Simplified transverse seismic analysis of buried structures

This paper presents a simplified method for the analysis of square cross-section buried structures (tunnel) subjected to seismic motion. Finite element analyses are performed to assess the fundamental modes of vibration of the soil layer with and without the tunnel. The influence of the tunnel on the modes of vibrations is taken into account by comparing the modal deformations in the free-field to those in the presence of the tunnel. From this comparison the zone of influence of the modal displacements due to the presence of the structure is determined. The resulting model is subjected to horizontal and vertical excitation of statistically independent accelerograms compatible with the response spectra of the Regulatory Guide 1.6 of the Nuclear Energy Commission. The free-field displacement is introduced at the boundaries of the zone of influence. The proposed simplified static analysis yields a state of stresses similar to that obtained from a full dynamic analysis of the complete soil–tunnel system. Several examples are solved to corroborate the validity of the method.     

Une méthode de simulation de l'évolution des profils d'altération

Calculations of transfer of elements between minerals and aqueous solutions can be extended to water open systems. With this method, we can obtain steady state for water composition. Furthermore, evolution in space and time of a weathering profile can be computed.     

The metamorphic evolution of the Muxia-Finisterre region (Galice,NW Spain) during the Hercynian Orogenesis

Mineral chemistry and crystal growth-deformation relationships in metapelites, orthogneises and metabasic rocks from the Muxia-Finisterre region show that this area has been affected by plurifacial regional metamorphism during the Hercynian Orogenesis. Paragenetic evolution seems to be related to a change of the metamorphic gradient towards relatively lower P_s conditions in the mesozone, while this character is less evident in catazonal rocks. In both cases there was a continuous increase in T and decrease in {ie657-02}.The metamorphic climax was reached during the second metamorphic episode (M₂). This event took place during and even after the second deformation phase (P₂). The latter gave rise to the main foliation observed in studied rocks (S₂) which almost practically erased signs of previous schistosity. Relationships between metamorphic evolution and different geotectonic models are discussed.

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Zusammenfassung Mineralchemismus und die Beziehungen Kristallwachstum-Deformation in Metapeliten, Orthogneisen und metabasischen Gesteinen aus der Muxia-Finisterra-Region, zeigen eine Beeinflussung dieses Gebietes durch eine plurifazielle Regionalmetamorphose während der herzynischen Orogenese.Die paragenetische Entwicklung scheint mit einer Veränderung des metamorphen Gradienten in Richtung niedrigerer P_s-Bedingungen in der Mesozone einherzugehen, während dies in katazonalen Gesteinen weniger deutlich ist.In beiden Fällen gab es eine kontinuierliche Zunahme der Temperatur (T) bzw. Abnahme des {ie657-01}.Der Höhepunkt der Metamorphose wurde während der zweiten metamorphen Episode (M₂) erreicht. Dieses Ereignis fand statt während und sogar nach der zweiten Deformationsphase (P₂). Letzteres verursachte die Hauptschieferung (S₂) in den untersuchten Gesteinen, die die Merkmale einer älteren Schieferung nahezu ausgelöscht hat.Beziehungen zwischen metamorpher Entwicklung und verschiedener geotektonischer Modelle werden diskutiert.

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Résumé Les compositions chimiques des minéraux ainsi que leur relation croissance-déformation dans les métapélites, ortho-gneiss et métabasites de la région Muxia-Finisterre, suggèrent que cette secteur a subi un métamorphisme régional plurifacial lors de l'Orogenèse Hercynienne. L'évolution des paragenèses semble être liée à un changement du gradient métamorphique vers des conditions de P_s relativement plus basses dans la mésozone, ceci étant moins évident dans les roches catazonales. Dans les deux cas il y a eu une augmentation continue de la T et une diminution de la {ie657-03}. Le paroxisme du métamorphisme a été atteint lors du deuxième épisode métamorphique (M₂). Cet événement a lieu généralement pendant ou légèrement après la deuxième phase de déformation (P₂). Celle-ci donne la foliation principale de la roche (S₂), laquelle a presque entièrement effacé les marques d'une schistosité pré-existante. Des relations entre l'évolution métamorphique et différents modèles géotectoniques sont discutées.

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, Muxia-Finisterre , . , , , P , , . (), {ie658-01}. (₂) . (₂). (S₂) , . .

