In planning of Sekigahara tunnel, 2809m long and situated in a disturbed area of Palaeozoic rocks at the midst Of Nagoya and Kyoto, a series of careful investigation (including borings and seismic prospectings) was made adequately and construction schedule was based closely on geological considerations. Seeing back from the actual results of driving, many faults and breccia zones were forecasted properly, and except several small troubles due to swelling of clay in altered slate, almost all the works have successfully been completed to;the end of this year.
Various data, such as obtained values of seismic velocity, kind of rocks, both infered and encountered, and thickness of lining concrete planned and adopted, are summarized in Fig.2.