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Modelling of hydraulic structures
Published in P. Novak, V. Guinot, A. Jeffrey, D.E. Reeve, Hydraulic Modelling – an Introduction, 2010
P. Novak, V. Guinot, A. Jeffrey, D.E. Reeve
Stepped spillways have recently received increased attention, mainly because of new material techniques (RCC dams and prefabricated blocks) and their enhanced energy dissipation, which contributes to the economy of overall design. The crucial problems encountered in their design are the flow regime (nappe flow or skimming flow, with a transitional zone between the two), air entrainment and energy dissipation. All investigations of cascade spillways (see e.g. Novak et al. (2007)) indicate that the flow regime is a function of the critical depth, yc (=(q2/g)1/3, which, of course, denotes a Froude number = 1). For a more detailed discussion of cascade (stepped) spillways, see, for example, Boes and Hager (2003a) and Chanson (2001).
Flow through hydraulic structures
Published in Maurice Bouvard, Mobile barrages and intakes on sediment transporting rivers, 2017
This method, applicable in particular to weirs, was once widely used. It is based on the principle that the flow velocity is known at every point on the free surface of a nappe. Since the pressure is constant, we obtain the following expression: z+V22g=Cte=H0
Anatomy of an obducted ultramafic unit (Tiébaghi Massif – Peridotite Nappe – New Caledonia): Polyphase brittle tectonics constrained by fault-slip data and crack seal mineralogy
Published in New Zealand Journal of Geology and Geophysics, 2023
Pierre Maurizot, Bernard Robineau, Julie Jeanpert, Marion Iseppi, Stéphane Lesimple, Farid Juillot, Michael Meyer, Patrick Fullenwarth, Vincent Mardhel
In this paper, we present several new sets data collected in the Tiébaghi Massif, a klippe of the Peridotite Nappe located in the north of New Caledonia. These data were collected by investigating two different types of mining works: the underground works of the Chromical hypogene chromite deposit and the open-cast works of the Société Le Nickel (SLN) supergene nickel deposits. In nickel mine, ground electro-magnetic (EM) survey and drilling data have been used to constrain the geometry of the mineralisation. In both the hypogene chromite deposit and supergene nickel works, structural, micro-structural measurements and oriented samples have been systematically collected to determine the chronology and kinematic parameters of the structural evolution of the ultrabasic unit. Raman spectrometry and TEM microscopy provided additional information on the composition of the minerals associated with the different kinematic indicators.
The Broken Hill Block, a new structure and mineral exploration target areas
Published in Australian Journal of Earth Sciences, 2022
The theory that the entire stratigraphic sequence is inverted has been widely accepted since the 1970s based on three lines of evidence: At the time, it was considered likely that the lodes had an origin like modern-day volcanogenic sea-floor deposits with a distinctive vertical mineralogical and chemical zoning. The Line of Lode was found to be zoned but inverted by comparison with the zoning found in modern-day deposits.Some overturned bedding, determined from relict sedimentary structures, was found in local folds, and was incorrectly assumed to have regional significance.The nappe structures were invoked to reconcile the apparent disconnect between the Line of Lode and the geology to the west. This apparent disconnect is reconciled by the interpreted slump folds A and B. In the 1970s, the outgoing western limb of the then Hanging Wall Syncline was extended to the west, whereas we have extended it to the east, culminating in fold structures outside the Line of Lode with no inversion.
The interplay of structure and metamorphism at Broken Hill, NSW, Australia
Published in Australian Journal of Earth Sciences, 2022
The D1 nappe fold model was developed by Laing et al. (1978) and Marjoribanks et al. (1980) before the detailed lithological mapping by the GSNSW was completed. It was later modified and detailed by Laing (1996) (Figure 4) utilising the GSNSW mapping. Hobbs et al. (1984) presented a variant of the D1 nappe model, describing F1 folds as (p. 355): ‘F1…comprises large (tens of kilometre-scale) tight, inclined to recumbent folds with associated axial plane schistosity (S1) defined by high-grade metamorphic assemblages’. Unlike Marjoribanks et al. (1980), Hobbs et al. (1984) do not show F1 and F2 folds as coaxial. In their block diagram for the northern Broken Hill Block, Hobbs et al. (1984, figure 7) show most F1 folds with axial planes dipping at ∼50–60°SE, with intersecting south-plunging F2 folds creating interference patterns. The Mt Robe Block is shown with totally overturned stratigraphy; the Mt Robe Structure is shown as an F3/F4 dome containing Thackaringa Group above Broken Hill Group rocks and, by logical extension, surrounded by Thorndale Composite Gneiss, a completely erroneous scenario and presumably an unintended error (see below).