Symposium über Fragen der Cyanophytentaxonomie im Seenforschungsinstitut der ETHZ/EAWAG in Kastanienbaum (Schweiz), 2.–15. August 1979 Verhandlungsbericht

The 8th Symposium of the International Association for Cyanophyte Research IAC was attended by 29 specialists from 11 countries. The 19 oral presentations and discussions centered on the following themes: The basic principles of cyanophyte taxonomy (3 lectures), systematic problems of certain taxonomic groups (5 lectures), morphology (6 lectures) and ecology (5 lectures). The intensive discussions between representatives of the classical (european) taxonomic treatment of cyanophytes (based on morphological and ecological characteristics) and those representing the bacteriological study of ‘cyanobacteria’ were especially valuable. The central theme of the meeting was, however, the mutual microscopic study and discussion of problematic blue-greens from natural habitats, that were mostly collected during the three field trips into different areas of central Switzerland (Grimsel-Gotthard-Nufenen. Klewenalp. Gerzensee).      

Basic considerations on tunnelling in squeezing ground

Summary Excessive rock pressure may cause the failure of the tunnel support resulting in large rock deformations. This phenomenon is referred to as squeezing rock behaviour. After discussion of the factors affecting squeezing the relation between rock deformation and rock pressure is described. The paper further deals with widely applied methods of excavation and support measures in squeezing rock.     

Stabilitätsberechnung ebener und räumlicher Felsböschungen

Zusammenfassung Stabilitätsberechnung ebener und räumlicher FelsböschungenFür die Bemessung der Ankerkräfte zur Sicherung einer gleitgefährdeten Felsmasse wird für das ebene Problem eine Grundformel hergeleitet. Der Einfluß der Kohäsion kommt dabei explizit zum Ausdruck, die Einflüsse der Geometrie, des Reibungswinkels und des Sicherheitsfaktors treten in zwei Faktoren zusammengefaßt in Erscheinung. Die Aufdeckung einer formalen Analogie zwischen dem Abgleiten auf einer Ebene und dem Abgleiten eines Felskeiles auf zwei Ebenen erlaubt es, die einfache Grundformel des ebenen Problems direkt für die Lösung des verwickelten räumlichen Problems anzuwenden. Die Bemessungsformel dient in beiden Fällen auch zur Durchführung einer umfangreichen Parameteranalyse um die Empfindlichkeit der Konstruktion auf die Variation der einzelnen Parameter zu ermitteln. Diese Untersuchungen können rasch und ohne langwierige Rechnungen selbst im Felde durchgeführt werden. Als Hilfsmittel hiezu dienen entweder die beiliegenden Diagramme oder das für den programmierbaren Taschenrechner Hewlett Packard HP-65 angegebene Programm. Anhand einiger Beispiele wird die Anwendung auf praktische Fälle des Felsbaues illustriert.

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Summary Stability Analysis of Rock Slopes for Plane and Wedge FailureA simple formula for plane slope failure is derived, which may be used for the design of anchors to ensure the safety of rock masses endangered by slides. The cohesional strength component appears explicitly in the formula, while the geometrical parameters, the friction angle and the safety factor are included in only two factors,k ₁ andk ₂. The discovery of a formal analogy between the plane failure problem and that of wedge failure on two intersecting plane surfaces makes it possible to use the basic formula also for the solution of the complicated three-dimensional wedge problem. The basic formula may in both cases also be used to make a detailed parametric study to investigate the sensitivity of the rock slope construction to variations in individual parameters. This investigation may be carried out quickly, without time consuming calculations, even at the site. As an aid for this either the accompanying charts or the given program for the Hewlett Packard HP-65 pocket calculator may be used. The application of the method is illustrated in several practical examples of the design of rock slopes.

