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21.
Faisal Rehman Helmy Salah Osman Abouelnaga Faisal Rehman 《Arabian Journal of Geosciences》2016,9(4):312
Ground penetrating radar is a noninvasive geophysical technique that can be used to infer subsurface geological, geotechnical, and petrophysical attributes. For water contamination studies, ultimate target, i.e., contaminant flow, is demarcated with the help of dielectric permittivity, water content, and porosity. The dielectric permittivity facilitates to evaluate water content; whereas the dielectric permittivity can be estimated by using the interval velocity, and porosity can be estimated by using the information of water content and dielectric permittivity. All these parameters are interlinked. This paper describes different empirical and mixing relationships to calculate approximately these parameters and their utilization in predicting the hydrogeological model of the area. 相似文献
22.
Salah Mahmoudi Ezzeddine Srasra Fouad Zargouni 《Geotechnical and Geological Engineering》2016,34(3):817-825
The relationship between composition and physical parameters such as specific surface area, cationic exchange capacity and plasticity is studied with the aim of developing regression models that would permit the prediction of clay properties. These models could be useful for mineralogists and industrial applications. Nineteen representative clay samples were collected from Jebel Ressas in north-eastern Tunisia. Mineralogical data show that clay samples cover a very large variety of minerals. The main clay mineral is illite (50–60 wt%), secondary minerals including quartz, calcite and minor amounts of Na-feldspar. This study reveals that the average amount of silica (SiO2) and alumina (Al2O3) are 51.9 and 19.6 wt%, respectively. The contents of lime (CaO) and iron (Fe2O3) vary between 4 and 8 wt% whereas the amount of alkalis (Na2O + K2O) is on average 4.1 wt%. The grain size data indicates a significant amount of silt fraction, and the fraction <2 µm varies between 23 and 35 wt%. Values for plasticity index range from 16 to 28 wt%. The cation exchange capacity and the specific surface values are 34.1–45.7 meq/100 g of air-dried clay and 302–374 m2/g, respectively. Lastly, regression models are used to correlate the properties with the mineralogical and chemical compositions. The significance and the validity of models were confirmed by statistical analysis and verification experiments. The regression models can be used to select the clay properties (plasticity index, cation exchange capacity and specific surface) in relation with clay minerals proportions and the finer fraction amounts. 相似文献
23.
Acta Geotechnica - The drained and undrained response of soft clays reinforced with granular columns has been the subject of numerous geotechnical research efforts to date. Although these studies... 相似文献
24.
Estimation of frequency dependent coda wave attenuation structure at the vicinity of Cairo Metropolitan Area 总被引:1,自引:0,他引:1
Salah El-Hadidy M. E. Mohamed Adel Ahmed Deif Ahmed Sayed Abu El-Ata S. R. Moustafa Sayed 《Acta Geophysica》2006,54(2):177-186
Estimation of seismic wave attenuation in the shallow crust in terms of coda wave Q structure previously investigated in the vicinity of Cairo Metropolitan Area was improved using seismograms of local earthquakes
recorded by the Egyptian National Seismic Network. The seismic wave attenuation was measured from the time decay of coda wave
amplitudes on narrow bandpass filtered seismograms based on the single scattering theory. The frequency bands of interest
are from 1.5 to 18 Hz. In general, the values obtained for various events recorded at El-Fayoum and Wadi Hagul stations are
very similar for all frequency bands. A regional attenuation law Q
c
= 85.66 f
0.79 was obtained. 相似文献
25.
