Ingenieurtechnische,geologische und mineralogische Probleme beim Bau einiger Tunnel der Tauernautobahn im Bereich von Werfen (Salzburg, Österreich)

Zusammenfassung Ingenieurtechnische, geologische und mineralogische Probleme beim Bau einiger Tunnel der Tauernautobahn im Bereich von Werfen (Salzburg, Österreich). In den Jahren 1974 bis 1976 wurden im Baulos 6 Werfen der Tauernautobahn (südlich von Salzburg) zwischen den Bau-Kilometern 34,2 und 42,3 insgesamt 3460 lfm Tunnel (Doppelröhren) ausgebrochen. Es sind dies, von N nach S gezählt, der Brentenbergtunnel, der Zetzenbergtunnel und der Helbersbergtunnel. Die Tunnelarbeiten wurden nach der Neuen Österreichischen Tunnelbauweise, überwiegend in konventionellem Sprengbetrieb (streckenweise auch mit Teilschnittfräse) durchgeführt.Im Brentenbergtunnel wurde nach Durchörterung einer im Norden vorgelagerten 60 m langen Hangschuttstrecke Ramsaudolomit durchfahren. Der Zetzenbergtunnel liegt in gut geschichteten Kalken und Dolomiten des Gutensteiner Niveaus. Im Helbersbergtunnel schließlich wurden beim Vortrieb von N nach den ersten 80 m, in denen noch Gutensteiner Kalke und Dolomite anstanden, Gips führende Quarzite, Quarzitschiefer und Sandsteine der Werfener Schichten durchörtert. Die Baugrubensicherung des Voreinschnittes am Nordportal des Brentenbergtunnels sowie Details zur bergmännischen Durchörterung der Hangschuttstrecke im Schutze eines Injektionsschirmes werden ausführlich beschrieben und weiters Sondermaßnahmen in den Gips führenden Strecken des Helbersbergtunnels sowie einige spezielle Beobachtungen zur Nachbrüchigkeit in diesem schwierigen Tunnelabschnitt behandelt.

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Summary Engineering, Geological and Mineralogical Problems With the Construction of Several Tunnels in the Course of the Tauern Highway (Salzburg, Austria). From 1974 to 1976 the Tauern Highway was further extended near Werfen in the federal state of Salzburg (Austria). Therefore a total tunnel length (twin tube tunnels) of 3460 meters was performed in the section from km 34,2 to 42,3. The three twin tube tunnels have been cut mainly through Lower and Middle Triassic members of the Northern Limestone Alps.Thus, the Brentenberg tunnel, 600 meters (eastern tube) and 540 meters (western tube) respectively, is situated in the so called Ramsau dolomite. The Zetzenberg tunnel, 503 m (eastern tube) and 500 m (western tube) respectively long, penetrates Gutenstein limestone and dolomite, whereas the main part of the longest tunnel, the Helbersberg tunnel, 750 m and 740 m respectively, traverses Werfen beds except its northernmost ninety meters in Gutenstein limestones and limey shales.Furthermore, tunneling through sixty meters of loose rock debris in the northern part of Brentenberg caused a lot of trouble. The holing of non-cohesive rock debris by means of the New Austrian Tunneling Method will be dealt with in detail as well as the supporting works for the surface entrances. Excavation site for Brentenberg tunnel portals was supported by a retaining wall of bored piles sunk at 30 to 90 centimeters centre. The bored piles were stabilized by means of anchors of up to 38 meters length. Tunneling through the section of loose rock debris was performed with the aid of injections of cement and bentonite grout at the crown and the side walls. By that means, the over-all property of the initially freely running loose debris could be improved up to rock quality class IV (classification according to Pacher and Rabcewicz).In the Helbersberg tunnel at least, as prognosticated by preliminary geological studies, two sections of gypsiferous rock, about 150 and 200 m respectively long, were encountered. Before taking precautionary measures, rock samples were collected at intervalls of several meters and investigated mainly by X-ray diffractometer therefore. The results showed, that gypsification of most of anhydrite has taken place in the rocks of Helbersberg already. Due to that fact, Thiodur — a sulphate-proof special cement — was used to construct the external supporting elements. Then, the supporting elements of the reinforced inner ring were performed in concrete quality B 400. Moreover, the inner ring had to be isolated completely by means of soft PVC-framework.Owing to a smoothly running teamwork of civil engineers and geologists optimal solution could be achieved for every problem on site.

