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RISS 인기검색어
- 검색키워드
- 저자 : Pires Luiz F. (검색결과 2 건)
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Pires Luiz F. 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.9
Soils are porous materials with high shielding capability to attenuate gamma and X-rays. The disposal of radionuclides throughout the soil profile can expose the living organisms to ionizing radiation. Thus, studies aiming to analyze the shielding properties of the soils are of particular interest for radiation shielding. Investigations on evaluating the shielding capabilities of highly weathered soils are still scarce, meaning that additional research is necessary to check their efficiency to attenuate radiation. In this study, the radiation shielding properties of contrasting soils were evaluated. The radiation interaction parameters assessed were attenuation coefficients, mean free path, and half- and tenth-value layers. At low photon energies, the photoelectric absorption contribution to the attenuation coefficient predominated, while at intermediate and high photon energies, the incoherent scattering and pair production were the dominant effects. Soils with the highest densities presented the best shielding properties, regardless of their chemical compositions. Increases in the attenuation coefficient and decreases in shielding parameters of the soils were associated with increases in clay, Fe2O3, Al2O3, and TiO2 amounts. In addition, this paper provides a comprehensive description of the shielding properties of weathered soils showing the importance of their granulometric fractions and oxides to the attenuation of the radiation
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Embankment Supported by Low Area Replacement Ratio Stone Columns, Monitoring and Numerical Studies
Mario V. Riccio F.,Marcio S. S. Almeida,Silvana M. Vasconcelos,Liliana G. S. Pires,Luiz F. Nicodemos R. 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.2
The focus of this study was to evaluate the behaviour of a test embankment supported on vibro stone columns (VSCs) installed with a low area replacement ratio (7.56%) based on data obtained from field instrumentation complemented by analytical and numerical methods. The test embankment is 5.35 m high and was built on top of a soft soil treated with VSCs arranged in a 10-column × 10-column square grid. Analytical and two-dimensional finite element methods using the axisymmetric unit cell approach were also employed in the study to analyse the instrumentation data. The measured settlement-time curves, for the embankment axis, were compatible with finite element analysis in which the coefficient of permeability was continuously updated with the void ratio. Comparison was also favourable regarding measuredand predicted values of settlements and improvement factors. All evidence indicates that VSCs installed with a low area replacement ratio (<10%) were quite effective in reducing the time for settlement stabilization and in providing adequate short-term stability against failure, but less effective in reducing the long-term settlement magnitude.
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