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D. Adam, R. Markiewicz:
"Block-in-matrix structure - tunneling in hard soil and/or weak rock";
in: "Proceedings of the 15th European Conference on Soil Mechanics and Geotechnical Engineering", issued by: National Technical University of Athens; IOS Press, Amsterdam, 2011, (invited), ISBN: 978-1-60750-800-7, 1607 - 1614.

The city bypass tunnel of Waidhofen an der Ybbs (Austria) is situated in an intricate geological-geotechnical complex consisting
of soil, hard soil, weak rock and solid rock. Marls and marly limestone (Waidhofener formation) predominate followed by tectonic
breccia of the Alpine cliff zone, which is a tectonic melange zone. Materials of this kind universally have isolated interior
blocks (shaded areas) embedded in a matrix (blank area) called "block-in-matrix" requiring a particular characterization of the
mechanical rock mass properties. The complex geological and morphological situation required the application of various tunneling
methods including open cuts, cut-and-cover sections and the New Austrian Tunneling Method (NATM). During construction
in creeping slopes increased movements were triggered, which required the installation of a sophisticated monitoring system.
On the basis of monitoring data and additional ground investigations structural measures were assessed that enabled safe
tunneling in the creeping slope.

city bypass tunnel; weak rock; solid rock; New Austrian Tunneling Method (NATM);

http://publik.tuwien.ac.at/files/PubDat_199041.pdf