Nouveaux éléments sur la structure et le fonctionnement hydrogéologique du plateau basaltique de l'Aubrac (Massif central,France). Première évaluation des potentialités en eau souterraine     

Pierre-Yves Bourlier  Patrick Lachassagne  Jean-François Desprats  Emmanuel Gille 《Comptes Rendus Geoscience》2005,337(7):663-673

In volcanic areas, the quality of the geological data at the various scales is of paramount importance for the estimation of aquifer potentialities and thus for groundwater exploitation. Geological and hydrogeological investigation (synthesis of existing data, field geological observations, reconstruction of the infra-volcanic morphology, stream gauging, field hydrogeology, etc.) have been performed on the 450-km² Aubrac basaltic plateau (Massif Central, France). These results allow us to specify the hydrological structure and functioning of this volcanic plateau that were quite unknown before. It is mainly constituted by the piling up of lava flows resting on a plutonic and metamorphic substratum. This volcanic unit constitutes an aquifer of regional importance whose groundwater resources are currently underexploited. These results allow us to delineate zones and strategies for priority hydrogeological prospecting. To cite this article: P.-Y. Bourlier et al., C. R. Geoscience 337 (2005).  相似文献   

A Global Experimental System Approach of Karst Springs¹ Hydrographs and Chemographs     

D. Alessandro Grasso  Pierre-Yves Jeannin 《Ground water》2002,40(6):608-618

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Validation of ADEOS-II GLI ocean color products using in-situ observations     

Hiroshi Murakami  Kosei Sasaoka  Kohtaro Hosoda  Hajime Fukushima  Mitsuhiro Toratani  Robert Frouin  B. Greg Mitchell  Mati Kahru  Pierre-Yves Deschamps  Dennis Clark  Stephanie Flora  Motoaki Kishino  Sei-Ichi Saitoh  Ichio Asanuma  Akihiko Tanaka  Hiroaki Sasaki  Katsumi Yokouchi  Yoko Kiyomoto  Hiroaki Saito  Cécile Dupouy  Absornsuda Siripong  Satsuki Matsumura  Joji Ishizaka 《Journal of Oceanography》2006,62(3):373-393

The Global Imager (GLI) aboard the Advanced Earth Observing Satellite-II (ADEOS-II) made global observations from 2 April 2003 to 24 October 2003. In cooperation with several institutes and scientists, we obtained quality controlled match-ups between GLI products and in-situ data, 116 for chlorophyll-a concentration (CHLA), 249 for normalized water-leaving radiance (nLw) at 443 nm, and 201 for aerosol optical thickness at 865 nm (Tau_865) and Angstrom exponent between 520 and 865 nm (Angstrom). We evaluated the GLI ocean color products and investigated the causes of errors using the match-ups. The median absolute percentage differences (MedPD) between GLI and in-situ data were 14.1–35.7% for nLws at 380–565 nm, 52.5–74.8% nLws at 625–680 nm, 47.6% for Tau_865, 46.2% for Angstrom, and 46.6% for CHLA, values that are comparable to the ocean-color products of other sensors. We found that some errors in GLI products are correlated with observational conditions; nLw values were underestimated when nLw at 680 nm was high, CHLA was underestimated in absorptive aerosol conditions, and Tau_865 was overestimated in sunglint regions. The error correlations indicate that we need to improve the retrievals of the optical properties of absorptive aerosols and seawater and sea surface reflection for further applications, including coastal monitoring and the combined use of products from multiple sensors.  相似文献   

Determination of geologic strain using randomly oriented strain markers of any shape     

Pierre-Yves F. Robin 《Tectonophysics》1977,42(1):T7-T16

Strain markers are geologic bodies within a rock which, during the deformation of that rock, have retained their identity but did not differ from their surrounding material in their mechanical behaviour. In sections they appear as closed contours. If it can be assumed that there was no preferred orientation of the markers, the axial-strain ratio in a planar section can be determined. Two lines are drawn through the centre of each marker, parallel respectively to the two axes of the sectional strain ellipse. If aj and cj are the segments defined by the intersection of these two lines with the contour of a marker j, then the axial-strain ratio is the logarithmic average of all aj/cj. As shown in an example, this method can also be used if the markers are ellipsoids. A statistical test of initial isotropy is proposed for this special case.  相似文献   

On the thermodynamics of pressure solution—interaction between chemical and mechanical forces: a discussion     

F. Robin Pierre-Yves 《Geochimica et cosmochimica acta》1978,42(3):333-334

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Landslide hazard assessment based on Bayesian optimization–support vector machine in Nanping City,China     

Xie  Wei  Nie  Wen  Saffari  Pooya  Robledo  Luis F.  Descote  Pierre-Yves  Jian  Wenbin 《Natural Hazards》2021,109(1):931-948

Natural Hazards - Landslide hazard assessment is critical for preventing and mitigating landslide disasters. The tuning of hyperparameters is of great importance to achieve better accuracy in a...  相似文献   

Cyclic and creep combination effects on the long-term undrained behavior of overconsolidated clay     

Han  Jian  Yin  Zhen-Yu  Dano  Christophe  Hicher  Pierre-Yves 《Acta Geotechnica》2021,16(4):1027-1041

