Weakness zones and faults are among the most important features in rock excavation. See the definitions for right understanding of these terms.
Weakness zones and faults are described in the Ph.D. thesis, Appendix 2.
See also the paper ‘The significance of weakness zones in rock tunnelling‘.
Weakness zones including fault zones have been responsible for many problems and collapses in rock tunnelling as described in the tab ‘Geological uncertainties‘.
More on weakness and fault zones is presented in the Rock Engineering book.