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Résumé Calculs de stabilité de talus rocheux à deux et trois dimensionsDans le cas du problème plan, on a mis au point une formule fondamentale pour le dimensionnement des ancrages qui doivent retenir une masse rocheuse susceptible de glisser. L'influence de la cohésion y figure explicitement, celle de la géométrie, de l'angle de frottement et du coefficient de sécurité y apparaissent implicitement dans deux facteurs. On a découvert une analogie formelle entre le glissement sur un plan et le glissement d'un coin de roche le long de deux plans. Ceci permet d'appliquer directement la formule fondamentale, du problème plan, qui est simple, à la résolution du problème enchevêtré qui se présente dans l'espace. Dans les deux cas, la formule de dimensionnement permet aussi la réalisation d'une vaste analyse paramétrique pour déterminer la sensibilité de la construction à la variation des paramètres individuels. Ces investigations peuvent êtres faites à la fois rapidement et sans calculs fastidieux sur le terrain-même, si on se sert soit des diagrammes ci-joints, soit du programme indiqué pour la calculatrice de poche Hewlett Packard HP-65. Quelques exemples illustrent l'application à des cas concrets.

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Mit 10 Abbildungen     

A fourth-order solution of the ideal resonance problem

The second-order solution of the Ideal Resonance Problem, obtained by Henrard and Wauthier (1988), is developed further to fourth order applying the same method. The solutions for the critical argument and the momentum are expressed in terms of elementary functions depending on the time variable of the pendulum as independent variable. This variable is related to the original time variable through a Kepler-equation. An explicit solution is given for this equation in terms of elliptic integrals and functions. The fourth-order formal solution is compared with numerical solutions obtained from direct numerical integrations of the equations of motion for two specific Hamiltonians.     

Grain-size analysis of the Neogene red clay formation in the Pannonian Basin

The red clay is a significant deposit underlying the Pleistocene loess-paleosols sequence in the Pannonian Basin. The sedimentary processes involved and the origin of the materials remain controversial. In order to determine the depositional processes of the Pliocene red clay formation we studied many red clay sections in Hungary. Here, we present results of grain-size analyses of the red clay from representative sites. In particular their grain-size distribution is compared with that of typical Pleistocene eolian loess-paleosols, as well as lacustrine and fluvial sediments. It appears from the sedimentological data that the majority of the red clay is of a wind-blown origin. The red clay might be transported by weak westerly winds and has been modified by post-depositional alteration.     

Crustal Architecture of the Inverted Central Lapland Rift Along the HUKKA 2007 Profile

We have studied the lateral velocity variations along a partly buried inverted paleo–rift in Central Lapland, Northern Europe with a 2D wide-angle reflection and refraction experiment, HUKKA 2007. The experiment was designed to use seven chemical explosions from commercial and military sites as sources of seismic energy. The shots were recorded by 102 stations with an average spacing of 3.45 km. Two-dimensional crustal models of variations in P-wave velocity and Vp/Vs-ratio were calculated using the ray tracing forward modeling technique. The HUKKA 2007 experiment comprises a 455 km long profile that runs NNW–SSE parallel to the Kittilä Shear Zone, a major deformation zone hosting gold deposits in the area. The profile crosses Paleoproterozoic and reactivated Archean terranes of Central Lapland. The velocity model shows a significant difference in crustal velocity structure between the northern (distances 0–120 km) and southern parts of the profile. The difference in P-wave velocities and Vp/Vs ratio can be followed through the whole crust down to the Moho boundary indicating major tectonic boundaries. Upper crustal velocities seem to vary with the terranes/compositional differences mapped at the surface. The lower layer of the upper crust displays velocities of 6.0–6.1 km/s. Both Paleoproterozoic and Archean terranes are associated with high velocity bodies (6.30–6.35 km/s) at 100 and 200–350 km distances. The Central Lapland greenstone belt and Central Lapland Granitoid complex are associated with a 4 km-thick zone of unusually low velocities (<6.0 km/s) at distances between 120 and 220 km. We interpret the HUKKA 2007 profile to image an old, partly buried, inverted continental rift zone that has been closed and modified by younger tectonic events. It has structural features typical of rifts: inward dipping rift shoulders, undulating thickness of the middle crust, high velocity lower crust and a rather uniform crustal thickness of 48 km.