     

Etude de l'uranium,du thorium et de leurs isotopes dans quelques carottes du Bassin angolais (Atlantique Sud-Est)

Uranium and thorium distributions are studied in top-oxidized, bottom-reduced cores. In sediments uranium is more abundant in the reducing zones than in the oxidized ones. In pore water also, uranium is more abundant in the reducing zones. In the cores studied, the Io/U chronology is completely disturbed.The general model of steady-state diagenesis cannot be applied to the uranium pattern.     

Etude de la repartition du manganese dans le Devonien Superieur de las Cabesses (Ariège)

The authors have studied the distribution of Si, Al, Ca, Mg, Fe, Mn, Ti, Ba, Cu, Ni éléments in Griotte upper devonian limestone by spectrography and polarography and have revealed a double correlation:

1. 1.
   Mn⁴⁺ - Ba confirmed as a result of the examination by Castaing microprobe micro fissures in which manganese has collected.     

Using the Relative Operating Characteristic to Quantify Certainty in Prediction of Location of Land Cover Change in India

This paper describes a methodology by which modelers, ecologists and planners can quantify the certainty in predicting the location of change for a given quantity of change. The specification of the quantity of a land cover category and the specification of the location of a land cover category are two distinct fundamental concepts in geographical analysis. It is crucial that scientists have appropriate quantitative tools to analyze each of these two concepts independently of one another. This paper gives methods whereby a scientist can convert a map of relative propensity for disturbance to a map of probability of future disturbance, based on a quantifiable validation of a map's predictive ability. The required inputs are: (1) maps that show a Boolean categorical variable at times 0, 1 and 2, (2) a technique to create a map that shows the relative propensity for membership in the Boolean category, and (3) a predicted proportion of the category at time 3.     

ANDALUSGeoid2002: The New Gravimetric Geoid Model of Andalusia (Southern Spain)

In 1991 the first determination of a gravimetric geoid in a test area in central Spain was computed by using least square collocation. In 1995 a gravimetric geoid in the Iberian Peninsula, Ibergeo95, was calculated by FFT. Nowadays an improved geoid of Andalusia, ANDALUSGeoid2002, has been computed by fast collocation procedure and remove-restore technique in the GRS80 Reference System. The computations have been done from 16562 free-air gravity anomaly data set, obtained from IGN (Instituto Geográfico Nacional) and BGI (International Gravity Bureau), the Earth Gravity Model EGM96 and detailed (100 m × 100 m), coarse (5 km × 5 km) and reference (20 km × 20 km) digital terrain models. Relative carrier-phase GPS measurements at 69 benchmarks of the Spanish Levelling Network in Andalusia have been done. The standard deviations of differences between ANDALUSGeoid2002 and GPS/levelling undulations after fitting the tilt have been ± 11 cm, ± 39 cm and ± 38 cm in western, eastern and whole Andalusia, respectively. The ANDALUSGeoid2002 shows an improvement of Ibergeo95 in this territory.     

The discovery of the Borobia world-class stratiform magnesite deposit (Soria,Spain): a preliminary report

A new world-class stratiform magnesite deposit has been recently discovered near the village of Borobia in Soria, Spain. The mineralization consists of a 25-45 m massive to banded magnesite layer sandwiched in between a Lower Cambrian carbonate formation and an upper shale horizon. It forms an arcuate belt striking NW-SE to W-E, which outcrops for 7.3 km in two elevations separated by a central valley that is covered by a thin layer of Pleistocene sediments. The orebody is confined by two regionally important faults and is probably associated with the dolomitization and silicification of the Cambrian limestones. Geological ore resources are estimated to exceed 175 Mt with MgO contents varying from 36 to 47% by weight. At present, the owners, Magnesitas y Dolomías de Borobia, S.L., are at an advanced stage of planning for extraction. This report presents some results of an ongoing geological exploration programme and shows the general features of the geology and mineralogy of the Borobia deposit.     

Investigation and Remediation of Petroleum Product Releases from Residential Storage Tanks

Releases of petroleum products from leaking residential storage tanks are a growing problem in the stale of New Jersey. Approximately two releases per day have been reported to the New Jersey Department of Environmental Protection. Product releases may cause aquifers to become contaminated, may affect surface water, or cause vapor problems inside households. As of 1992, there arc no federal or state regulations pertaining to the maintenance and monitoring of residential petroleum storage tanks. Regulations are essential for protecting drinking water supplies. The regulations must address installation procedures, lank materials, monitoring, and tank location.