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Determining osmotic suction through electrical conductivity for unsaturated low-plasticity soils

Journal of Rock Mechanics and Geotechnical Engineering 2022年第6期14卷 1946-1955页

作者： Zi Ying nadia benahmed Yu-Jun Cui Myriam Duc Ecole des Ponts ParisTech Laboratoire Navier/CERMES6-8 Av.Blaise PascalCitéDescartesChamps-sur-MarneMarne-la-ValléeCedex277455France INRAE Aix Marseille UniversityUnitéde Recherche RECOVER3275 Route CézanneAix-en-Provence13182France UniversitéGustave Eiffel IFSTTAR/GERS/SRO14-20 Boulevard NewtonChamps-sur-MarneMarne-la-Vallée77447France

Determining osmotic suction from the electrical conductivity(EC)of soil pore water was widely reported in the ***,while dealing with unsaturated soils,they do not have enough soil pore water to be extracted for a reliable measurement of *** this paper,the chilled-mirror dew-point hygrometer and contact filter paper method were used to determine the total and matric suctions for low-plasticity soils with different salinities(0.05‰,2.1‰,and 6.76‰).A new piecewise function was proposed to calculate the osmotic suction,with the piecewise point corresponding to the first occurrence of precipitated salt in mixed salt solutions(synthetic seawater).EC,ion and salt concentrations used for osmotic suction calculation were transformed from the established relationships of mixed salt solution instead of experimental *** calculated osmotic suction by the proposed equation and the equations in the literature was compared with the indirectly measured one(the difference between the measured total and matric suctions).Results showed that the calculated osmotic suction,especially the one calculated using the proposed function,was in fair agreement with the indirectly measured data(especially for specimens with higher salinity of 6.76‰),suggesting that the transformation of EC and concentrations from the established relationship is a good alternative to direct measurement for lowplasticity *** particular,the proposed method could be applied to unsaturated low-plasticity soils which do not have enough soil pore water for a proper EC measurement.

关键词： Unsaturated soils Mixed salt solutions Osmotic suction Electrical conductivity(EC)

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Salinity effect on the compaction behaviour,matric suction,stiffness and microstructure of a silty soil

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第4期13卷 855-863页

作者： Zi Ying Yu-Jun Cui nadia benahmed Myriam Duc Ecole des Ponts ParisTech Laboratoire Navier/CERMES6-8 av.Blaise PascalCite DescartesChamps-sur-MarneMarne-la-Vallee cedex 277455France INRAE Aix Marseille UnivRECOVEREquipe G2DR3275 route CezanneCS 40061Aix-en-Provence13182France Universite Gustave Eiffel IFSTTAR/GERS/SRO14-20 boulevard NewtonChamps-sur-MarneMarne-la-Vallee77447France

To better understand the salinity effect on the compaction behaviour of soil,standard Proctor compaction test was conducted on soil samples with different *** suction and small-strain shear modulus,G_(max),were determined and pore size distribution was also investigated on samples statically compacted at different water *** showed that with the decrease of soil salinity from initial value of 2.1‰(g of salt/kg of dry soil)to zero,the maximum dry density increased and the optimum water content decreased,whereas there was no significant change with the increase of soil salinity from 2.1‰ to 6.76‰.Interestingly,it was observed that G_(max) also decreased when the soil salinity decreased from initial value of 2.1‰ to zero and kept almost constant when the soil salinity increased from 2.1‰ to 6.76‰,for dry samples with similar matric suction and also for samples compacted at optimum state and on wet side whose matric suctions were slightly different due to the difference in remoulded water ***,the effect of salinity on compaction behaviour and G_(max) decreased for samples compacted from dry side to wet *** pore size distribution exhibited bi-modal characteristics with two populations of micro-and macro-pores not only for samples compacted on dry side and at optimum state,but also for those compacted on wet *** examination showed that the modal size of micro-pores shifted to lower values and that of macro-pores shifted to higher values for saline soil compared to the soil without salt.

关键词： Silts Compaction Suction Stiffness Microstructure

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MoM Analysis and Design of a Compact Coaxial-to-Microstrip Directional Coupler

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Wireless Engineering and Technology 2011年第2期2卷 45-52页

作者： nadia Benabdallah Nasreddine benahmed Fethi Tarik Bendimerad Boumedienne Benyoucef 不详

In order to overcome the main drawbacks of coaxial, waveguide, and stripline couplers, the analysis and the design of a compact coaxial-to-microstrip directional coupler convenient for power and antenna control application, are presented using the method of moments (MoM) in two dimensions. This technique is adapted to study the complex configuration of the line’s system, which does not have a simple analytical solution. The modeling of this structure consists in analyzing the primary inductive and capacitive matrices ([L] and [C]). When these matrices are determined, it is possible to calculate the inductive and capacitive coupling coefficients (kL and kC) and estimate the resulting scattering parameters of the coupler using an adapted numerical model. The coupler can be integrated into a printed circuit board (PCB) and operates over 17 to 35 dB coupling coefficients and is always compensated. The compensation is achieved by the proper displacement of a tuning ground plane with respect to the edge of the PCB from 0.1 to 3.3 mm. As an application, we present the design of a compact coupler with 7.5 × 4.8 × 25.8 mm of size and having approximately 20 dB of coupling coefficient at 2 GHz and a minimum directivity of 23.3 dB in the frequency range [0.1 - 4] GHz. In order to check our numerical calculations by the MoM we made simulations in 3D by using CST MICROWAVE STUDIO software for the same geometrical and physical parameters of our designed coupler. The results obtained by the two numerical models (MoM and CST) show a good agreement of the frequency responses of the coaxial-to-microstrip directional coupler. The studied structure represents a great improvement for high power measurement systems, since it has broad-band, good directivity, and can be easily designed and fabricated.

关键词： Coaxial-to-Microstrip Coupler Inhomogeneous Asymmetrical Coupler A 20 dB Compact Directional Coupler Analysis and Design MoM Method CST MICROWAVE STUDIO Software

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Analyzing an UWB Bandpass Filter for High Power Applications Using Rectangular Coaxial Cables with Square Inner Conductors

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Circuits and Systems 2011年第3期2卷 121-126页

作者： Nasreddine benahmed nadia Benabdallah Salima Seghier Fethi Tarik Bendimerad Boumedienne Benyoucef 不详

Using the finite element method (FEM) in two dimensions and the CST MICROWAVE STUDIO? (CST MWS) Transient Solver, the electromagnetic (EM) analysis and the design of a novel compact ultra wideband (UWB) bandpass filter using rectangular coaxial cables with square inner conductors, convenient for high power applications, are presented. The design of the UWB BP filter is based on the use of impedance steps and coupled-line sections. The center frequency around 6.85 GHz was selected, the bandwidth is between 3-10 GHz, the insertion-loss amounts to around 0.35 dB and the return loss is found higher than 10 dB in a large frequency range (4-9.5) GHz. The simulated results of stopband performances are better than 15 dB for a frequency range up to 11 GHz. For the selected center frequency and on a substrate with a dielectric constant of 2.03, the rectangular coaxial cables BPF with square inner conductors is only 6.7 × 8.9 × 33.4 mm in size.

关键词： Rectangular Coaxial Cables Square Inner Conductors Ultra Wideband Bandpass Filter Compact Filter Electromagnetic Parameters Analysis and Design FEM Method CST MWS Transient Solver

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