Investigation into MOGA for identifying parameters of a critical-state-based sand model and parameters correlation by factor analysis   总被引：1，自引：1，他引：0  

Yin-Fu Jin  Zhen-Yu Yin  Shui-Long Shen  Pierre-Yves Hicher 《Acta Geotechnica》2016,11(5):1131-1145

Adding refinement and accuracy to constitutive models of soil results in the introduction of complexities along with more model parameters. These parameters (such as hardening-/softening-, dilatancy-/contractancy-related parameters and critical state parameters) are usually not easily obtained in a straightforward way. How to identify these key parameters and estimate their correlations of advanced soil models is a particular issue for geotechnical engineering. This paper was aimed to investigate multi-objective genetic algorithms for identifying parameters of advanced sand models based on standard laboratory tests, followed by the correlation analysis of parameters. A critical-state-based sand model has been developed to simulate three triaxial compression tests performed on loose and dense Hostun sand. Two widely used genetic algorithms with two initialisation methods are examined. The performance of the two genetic algorithms is assessed by comparing their simulation performance using optimal parameters, the convergence speed and the distribution of solutions on the Pareto front. The optimal parameters can then be classified into two factors by their correlation relationship.  相似文献   

KARSYS hydrogeological 3D modeling of alpine karst aquifers developed in geologically complex areas: Picos de Europa National Park (Spain)     

Daniel Ballesteros  Arnauld Malard  Pierre-Yves Jeannin  Montserrat Jiménez-Sánchez  Joaquín García-Sansegundo  Mónica Meléndez-Asensio  Gemma Sendra 《Environmental Earth Sciences》2015,74(12):7699-7714

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Assessing karst-hydraulic hazards in tunneling—the Brunnmühle spring system—Bernese Jura,Switzerland   总被引：1，自引：1，他引：0  

Pierre-Yves Jeannin  Arnauld Malard  Demian Rickerl  Eric Weber 《Environmental Earth Sciences》2015,74(12):7655-7670

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Geochemistry of post-extinction microbialites as a powerful tool to assess the oxygenation of shallow marine water in the immediate aftermath of the end-Permian mass extinction   总被引：1，自引：0，他引：1  

P. Y. Collin  S. Kershaw  N. Tribovillard  M. B. Forel  S. Crasquin 《International Journal of Earth Sciences》2015,104(4):1025-1037

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Study of the soil–atmosphere moisture exchanges through convective drying tests in non‐isothermal conditions     

Pierre Gerard  Angélique Léonard  Jean‐Pierre Masekanya  Robert Charlier  Frédéric Collin 《国际地质力学数值与分析法杂志》2010,34(12):1297-1320

This paper deals with the moisture exchanges occurring between soils and the surrounding atmosphere. Convective drying tests are performed on Awans silts at different drying temperatures and air relative humidities in order to reproduce the natural drying conditions. The experiments improve the understanding of the vapour transfers kinetics between the soil samples and the atmosphere. The experimental results are analysed assuming that the transfers take place in a boundary layer existing at the surface of the porous medium. The influence of the thermal conditions on the evaporation is also taken into account. In our model, coupled vapour and energy exchanges are controlled by mass and heat transfer coefficients characterizing the boundary layer. These coefficients are determined from the drying experiments. The modelling of the drying tests in non‐isothermal conditions is performed in order to validate the formulation of the vapour and heat exchanges. The numerical results present a good agreement with the kinetic of the materials desaturation determined during the tests. The analysis of the moisture transport mechanisms into the sample and at the boundary shows that at the beginning of the test, the drying is first achieved by the transport of moisture in its liquid form and its evaporation at the sample outer boundary in contact with the atmosphere. In a second step, vapour diffusion becomes predominant into the sample and it corresponds to the most important decrease of relative humidity. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Diffracted waves and displacement field over two-dimensional elevated topographies   总被引：3，自引：0，他引：3  

Pierre-Yves Bard 《Geophysical Journal International》1982,71(3):731-760

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Analysis of the structure of dissolved marine humic substances and their phytoplanktonic precursors by H and C nuclear magnetic resonance     

Michael A. Wilson  Andrew H. Gillam  Philip J. Collin 《Chemical Geology》1983,40(3-4):187-201

The structure of dissolved marine humic material and the intracellular and extracellular material from the diatom Phacodactylum tricornutum has been investigated by ¹H- and ¹³C-NMR spectroscopy. The results show that carbohydrates, highly-branched alkyl chains and to a lesser extent aromatic materials are important contributors to the structure of marine humic substances and aqueous extracts of P. tricornutum. There is a close relationship between the chemical structure of P. tricornutum exudate and dissolved marine humic material.  相似文献   

