In tunnelling projects characterized by significant overburden and limited pre-excavation ground information, maximizing the utilization of geotechnical information acquired during the excavation process emerges crucial. Currently, construction is underway for a 25-kilometer-long tunnel as part of the Chuo Shinkansen, which traverses beneath the Akaishi Mountains in central Japan, reaching depths of up to 1400 meters. To effectively handle the diverse geological and groundwater conditions encountered, a specific excavation procedure has been implemented. This procedure combines the use of extra-long range controlled boring, reaching horizontally as far as 1000 meters, with displacement monitoring of the excavated tunnel. Thus far, this approach has proven effective in ensuring safe and rational excavation operations under high overburden conditions.

Specific storage Ss is an aquifer parameter that affects the transient behavior of groundwater within a saturated formation. In general, the evaluation of groundwater seepage flow under steadystate conditions is taken into account in engineering design, but with the popular of numerical analysis techniques, there are more and more opportunities to evaluate groundwater flow under transient conditions, and the use of Ss values is increasing. We can find some differences and errors of Ss values in references due to cancellation of significant digits, incorrectly transcribed, or incorrectly converted in the process of unit conversion. This report points out these problems and summarize corrected values of Ss.