492 research outputs found
Improvement of Mechanical Properties of Soft Soils by Use of a Pre-Loading Embankment
A preloading embankment, and its foundation soil, have been closely monitored in the Po river delta (Italy). After showing that the complete consolidation of the peaty and clayey soil has taken place, the shear strength increase measured with various tests has been considered and analyzed
Effectiveness of distributed temperature measurements for early detection of piping in river embankments
Abstract. Internal erosion is the cause of a significant percentage of failure and
incidents involving both dams and river embankments in many countries. In the
past 20 years the use of fibre-optic Distributed Temperature Sensing (DTS) in
dams has proved to be an effective tool for the detection of leakages and
internal erosion. This work investigates the effectiveness of DTS for dike
monitoring, focusing on the early detection of backward erosion piping, a
mechanism that affects the foundation layer of structures resting on
permeable, sandy soils. The paper presents data from a piping test performed
on a large-scale experimental dike equipped with a DTS system together with a
large number of accompanying sensors. The effect of seepage and piping on the
temperature field is analysed, eventually identifying the processes that
cause the onset of thermal anomalies around piping channels and thus enable
their early detection. Making use of dimensional analysis, the factors that
influence this thermal response of a dike foundation are identified. Finally
some tools are provided that can be helpful for the design of monitoring
systems and for the interpretation of temperature data
Evaluation of dynamic explicit mpm formulations for unsaturated soils
Many applications in geohazards prevention involve large deformations of unsaturated soils, e.g. rainfall induced landslides, embankment collapses due to wetting etc. These phenomena can be investigated with multiphase implementations of the Material Point Method (MPM) able to account for the behaviour of unsaturated soils. This paper compares two formulations: (i) afully coupled three-phase formulation(3P)in which the governing equations are derived from the momentum balance and the mass balance equations of solid, liquid and gas phase assuming non-zero gas pressure,the primary unknowns are the absolute accelerationsof the phases (aS–aL–aG formulation); (ii)a simplified approachthatneglectsthe momentum balance equation of the gas(2P_s).Potentialities and limitations of these approaches are highlighted consideringa 1D infiltration problem.Despite the introduced simplifications, the simplified formulation gives reasonably good results in many engineering cases
Current evidence of MTX efficacy in childhood chronic uveitis: a systematic review and meta-analysis
The application of the Boolean Stochastic Generation Method to model seepage under levees in heterogeneous soils
Soil heterogeneity plays an important role in incrementing the uncertainty about the reliability of geotechnical engineering works, especially levees. The presence of thin layers of soils more permeable than the surrounding matrix significantly changes the seepage flow net below and within the dike. However, the detection of these layers is extremely difficult. Consequently, to evaluate the overall safety of dikes it may be useful to adopt stochastic computation methods. The paper presents the calibration of a seepage model of an operational river embankment subject to sand boils. The levee, located along the Adige River (South Tyrol, Italy), has been monitored since 2016. Piezometers and spot temperature sensors are installed in the lateral banks while a distributed fiber optic sensors (FOS), buried in a 350 m long trench at the toe of the levee, is used to check temperature distribution in the subground. The Boolean Stochastic Generation (BoSG) method addresses the influence of layers of material with different properties with respect of the surrounding soil. 360 soil configurations were generated for a two-dimensional groundwater flow model of the levee and confronted with the monitoring data of two piezometers. This analysis permits to identify the configuration that has effects more congruent with piezometers data, which in this case is a configuration with a major presence of lenses on the waterside respect the field-side. This evidence could guide strategies for remedial works
Does the cost of a function affect its degree of plasticity? A test on plastic sex allocation in three closely related species of hermaphrodites
Erratum to: Successful treatment with adalimumab for severe multifocal choroiditis and panuveitis in presumed (early-onset) ocular sarcoidosis
Fast recovery of cardiac function in PIMS-TS patients early using intravenous anti-IL-1 treatment
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