Answers are grounded in this paper and cite their sources.
In planning the construction of a tunnel, a geological prognosis is necessary. The reliability of the prognosis is directly related to the amount of information available from surface geology, drillholes and geophysical surface investigations. During the excavation phase the tunnel engineer requires detailed and quantitative information about abrupt changes in rock quality and formation boundaries lying ahead, and these cannot always be obtained from surface investigations.
No takes yet. Share an insight, caveat, or question.
Sattel et al. (1992) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: