Table Japan 1
Tc and Soil classification

Soil type Ground characteristics Tc
Hard soil Ground consisting of rock, hard sandy gravel, etc. classified as Tertiary or older. 0.4
Medium soil Other than hard type or soft one. 0.6
Soft soil Alluvium consisting of soft delta deposits, topsoil, mud, or the like (including fills, if any), whose depth is 30 meters or more, land obtained by reclamation of a marsh, muddy sea bottom, etc., where the depth of the reclaimed ground is 3 meters or more and where 30 years have not yet elapsed since the time of reclamation. 0.8