Deformation of the foundation and structure of Tomioka Silk Mill’s East Cocoon Warehouse

Abstract

The East Cocoon Warehouse of the Tomioka Silk Mill was constructed in Japan in the Meiji era using technology introduced from abroad. Deformation of its foundation stones and the building as a whole was measured as part of a civil heritage geotechnical study. The maximum differential settlement among the 92 foundation stones of the warehouse spanning a total wall length of 233.4 m was 44 mm. The distance between the foundation stones of the eastern and western walls was 12.5 m, and the maximum differential settlement among the four foundation stones along the southern and northern walls was 13 and 19 mm, respectively. The measurement results indicate that the inclinations of the pillars were not influenced by changes in the elevation of the foundation stones or the presence of gaps in the continuous stone rows. The difference between the maximum and minimum elevations in the silk reeling mill was 33 mm for the 71 foundation stones along the total 325-m wall length. These results illustrate that the level of geotechnology at the beginning of the Meiji era was similar to that of recent technology, and the East Cocoon Warehouse has remained in its original state and location, standing on its simply and suitably built foundation for 145 years.