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ePaper created 2015-04-27, 13:22:39 | version 1.38.0
FORSCHUNG | RECHERCHE | 39 Anzeige Lesen Sie «Strasse und Verkehr» jetzt auch online oder auf Ihrem Tablet als e-paper! Lisez dès maintenant «route et trafic» également en ligne ou sous forme de e-paper sur votre tablette! X www.vss.ch STRASSE UND VERKEHR ROUTE ET TRAFIC 112014 ITS: Wie London und Lyon eine nachhaltige Verkehrsplanung gestalten VSS-Erfolgsstory: Aus- und Weiterbildungen sind konstant ausgebucht Einfluss des Siedlungswachstums auf die Leistungsreserven im Verkehrsnetz ITS: comment Londres et Lyon mettent en œuvre une planification durable du trafic Succès à la VSS: les formations et les formations continues sont constamment prises d’assaut Influence de la croissance urbaine sur les réserves de performances du réseau EN RESEARCH REPORT NO. 1503 Research Package on Bridge-deck Waterproofing Systems: EP5-Mechanisms of Blister Formation KTH, DIVISION OF HIGHWAY ENGINEERING MANFRED N. PARTL, Prof. Dr. BIRUK HAILESILASSIE Forschungsprojekt VSS 2006/515_OBF auf Antrag des Schweizerischen Verbandes der Strassen- und Verkehrsfachleute (VSS) Short-term blisters occur during placing of hot mastic asphalt and result from humid air trapped in the asphalt mix- ture. These blisters are often removed in practice by punching a steel stick into the blister of the mixture to release pressure. Since it is practically impos- sible to release all pressure by punch- ing through the blisters, some of the smaller blisters may get “frozen” dur- ing the cooling process and the trapped air may be the trigger for the formation of long term blisters that may gradually grow under service condition. This research work includes two parts; in the first part blister formation under the mastic asphalt layer is investigated alone. In the second part blister forma- tion under the water proofing mem- brane is studied. The primary objective of the first part of the study includes investigation of blister growth in the laboratory with finite element simulation focusing on blistering of mastic asphalt and first order shear deformation of thick plates. The time dependent vertical deflection in mastic asphalt blisters depends on three factors: material characterization of the model, temperature of the mastic asphalt at the time of loading and the rate at which the load is applied to the material. It was found that vertical de- flection of mastic asphalt is much more depending on the rate of the applied temperature than on the applied pres- sure. In the second part, the main objective was to investigate and model adhe- sive blister propagation between an orthotropic PBM and concrete. From this study it was found that the plane stress orthotropic property of the PBM material creates blister crack propa- gation with an elliptical propagation front other than in the general case of circular blister growth. Moreover the analytical blister propagation energy was compared with a standard peeling test method, as described in the Swiss standards, and the adhesive fracture en- ergy from literature. The result shows that by conducting the peeling test and uniaxial test, it is possible to interpret the peeling force in terms of peeling fracture energy of the PBM. Therefore taking in to account the correlation be- tween the fracture energy between the peeling and blister test, it is possible to use a peeling test as investigation method for blister propagation. ing from existing models and charac- terising indexes proper to good rocks. Thus, a specific classification system for highly fractured rock masses and fault zones has been developed with the aim of selecting representative parameters that should be considered in order to obtain a more complete geomechanical description of disturbed zones. Four “fault zone” classes have been identi- fied. Through data analyses, it has been possible to evaluate for each class a spe- cific reduction rate of TBM-performance parameters (i.e. penetration rate, cutter- head rotation speed and daily advance rate) with respect to the best tunnelling performance recorded in good ground conditions. The results of these analy- ses allow to effectively quantify the ef-ff fect of degrading rock mass conditions on the TBM advance (in terms of both penetration and daily advance rates). Moreover, these results have been used to carry out probabilistic analyses of the tunnel construction time and costs by means of the “Decision Aids for Tun- nelling” (DAT). The outcomes of those simulations give a reliable estimation of the effect of degrading geological con- ditions (from highly fractured rocks, to faulted and crushed material) on tunnel excavation. The results of this research may provide useful insights regarding the reduction of the machine performance that can take place in bad grounds, with respect to an estimated best performance in good tunnelling conditions.