Geology of the Early Devonian oolitic iron ore of the Gara Djebilet Field, Saharan Platform, Algeria
Salah Guerrak 《Ore Geology Reviews》1988,3(4)
The oolitic iron ore of the Gara Djebilet field occurs within the Early Devonian sediments of the Tindouf Basin (Algerian Sahara), particularly in the Upper Djebilet Formation of Pragian age. Three large lenses form three individual deposits, extending E-W for about 60 km, namely Gara West, Gara Center and Gara East.The mineralization is interbedded with argillaceous to sandy sediments and it can be related to a barrier island palaeoenvironment, bordered by an inner lagoon or shallow embayment and an epicontinental sea. Trapped by Palaeozoic shoals, the oolitic sediments show a mineralogy marked mainly by magnetite, hematite, goethite, maghemite, chamosite (bavalite), siderite, apatite and quartz. Three paragenetic associations present a vertical distribution with a Lower non-magnetitic ore, a magnetitic ore and an Upper non-magnetitic ore.Three petrographical facies types have been defined: a cemented facies (FOC); a detrital facies (FOD); and a non-detrital facies (FOND).Chemical data for the whole field show a difference between the Lower non-magnetitic ore (Fe=54.6%), the Magnetitic ore (Fe=57.8%) and the Upper non-magnetitic ore (Fe=53%). The Magnetitic ore, which corresponds mainly to the workable ore (cutoff grade at 57%), has the following composition: SiO2=4.9%, Al2O3=4.2%, Fe2O3=61.43%, FeO=19.2%, and P2O5=1.8%. The corresponding calculated economical ore reserves are 985×106t, with 57.8% Fe.Regarding the genesis of the oolitic iron ore, a southern source is suggested for the iron, with deposition taking place in a quiet environment. There, the ooids developed by an intrasedimentary accretion mechanism around detrital grain within an iron-rich mud.The Gara Djebilet field is an important occurrence of the “North African Palaeozoic Ironstone Belt” extending from the Zemmour to Libya which also includes ironstones of Ordovician, Silurian and Devonian age. 相似文献
26.
The potential damage to man-made structures associated with earthquake-induced liquefaction has been demonstrated in catastrophic
fashion over the past 40–50 years. The phenomenon of liquefaction of relatively clean, poorly graded, sands is well understood.
However, the same cannot be said for cases when fine-grained materials are present within the sand matrix. A resolution of
what appears in some reported studies as conflicting observations related to the effect of fines on cyclic resistance is of
concern, particularly for land reclamation projects and sea fills where the material source is variable and may contain significant
levels of fines. The nature of the fines themselves may have a measurable effect on the matrix behavior. The work presented
herein explores the effect of silt and clay-size carbonaceous fines on the liquefaction susceptibility of sand. The choice
of fines was guided by the conditions associated with the Lebanon coastal reclamation projects, where limestone/marlstone
quarry source materials are dominant. The results obtained confirm the significant effect of fines on the cyclic resistance.
They also confirm the existence of a limit fines content and a plasticity index threshold and establish their effect on observed
behavior. 相似文献
27.
Egypt and the Nile Basin 总被引:1,自引:0,他引:1
28.
29.
Merzouk Ouyed Mouloud Idres Amar Bourmatte Mohamed Salah Boughacha Sadek Samai Abdelkrim Yelles Abderrahmene Haned Chafik Aidi 《Journal of Seismology》2011,15(2):173-189
In order to try to identify the seismogenic sources in the epicentral area, we interpreted data collected from gravity and
aftershocks in the eastern part of the Mitidja basin after the occurrence of the 21 May 2003 Boumerdes earthquake (Mw = 6.8).
The residual gravity anomaly and the horizontal gradient maps revealed the basement shape and density discontinuities. A seismotectonic
model obtained from the aftershocks distribution and gravity data is proposed. This model highlights three active faults:
one offshore and two onshore. The offshore reverse fault striking NE-SW, parallel to the coast, is consistent with the USGS
focal mechanism of the main event, which is assumed to have the most moment release. The two onshore dipping blind active
faults are postulated at crossing angles near the SW tip of the main fault. The interpretation is based mainly on the re-location
and distribution of aftershocks, and their focal solutions. It is also supported by the basin structures obtained from the
inversion and interpretation of residual gravity anomalies, as well as by additional compiled information such as the pattern
of coastal co-seismic uplift. This configuration puts forward the failure mode complexity during the main shock. The topography
of the basement obtained from 3D gravity inversion shows that all the onshore located aftershocks occurred in the basement,
and the area between the two onshore faults rose as a consequence of their sliding. 相似文献
30.
The condition of hydrostatic equilibrium of relativistic stellar models is formulated as an optimal control problem. Application
of Pontryagin's maximum principle leads directly to the Tolman-Oppenheimer-Volkoff equation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献