<p>Overbreak is a considerable cost factor in underground construction. In literature virtually no information is available relating rock mechanical parameters quantitatively to overbreak. During the construction (drilling, blasting&amp;mucking) of the Soumagne ...

<p>Principal geotechnical difficulties likely to be encountered when driving a tunnel through a fault zone are: instability of the face; excessive overbreak and deformation from squeezing and/or swelling fault rocks; instability of intermediate construction ...