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Résumé Problèmes techniques, géologiques et minéralogiques résultant de la construction de l'autoroute du Tauern dans la région de Werfen (Salzbourg, Autriche). Dans la section 6 Werfen de l'autoroute du Tauern, au sud de Salzbourg, on a construit pendant les années 1974–1976, entre les kms 34,2 et 42,3, des tunnels à deux tubes dont la longueur s'élève à 3460 mètres en total. Ce sont, énumérés selon la direction nord-sud: le tunnel Brentenberg, le tunnel Zetzenberg et le tunnel Helbersberg. Les travaux ont été effectués selon la Nouvelle Méthode Autrichienne de Construction de Tunnels, en grande partie par attaque conventionnelle à l'explosif, partiellement à l'aide de fraiseuse.Après le percement d'une section à éboulis instable d'une longueur de 60 mètres, on a traversé dans le tunnel Brentenberg de la dolomie Ramsau. Le tunnel Zetzenberg est situé dans des strates stables de calcaire et de dolomie du niveau de Gutenstein. Dans le tunnel Helbersberg, il a fallu percer d'abord, sur une distance de 80 mètres, du calcaire de Gutenstein et des dolomies, ensuite du quartzite gypseux ou schisteux et du grès des couches de Werfen.Le travail présenté décrit les consolidations de la fouille pour l'excavation à ciel ouvert débouché nord du tunnel Brentenberg et des détails concernant le percement minier de l'éboulis après installation, en tant que dispositif de sécurité, d'un écran d'injection. Il y est question aussi de mesures additionnelles prises le long des sections gypsifères du tunnel Helbersberg ainsi que d'observations particulières concernant l'écroulement dans ce passage difficile.

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Radiant flux as a guide to relative seismic efficiency

The parameters “radiant flux” (energy radiated per unit area of an earthquake fault in unit time) and “radiant flux per unit displacement” reflect the power dissipated on a fault during slip. Values for moderate-to-large earthquakes range over two orders of magnitude, implying considerable variations in seismic efficiency, even for events of similar magnitude occurring on faults of the same type.     

Distinct brief major events in the Karoo large igneous province clarified by new Ar/Ar ages on the Lesotho basalts

Recent mineral separate ages obtained on the Karoo large igneous province (southern Africa) suggest that the province was built by several distinct magmatic pulses over a rather long period on the order of 5–6 Ma concerning the main erupted volume [Jourdan, F., Féraud, G., Bertrand, H., Kampunzu, A.B., Tshoso, G., Watkeys, M.K., Le Gall., B., 2005. The Karoo large igneous province: Brevity, origin, and relation with mass extinction questioned by new ⁴⁰Ar/³⁹Ar age data, Geology 33, 745–748]. Although this apparently atypical province is dated in more detail compared to many other large igneous provinces, volumetrically important areas still lack sufficient high-quality data. The timing of the Karoo province is crucial as this event is correlated with the breakup activity of the Gondwana supercontinent. The Lesotho basalts represent a major lava sequence of the province, but have not yet been precisely dated by systematic analysis of mineral separates. We analyzed plagioclase separates from five lava flows encompassing the complete 1.4-km-thick Lesotho sequence from top to bottom using the ⁴⁰Ar/³⁹Ar method. We obtained five plateau and mini-plateau ages statistically indistinguishable and ranging from 182.3 ± 1.6 to 181.0 ± 2.0 Ma (2σ). We derived an apparent maximum duration for this event of  0.8 Ma by neglecting correlated errors embedded in the age uncertainties.

