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Abstract:	Im maschinellen Tunnelbau mit Schildvortrieben mit Erddruck- oder Flüssigkeitsstützung stellen die Verklebungen von Schneidrad und Abbaukammer sowie der Verschleiß der Schneidwerkzeuge nach wie vor ein Problem dar. Infolge Verklebungen kommt es trotz verschiedener Prognoseverfahren anhand der Plastizitäts- und Konsistenzzahl für weiche Böden noch immer zu erheblichen Behinderungen des Bauablaufs, weil Stillstände zur Reinigung von Schneidrad und Abbaukammer erforderlich werden. Neben der Verklebungsproblematik stellt auch die Abrasivität des Baugrunds häufig ein Problem dar, da bei stark abrasivem Gebirge häufige Werkzeugwechsel erforderlich sind. Eine korrekte Bewertung des Verklebungspotenzials wie auch der Abrasivität, insbesondere im Lockergestein und in Mischböden, stellt nach wie vor für Auftraggeber bei der Erstellung einer möglichst umfassenden Ausschreibung sowie auch für Auftragnehmer, die die Verklebungsneigung und Abrasivität möglichst zutreffend einkalkulieren müssen, eine schwierige Aufgabe dar. In diesem Beitrag wird ein neuartiger Modellschneidradversuchsstand vorgestellt, der im Gegensatz zu bestehenden Methoden die Interaktion der Faktoren Mensch, Maschine und Baugrund bei der Prognose von Verklebungs- und Verschleißproblemen für den mechanisierten Tunnelbau berücksichtigen soll. Evaluation of clogging and wear of tools in loose rock based on model tests. The occurrence of clogging of the cutting wheel and in the mixing chamber as well as the wear of cutting tools still represent a problem in mechanized tunneling with earth pressure balanced shield drives (EPB) and hydroshield drives. Despite different procedures for prognosis based on the plasticity and consistency indices, still massive delays of tunnel excavation occur due to clogging because interruptions are needed for cleaning of the cutting wheel and the mixing chamber. Besides the clogging problems, also abrasiveness of the subsoil frequently represents a problem, because strongly abrasive soil leads to the frequent need for changing the cutting tools. A correct assessment of clogging potential as well as of abrasiveness, especially in loose rock and mixed soils still represents a difficult task for the employer and his ideally all-embracing request for bids as well as for the contractor who has to consider the clogging potential and abrasiveness as exactly as possible in his offer. In this contribution, a new cutting wheel model test is presented, which is, in contrast to existing methods, supposed to consider the interaction of human influence, machine and subsoil in a harmonic way for the prognosis of clogging problems and problems of cutting tool wear in mechanized tunneling.
Source:	geotechnik 42 (2019), No. 2
Page/s:	59-75
Language of Publication:	German

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