Geomagnetic field intensity between 70 000 and 130 000 years B.P. from a volcanic sequence on La Réunion, Indian Ocean     

Asmae Raïs  Carlo Laj  Jrme Surmont  Pierre-Yves Gillot  Herv Guillou 《Earth and Planetary Science Letters》1996,140(1-4):173-189

A detailed paleointensity study was made of a sequence of 70 successive lava flows of the Piton des Neiges volcano on the island of La Réunion (Indian Ocean). Radiometric dating brackets the age of this sequence between 130 ± 3 ka and 72 ± 3 ka. Rock magnetic investigations show that titanomagnetites in the pseudo single domain range are the main magnetic carrier of the Natural Remanent Magnetisation (NRM). Over 350 samples were used for paleointensity determinations carried out with the Thellier method in vacuum or in an argon atmosphere. Of these, 89 samples yielded reliable results, with within-flow scatter often lower than 20%. These results indicate that the geomagnetic field intensity has varied at La Réunion between 13 and 65 μT during the period of time explored. The average value, 42 μT, is higher than the present field at La Réunion (35 μT). The results from the upper part of the section are consistent with previous results obtained for the 82–98 ka period also at La Réunion [1] and document a broad low around 95 ka. not associated with large directional changes. On a larger geographic scale, the paleointensity values from La Réunion are significantly higher than those obtained from Mount Etna [2]. Precise comparison is, however, difficult because of the lack of detail in the Etna results. In the lower part of the section, a marked intensity low, coinciding with significant deviation from the dipole field direction is observed at 115 ka and could correspond to the end of the Blake event.  相似文献   

Pressure solution at grain-to-grain contacts     

Pierre-Yves F. Robin 《Geochimica et cosmochimica acta》1978,42(9):1383-1389

Whereas much petrographic evidence for pressure solution, in sedimentary rocks has been accumulated since Sorby's work, its thermodynamic justification has never been clearly established, and has been challenged by some authors. Difficulties disappear when it is recognized that in the most general case migration of chemical components proceeds down chemical-potential gradients rather than down concentration gradients. Along a grain contact a chemical-potential gradient is produced by variations in contact pressure and by local variations in Helmholtz energy of the solid. For example, in a sand made up of even-sized spherical grains buried 500 m, the ratio of the diameter (D) of the grains to that of a spherical elastic contact circle (a) is D/a ～- 26. The chemical potential at the center of such an elastic contact is ～- 14kcal mol^?1 higher than in surrounding pore water saturated with respect to quartz. For comparison, at a temperature of 30°C, saturation with respect to amorphous silica rather than quartz raises the chemical potential by only 1.6 kcal mol^?1. If the diameter of the contact circle has enlarged to e.g. a = D/5, the chemical potential at its center is still 0.5 kcal mol ^?1 greater than that of free quartz under hydrostatic pressure. The corresponding potential gradients are the driving force of pressure solution. The concept of pressure solution thus does not contradict any thermodynamic principle; in particular, it does not require that the chemical component of the solid have a smaller partial volume in solution than in the solid state. Petrographic and experimental evidence can therefore be accepted without reservation.  相似文献   

Speleoseismology: A critical perspective     

Arnfried Becker  Colin A. Davenport  Urs Eichenberger  Eric Gilli  Pierre-Yves Jeannin  Corinne Lacave 《Journal of Seismology》2006,10(3):371-388

Speleoseismology is the investigation of earthquake records in caves. Traces can be seen in broken speleothems, growth anomalies in speleothems, cave sediment deformation structures, displacements along fractures and bedding plane slip, incasion (rock fall) and co-seismic fault displacements. Where earthquake origins can be proven, these traces constitute important archives of local and even regional earthquake activity. However, other processes that can generate the same or very similar deformation features have to be excluded before cave damage can be interpreted as earthquake induced. Most sensitive and therefore most valuable for the tracing of strong earthquake shocks in caves are long and slender speleothems, such as soda straws, and deposits of well-bedded, water-saturated silty sand infillings, particularly in caves close to the earth's surface. Less easily proven is a co-seismic origin of an incasion and other forms of cave damage. The loads and creep movements of sediment and ice fillings in caves can cause severe damage to speleothems which have been frequently misinterpreted as evidence of earthquakes. For the dating of events in geological archives, it is important to demonstrate that such events happened at approximately the same time, i.e. within the error bars of the dating methods. A robust earthquake explanation for cave damage can only be achieved by the adoption of appropriate methods of direct dating of deformation events in cave archives combined with correlation of events in other geological archives outside caves, such as the deformation of lake and flood-plain deposits, locations of rock falls and active fault displacements.  相似文献