Supercontinuum generation from 1.35 to 1.7 mu m by nanosecond pumping near the second zero-dispersion wavelength of a microstructured fiber

International audienceWe experimentally study a new regime for supercontinuum (SC) generation in the nanosecond pulsed regime using a nucrostructured optical fiber with two zero-dispersion wavelengths (ZDWs). Pumping at 1535 nm around the second ZDW yields a nearly flat SC over 1350-1700 nm. The interplay between the effects of modulation instability and stimulated Raman scattering are described through simple phase-matching relations

Milieux naturels: sols et roches

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Microstructural change identification in the Mix- Kaolin/Montmorillonite Clays at the Ultimate State: Microstructural identification in a clayey mix material at the ultimate state

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Degradability of unpaved roads submitted to traffic and environmental solicitations: Laboratory scale

International audienceDust emission generated during earthwork induces security nuisances for workers, residents and other activities around the site. At present, dust abatement is mainly done by water spraying. Since water spraying is not environmentally friendly, it becomes an economic and ecological challenge for companies. To enhance water saving, analysis of the mechanism of dust production is fundamental. This study aims to analyse the combined effects of traffic cycles and hydromechanical stresses on surface erosion and the modification of the microstructure of compacted soils. Roller compaction and traffic cycles were carried out in the laboratory on two soils composed by mixtures of Speswhite kaolin clay and Hostun sand, submitted to different hydric states and compaction degrees. Test results underline that the soil degradation under traffic cycles is governed by the compaction configuration. The grain size distribution of eroded particles features aggregates coarser than in the reference soil. Traffic cycles and compaction modify the soil microstructure. A decrease in the macropore size is measured for all the tested compaction configurations. However, combination of traffic cycles and drying presents a less significant effect on the decrease of the macro-pore sizes

Une digue expérimentale en sol traité à la chaux à échelle un : évaluation des performances méthodologiques, mécaniques et hydrauliques

International audienceSoil improvement and stabilization with lime is a technique widely used for roads, highways and platforms construction. Addition of lime improves workability, bearing capacity, mechanical resistance of silty and clayey soils; although not a new concept, it has been practised less frequently in dike construction. Recent research programs led by Lhoist Group, a lime producer, have shown the specific conditions which should be applied in the context of hydraulic structures both for the treatment with lime and placement of treated materials. A series of relevant properties was evidenced, enhancing the real potential of this technique for construction or renovation of hydraulic earthen structures. To confirm those results at large scale, an experimental structure was constructed by CER (Experimental and Research Center) of Cerema, in Le Grand Quevilly/France. The structure consists in 2 full-scale experimental dry dikes, the first one built with 2.5% lime-treated silty soil and the other using the native soil (without treatment). The present paper deals with the results of short- and long-term behaviour of those two dikes through in situ and lab tests (on cored specimens). Both mechanical and hydraulic properties have been investigated. Those contributions show that the lime treatment is a promising technique allowing the valorisation of soils with poor engineering properties and inadequate hydraulic behaviour