RESUMEN
Daily freezing-thawing-repetitive loading is a critical factor affecting soil stability. This study assesses the strength of sand-silt mixtures with various silt fractions (SFs) subjected to cyclic freezing-thawing-repetitive loading. Specimens with SF of 0-100% were prepared with a fixed relative density of 60%. The number of repetitive loadings (N) was 1, 100, and 1000 for each specimen with different SFs. After three cycles of freezing-thawing-repetitive loading, the specimens were frozen at -5 °C for the uniaxial compression test. Test results show that the change in relative density (∆Dr) increases with the increase in SF up to 30% and decreases as SF increases beyond 30% owing to the change in the void ratio. The volumetric unfrozen water content (θu) increases with the increase in both SF and N owing to the effect of the physicochemical characteristics of soils on small voids. Unconfined compressive strength of sand-dominant mixtures (SF ≤ 30%) is reinforced by ∆Dr. By contrast, for silt-dominant mixtures (SF > 30%), the unconfined compressive strength decreases with the increase in θu and N due to lubricant role and sands dispersion. Thus, the effects of SF and N should be considered for sand-silt mixtures that have a probability to undergo cyclic freezing-thawing-repetitive loading.
RESUMEN
Obesity is a global phenomenon affecting all socioeconomic groups, irrespective of age, gender or ethnicity. In many countries, obesity trends are causing serious public health concerns threatening the viability of basic health care delivery. In this article, we examine the trends of adolescent obesity at the national level in South Korea introducing a new approach for visualising data at the local level based on linked micromap plots. Our analysis shows that the obesity rates for 2013 have only increased slightly since 2006 for South Korean adolescents of both genders in various age groups. However, considerable increases could be observed for the subgroup of adolescent males and adolescent females living in rural areas. Trends at the local level show a slight increase of the prevalence of obesity in most regions of the country, with the highest obesity prevalence found in the Northeast.
