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L’Her Alexandre Reinert Markus Prants Sergey Carton Xavier Morvan Mathieu 《Ocean Dynamics》2021,71(5):601-612
Ocean Dynamics - The Eastern Kamchatka Current (EKC) is the western boundary current of the North Pacific subpolar gyre. Southeast of the Kamchatka Peninsula lies a large anticyclonic eddy, the... 相似文献
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Weathering of sandstone lotus petals at the Angkor site: a 1,000-year stone durability trial 总被引：1，自引：1，他引：0
Marie-Françoise André Bruno Phalip Olivier Voldoire Franck Vautier Yves Géraud Mhammed Benbakkar Christophe Constantin Fabienne Huber Gilles Morvan 《Environmental Earth Sciences》2011,63(7-8):1723-1739
This article is based on field investigations carried out at Ta Keo and Banteay Srei temples (Angkor, Cambodia), which have similar environmental histories and display the same recurrent decorative pattern (lotus petal) in three different sandstone lithotypes. Based on two original scales of mechanical and chemical weathering, the degree of deterioration of c.2000 sandstone petals was visually assessed, resulting in the proposal of a durability scale. An explanatory scheme was provided, based on laboratory analyses of stone materials (ICP-AES, XRD, SEM-EDS, polarizing microscopy and mercury injection). The key drivers of sandstone durability are both mineralogical and petrophysical. The remarkable preservation of the pink sandstone is due to the quartzose nature of its clasts, the non-swelling clay content of its abundant matrix (kaolinite) and its porosity structure (large connected pores and probable non-connected porosity). The overall good preservation of the green sandstone is due to its extremely low porosity and specific surface area, associated with its strong cementation. The severe deterioration of the grey sandstone is due to its laminated structure (oriented biotites), the susceptibility to hygric swelling and solution of its binding agents (chlorite/smectite and calcite) and its porosity structure, which evolves during a two-stage weathering sequence. The first stage is characterized by a bimodal porosity due to the partial clogging of macropores by swelling clays, and the second stage by a substantial increase in porosity and the penetration of salts (barite and anhydrite). Conversely, oxidation phenomena associated with weathering can lead to a drastic reduction of porosity. 相似文献
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Bounding surface‐based modeling of compacted silty sand exhibiting suction dependent postpeak strain softening 
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下载免费PDF全文 Ujwalkumar D. Patil Laureano R. Hoyos Mathilde Morvan Anand J. Puppala 《国际地质力学数值与分析法杂志》2018,42(14):1741-1761
This article focuses on modeling the strain hardening‐softening response of statically compacted silty sand as observed from a comprehensive series of suction‐controlled, consolidated‐drained triaxial tests accomplished in a fully automated, double‐walled triaxial test system via the axis‐translation technique. The constitutive model used in this work is based on the theory of Bounding Surface (BS) plasticity and is formulated within a critical state framework. The essential BS model parameters are calibrated using the full set of triaxial test results and then used for predictions of compacted silty sand response at matric suction states varying from 50 to 750 kPa. Complementary simulations using the Barcelona Basic Model have also been included, alongside BS model predictions, in order to get further enlightening insights into some of the main limitations and challenges facing both frameworks within the context of the experimental evidence resulting from the present research effort. In general, irrespective of the value of matric suction applied, the Barcelona Basic Model performs relatively well in predicting response at peak and critical state failure under low net confining pressure while the Bounding Surface Model performs relatively well under high net confining pressures. 相似文献
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This paper is interested in the hydro‐mechanical behaviour of an underground cavity abandoned at the end of its service life. It is an extension of a previous study that accounted for a poro‐elastic behaviour of the rock mass (Int. J. Comput. Geomech. 2007; DOI: 10.1016/j.compgeo.2007.11.003 ). Deterioration of the lining support with time leads to the transfer of the loading from the exterior massif to the interior backfill. The in situ material has a poro‐visco‐elastic constitutive behaviour while the backfill is poro‐elastic, both saturated with water. This loading transfer is accompanied by an inward cavity convergence, thereby compressing the backfill, and induces an outward water flow. This leads to a complex space–time evolution of pore pressures, displacements and stresses, which is not always intuitive. In its general setting, a semi‐explicit solution to this problem is developed, using Laplace transform, the inversion being performed numerically. Analytical inversion leading to a quasi‐explicit solution in the time domain is possible by identifying the characteristic creep and relaxation times of volumetric strains with those of the deviatoric strains, on the basis of a parametric study. A few numerical examples are given to illustrate the hydro‐mechanical behaviour of the cavity and highlight the influence of key parameters (e.g. stiffness of backfill, lining deterioration rate, etc.). Further studies accounting for more general material behaviours for the backfill and external ground are ongoing. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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The morphological impact of storms on coastal accumulations varies considerably in space along the coast of western France. At some locations, the storm produces erosion, whereas at others, impacts may vary from erosion to accumulation, or no effect. This is explained by the variability of incident waves. Wave amplitude variability, cross-checked with wave direction variability, is presented on a phase diagram and shows that the response of the coast is not linked to the absolute values reached during the storm, but to changes in wave patterns that take place during the event. The morphology of the bottom (skerries, banks) is greatly forcing these changes because of the high tidal range and the complicated and fast-changing patterns of refraction. Locations with a flat seafloor have an almost predictable response to storms. Places with a complex submarine morphology have a response characterized by high variability. The variability of the wave pattern during a half tidal cycle storm (from low tide at 1 m to high tide at 13 m in 6 h) is a microscale equivalent of the variability of wave patterns changing during sea level rise in the Holocene (from −7 to 0 m in 6 ka). This fact explains why, during the late Holocene, the same locations (1) have displayed a very chaotic response to sea level rise and (2) are displaying, today, a highly variable response to storms. In that respect, seafloor morphology is a mesoscale to macroscale control on beach/barrier behaviour. 相似文献
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Oil exploration requires quantitative determination of structural geometry in sedimentary basins. This leads to back-and-forth use of geological methods, e.g. cross-section balancing and geophysical techniques, such as tomography, and the synthesis becomes tedious, especially in three dimensions. This suggests that they should be as much as possible quantitatively integrated into a single consistent framework. For this integration, we propose using inversion techniques, i.e. multicriteria optimization. We locally model a geological structure as a ( geometric) foliation , the leaves of which represent deposition isochrons. We consider a geological structure as a set of foliations joined along faults and unconformities. We propose five kinds of geological data to constrain structural geometry quantitatively: dip measurements that may be available along wells, developability and smoothness of deposition isochrons, the directions of fold axes, and layer parallelism. Using concepts of differential geometry, we formulate these data in terms of least-squares criteria. To solve the canonical non-uniqueness problem raised by the inversion of parametric representations of geometrical objects such as foliations (many parametrizations describe the same object), we introduce the additional criterion method which consists of adding an unphysical objective function to the physical objective function, so as to make the solution unique. Assuming well trajectories and borehole correlations to be known, we optimize, with respect to these criteria, several simple structures comprising one foliation, including a field example. 相似文献
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