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Application of wave equation theory to improve dynamic cone penetration test for shallow soil characterisation

Journal of Rock Mechanics and Geotechnical Engineering 2022年第1期14卷 289-302页

作者： miguel angel Benz Navarrete Pierre Breul Roland Gourvès Sol Solution Géotechnique Réseaux ZA des Portes de Riom Nord23 Avenue Georges GershwinRiom Cedex63204France UniversitéClermont Auvergne Institut PascalUMR CNRS 6602Clermont-Ferrand63000France Polytech Clermont-Ferrand Campus des Cézeaux 2 Avenue Blaise PascalAubière Cedex63178France

Among the geotechnical in situ tests,the dynamic penetration test(DPT)is commonly used around the world.However,DPT remains a rough technique and provides only one failure parameter:blow count or cone resistance.This paper presents an improvement of the dynamic cone penetration test(DCPT)for soil characterisation based on the wave equation theory.Implemented on an instrumented lightweight dynamic penetrometer driving with variable energy,the main process of the test involves the separation and reconstruction of the waves propagating in the rods after each blow and provides a dynamic cone load-penetration(DCLT)curve.An analytical methodology is used to analyse this curve and to estimate additional strength and deformation parameters of the soil:dynamic and pseudo-static cone resistances,deformation modulus and wave velocity.Tests carried out in the laboratory on different specimens(wood,concrete,sand and clay)in an experimental sand pit and in the field demonstrated that the resulting DCLT curve is reproducible,sensitive and reliable to the test conditions(rod length,driving energy,etc.)as well as to the soil properties(nature,density,etc.).Obtained results also showed that the method based on shock polar analysis makes it possible to evaluate mechanical impedance and wave velocity of soils,as demonstrated by the comparisons with cone penetration test(CPT)and shear wave velocity measurements made in the field.This technique improves the method and interpretation of DPT and provides reliable data for shallow foundation design.

关键词： In situ test Dynamic cone penetrometer P.A.N.D.A. Wave equation Wave decoupling Dynamic cone load-penetration(DCLT)curve

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Isobars Separation (137Cs-137mBa-137Ba) from Marine Sediments, in Order to Evaluate Directly Their Radioactive Contamination by Mass Spectrometry

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World Journal of Nuclear Science and Technology 2020年第1期10卷 32-38页

作者： Karla Fernández Juan Manuel navarrete miguel angel Zúñ iga Ernesto Hernández Department of Inorganic and Nuclear Chemistry Faculty of ChemistryNational Autonomous University of MexicoMexico CityMexico

Marine sediments contamination by fission product 137Cs-137mBa is a fact since the period 1945-65, when plus than two thousand atomic explosion tests were performed mainly in the southern seas, earth region with minor population density. However, marine flows have produced dissemination of this radioactive pair through the sea bottom all over the world, at different levels, because the sea movement and natural decaying of radioactive pair: parent 137Cs (t1/2 = 30.17 years) and daughter 137mBa (t1/2 = 2.55 minutes). Radioactive detection of these contaminants, compared as percentage with that of natural 40K (t1/2 = 1.28 × 109 years, 0.0118% of elementary K) leads to radiation contamination factor (RCF), as one possible unit to measure the radioactive contamination intensity in different regions, as well to determine if there is some other possible source of this contaminant, for example water cooling from power nuclear reactors when it is discharged at sea. However, radioactive detection always implies an unavoidable statistical variation, which makes more difficult to appreciate the changes as function of time and region. But at beginning of this century, mass spectrometry has got impressive advances, which makes it much more precise and sensible than radioactive detection [1]. This paper attempts to measure with other units the radioactive contamination: 137Cs atoms number per gram of sample, instead radioactivity, which could be more direct and with minor standard deviation that radioactive detection, solving at same time the isobars separation: 137Cs versus 137mBa plus elementary 137Ba (11.23% of Ba element).

关键词： Isobars Separation 137Cs-137mBa-137Ba

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Assessment of Present and Future Radioactive Contamination at Global Scale

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Journal of Chemistry and Chemical Engineering 2012年第11期6卷 1010-1015页

作者： Juan Manuel navarrete miguel angel ZUNiga Guillermo Espinosa Jose Ignacio Golzarri Faculty of Chemistry National University of Mexico Mexico City 04510 Mexico Institute of Physics National University of Mexico Mexico City 04510 Mexico

As a result of more than two thousand nuclear tests performed since 1945, two war actions and few accidents in nuclear reactor, it does already exist a radioactive contamination at global scale. This contamination has been accumulated mainly in marine sediments, because sea is about 80% of planet surface, and solid fission products released by nuclear explosions are transported by wind first and then by rain to liquid and solid portions on earth, while gaseous fission products are diffused in the atmosphere. In this way, heavy, high yielding fission products, such as 137Cs, get marine sediments, where they are found mixed with heavy radioactive natural elements such as U, Th and their also radioactive decay products. But since alkaline are so abundant on earth, it is also found natural radioactive isotope 40K, 0.0118% of isotopes forming K element, with half life 1.28 × 109, in the time range of planet age and elements origin. So, one easy way to assess both the importance and evaluation of radioactive contamination at global scale should be to establish a RCF (radioactive contamination factor) as a percentage of 137Cs contaminant radioactivity in marine sediments, compared to 40K natural radioactivity present from the very beginning of earth, both expressed as Bq per gram of sediment. In the frame of these rather general considerations, a research project has started in Mexico whose varied purposes are: to characterize sea regions in both vast littorals in the country, by its natural 40K radioactivity present in sea salts, as well as to determine if 137Cs traces produced by recent radioactive contamination have reached their coasts. Also, to assess the 137Cs traces already present in marine sediments as a result of more than two thousand nuclear test explosions performed till now, rather than contamination produced by four main accidents in nuclear reactors during the last 60 years. It is proposed a radioactive contamination factor obtained from samples taken up in both coasts during the last two years, which sh

关键词：放射性污染全球范围评估天然放射性水平海洋沉积物铯-137 反应堆事故裂变产物

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Potassium Concentration by Natural ^40K-^40Ar Y Rays Detection in Four Basic Diet Products （Milk, Eggs, Wheat and Corn）

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Journal of Life Sciences 2011年第8期5卷 614-617页

作者： Juan Manuel navarrete Trinidad Martinez Luis Cabrera Pilar Lizarraga miguel angel Zuniga Michelle Camacho Faculty of Chemistry Building D National University of Mexico CU Mexico City ZC 04510 Mexico

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