A critical review of previous ages obtained on the Lesotho sequence [Duncan R.A., Hooper, P.R., Rehacek, J., Marsh, J.S., Duncan, A.R., 1997. The timing and duration of the Karoo igneous event, southern Gondwana. Journal of Geophysical Research 102, 18127–18138] shows that groundmass analyses are unreliable for high-resolution geochronology, due to alteration and ³⁹Ar recoil effects. Discrepancy between our ages and a previous plagioclase age at  184 Ma obtained by the later workers is tentatively attributed to the heterogeneity of the monitor used and/or cryptic excess ⁴⁰Ar. The current age database suggests that at least three temporally and spatially distinct brief major events (the Lesotho and southern Botswana lava piles and the Okavango dyke swarm) are so far recognized in the Karoo province. Identification of brief and volumetrically important Karoo magmatic events allows detecting the migration of the Karoo magmatism and potentially the stress regime that affected the southern African lithosphere at this time. A filtered compilation of 60 ages obtained with homogeneous intercalibrated standards suggests a shorter duration for the main pulses of the magmatism between 3 and 4.5 Ma, compared to a whole province duration of  10 Ma, between  182 and  172 Ma.     

Robustness of the holistic seismic risk evaluation in urban centers using the USRi

The Urban Seismic Risk index (USRi) published in a previous article (Carreño et al., Nat Hazards 40:137–172, 2007) is a composite indicator that measures risk from an integrated perspective and guides decision-making for identifying the main interdisciplinary factors of vulnerability to be reduced or intervened. The first step of the method is the evaluation of the potential physical damage (hard approach) as a result of the convolution of the seismic hazard with the physical vulnerability of buildings and infrastructure. Subsequently, a set of social context conditions that aggravate the physical effects is also considered (soft approach). According to this procedure, the physical risk index is evaluated for each unit of analysis from existing loss scenarios, whereas the total risk index is obtained by multiplying the former index by an impact factor using an aggravating coefficient, based on variables associated with the socio-economic conditions of each unit of analysis. The USRi has been developed using the underlying holistic and multi-hazard approach of the Urban Risk Index framework proposed for the evaluation of disaster risk in different megacities worldwide. This article presents the sensitivity analysis of the index to different parameters such as input data, weights and transformation functions used for the scaling or normalization of variables. This analysis has been performed using the Monte Carlo simulation to validate the robustness of this composite indicator, understanding as robustness how the cities maintain the ranking as well as predefined risk level ranges, when compared with the deterministic results of risk. Results are shown for different cities of the world.     

U-Pb SHRIMP and Nd isotopic data from the western Bohemian Massif (Bayerischer Wald,Germany): Implications for Upper Vendian and Lower Ordovician magmatism

U-Pb SHRIMP dating of zircons of metamagmatites from the Bayerischer Wald (Germany) reveals a complex evolution of this section of the Moldanubian Zone exposed in the western Bohemian Massif of the central European Variscan belt. In the south-western part of the Bayerischer Wald Upper Vendian magmatism is constrained by pooled ²⁰⁶Pb/²³⁸U mean ages of 555±12, 549±7 and 549±6 Ma from metarhyolites and a metabasite. Inherited zircon cores were not observed. Zircon overgrowths, yielding pooled ²⁰⁶Pb/²³⁸U ages of 316±10 and 319±5 Ma, provide evidence for Variscan metamorphic zircon growth; cathodoluminescence imaging reveals a two-stage metamorphic overprint.In contrast, Lower Ordovician magmatism and anatexis are documented in the north-eastern parts of the Bayerischer Wald by metagranitoids (480±6, 486±7 Ma), an eclogitic metabasite (481±8 Ma) and a leucosome (491 to 457 Ma). Inherited zircon cores are found in Lower Ordovician metagranitoids and the leucosome, indicating a Palaeoproterozoic-Archaean (ca. 2.7, 2.0 Ga) source region, presumably of Gondwana affinity (West African craton), and documenting Cadomian magmatism (ca. 640 Ma). Post-Cadomian metamorphism is inferred from concordant ages of 433±4 and 431±7 Ma.Upper Vendian magmatism is assumed at an active continental margin with ensialic back-arc development (ε_Nd(t) –3.01 to +1.22); the lack of inherited zircon is due to either derivation from juvenile (?volcanic arc) material or complete isotopic resetting of pre-existing zircon. An active continental margin setting, possibly with some lateral variation (accretion/collision) is envisaged for the Lower Ordovician, producing granitoids, rhyolites and leucosomes (ε_Nd(t) -0.5 to -6.27); MORB-type metabasites may be related to ZEV or Mariánské Lázně Complex metabasites. A tentative palaeogeographic reconstruction puts the “Bayerischer Wald” in close relationship with the Habach terrane (proto-Alps), as the “eastern” extension of terranes of the northern Gondwana margin.     

