Additional insights to EC7 from the application of reliability-based design methods: the case of debris flow protection structures

Debris flows are dangerous natural processes that cause extensive damages to infrastructures and urbanized areas and can lead to loss of human lives. Their unpredictability, their extremely high motion and their magnitude are the main causes of these harms. Mitigation measures are fundamental for reducing the associated risk and protecting infrastructures in mountainous areas. Their design is still an open issue: there are many formulations to evaluating impact pressure. Moreover, the uncertainties in the determination of flow characteristics (velocity and thickness) are significantly high and difficult to quantify. In the European Union, the design of any type of structures involved in rock mechanics field must comply with EN-1997 Geotechnical Design (CEN 2004) (EC7). For debris flow countermeasures, EC7 requirements are very difficult to apply in practice since partial safety factors are not provided for these phenomena. However, the basic philosophy of reliability-based design (RBD), as defined in EN1990 (CEN 2002) may be a suitable and complementary approach to provide geotechnical structures with a uniform probability of failure. Reliability Based Design (RBD) can provide additional insights to EC7 design and can be applied when partial factors have still to be proposed (by EC7) to cover uncertainties of less common parameters, as in case of debris flow countermeasures. This paper presents an analysis of the advantages and limitations on the applicability of RBD approach to debris flow countermeasures, by using the first-order reliability method (FORM). In particular, data availability, the possibilities for analysing data in a statistical framework and the choice of performance function are the main limitation of the method, which force to make assumptions regarding statistical distribution of the considered parameters. A sensitivity analyses, comparing different equations, commonly used for debris flow impact pressure estimation, were performed for quantifying the effect of the selected performance function on the RBD results

Allocating Resources and Creating Incentives to Improve Teaching and Learning

Offers insights from scholarly literature, related theory, and practical activities to inform the efforts of policymakers, researchers and practitioners to allocate resources and create incentives that result in powerful, equitable learning for all

In situ stress measurement near faults and interpretation by means of discrete element modelling

The design of underground caverns of significant size and of complex geometry is often accompanied by the use of numerical models able to estimate the range of stresses and strains induced by the excavations and, consequently to evaluate the stability of the caverns. In this context, it is convenient to estimate the natural state of stress of the rock mass, the mechanical properties of the rock matrix and the discontinuities and to carry out in situ measurements to calibrate the model. In the Carrara basin (Italy) there is a huge number of underground excavations that need to be monitored and, for this purpose, a series of models and in situ measurements have been performed. This study aims to point out the difficulties involved in understanding the in-site measured stress. A series of tests were conducted in Carrara, in an underground marble quarry site, focusing to study the complex tectonic environment in the area. A series of comparisons between 3D DEM numerical models has been performed in order to understand the influence of the presence of the main faults on the in situ state of stress. Some final comments regarding the variability of stress fields in faulted rock masses are provided

El potencial de crecimiento radical en planta de vivero de Pinus halepensis Mill. Influencia de la fertilización

In response to the importance of Root Growth Potential (RGP) attribute as a field performance potential predictor, this paper analyses the relationship between nursery fertilization and this attribute by mean of applying several mineral nutrition treatments (3, 5, 7 g/L Osmocote 9-13-18, Osmocote 17-10-10, 5 g/L Osmocote 15-8-11) in an experiment with Aleppo pine seedlings. Significative differences in the Root Growth Potential response between treatments were found; in particular, seedlings produced with 9-13-18 showed an increase in new roots produced (maximum value of 74 new roots > 1 cm corresponding to 7 g/L of this fertilizer) comparing with other compositions. After seeking univariable relationships between morphological or physiological attributes and RGP, no significative correspondence was found. In addition, seedlings survived over 70 per cent one year after planting in semiarid conditions, irrespective the mineral nutrition treatment considered; this indicates high vigor of the stock, even for the treatment showing a lower response in PCR (17 roots > 1 cm).Dado el interés que posee el atributo Potencial de Crecimiento Radical de la planta de vivero como predictor de la respuesta postrasplante, este trabajo analiza el efecto de varios tratamientos de fertilización en vivero (5g/L de Osmocote 15-8-11; 3, 5, 7 g/L de Osmocote 9-13-18, idem de Osmocote 17-10-10) sobre el Potencial de Crecimiento Radical de planta de pino carrasco de una savia, concluyéndose la existencia de diferencias significativas que discriminan grupos de formulaciones a favor de las tres dosis de 9-13-18, que produjeron los mejores resultados (hasta 74 raíces mayores de 1 cm en promedio para 7 g/L). Sin embargo, no se han encontrado relaciones univariables significativas entre atributos morfológicos o fisiológicos de la planta y Potencial de Crecimiento Radical. Por otra parte, todos los tratamientos sobrevivieron en plantación con valores superiores al 70 por ciento en condiciones de semiaridez, indicando un buen estado de vigor de todos los lotes ensayados, incluídos los de menor expresión del potencial de formación de nuevas raíces (17 raíces > 1cm)