ole e 2 é de apenas 4%. A percentagem dos que são sensíveis a um dos extractos é de 19% e a dos que não apresentaram qualquer sensibilidade é de 32%. Conclusões: Podemos concluir que 89% dos doentes mostraram ser sensíveis aos alergénios da gramínea Phleum pratense pois mostraram positividade tanto ao extracto de Phleum e/ou aos seus alergénios Phl p 1 e Phl p 5. Em relação à oliveira, 44% dos doentes são alérgicos a este pólen pois são sensíveis ao seu alergénio major, Ole e 1. Em ambos os casos estão correlacionados com os aeroalergenos detectados nas amostras de ar, sendo a sensibilidade aos pólenes de gramíneas maior que a sensibilidade ao pólen de oliveira. Mais estudos devem ser realizados para despiste de reacções cruzadas nomeadamente quanto à Olea com outras plantas da região

Tempranillo physiological and agronomical responses to heat and drought stress – perspectives on its vulnerability under climate change scenarios

With the aim to characterize the ability of Tempranillo grapevines, one of the most widely used varieties in Spain and Portugal, to withstand drought and heat stress, ecophysiological and agronomical data from irrigation experiments conducted in the hot and dry region of Alentejo, south of Portugal, are presented. The impact of different irrigation treatments on physiological parameters (leaf water potential, photosynthesis, and stomatal conductance) and water use efficiency are showed. Leaf senescence observed in non-irrigated and deficit irrigated plants and its consequences on cluster exposure and berry temperature are compared with those of fully irrigated plants. The consequences on berry ripening and juice composition are discussed in order to evaluate the vulnerability of Tempranillo to the expected global climatic changeinfo:eu-repo/semantics/publishedVersio