Magma mixing: the Marsco suite,Isle of Skye,Scotland

Magma mixing has been proposed as a major mechanism for the origin of a wide variety of rock suites. In mid-ocean basalts there are few obstacles to mixing because of the similarities in chemical and physical properties of the proposed end-members. However, in calc-alkaline rocks the proposed end-members have disparate properties and these present obstacles to mixing.The Marsco suite is ideal to evaluate the process of magma mixing because it is considered to be a classic example of magma mixing of diverse magma types and because compositionally diverse, coexisting liquids were present throughout the area.The results of this study are that the chemical data for the Marsco suite fit a mixing model remarkably well and that the mixing did not take place at the present level of exposure. The Marsco mixed suite is similar to the experiments of Kouchi and Sunagawa (1982, 1983) in which mixing was produced by forced convection. Based on the Marsco suite, a similar occurrence in Ardnamurchan, and the experimental data, we conclude that mixing was dominated by mechanical mixing and this mechanical mixing was efficient enough to allow diffusional processes to homogenize the liquids.It is postulated that injection of mafic magma into the base of a silicic magma system leads to mixing and mobilization of the system. The mechanical interaction that produces the mixing also leads to disruption of the system. Liquids involved with the mixing process at depth are mobilized and coexist at shallower levels.     

Controlling factors of groundwater hydrochemistry in a small island’s aquifer

Factor analysis was applied to the hydrochemical data set of Manukan Island in order to extract the principal factors corresponding to the different sources of variation in the hydrochemistry. The application of varimax rotation was to ensure the clear definition of the main sources of variation in the hydrochemistry. The geochemical data of dissolved major, minor and trace constituents in the groundwater samples indicates the main processes responsible for the geochemistry evolution. By using Kaiser normalization, principal factors were extracted from the data for each location. The analysis reveals that there are four sources of solutes: (1) seawater intrusion; (2) leaching process of underlying rock mediated by pH; (3) minerals weathering process and (4) dissolution of carbonate minerals characterized by high loadings of Ca, Zn and Mg. Such processes are dominated by the significant role of anthropogenic impact from the over abstraction of fresh water from the aquifer. Those factors contributed to the changes of the groundwater geochemistry behavior explain the effect of rising extraction of freshwater from the aquifer.     

Formulation of the Caspian Sea’s legal regime using a joint zone approach

The legal regime of the Caspian Sea has been determined under Treaties 1921 and 1940 by and between Iran and former Soviet Union. In fact, we are neither to explain it nor to determine. As understood from the provisions therein, the exploitation and use of the Caspian Sea by both countries are based on the Condominium. However, there is a 10-nautical mile strip as exclusive fishing areas which have been allocated to the states under the 1940 treaty. It means that Soviet Union and Iran may benefit the marine livings resources out of that strip on an equal manner. This right also includes the seabed and underlying bed. So, the legal regime of this sea may be based on a 10-nautical mile exclusive region for all five states and the remaining part as common and joint area under an agreement until an explaining and supervising organization is established to exploit and supervise over living and non-livings resources.     

The Mars oxidant experiment (MOx) for Mars '96

The MOx instrument was developed to characterize the reactive nature of the martian soil. The objectives of MOx were: (1) to measure the rate of degradation of organics in the martian environment; (2) to determine if the reactions seen by the Viking biology experiments were caused by a soil oxidant and measure the reactivity of the soil and atmosphere: (3) to monitor the degradation, when exposed to the martian environment, of materials of potential use in future missions; and, finally, (4) to develop technologies and approaches that can be part of future soil analysis instrumentation. The basic approach taken in the MOx instrument was to place a variety of materials composed as thin films in contact with the soil and monitor the physical and chemical changes that result. The optical reflectance of the thin films was the primary sensing-mode. Thin films of organic materials, metals, and semiconductors were prepared. Laboratory simulations demonstrated the response of thin films to active oxidants.