Review of In Situ Measurements as Indications of Liquefaction Potential at Numerous Sites

Current practice for assessing liquefaction potential of granular soils depends heavily on in situ indices of density, and sometimes direct measurements of density. Correlations have been developed to predict resistance to liquefaction as a function of standard penetration test (SPT) blow count, cone penetrometer (CPT) tip resistance, shear-wave velocity (VS), or other index property. Recognizing that each correlation entails its own uncertainties, and that different indices of liquefaction potential may provide conflicting conclusions, the Bureau of Reclamation reviewed in situ test results from a large number of sites where multiple tests had been used. The goals were to 1) evaluate consistency among the various indices of liquefaction potential, 2) compare indirect indices of density, such as penetration resistance, against actual density measurements, and 3) survey current practice throughout the industry. This paper will provide a summary of the results

On the Use of Empirical Correlations for Estimating the Residual Undrained Shear Strength of Liquefied Soils in Dam Foundations

Current practice (2009) for seismic analysis of embankment dams relies heavily on empirical correlations with penetration resistance (standard penetration test or cone penetration test) to predict the residual undrained shear strength of liquefied foundation materials. At least six such relationships have been published for the SPT alone, in different “formats.” Some apply a fines adjustment to the SPT blowcounts, but others do not; some express the predicted strength as a ratio with pre-earthquake effective overburden stress, whereas others predict it directly, without explicit consideration of overburden. For the foundations of embankment dams, the difference between the strength-ratio approach and prediction of Sur directly, from the SPT alone, can be important. In this paper, the underlying assumptions and data are reviewed critically, including the effects of different material types and different mechanisms governing the strength. Simplified statistical analyses were applied in attempt to determine the most appropriate format for a correlation and to obtain a new correlation that explicitly accounts for both overburden and blowcount

Evaluation of Structural Alternatives for Seismic Risk Mitigation at Deer Creek Dam

Deer Creek Dam is a zoned earthen embankment on the Provo River in central Utah. The site is potentially subject to very severe earthquake loading, and some foundation materials have been identified as being likely to be liquefied by strong shaking. This could lead to instability or large dynamic deformations of the downstream slope, and possibly a breach of the dam. Several structural concepts were evaluated by the U.S. Bureau of Reclamation to determine the best method to stabilize the embankment. The selected modification concept was a rolled earthfill key under the downstream toe of the embankment, with a berm over it to weight the key and buttress the slope. This concept was selected in the fall of 2002, and in July 2003, a contract was awarded to modify the dam. This paper presents background information on the dam and its foundation, and describes the process of determining that modification is required and designing the modification. The latter includes potential earthquake loadings, in situ and laboratory testing to evaluate the foundation, and analyses of liquefaction potential and the stability of the unmodified embankment. The various concepts for modification are described, along with the rationale for selecting the preferred concept

Neuroinflammatory processes in cognitive disorders:Is there a role for flavonoids and n-3 polyunsaturated fatty acids in counteracting their detrimental effects?

Neuroinflammatory processes are known to contribute to the cascade of events culminating in the neuronal damage that underpins neurodegenerative disorders such as Parkinson's and Alzheimer's disease. With the ageing population and increased cases of neurodegenerative diseases, there is a crucial need for the development of new strategies capable to prevent, delay the onset or treat brain dysfunction and associated cognitive decline. Growing evidence sheds light on the use of dietary polyphenols and n-3 long chain polyunsaturated fatty acids to improve cognitive performances and reduce the neuroinflammatory and oxidative stress responses occurring with age and neurodegenerative pathologies. This review will summarise the most recent information related to the impact and mechanisms underlying the neuroinflammatory processes in neurodegenerative disorders. We will also detail the current evidence indicating that flavonoids and n-3 polyunsaturated fatty acids are strong candidate in preventing neuroinflammation and modulating age-related memory decline, and will describe the potential mechanisms of action underlying their neuroprotective effects. As such, these dietary bioactives represent important precursor molecules in the quest to develop of a new generation of drugs capable of counteracting neuroinflammation and neurodegenerative diseases

Human health risk assessment for aluminium, aluminium oxide, and aluminium hydroxide.

International audienc