Hydraulique des turbines de forage, essais en laboratoire, performances d’exploitation

Hydraulic considerations on turbodrills, laboratory tests and industrial performances. I. — Hydraulic considerations on turbodrills. 1.1. — Jonval turbine — Introduction to turbodrills — Idea of multiple stages — Rotors and stators — The turbodrill described. 1.2. — Influence of fluid medium — Drilling muds — Wear problems affecting the hydraulic circuits. II. — Laboratory tests. II. 1. — Hydraulic tests. II. 2. — Wear tests. II. 3. — Test rig for complete turbodrills. III. — Industrial turbodrill management, performance and operating parameters.I. — Hydraulique des turbines de forage. I.1. — Turbine Jonval. — Introduction à la turbine de forage. — Notion d'étages multiples. — Roues et distributeurs. — Description de la turbine. I.2. — Influence de la nature du fluide utilisé. — Boues de forage. — Problèmes d'usure concernant les circuits hydrauliques. II. — Essais en laboratoire. II.1. — Essais hydrauliques. II.2. — Essais d'usure. II.3. — Banc d'essai pour turbines complètes. III. — Exploitation des turbines de forage : performances et paramètres d'utilisation.Dagallier B., Lagacherie G. Hydraulique des turbines de forage, essais en laboratoire, performances d’exploitation. In: Turbines et pompes hydrauliques. Compte rendu des cinquièmes journées de l'hydraulique, Aix-en-Provence, 26, 27 et 28 juin 1958. Tome 2, 1959

Altération du minerai de fer dans les mines abandonnées de Lorraine

Une étude de l’évolution minéralogique du minerai de fer de Lorraine formant les piliers abandonnés des anciens travaux a été réalisée pour mieux comprendre le mécanisme des effondrements miniers. Des échantillons ont été prélevés dans une zone sans travaux miniers, au cœur de certains piliers et au bord de piliers dont la date d’exposition à l’atmosphère minière est connue. Les échantillons ont été analysés au MEB, à la microsonde et au diffractomètre à rayons X. Il en résulte que la minéralogie et la microstructure du minerai de fer exploité évoluent avec le temps. Cette évolution, d’origine anthropique, diffère de l’évolution diagénétique. Elle correspond à une première phase d’altération du ciment inter-oolitique (carbonates de fer et phyllosilicates ferrifères) suivie par une seconde phase de néoformation de phyllosilicates ferrifères puis d’un dépôt d’oxydes de fer. Une étude de microbiologie a montré l’influence des bactéries sur ces phénomènes. L’influence des conditions physico-chimiques environnantes a également été discutée. Ces modifications microscopiques se traduisent à l’échelle macroscopique par une diminution de la cohésion et donc de la résistance de la roche, et influent donc sur la stabilité à long terme des piliers abandonnés

Delineating shallow Neogene deformation structures in northeastern Pará State using Ground Penetrating Radar

The geological characterization of shallow subsurface Neogene deposits in northeastern Pará State using Ground Penetrating Radar (GPR) revealed normal and reverse faults, as well as folds, not yet well documented by field studies. The faults are identified mostly by steeply-dipping reflections that sharply cut the nearby reflections causing bed offsets, drags and rollovers. The folds are recognized by reflections that are highly undulating, configuring broad concave and convex-up features that are up to 50 m wide and 80 to 90 ns deep. These deformation structures are mostly developed within deposits of Miocene age, though some of the faults might continue into younger deposits as well. Although the studied GPR sections show several diffractions caused by trees, differential degrees of moisture, and underground artifacts, the structures recorded here can not be explained by any of these ''noises''. The detailed analysis of the GPR sections reveals that they are attributed to bed distortion caused by brittle deformation and folding. The record of faults and folds are not widespread in the Neogene deposits of the Bragantina area. These GPR data are in agreement with structural models, which have proposed a complex evolution including strike-slip motion for this area from the Miocene to present.<br>A caracterização geológica de depósitos neógenos ocorrentes em sub-superfície rasa no nordeste do Estado do Pará, usando Radar de Penetração no Solo (GPR), revelou a presença de falhas normais e reversas, bem como dobras, ainda não documentadas em estudos de campo prévios. As falhas são identificadas por reflexões inclinadas que cortam bruscamente reflexões vizinhas, causando freqüentes deslocamentos de camadas. As dobras são reconhecidas por reflexões fortemente ondulantes, configurando feições côncavas e convexas que medem até 50 m de amplitude e 80 a 90 m de profundidade. Estas estruturas deformacionais desenvolvem-se, principalmente, em depósitos de idade miocênica, embora algumas falhas possam estender-se, também, a depósitos mais jovens. Embora as seções de GPR estudadas mostrem várias difrações causadas por árvores, umidade do solo, e objetos enterrados, as estruturas registradas aqui não podem ser explicadas por nenhum destes ''ruídos''. A análise detalhada das seções de GPR revelou que as feições deformacionais estudadas estão relacionadas com distorções de camadas causadas por deformações rúptil e dúctil. Embora falhas e dobras não sejam amplamente registradas em depósitos neógenos da Zona Bragantina, os dados aqui apresentados são consistentes com modelos estruturais, que propõem uma evolução complexa incluindo movimentações transcorrentes para esta área, do Mioceno até o presente