Acta Geotechnica - Soft soil subjected to cyclic loading typically exhibits an increase in excess pore pressure under undrained condition which brings the soil to an overconsolidated state. Then,...  相似文献   

Seismic response of Beirut (Lebanon) buildings: instrumental results from ambient vibrations   总被引：1，自引：1，他引：0  

Christelle Salameh  Bertrand Guillier  Jacques Harb  Cécile Cornou  Pierre-Yves Bard  Christophe Voisin  Armand Mariscal 《Bulletin of Earthquake Engineering》2016,14(10):2705-2730

Resonance period is a key parameter in the seismic design of a structure, thus dynamic parameters of buildings in Beirut (Lebanon) were investigated based on ambient vibration method for risk and vulnerability assessment. Lebanon is facing high seismic hazard due to its major faults, combined to a high seismic risk caused by dense urbanization in addition to the lack of a seismic design code implementation. For this study, ambient vibration recordings have been performed on 330 RC buildings, period parameters extracted and statistically analyzed to identify correlations with physical building parameters (height, horizontal dimensions, age) and site characteristics (rock sites or soft sites). The study shows that (1) the building height or number of floors (N) is the primary statistically robust parameter for the estimation of the fundamental period T; (2) the correlation between T and N is linear and site dependent: T ≈ N/23 for rock sites and N/18 for soft sites; (3) the measured damping is inversely proportional to the period: the taller the building the lower is the damping; (4) a significant overestimation of the period exists in current building codes. However part of the large discrepancy with building code recommendations may be due to the very low level of loading.  相似文献   

Characterization of site conditions (soil class,V<Subscript>S30</Subscript>, velocity profiles) for 33 stations from the French permanent accelerometric network (RAP) using surface-wave methods     

Fabrice Hollender  Cécile Cornou  Aline Dechamp  Kaveh Oghalaei  Florence Renalier  Emeline Maufroy  Clément Burnouf  Sylvette Thomassin  Marc Wathelet  Pierre-Yves Bard  Vincent Boutin  Clément Desbordes  Isabelle Douste-Bacqué  Laetitia Foundotos  Cédric Guyonnet-Benaize  Vincent Perron  Julie Régnier  Agathe Roullé  Mickael Langlais  Deborah Sicilia 《Bulletin of Earthquake Engineering》2018,16(6):2337-2365

Data provided by accelerometric networks are important for seismic hazard assessment. The correct use of accelerometric signals is conditioned by the station site metadata quality (i.e., soil class, V_S30, velocity profiles, and other relevant information that can help to quantify site effects). In France, the permanent accelerometric network consists of about 150 stations. Thirty-three of these stations in the southern half of France have been characterized, using surface-wave-based methods that allow derivation of velocity profiles from dispersion curves of surface waves. The computation of dispersion curves and their subsequent inversion in terms of shear-wave velocity profiles has allowed estimation of V_S30 values and designation of soil classes, which include the corresponding uncertainties. From a methodological point of view, this survey leads to the following recommendations: (1) perform both active (multi-analysis surface waves) and passive (ambient vibration arrays) measurements to derive dispersion curves in a broadband frequency range; (2) perform active acquisitions for both vertical (Rayleigh wave) and horizontal (Love wave) polarities. Even when the logistic contexts are sometimes difficult, the use of surface-wave-based methods is suitable for station-site characterization, even on rock sites. In comparison with previous studies that have mainly estimated V_S30 indirectly, the new values here are globally lower, but the EC8-A class sites remain numerous. However, even on rock sites, high frequency amplifications may affect accelerometric records, due to the shallow relatively softer layers.  相似文献   

Modeling the effect of wetting on the mechanical behavior of crushable granular materials     

Carlos Ovalle  Pierre-Yves Hicher 《地学前缘(英文版)》2020,(2):487-494

It is well known that the compressibility of crushable granular materials increases with the moisture content,due to the decrease of particle strength in a humid environment.An existing approach to take into account the effect of grain breakage in constitutive modeling consists in linking the evolution of the grain size distribution to the plastic work.But how the material humidity can affect this relationship is not clear,and experimental evidence is quite scarce.Based on compression tests on dry and saturated crushable sand recently reported by the present authors,a new non-linear relationship is proposed between the amount of particle breakage and the plastic work.The expression contains two parameters:(1)a material constant dependent on the grain characteristics and(2)a constant depending on the wetting condition(in this study,dry or saturated).A key finding is that the relationship does not depend on the stress path and,for a given wetting condition,only one set of parameters is necessary to reproduce the results of isotropic,oedometric,and triaxial compression tests.The relationship has been introduced into an elastoplastic constitutive model based on the critical state concept with a double yield surface for plastic sliding and compression.The breakage ratio is introduced into the expression of the elastic stiffness,the critical state line and the hardening compression pressure.Incremental stress-strain computations with the model allow the plastic work to be calculated and,therefore,the evolution of particle crushing can be predicted through the proposed non-linear relationship and reintroduced into the constitutive equations.Accurate predictions of the experimental results in terms of both stress-strain relationships and breakage ratio were obtained.  相似文献